5-Hydroxytryptamine (<em>5HT</em>) levels were measured in blood and tissues from pregnant mice. Blood levels remained constant during pregnancy and were the same as those in nonpregnant female mice. Placental levels of <em>5HT</em> increased throughout pregnancy as did the foetal levels. The maternal blood volume of the placenta also increased with advancing gestation. <em>5HT</em> levels were measured after treatment of the mother with <em>5HT</em>, and the critical placental level of <em>5HT</em> observed at about the time of death of the foetus was determined. The levels of <em>5HT</em> in the placenta and foetus after treatment of the mother with several monoamine oxidase inhibitors were measured, and found to show no significant increase above the normal levels in these tissues. Treatment with cyproheptadine, a <em>5HT</em> antagonist, did not delay parturition.

Ethanol (EtOH) and cocaine are both self-administered into the posterior ventral tegmental area (VTA). Self-administration of either drug is prevented by coadministration of a serotonin (5-HT₃) receptor antagonist. Electrophysiological studies indicated that cocaine and EtOH can act synergistically to stimulate VTA dopamine neurons. The current experiment assessed whether cocaine and EtOH would synergistically interact to produce a reinforcing action within the posterior VTA. Adult female Wistar rats were randomly assigned to one of 13 groups. There were three control groups: artificial cerebrospinal fluid (aCSF), a subthreshold EtOH (100 mg%) group, and a subthreshold cocaine (25 pmol/100 nl) group. The other groups self-administered 50 or 75 mg% EtOH containing 6.25, 12.5, or 25 pmol/100 nl cocaine or 100 mg% EtOH containing 3.12, 6.25, 12.5, or 25 pmol/100 nl cocaine. All rats received the assigned infusate for sessions 1 through 4, aCSF alone in sessions 5 and 6, and the original infusate during session 7. The effects of adding a 5-HT₃ receptor antagonist [tropisetron, C₁₇H₂₀N₂O₂ (ICS 205,930) and C₁₇H₂₂N₄O.C₄H₄O₄ (LY278-584)] on coadministration of EtOH and cocaine (75 mg% + 12.5 pmol/100 nl) were determined. Rats failed to self-administer aCSF or the subthreshold concentration of EtOH or cocaine. All three concentrations of EtOH (50, 75, and 100 mg%) combined with cocaine (12.5 and 25 pmol/100 nl) supported self-administration. Adding a <em>5HT</em>₃ receptor antagonist attenuated coadministration of EtOH + cocaine. Overall, the data indicate that the reinforcing properties of EtOH and cocaine interacted synergistically within the posterior VTA, and these synergistic effects were mediated, at least in part, by activation of local 5-HT₃ receptors.

The behavioral effects of GBR 12909, a selective dopamine uptake inhibitor, were determined in squirrel monkeys trained to respond under a fixed-interval (FI) schedule of stimulus termination and a second-order schedule of IV drug self-administration. Intermediate doses of GBR 12909 increased FI response rate markedly, and the highest dose decreased response rate below control values. The <em>5HT</em> uptake inhibitors, alaproclate and fluoxetine, and the <em>5HT</em> agonist, quipazine, attenuated the behavioral-stimulant effects of GBR 12909, whereas the <em>5HT</em>2A/2C antagonist, ritanserin, enhanced the behavioral-stimulant effects of the lowest dose. GBR 12909 reliably maintained self-administration, and ritanserin increased response rate maintained by the highest dose. The dopamine agonist, quinpirole, increased FI response rate in only one of three subjects, and ritanserin enhanced the behavioral-stimulant effects of quinpirole in that subject. The dopamine agonist, apomorphine, only decreased FI response rate, and ritanserin did not alter its behavioral effects. The pharmacological profile of GBR 12909 administered alone and in combination with selective <em>5HT</em> drugs in the present study was similar to that obtained previously with cocaine, further demonstrating that <em>5HT</em> can reliably modulate the behavioral effects of psychomotor stimulants with prominent dopaminergic actions.

