The distribution of tetrodotoxin (TTX)-sensitive and -insensitive Na+ currents and their modulation by serotonin (<em>5HT</em>) and prostaglandin E2 (PGE2) was studied in four different types of dorsal root ganglion (DRG) cell bodies (types 1, 2, 3, and 4), which were previously identified on the basis of differences in membrane properties (). Types 1 and 2 DRG cells expressed TTX-insensitive Na+ currents, whereas types 3 and 4 DRG cells exclusively expressed TTX-sensitive Na+ currents. Application of <em>5HT</em> (1-10 microM) increased TTX-insensitive Na+ currents in type 2 DRG cells but did not affect Na+ currents in type 1, 3, or 4 DRG cells. The <em>5HT</em> receptor involved resembled the <em>5HT</em>4 subtype. It was activated by 5-methoxy-N,N-dimethyltryptamine (10 microM) but not by 5-carboxyamidotryptamine (1 microM), (+)-8-hydroxydipropylaminotetralin (10 microM), or 2-methyl-<em>5HT</em> (10 microM), and was blocked by ICS 205-930 with an EC50 of approximately 2 microM but not by ketanserin (1 microM). PGE2 (4 or 10 microM) also increased Na+ currents in varying portions of cells in all four groups. The effect of <em>5HT</em> and PGE2 on Na+ currents was delayed for 20-30 sec after exposure to <em>5HT</em>, suggesting the involvement of a cytosolic diffusible component in the signaling pathway. The agonist-mediated increase in Na+ current, however, was not mimicked by 8-chlorophenylthio-cAMP (200 microM), suggesting the possibility that cAMP was not involved. The data suggest that the <em>5HT</em>- and PGE2-mediated increase in Na+ current may be involved in hyperesthesia in different but overlapping subpopulations of nociceptors.

The serotonin (5-hydroxytryptamine [<em>5HT</em>]) system has recently emerged as an important player in the appearance of l-3,4-dihydroxyphenylalanine (levodopa [l-dopa])-induced dyskinesia in animal models of Parkinson's disease. In fact, dopamine released as a false transmitter from serotonin neurons appears to contribute to the pulsatile stimulation of dopamine receptors, leading to the appearance of the abnormal involuntary movements. Thus, drugs able to dampen the activity of serotonin neurons hold promise for the treatment of dyskinesia. The authors investigated the ability of the mixed 5-HT 1A/1B receptor agonist eltoprazine to counteract l-dopa-induced dyskinesia in 6-hydroxydopamine-lesioned rats and in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated macaques. The data demonstrated that eltoprazine is extremely effective in suppressing dyskinesia in experimental models, although this effect was accompanied by a partial worsening of the therapeutic effect of l-dopa. Interestingly, eltoprazine was found to (synergistically) potentiate the antidyskinetic effect of amantadine. The current data indicated that eltoprazine is highly effective in counteracting dyskinesia in preclinical models. However, the partial worsening of the l-dopa effect observed after eltoprazine administration represents a concern; whether this side effect is due to a limitation of the animal models or to an intrinsic property of eltoprazine needs to be addressed in ongoing clinical trials. The data also suggest that the combination of low doses of eltoprazine with amantadine may represent a valid strategy to increase the antidyskinetic effect and reduce the eltoprazine-induced worsening of l-dopa therapeutic effects.

Serotonin (5-hydroxytryptamine, 5-HT) has been shown to play a role in immunoregulation; however, little is known about specific subtypes of 5-HT receptors involved in peripheral immunomodulation. In the present study we used RT-PCR methods to examine the mRNA expression of 5-HT receptors in the cells of lymphoid tissues of the rat. All 13 rat 5-HT receptor genes cloned so far were examined in ex vivo isolated spleen, thymus, and peripheral blood lymphocytes, as well as in mitogen-stimulated spleen cells. Positive signals were obtained for 5-HT1B, 5-HT1F, 5-HT2A, 5-HT2B, 5-HT6, and 5-HT7 receptor mRNAs in all three compartments. Mitogen (ConA and PWM) stimulated cells additionally expressed mRNA corresponding to the <em>5HT</em>-3 receptor subtype. In contrast, 5-HT1A, 5-HT1D, 5-HT2C, 5-HT4, 5-HT5A, and 5-HT5B mRNAs were not detected in any of the examined cell populations. These results may be useful as a starting point for future functional studies on immunomodulatory effects of 5-HT and may help to understand conflicting serotonergic effects on immune functions as found in the literature.