Chronic depressive illness may cause shrinkage of the hippocampus with stress-induced release of glutamate and nitric oxide possibly causally linked to this pathology. Poor antidepressant compliance may contribute to this pathology as well as to long term morbidity. However, antidepressant withdrawal-associated symptoms in depressed patients often reflect hyperserotonergia. The effect of chronic imipramine (IMI; 15 mg/kg/d ip x 3wks) treatment and withdrawal on swim stress responsiveness was studied in Sprague-Dawley rats together with assay of hippocampal NO synthase (NOS) activity. The dependence of any biobehavioral changes following IMI withdrawal on <em>5HT</em>(2A/C) receptor-mediated events was studied using the <em>5HT</em>(2A/C) receptor antagonist, ritanserin (RIT; 4 mg/kg/day ip x 7 days), administered alone or during IMI withdrawal. IMI significantly inhibited the situational stress response to forced swimming while also significantly decreasing NOS activity. IMI withdrawal was associated with a significant increase in swim immobility together with a significant increase in NOS activity compared to both control and IMI-treated groups. RIT re-established the anti-immobility effects and reversed NOS hyper-function during IMI withdrawal, although alone it increased NOS activity. Antidepressant discontinuation therefore increases stress responsiveness together with disinhibition of hippocampal NOS through a mechanism involving <em>5HT</em>(2A/C) receptor activation. The resulting increased nitrergic activity may have significant implications for depressive illness and its treatment.

Reductions in function within the serotonin (<em>5HT</em>) neuronal system have long been proposed as etiological factors in depression. Selective serotonin reuptake inhibitors (SSRIs) are the most common treatment for depression, and their therapeutic effect is generally attributed to their ability to increase the synaptic levels of <em>5HT</em>. Tryptophan hydroxylase 2 (TPH2) is the initial and rate-limiting enzyme in the biosynthetic pathway of <em>5HT</em> in the CNS, and losses in its catalytic activity lead to reductions in <em>5HT</em> production and release. The time differential between the onset of <em>5HT</em> reuptake inhibition by SSRIs (minutes) and onset of their antidepressant efficacy (weeks to months), when considered with their overall poor therapeutic effectiveness, has cast some doubt on the role of <em>5HT</em> in depression. Mice lacking the gene for TPH2 are genetically depleted of brain <em>5HT</em> and were tested for a depression-like behavioral phenotype using a battery of valid tests for affective-like disorders in animals. The behavior of TPH2(-/-) mice on the sucrose preference test, tail suspension test, and forced swim test and their responses in the unpredictable chronic mild stress and learned helplessness paradigms was the same as wild-type controls. While TPH2(-/-) mice as a group were not responsive to SSRIs, a subset responded to treatment with SSRIs in the same manner as wild-type controls with significant reductions in immobility time on the tail suspension test, indicative of antidepressant drug effects. The behavioral phenotype of the TPH2(-/-) mouse questions the role of <em>5HT</em> in depression. Furthermore, the TPH2(-/-) mouse may serve as a useful model in the search for new medications that have therapeutic targets for depression that are outside of the <em>5HT</em> neuronal system.

Serotonin (5-hydroxytryptamine, <em>5HT</em>) is believed to play a role in vasospasm and increased platelet aggregability that in turn could contribute to atherosclerosis. The present study was designed to evaluate a possible participation of serotonin in the development of vascular complications in diabetes mellitus. Whole blood and plasma serotonin, the platelet uptake and release of the amine and serotonin- induced platelet aggregation were studied in 32 patients with Type 2 diabetes. The patients were divided into three groups according to the presence and advancement of retinopathy. Mean levels of blood serotonin content were significantly lower in diabetic patients. The concentration of the amine in the plasma was markedly increased in diabetes. It was correlated with vascular changes of the retina. We established that platelets from diabetic patients took up less serotonin when compared to the control group. Concomitantly enhanced spontaneous release of <em>5HT</em> from platelets was observed. The platelets of diabetic patients showed increased response to serotonin. There was a relation between serotonin-induced aggregation and the presence of retinopathy. These results suggest that serotonin may be involved in the pathogenesis of diabetic vasculopathy.

The role of brain epinephrine (EPI) in the regulation of motor activity and movement in mice was examined. Blockade of EPI synthesis with i.p. 2,3-dichloro-alpha-methylbenzylamine (DCMB) or LY134046 was found to produce marked behavioral inactivity which could be significantly reversed by intraventricular injection of EPI and by three other alpha(1)-adrenoceptor agonists, norepinephrine (NE), 6-fluoronorepinephrine (6FNE), and phenylephrine (PE), as well as by serotonin (<em>5HT</em>). EPI had the largest effect of these agonists and also was the only one that reversed nondrug-induced inactivity of mice in their home cages during the light phase. The effects of EPI were blocked by coinfusion of an alpha(1)-adrenoceptor antagonist (terazosin) but not of an alpha(2)-(atipamezole) or beta(1) (betaxolol)-blocker. The rank order of maximal behavioral responses to EPI, 6FNE, and PE in DCMB-treated mice was the same as the rank order of their maximal stimulation of hydrolysis of phosphatidylinositol at cloned alpha(1B)-adrenoceptors in cell culture. On the basis of the above findings and of the central distributions of adrenergic neurons and alpha(1)-adrenoceptors, the existence of a central EPI-innervated alpha(1)-adrenergic receptor system is postulated which serves to coexcite or enhance signaling in several monoaminergic brain regions involved in movement and motor activity.

The effect of glycine was studied on the efflux of tritium-labelled dopamine, 5-HT and GABA from small slices of rat substantia nigra in vitro. A depolarising stimulus (50 mM KCl) stimulated the efflux of 3H-<em>5HT</em>, 3H-dopamine and 3H-GABA in a calcium-dependent fashion. Glycine (50 and 100 micromoles) stimulated the spontaneous efflux of 3H-dopamine but not that of 3H-<em>5HT</em> or 3H-GABA. Taurine, GABA and beta-alanine, all at 100 micromoles, had no effect on release of radioactivity after prelabelling nigral slices with 3H-dopamine. In keeping with a transmitter role for glycine at this site, 3H-glycine was taken up by small slices of rat substantia nigra by both high affinity (Km = 2.4 micromoles) and low affinity systems (Km = 5.96 mM). However 50 mM KCl was without effect on the efflux of radioactivity from nigral slices prelabelled with 3H-glycine.

OBJECTIVE

This study aimed to review quantitative literature pertaining to studies of music-based interventions in palliative cancer care and to review the neurobiological literature that may bare relevance to the findings from these studies.

METHODS

A narrative review was performed, with particular emphasis on RCTs, meta-analyses, and systematic reviews. The Cochrane Library, Ovid, PubMed, CINAHL Plus, PsycINFO, and ProQuest were searched for the subject headings music, music therapy, cancer, oncology, palliative care, pain, anxiety, depression, mood, quality of life, prevalence, neuroscience, functional imaging, endogenous opioids, GABA, <em>5HT</em>, dopamine, and permutations of these same search terms. Data for the review were comprised of articles published between 1970 and 2012. References of all the cited articles were also reviewed.

RESULTS

Available evidence suggests that music-based interventions may have a positive impact on pain, anxiety, mood disturbance, and quality of life in cancer patients. Advances in neurobiology may provide insight into the potential mechanisms by which music impacts these outcomes.

CONCLUSIONS

More research is needed to determine what subpopulation of cancer patients is most likely to respond to music-based interventions, what interventions are most effective for individual outcomes, and what measurement parameters best gauge their effectiveness.