The effects of melatonin on proliferation and on the induction of melanogenesis in rodent melanoma cells were investigated. It was found that melatonin at low concentrations (0.1-10 nM) inhibited cell growth but had no effect on melanogenesis, while at high concentrations >> or = 0.1 microM) it inhibited the induction of melanogenesis but not cell growth. These effects were specific since corresponding concentrations of the direct precursor and product of melatonin degradation N-acetylserotonin (N-Ac-<em>5HT</em>) and 5-methoxytryptamine (5MT), respectively, did not have any effect on cell proliferation or melanogenesis. At very high concentration (100 microM) both N-Ac-<em>5HT</em> and melatonin could stimulate melanoma proliferation while 5MT inhibited it. The demonstration of differential and unparalleled effects of melatonin on cell proliferation and melanogenesis suggests that melatonin can regulate or modify both processes via different mechanisms.

The neurotransmitter, serotonin (5-hydroxytryptamine, <em>5HT</em>), has been shown to affect function of cells of the immune system. More recently, specific <em>5HT</em> receptors have been identified and partially characterized on Jurkat cells. Results presented here characterize the receptor on Jurkat cells as the <em>5HT</em>1a receptor subtype and show that mitogen-activated but not resting human T cells also express the <em>5HT</em>1a receptor subtype. Analysis of mRNA in Jurkat cells and activated and resting T cells by PCR or by Northern analysis revealed the presence of <em>5HT</em>1a receptor. Pharmacologic analysis of this receptor demonstrated that the receptors on Jurkat cells and activated T cells are similar to each other and that they resemble the <em>5HT</em>1a receptor found in the brain. Analysis of the second messenger pathways activated by the <em>5HT</em>1a receptor show that ligand-binding to the Jurkat cell <em>5HT</em>1a receptor results in elevation of intracellular inositol phosphates and Ca2+ and that ligand binding to the <em>5HT</em>1a receptor on activated T cells modulated intracellular levels of cAMP.

We report here on the isolation and characterization of a serotonin (<em>5HT</em>) transporter from Drosophila melanogaster. A 3.1-kb complementary DNA clone (dSERT) was found to encode a protein of 622 amino acid residues with a predicted molecular mass of approximately 69 kDa and a putative transmembrane topology characteristic of cloned members of the mammalian Na+/Cl- neurotransmitter cotransporter gene family. dSERT displays highest overall amino acid sequence identity with the mammalian <em>5HT</em> (51%), norepinephrine (47%), and dopamine (47%) transporters and shares with all transporters 104 absolutely conserved amino acid residues. Upon transient expression in HeLa cells, dSERT exhibited saturable, high-affinity, and sodium-dependent [3H]<em>5HT</em> uptake with estimated Km and Vmax values of approximately 500 nM and 5.2 x 10(-18) mol per cell per min, respectively. In marked contrast to the human SERT (hSERT), <em>5HT</em>-mediated transport by dSERT was not absolutely dependent on extracellular Cl-, while the sodium-dependent uptake of <em>5HT</em> was facilitated by increased extracellular Cl- concentrations. dSERT displays a pharmacological profile and rank order of potency consistent with, but not identical to, mammalian <em>5HT</em> transporters. Comparison of the affinities of various compounds for the inhibition of <em>5HT</em> transport by both dSERT and hSERT revealed that antidepressants were 3- to 300-fold less potent on dSERT than on hSERT, while mazindol displayed approximately 30-fold greater potency for dSERT. Both cocaine and RTI-55 inhibited <em>5HT</em> uptake by dSERT with estimated inhibition constants of approximately 500 nM, while high concentrations >> 10 microM) of dopamine, norepinephrine, octopamine, tyramine, and histamine failed to inhibit transport. In situ hybridization reveals the selective expression of dSERT mRNA to specific cell bodies in the ventral ganglion of the embryonic and larval Drosophila nervous system with a distribution pattern virtually identical to that of <em>5HT</em>-containing neurons. The dSERT gene was mapped to position 60C on chromosome 2. The availability of the gene encoding the unique ion dependence and pharmacological characteristics of dSERT may allow for identification of those amino acid residues and structural motifs that confer the pharmacologic specificity and genetic regulation of the <em>5HT</em> transport process.