A series of benzazepines related to SCH 23390 were tested for binding to the <em>5HT</em>-2 receptor. The compounds tested inhibited the binding of 3H-ketanserin with KI values generally greater than those observed for the D-1 receptor, but less than those for the D-2 receptor. When this serotonergic activity was correlated to the D-1 activity, the resulting coefficient was 0.84, indicating a strong correlation between the two activities. Conversely, the <em>5HT</em>-2 activity did not show a good correlation with the D-2 activity. To further test the significance of the <em>5HT</em>-2 binding of the SCH 23390, in vivo binding studies were performed using 125I-SCH 38840 in the frontal cortex, an area containing both D-1 and <em>5HT</em>-2 receptors. The in vivo binding of 125I-SCH 38840 to frontal cortex exhibited peak levels one hour following subcutaneous administration, similar to the time course previously observed in striatum. The binding was both D-1 and tissue specific. Competition studies with selected standards demonstrated that inhibition of the binding to frontal cortex, in contrast to the inhibition observed in the striatum, exhibited a Hill coefficient less than unity, implying interaction at more than one receptor subtype. When SCH 23390 and ketanserin were administered simultaneously, the inhibition of the in vivo binding of 125I-SCH 38840 to striatum was not different than that observed with SCH 23390, alone. However, the inhibition of binding to frontal cortex was significantly greater than that demonstrated with either SCH 23390 or ketanserin, alone, suggesting that 125I-SCH 38840 was binding to both D-1 and <em>5HT</em>-2 receptors, in vivo.

Structural hippocampus and prefrontal cortex changes occur in patients with posttraumatic stress disorder (PTSD) that appears correlated with cognitive dysfunction. In these brain regions, serotonin (<em>5HT</em>) plays a prominent role in symptom presentation and treatment of PTSD. However, <em>5HT</em> is both anxiogenic and anxiolytic, and while <em>5HT</em> reuptake inhibitors are effective in treatment, the role of <em>5HT</em> in the development of PTSD remains uncertain. Using a model of repeated trauma in rats, we observed significant spatial memory impairment together with significantly increased <em>5HT</em>(1A) receptor density (B(max)), decreased <em>5HT</em>(1A) receptor affinity (K(d)), and significantly increased <em>5HT</em>(2A) receptor affinity on day 7 poststress. The serotonergic agent fluoxetine (FLX; 10 mg/kg/d ip) administered 1 week before stress and continuing throughout the stress procedure, but not the <em>5HT</em> depleter p-chloro-phenylalanine (PCPA; 300/100/50 mg/kg/d ip), prevented stress-induced cognitive dysfunction. PCPA, however, reversed stress-induced hippocampal <em>5HT</em>(1A) receptor affinity changes, with FLX narrowly missing significance. Neither drug reversed stress effects on <em>5HT</em>(2A) receptor affinity. Thus, <em>5HT</em> plays an important part in the cognitive-behavioral changes evoked by repeated trauma. That raised <em>5HT</em> activity may mediate hippocampal <em>5HT</em>(1A) receptor changes evoked by stress suggests a bidirectional role for <em>5HT</em> in the development of PTSD.