The olfactory bulb, first relay of olfactory pathways, is densely innervated by serotoninergic centrifugal fibers originating from the raphe nuclei. Although serotonin innervation was reported to be involved in olfactory learning in mammals, the action of this neurotransmitter on its putative cellular targets has been never described through unitary recordings. This lack of data initiated the present study where the effects of <em>5HT</em> on juxtaglomerular and mitral cells are analyzed using whole-cell recordings on olfactory bulb slices. Serotonin depolarizes 34% of 525 JG cells. A multivariate statistical analysis of juxtaglomerular cells characteristics shows that the serotonin responsive cell group can be individualized regarding their tonic discharge-mode in response to a direct current injection, their lower expression of hyperpolarization-activated cation current and their low membrane capacities. The use of ion channel blockers and ramp voltage protocol indicate that serotoninergic depolarization of juxtaglomerular cells may be due to a nonselective cation current with a reversal potential of -44 mV. Pharmacological tests with serotonin receptor antagonists and agonists reveal that <em>5HT</em> action on juxtaglomerular cells would be mainly mediated by <em>5HT</em>2C receptors. In mitral cells, serotonin acts on 49.1% of the 242 tested cells, inducing two types of responses. A first subset of mitral cells (26.8%, n=65) were hyperpolarized by serotonin. This response would be indirect and mediated by action of GABA on GABAA receptors since it was antagonized by bicuculline. The involved GABAergic neurons are hypothesized to be juxtaglomerular and granular cells, on which serotonin would act mainly via <em>5HT</em>2C and via <em>5HT</em>2A receptors respectively. The second subset of mitral cells (22.3%, n=54) were directly depolarized by serotonin acting through <em>5HT</em>2A receptors. Our data on serotonin action on juxtaglomerular cells and mitral cells reveal a part of functional mechanisms whereby serotonin can act on olfactory bulb network. This is expected to enrich the understanding of its determining role in olfactory learning.

Migraine headache involves the activation of trigeminal afferents that are predominantly found in the first or ophthalmic division of the nerve. The headache is often pounding and the connections of the trigeminal nerve, the trigeminovascular system, have therefore been implicated in the pathophysiology of migraine and studied extensively. Considerable attention has been given to the peripheral ramifications of the system as a possible locus of action for anti-migraine drugs while little attention has been focused upon possible central sites of action. It has been shown that certain peptides can act as markers for the trigeminal system, in particular calcitonin gene-related peptide (CGRP), and that CGRP is elevated in migraine. We have employed an animal model for activation of the trigeminovascular system to evaluate a new antimigraine compound, 311C90, that may have central and as well as peripheral trigeminal actions. Cats were anesthetized by halothane induction and alpha-chloralose maintenance (60 mg/kg, intraperitoneal), intubated, paralyzed and ventilated. Biparietal craniotomies were carried out to measure cerebral blood flow using laser Doppler flowmetry (CBFLDF). The external jugular vein was cannulated and blood drawn, centrifuged and frozen until processing. Stimulation of the trigeminal ganglion resulted in a mean maximum increase in CBFLDF of 39 +/- 5% at 20/s. The 5HT1 agonist 311C90 was administered intravenously in two doses (30 and 100 micrograms/kg) to cover the range of doses likely to be effective clinically. At each dose the CBFLDF effect of trigeminal ganglion stimulation was inhibited.(ABSTRACT TRUNCATED AT 250 WORDS)

Descending projections arising from brainstem serotonergic (<em>5HT</em>) neurons contribute to both facilitatory and inhibitory controls of spinal cord "pain" transmission neurons. Unclear, however, are the brainstem networks that influence the output of these <em>5HT</em> neurons. To address this question, here we used a novel neuroanatomical tracing method in a transgenic line of mice in which Cre recombinase is selectively expressed in <em>5HT</em> neurons (ePet-Cre mice). Specifically, we injected the conditional pseudorabies virus recombinant (BA2001) that can replicate only in Cre-expressing neurons. Because BA2001 transports exclusively in a retrograde manner, we were able to reveal a subset of the neurons and circuits that are located upstream of the Cre-expressing <em>5HT</em> neurons. We show that diverse brainstem regions differentially target the <em>5HT</em> neurons of the dorsal raphe (DR) and the nucleus raphe magnus of the rostroventral medulla (RVM). Among these are several catecholaminergic and cholinergic cell groups, the periaqueductal gray, several brainstem reticular nuclei, and the nucleus of the solitary tract. We conclude that a brainstem <em>5HT</em> network integrates somatic and visceral inputs arising from various areas of the body. We also identified a circuit that arises from projection neurons of deep spinal cord laminae V-VIII and targets the <em>5HT</em> neurons of the NRM, but not of the DR. This spinoreticular pathway constitutes an anatomical substrate through which a noxious stimulus can activate <em>5HT</em> neurons of the NRM and in turn could trigger descending serotonergic antinociceptive controls.

The diagnosis, treatment, and pathophysiology of obsessive-compulsive disorder (OCD) were examined in a series of studies utilizing psychobiological approaches. Putative biological markers previously reported in depression were studied in this disorder and revealed that on some measures [Dexamethasone Suppression Test and rapid eye movement (REM) latency on sleep electroencephalogram (EEG)], OCD patients resemble those with major depressive disorder (MDD), whereas on others [REM density, platelet serotonin uptake, probably platelet 3H-imipramine binding, and 5-hydroxy-indoleacetic acid (5-HIAA) in cerebral spinal fluid (CSF)] they do not. The relationship between OCD and MDD was further explored in a double-blind, randomized crossover study designed to compare the antiobsessional effects of two tricyclic antidepressants, clomipramine (CMI) and desipramine (DMI), in a nondepressed cohort of OCD patients. CMI was found to have significant antiobsessional effects in this group, whereas in the same patients, DMI lacked therapeutic effects. These results suggest that not all antidepressants are antiobsessive and that some property of CMI, such as its potent serotonergic effects, may be of pathophysiological relevance for OCD. The role of serotonin in this disorder was then tested using the pharmacological challenge strategy. A novel serotonin postsynaptic receptor (<em>5HT</em>-1) agonist, m-chlorophenylpiperazine (m-CPP), was administered orally (0.5 mg/kg) under double-blind, placebo-controlled conditions to OCD patients and controls. In addition, a serotonergic receptor antagonist, metergoline (4 mg), was given to a subset of OCD patients. Relative to healthy volunteers, the OCD patients became significantly more anxious, depressed, and dysphoric after m-CPP administration. Moreover, in the OCD patients, obsessive-compulsive symptoms increased markedly after m-CPP and decreased significantly following metergoline administration. These results demonstrate that agents that bind to the <em>5HT</em>-1 receptor can acutely affect the symptoms of OCD patients. The striking behavioral effects of these direct postsynaptic receptor ligands and the relative specificity of clomipramine as an antiobsessional agent suggest that serotonergic neurons may play a role in the pathophysiology, as well as mediating the pharmacological reduction, of obsessional symptoms.

The molecular mechanisms of nicotinic receptor activation are still largely unknown. The crystallographic structure of the acetylcholine binding protein (AChBP) reveals a single H-bond between two different acetylcholine binding loops. Within these homologous loops we systematically introduced alpha4 residues into the alpha7/<em>5HT</em>(3) chimeric receptor and found that the single point mutations G152K (loop B) and P193I (loop C) displayed a non-additive increase of equilibrium binding affinity for several agonists compared with the double mutant G152K/P193I. In whole-cell patch-clamp recordings, G152K, P193I and G152K/P193I mutants displayed an increase up to 5-fold in acetylcholine potency with a large decrease of the apparent Hill coefficients (significantly smaller than one). Concomitantly, the G152K/P193I mutant showed a dramatic loss of high-affinity alpha-bungarotoxin binding (100-fold decrease), thus pinpointing a new contact area for the toxin. Fitting the data with an allosteric-kinetic model, together with molecular dynamic simulations, suggests that the presence of the inter-backbone H-bond between positions 152 and 193, revealed in alpha4 and in alpha7 double mutant but not in alpha7, coincides with a large stabilization of both open and desensitized states of nicotinic receptors.

We studied the functional role and modulation of the hyperpolarization-activated inward current (I(h)) in the pyloric network of the lobster stomatogastric ganglion. In isolated neurons, I(h) is a small current with a hyperpolarized voltage of half-activation (V(Act)) and a slow time constant of activation (tau(Act)). Bath application of dopamine (DA), octopamine (OCT), or serotonin (<em>5HT</em>) modified I(h) in selected synaptically isolated pyloric neurons. DA significantly enhanced I(h) in the anterior burster (AB) neuron by depolarizing its V(Act), accelerating its tau(Act), and enhancing its maximal conductance (g(max)). DA more weakly enhanced I(h) in the pyloric constrictor (PY) and ventricular dilator (VD) neurons. OCT weakly depolarized V(Act) and accelerated tau(Act) in the VD and inferior cardiac (IC) neurons. <em>5HT</em> depolarized V(Act) in the IC neuron. Under control conditions with intact modulatory inputs from other ganglia, the pyloric rhythm cycles strongly at about 1-2 Hz. Bath application of the I(h) blocker cesium (Cs(+)) caused a mean increase in the period of 8%, although this effect was highly variable. When Cs(+) was applied to an isolated ganglion where the pyloric rhythm had been activated only by DA, the cycle period was consistently increased by 13.5%, with no other strong changes in rhythm parameters. These results suggest that I(h) regulates the pyloric rhythm by accelerating AB pacemaker frequency, but that this effect can vary with the modulatory conditions.