There is significant evidence that in addition to reward-punishment based decision making, the Basal Ganglia (BG) contributes to risk-based decision making (Balasubramani et al., 2014). Despite this evidence, little is known about the computational principles and neural correlates of risk computation in this subcortical system. We have previously proposed a reinforcement learning (RL)-based model of the BG that simulates the interactions between dopamine (DA) and serotonin (<em>5HT</em>) in a diverse set of experimental studies including reward, punishment and risk based decision making (Balasubramani et al., 2014). Starting with the classical idea that the activity of mesencephalic DA represents reward prediction error, the model posits that serotoninergic activity in the striatum controls risk-prediction error. Our prior model of the BG was an abstract model that did not incorporate anatomical and cellular-level data. In this work, we expand the earlier model into a detailed network model of the BG and demonstrate the joint contributions of DA-<em>5HT</em> in risk and reward-punishment sensitivity. At the core of the proposed network model is the following insight regarding cellular correlates of value and risk computation. Just as DA D1 receptor (D1R) expressing medium spiny neurons (MSNs) of the striatum were thought to be the neural substrates for value computation, we propose that DA D1R and D2R co-expressing MSNs are capable of computing risk. Though the existence of MSNs that co-express D1R and D2R are reported by various experimental studies, prior existing computational models did not include them. Ours is the first model that accounts for the computational possibilities of these co-expressing D1R-D2R MSNs, and describes how DA and <em>5HT</em> mediate activity in these classes of neurons (D1R-, D2R-, D1R-D2R- MSNs). Starting from the assumption that <em>5HT</em> modulates all MSNs, our study predicts significant modulatory effects of <em>5HT</em> on D2R and co-expressing D1R-D2R MSNs which in turn explains the multifarious functions of <em>5HT</em> in the BG. The experiments simulated in the present study relates <em>5HT</em> to risk sensitivity and reward-punishment learning. Furthermore, our model is shown to capture reward-punishment and risk based decision making impairment in Parkinson's Disease (PD). The model predicts that optimizing <em>5HT</em> levels along with DA medications might be essential for improving the patients' reward-punishment learning deficits.

This study was undertaken as part of the NIH "Facilities of Research Excellence-Spinal Cord Injury" project to support independent replication of published studies. Here, we repeat key parts of a study reporting that rats treated with ibuprofen via subcutaneous minipump exhibited greater recovery of motor function and enhanced axonal growth after spinal cord injury. We carried out 3 separate experiments in which young adult female Sprague-Dawley rats received dorsal over-hemisections at T6-T7, and then were implanted with osmotic minipumps for subcutaneous delivery of ibuprofen or saline. Motor function was assessed with the BBB Locomotor Rating Scale, footprint analysis, and with a grid walk task. Combined group sizes for functional analyses were n=34 rats treated with ibuprofen and n=39 controls. Bladder function was assessed by measuring the amount of urine retained in the bladder twice per day. Four weeks post-injury, CST axons were traced by injecting BDA into the sensorimotor cortex; <em>5HT</em> axons were assessed by immunostaining. Analysis of data from all rats revealed no significant differences between groups. Analysis of data excluding rats with lesions that were larger than intended indicated improved locomotor function in ibuprofen-treated rats at early post-lesion intervals in one of the individual experiments. Rats that received Ibuprofen did not demonstrate statistically significant improvements in bladder function. Quantitative analyses of CST and <em>5HT</em> axon distribution also did not reveal differences between ibuprofen-treated and control rats. Taken together, our results only partially replicate the findings that treatment with ibuprofen improves motor function after SCI but fail to replicate findings regarding enhanced axon growth.

Little is known about the molecular abnormalities associated with canine degenerative mitral valve disease (DMVD). The pathology of DMVD involves the differentiation and activation of the normally quiescent mitral valvular interstitial cell (VIC) into a more active myofibroblast phenotype, which mediates many of the histological and molecular changes in affected the valve tissue. In both humans and experimental animal models, increased serotonin (5-hydroxytryptamine, <em>5HT</em>) signaling can induce VIC differentiation and myxomatous valve damage. In canine DMVD, numerous lines of evidence suggest that <em>5HT</em> and related molecules such as transforming growth factor-beta play a critical role in the pathogenesis of this disease. A variety of investigative techniques, including gene expression, immunohistochemistry, protein blotting, and cell culture, shed light on the potential role of <em>5HT</em> in the differentiation of VIC, elaboration of myxomatous extracellular matrix components, and activation of mitogen-activated protein kinase pathways. These studies help support a hypothesis that <em>5HT</em> and its related pathways serve as an important stimulus in canine DMVD. This review describes the pathological characteristics of canine DMVD, the organization and role of the <em>5HT</em> pathway in valve tissue, involvement of <em>5HT</em> in human and experimental models of valve disease, avenues of evidence that suggest a role for <em>5HT</em> in naturally occurring DMVD, and finally, a overarching hypothesis describing a potential role for <em>5HT</em> in canine DMVD.