Experimental evidence suggests that serotonin (<em>5HT</em>) is excitatory to the hypothalamic-pituitary-adrenal axis and that this effect involves activation of both hypothalamic corticotropin-releasing hormone (CRH) and pituitary ACTH secretion. The present study was undertaken to examine the mechanism by which <em>5HT</em> stimulates the central component of the HPA axis. To accomplish this we employed an in vitro rat hypothalamic organ culture system in which CRH secretion from single explanted hypothalami was measured by specific radioimmunoassay (IR-rCRH). All experiments were performed after an overnight (15-18 hr) preincubation. Serotonin stimulated IR-rCRH secretion in a dose-dependent fashion. The response was bell-shaped and the peak effect was observed at the concentration of 10(-9) M. The stimulatory effect of 10(-9) M <em>5HT</em> was antagonized by the <em>5HT</em>1 and <em>5HT</em>2 receptor metergoline and by the selective <em>5HT</em>2 receptor antagonists ketanserin and ritanserin. The muscarinic antagonist atropine, the nicotinic antagonist hexamethonium and the alpha-adrenergic receptor antagonist phentolamine, on the other hand, did not inhibit <em>5HT</em>-induced IR-rCRH secretion. The specific <em>5HT</em>2 receptor agonist 1-(2,5-dimethoxy-4-iodo-phenyl)-2-aminopropane (DOI) stimulated IR-rCRH secretion in a dose-dependent fashion. The response was bell-shaped with peak of effect reached at the concentration of 10(-9) M. We also tested the ability of the <em>5HT</em> agonist meta-chlorophenylpiperazine (m-CPP) and of the selective <em>5HT</em>1A receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) to cause CRH secretion. Although both m-CPP and 8-OH-DPAT stimulated IR-rCRH secretion in a dose-dependent fashion, several differences were observed when their effect was compared to that of <em>5HT</em>. These included a different shape of the dose-response curve, a lower maximal stimulatory effect and a different maximal stimulatory concentration. These findings suggest that serotonin stimulates CRH secretion by explanted rat hypothalami and that this effect appears to be mediated mainly through a <em>5HT</em>2 receptor mechanism.

The recent completion of the human genome predicted the presence of only 30,000 genes, stressing the importance of mechanisms that increase molecular diversity at the post-transcriptional level. One such post-transcriptional event is RNA editing, which generates multiple protein isoforms from a single gene, often with profound functional consequences. The human serotonin 5-HT(2C) receptor undergoes RNA editing that creates multiple receptor isoforms. One consequence of RNA editing of cell surface receptors may be to alter the pattern of activation of heterotrimeric G-proteins and thereby shift preferred intracellular signaling pathways. We examined the ability of the nonedited 5-HT(2C) receptor isoform (INI) and two extensively edited isoforms, VSV and VGV, to interact with various G-protein alpha subunits. Two functional assays were utilized: the cell-based functional assay, Receptor Selection/Amplification Technology(TM), in which the pharmacological consequences of co-expression of <em>5HT</em>(2C) receptor isoforms with G-protein alpha subunits in fibroblasts were studied, and <em>5HT</em>(2C) receptor-mediated rearrangements of the actin cytoskeleton in stable cell lines. These studies revealed that the nonedited 5-HT(2C) receptor functionally couples to G(q) and G(13). In contrast, coupling to G(13) was not detected for the extensively edited 5-HT(2C) receptors. Thus, RNA editing represents a novel mechanism for regulating the pattern of activation of heterotrimeric G-proteins, molecular switches that control an enormous variety of biological processes.