Advanced high-throughput screening (HTS) technologies generate great amounts of bioactivity data, and this data needs to be analyzed and interpreted with attention to understand how these small molecules affect biological systems. As such, there is an increasing demand to develop and adapt cheminformatics algorithms and tools in order to predict molecular and pharmacological properties on the basis of these large data sets. In this manuscript, we report a novel machine-learning-based ligand classification algorithm, named Ligand Classifier of Adaptively Boosting Ensemble Decision Stumps (LiCABEDS), for data-mining and modeling of large chemical data sets to predict pharmacological properties in an efficient and accurate manner. The performance of LiCABEDS was evaluated through predicting GPCR ligand functionality (agonist or antagonist) using four different molecular fingerprints, including Maccs, FP2, Unity, and Molprint 2D fingerprints. Our studies showed that LiCABEDS outperformed two other popular techniques, classification tree and Naive Bayes classifier, on all four types of molecular fingerprints. Parameters in LiCABEDS, including the number of boosting iterations, initialization condition, and a "reject option" boundary, were thoroughly explored and discussed to demonstrate the capability of handling imbalanced data sets, as well as its robustness and flexibility. In addition, the detailed mathematical concepts and theory are also given to address the principle behind statistical prediction models. The LiCABEDS algorithm has been implemented into a user-friendly software package that is accessible online at http://www.cbligand.org/LiCABEDS/ .

Blood serotonin (<em>5HT</em>) has been shown to be elevated in 30% of autistic children and 50% of severely mentally retarded children. Ninety-eight normal adult subjects were studied to determine if there was an inverse relationship between whole blood <em>5HT</em> in normal adults of average and above-average intelligence. There was a trend toward a negative correlation between whole blood <em>5HT</em> and Vocabulary scores that would not account for hyperserotonemia in autistic or mentally retarded individuals. Female subjects had significantly greater whole blood <em>5HT</em> than male subjects. There was no difference in whole blood <em>5HT</em> collected before and after volume depletion of 450 ml, providing further evidence of the intraindividual stability of whole blood serotonin levels. There was no relationship between age and whole blood <em>5HT</em> in a group of normal adult subjects.

Inhibition of platelet thromboxane A(2) (TXA(2)) by aspirin is critical in patients with acute myocardial infarction (AMI), but some patients have persistent platelet TXA(2) production within 48 hours of the onset of AMI. Statins are known to reduce TXA(2) in aspirin-free patients with hypercholesterolemia. We hypothesized that treatment with aspirin plus atorvastatin could reduce persistent TXA(2) synthesis and aspirin resistance in patients with AMI. We evaluated platelet function in 184 aspirin-treated patients within 48 hours of the onset of AMI. Patients were divided into group A (treated with aspirin alone, n = 139) and group B (treated with aspirin plus atorvastatin, n = 45). We studied collagen-induced platelet TXA(2) synthesis, serotonin ((14)C-<em>5HT</em>) release and recruitment, and adenosine diphosphate-, arachidonic acid-, and collagen-induced platelet aggregation. Persistent TXA(2) synthesis was detected in 25% and 9% of groups A and B, respectively (p = 0.03). TXA(2), arachidonic acid-aggregation, and collagen-induced responses were significantly reduced in patients receiving dual treatment compared to those receiving aspirin monotherapy. Atorvastatin did not modify platelet reactivity in patients with efficiently blocked TXA(2) synthesis. These results strongly suggest a direct effect of the statin on platelet eicosanoid synthesis. This was confirmed in vitro by incubating washed aspirin-free and aspirin (1 muM)-treated platelets from normal subjects with 1 to 20 microM atorvastatin. Atorvastatin in vitro significantly reduced platelet TXA(2) synthesis and collagen-induced aggregation. In conclusion, atorvastatin combined with aspirin early in the onset of the acute event significantly reduced persistent TXA(2) and TXA(2)-dependent aspirin resistance. This could contribute to the clinical benefit of atorvastatin in patients with AMI.