Progesterone increases prolactin secretion in estrogen-primed primates. This action is probably mediated through a neural mechanism since lactotropes do not have progestin receptors (PR). This laboratory recently reported localization of PR in serotonin neurons of female macaques. Since serotonin (<em>5HT</em>) is a putative prolactin stimulatory agent, it was of interest to examine the regulation of PR in this neural system. Spayed monkeys were treated with either (1) an empty silastic capsule; (2) an estrogen (E)-filled capsule for 28 days, or (3) an E-filled capsule for 28 days supplemented with a progesterone (P)-filled capsule for the last 14 of the 28 days. Pontine tissue blocks were obtained at autopsy and processed for immunocytochemistry. Adjacent sections (10 microns) throughout the extent of the raphe nuclei were immunostained for <em>5HT</em> and PR. <em>5HT</em>-positive and PR-positive cells were counted in the same area of the dorsal and ventral raphe of adjacent sections at 4 representative levels and the PR/<em>5HT</em> ratio was calculated. The number of <em>5HT</em>-positive cells was not different in spayed, E- or E+P-treated groups. E-treatment significantly increased the number of PR-positive cells and the PR/<em>5HT</em> ratio in the dorsal and ventral raphe. Supplementary P treatment did not significantly decrease the PR/<em>5HT</em> ratio in these areas. This data suggests that E induces PR in the <em>5HT</em> neuronal system and that the expression of PR is maintained in the presence of chronically elevated progestin. Thus, the expression of PR in the raphe is consistent with the manner in which P increases prolactin secretion in estrogen-primed primates.

A method for washing platelets by albumin density gradient separation, originally designed for the study of platelet coagulant activities, has been modified for platelet aggregation and metabolic studies. Platelets are sedimented into a continuous density gradient of isosmolar albumin containing apyrase to protect them from clumping and physical injury and are resuspended in calcium-free Tyrode's solution. The mean recovery of platelets after two separations relative to platelet-rich plasma (PRP) was 90.3%. When small amounts of plasma were added to washed platelet suspensions, aggregation and release of [14C]5-hydroxytryptamine (<em>5HT</em>) in response to adenosine diphosphate (adp) or <em>5HT</em> were similar to results obtained with PRP. When fibrinogen was substituted for plasma, ADP-induced aggregation occurred but was feeble. Without added plasma or fibrinogen, platelets were refractory to ADP and insensitive to the cyclic endoperoxide analogue U44619. When both ADP and U44619 were added simultaneously, in low concentrations, to washed platelets without added plasma or fibrinogen, aggregation occurred immediately. Washed platelets were not aggregated by adrenaline, which potentiated ADP-induced aggregation. Several biochemical measurements which are sensitive indicators of cellular damage were normal in washed platelets, including [14C]adenine uptake, adenylate energy charge, hypoxanthine formation and the response of adenylate cyclase to stimulation by PGE1 or PGD2. Platelet coagulant activities were not made available and heparin-neutralizing activity (HNA) was not spontaneously released by the washing procedure, but the washed platelets responded normally to appropriate agents by developing coagulant activities and releasing HNA. The ultrastructure of washed platelets was similar to those in control PRP. Inclusion of apyrase in the first albumin gradient had a beneficial effect on platelet morphology, aggregation and metabolism, but washing at 37degreesC compared with 25degreesC did not. Albumin density gradient separation is a useful method for isolating platelets for aggregation and metabolic studies.

The cholinergic and monoaminergic innervation of the lateral geniculate nucleus (GL) and other thalamic nuclei in the cat was examined by using immunocytochemical and tract-tracing techniques. Cholinergic fibers, identified with an antibody to choline acetyltransferase (ChAT), are present in all layers of the GL. They are fine in caliber and exhibit numerous swellings along their lengths. The A layers, the magnocellular C layer, and the medial interlaminar nucleus are rich in cholinergic fibers that give rise to prominent clusters of boutons, while the parvicellular C layers contain fewer fibers that are more uniformly distributed. The interlaminar zones are largely devoid of ChAT-immunoreactive fibers. Double-label experiments show that cholinergic projections to the GL originate from two sources, the pedunculopontine reticular formation (PPT) and the parabigeminal nucleus (Pbg). The PPT contributes cholinergic fibers to all layers, while Pbg projections are limited to the parvicellular C layers. The lateral geniculate nucleus has a much greater density of cholinergic fibers than the other principal sensory nuclei: the density of fibers in the A layers is more than three times greater than that in the ventral posterior nucleus (VP) or the ventral division of the medial geniculate nucleus (GMv). In contrast, serotonin (5-HT)-immunoreactive fibers are distributed with equal density across the principal thalamic nuclei, while tyrosine hydroxylase (TH)-immunoreactive fibers (presumed to contain norepinephrine) are noticeably less dense in the GL than in the others. Monoaminergic fibers also differ from cholinergic fibers in their laminar distribution within the GL: both TH- and <em>5HT</em>-immunoreactive fibers are distributed evenly across the layers and interlaminar zones and are slightly more abundant in the parvicellular C layers than in the other layers. Other thalamic nuclei rich in cholinergic fibers include the pulvinar nucleus, the ventral lateral geniculate nucleus, the intermediate nucleus of the lateral group, the lateral medial and suprageniculate nuclei (Graybiel and Berson: Neuroscience 5:1175-1238, '80), and the paracentral and central-lateral components of the intralaminar nuclei. This pattern matches the distribution of projections from the PPT and is similar, but not identical, to the pattern of acetylcholinesterase staining. The fact that most of the nuclei rich in cholinergic fibers have been implicated in visual sensory or visual motor functions suggests that cholinergic projections from the reticular formation play an especially important role in visually guided behavior.

Alterations of <em>5HT</em> and its chief metabolite 5HIAA were studied in four regions of the rat brain following acute 1-h swim exercise and 4 week chronic swim exercise (30 min/day, 6 days per week). Acute exercise significantly increased the synthesis and metabolism of <em>5HT</em> in brain stem. Hypothalamus also showed increased levels of <em>5HT</em>. However, no changes were observed in the cerebral cortex and hippocampus. Chronic exercise activated not only the synthesis but also the metabolism of <em>5HT</em> in the cerebral cortex; this neuronal adaptation was sustained even 1 week after the termination of training. In brain stem, increased <em>5HT</em> turnover was observed immediately after training. In hypothalamus, decrease in <em>5HT</em> and 5HIAA levels occurred immediately after training, followed by a rebound increase in their levels after 1 week posttraining rest. In hippocampus, a delayed effect was observed, because <em>5HT</em> level was unaltered immediately after the training, but its turnover decreased after 1 week rest. These findings have been discussed in an attempt to explain the antidepressant effect of exercise based on the <em>5HT</em> deficiency theory of endogenous depression.

Cognitive dysfunction in schizophrenia differs from cognitive dysfunction in neurodegenerative illnesses because it is associated with neuronal dysfunction and not neurodegeneration. Pharmacologically, potential targets for developing treatments may differ from cognition in dementing disorders. Several putative molecular targets for treating cognition in schizophrenia show promise, such as treatments that act on the D(1) receptor of the dopamine system; the <em>5HT</em>(1A), <em>5HT</em>(2A), and <em>5HT</em>(6), receptors of the serotonin system; and ampakines, Glycine/D-cycloserine, D-serine, and mGluR 2/3 agonists of the glutamatergic system. Other receptors associated with improvement in cognition include nicotinic and muscarinic receptors, and the alphalpha2 subunit receptor of the brain GABA system. Domain treatment of schizophrenia is a new method of treating schizophrenia that involves treating a single domain of dysfunction at a time.

Fourteen substances from the class of drugs sometimes known as "legal highs" were screened against a battery of human receptors in binding assays, and their potencies as inhibitors of monoamine uptake determined in functional in vitro assays. Thirteen of the test substances acted as inhibitors of monoamine uptake at submicromolar concentrations, including 9 potent inhibitors of the dopamine transporter (DAT), 12 potent inhibitors of the norepinephrine transporter (NET) and 4 potent inhibitors of the serotonin transporter (SERT). Seven compounds acted as submicromolar inhibitors of both DAT and NET, and three substances 1-(benzofuran-5-yl)propan-2-amine (5-APB), 1-naphthalen-2-yl-2-pyrrolidin-1-ylpentan-1-one hydrochloride ("naphyrone") and 1-naphthalen-1-yl-2-pyrrolidin-1-ylpentan-1-one hydrochloride ("1-naphyrone") were submicromolar inhibitors of all three monoamine transporters. There was a lack of correlation between results of functional uptake experiments and in vitro binding assays for the monoamine transporters. There was also no correlation between the human behavioral effects of the substances and the results of bindings assays for a range of receptor targets, although 1-(benzofuran-5-yl)propan-2-amine (5-APB), 1-(benzofuran-6-yl)propan-2-amine hydrochloride (6-APB) and 5-iodo-2,3-dihydro-1H-inden-2-amine hydrochloride (5-iodo-aminoindane) exhibited <100 nM affinities for <em>5HT</em>(2B) and α(2C) receptors. Functional assays revealed that 5-APB and 6-APB were potent full agonists at <em>5HT</em>(2B) receptors.