In the cat, serotoninergic (<em>5HT</em>) axons and terminals form a dense plexus that is present throughout the granule cell and Purkinje cell layers of the cerebellar cortex and all of the cerebellar nuclei. The intent of the present study was to identify the source of <em>5HT</em> fibers in the cerebellar nuclei. The medial, interposed, and lateral cerebellar nuclei were selectively injected with either rhodamine or fluorescein-labeled latex microspheres that were retrogradely transported to brainstem neurons. Transverse sections of the brainstem were processed with a primary antibody to <em>5HT</em> and secondary antibody tagged with either rhodamine or fluorescein. The location of neurons containing both serotonin-like immunoreactivity and retrogradely transported microspheres was plotted. All three of the cerebellar nuclei receive <em>5HT</em> afferents from the nucleus locus coeruleus, the dorsal raphe nucleus, and the dorsal tegmental nucleus. In addition, the medial nucleus receives projections from the superior central nucleus, the nucleus raphe obscurus, the nucleus raphe magnus, and the periolivary reticular formation. The interposed nuclei receive additional projections from the nucleus raphe magnus, whereas the lateral nucleus receives additional projections from the superior central nucleus. In conclusion, the <em>5HT</em> projections to the cerebellar nuclei do not appear to be collaterals of those projecting to the cortex (Kerr and Bishop, J Comp Neurol 304:502-515, 1991). These findings suggest that, although the cortex and nuclei are anatomically and physiologically related, they do not process all information in parallel.

Single nucleotide polymorphisms (SNPs) in the serotonergic (<em>5HT</em>) system seem to have modulatory effects on depression and physical function. Preliminary evidence suggests that gene×environment interactions play a role in the development of depression, with somatic complaints serving as environmental stressors. We hypothesized that pain intensity may serve as a stress factor that modulates the association between SNPs in the <em>5HT</em> system and depression. We investigated symptoms of pain, depression, physical functioning, and disability in 224 patients 6months after lumbar disc surgery. Associations between these variables and functional promoter SNPs in the serotonin receptor genes <em>5HT</em>R1A (rs6295) and <em>5HT</em>R2A (rs6311) were analyzed. For <em>5HT</em>R2A, we found a significant gene×environment×sex interaction, as female patients carrying at least one A allele of the -1438A/G promoter SNP had significantly higher depression scores when confronted with severe pain compared to women harboring the GG genotype (P=.005). For <em>5HT</em>R1A, patients homozygous for the -1019 G allele presented higher Beck Depression Inventory scores relative to the CG/CC group, indicating a major effect of this SNP on depression. Furthermore, women homozygous for either the <em>5HT</em>R1A G allele or the <em>5HT</em>R2A A allele had lower levels of physical functioning than patients with the other genotypes. These results suggest that <em>5HT</em>R1A and <em>5HT</em>R2A promoter variations have gender-dependent modulatory effects on depression and physical function in patients with pain. Furthermore, this study demonstrates that pain after lumbar surgery modulates the association between <em>5HT</em> gene polymorphisms and depression.