This study is part of the NIH "Facilities of Research-Spinal Cord Injury" contract to support independent replication of published studies. We repeated a study reporting that delayed transplantation of olfactory lamina propria (OLP) into the site of a complete spinal cord transection led to significant improvement in hindlimb motor function and induced axon regeneration. Adult female rats received complete spinal cord transections at T10. Thirty days post-injury, pieces of OLP, which contains olfactory ensheathing cells (OECs), or respiratory lamina propria (RLP), which should not contain OECs, were placed into the transection site. Hindlimb motor function was tested using the BBB scale from day 1 post-injury through 10 weeks following transplantation. To assess axonal regeneration across the transection site, Fluorogold was injected into the distal segment, and the distribution of <em>5HT</em>-containing axons was assessed using immunostaining. BBB analyses revealed no significant recovery after OLP transplantation and no significant differences between OLP vs. RLP transplant groups. Fluorogold injections into caudal segments did not lead to retrograde labeling in any animals. Immunostaining for <em>5HT</em> revealed that a few <em>5HT</em>-labeled axons extended into both RLP and OLP transplants and a few <em>5HT</em>-labeled axons were present in sections caudal to the injury in 2 animals that received OLP transplants and 1 animal that received RLP transplants. Our results indicate that, although OLP transplants may stimulate regeneration under some circumstances, the effect is not so robust as to reliably overcome the hostile setting created by a complete transection paradigm.

An immunohistochemically derived morphological description of a diverse population of rat lamina VII and X intraspinal <em>5HT</em> neurons is provided. These bipolar or multipolar neurons occur most frequently in lamina X, dorsal or dorsolateral to the central canal, in thoracolumbar, sacral, and coccygeal spinal segments. These <em>5HT</em> intraspinal neurons are found in normal rat spinal cords as well as in spinal cords that have been hemisected or transected 60 days prior to serotonin immunostaining. Therefore, <em>5HT</em> intraspinal neurons are the probable source of the biochemically detectable <em>5HT</em> that remains in the spinal cord distal to a spinal transection. In the rat, serotonin intraspinal neurons are most often associated with spinal autonomic nuclei but it is unknown if they are preganglionic in nature.

Hyperserotonemia is the most consistent serotonin-related finding in autism. The basis of this phenomenon, and its relationship to the central serotonergic dysfunction remains unclear. Platelet serotonin level (PSL) in 53 autistic adults and 45 healthy controls was measured. Mean PSL in autistic group (75.7 +/- 37.4 ng/microL) was significantly higher than the control sample (59.2 +/- 16.2 ng/microL) due to a presence of hyperserotonemic subjects which comprised 32% of the patients. PSL of autistic subjects did not correlate with the severity of symptoms, as measured by total CARS score, or the degree of mental retardation. However, significant negative relationship was observed between PSL and speech development, indicating the relationship between the peripheral <em>5HT</em> concentrations and verbal abilities in autistic subjects.

Stimulation of a restricted area of the rat's hypothalamus elicits unprovoked violent attacks of a species-specific and strain-specific nature. Serotonergic drugs affecting <em>5HT</em>1 receptors, propranolol, the <em>5HT</em> re-uptake inhibitor fluvoxamine, and the anxiolytic oxazepam, inhibit hypothalamic attack selectively. However, hypothalamic attack is extremely unsensitive for many drugs that do affect attack provoked by natural stimuli. The pharmacology, the form, the impulsive nature, the absence of preliminaries, the insensitivity for contexts and ultimate aims of aggressive behaviour, suggest that a mechanism with the limited function of damaging adversaries of any kind is activated in the hypothalamus. This hypothalamic attack release mechanism (harm) requires specific sensory input for the expression of specific motor components, such as biting and kicking. The back and dorsal part of the opponent's head are the important attack releasing and directing stimuli. Attacks of this nature are part of the "aggressive" repertoire of the rat in natural settings. "Lateral" or "sideways" postures, specific for intermale fighting cannot be induced by hypothalamic stimulation. Drug, lesion, and stimulation studies suggest that attack and "sideways" postures are under the control of different central mechanisms. These results suggest new ways to describe the patterning of aggressive behaviour. There are interesting ethopharmacological similarities between hypothalamic responses and obsessive compulsive disorders (OCD) in man. It is suggested that further study of the ethopharmacology of hypothalamic responses may shed light on the pathophysiology of impulsive behavioural symptoms which in man seem to be beyond the control of appraisal or context.