Mammalian circadian activity rhythms are generated by pacemaker cells in the suprachiasmatic nucleus (SCN). As revealed by the actions of diverse agonists, serotonergic input from raphe nuclei generally inhibits photic signaling in the suprachiasmatic nucleus. In contrast, the serotonin (<em>5HT</em>)1A partial agonist, 4-(benzodioxan-5-yl)1-(indan2-yl)piperazine (S 15535), was found to enhance the phase-shifting influence of light on hamster circadian rhythms [Gannon, Neuroscience 119 (2003) 567]. Herein, we extend this observation in showing that S 15535 (5.0 mg/kg, i.p.) markedly (275%) enhanced the light-induced phase shift in circadian activity rhythms: further, this action was dose-dependently abolished by the highly-selective <em>5HT</em>1A receptor antagonist, WAY 100,635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]N-2-pyridinyl-cyclohexane-carboxamide maleate) (0.1-0.5 mg/kg, i.p.). WAY 100,635, which was inactive alone, shares the antagonist actions of S 15535 at postsynaptic <em>5HT</em>1A sites, yet blocks its effects at their presynaptic counterparts. Thus, <em>5HT</em>1A autoreceptor activation must be involved in this effect of S 15535 which contrasts with the opposite, inhibitory influence upon phase shifts of the "full" agonist, 8-OH-DPAT, which acts by stimulation of postsynaptic <em>5HT</em>1A receptors [Rea et al., J Neurosci 14 (1994) 3635]. Despite the occurrence of <em>5HT</em>2A and <em>5HT</em>2C receptors in the (rat) suprachiasmatic nucleus, their influence on circadian rhythms is unknown since actions of selective ligands have never been evaluated. This issue was investigated with the most selective agents currently available. However, the <em>5HT</em>2A agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) (0.25 and 0.5 mg/kg), and the <em>5HT</em>2C agonist, alphaS-6-chloro-5-fluoro-a-methyl-1H-indole-1-ethanamine fumarate (Ro-60-0175) (1.0 and 5.0 mg/kg), failed to affect light-induced phase shifts in hamsters. Moreover, even over broad dose-ranges, the <em>5HT</em>2A antagonist, (+)-(2,3-dimethoxy-phenyl)-[1-[2-(4-fluoro-phenyl)-ethyl]-piperidin-4-yl]methanol (MDL 100,907) (0.1-1.0 mg/kg), and the <em>5HT</em>2C antagonist, 6-chloro-5-methyl-1-[6-(2-methylpyridin-3-yloxy)pyridin-3-yl carbamoyl]indoline (SB 242,084) (1.0-10.0 mg/kg), were likewise inactive. In view of evidence that <em>5HT</em>2A and <em>5HT</em>2C sites functionally interact with <em>5HT</em>1A receptors, we also examined the influence of these agents upon the actions of S 15535, but no significant alteration was seen in its enhancement of rhythms. In conclusion, S 15535 elicits a striking enhancement of light-induced phase shifts in circadian rhythms by specifically recruiting <em>5HT</em>1A autoreceptors, which leads to suppression of serotonergic input to the suprachiasmatic nucleus. Surprisingly, no evidence for a role of <em>5HT</em>2A or <em>5HT</em>2C sites was found, though comparable functional studies remain to be undertaken in rats. Indeed, the present work underlines the importance of comparative studies of circadian rhythms in various species, as well as the need for further study of potential interactions among <em>5HT</em> receptor subtypes in their control.

Trazodone is one of the most commonly prescribed medicines for treating depression and insomnia. However, the pharmacological mechanism of action underlying trazodone's unique effects is unclear. Despite its nanomolar affinity for <em>5HT</em>(2A) receptors, histamine(1) receptors and alpha(1) adrenoceptors the drug is given at high doses to achieve clinical efficacy suggesting that other target activities may also contribute to its effects. Here we report that trazodone inhibits recombinant T-type calcium channels (Ca(v)3.1, Ca(v)3.2 and Ca(v)3.3) in whole-cell patch-clamp studies at therapeutically relevant concentrations (IC(50)=43 microM, 45 microM, 23 microM, respectively). Inhibition was not use-dependent and showed only moderate voltage-dependence. Tonic block of Ca(v)3.1 channels held at negative membrane potentials suggested drug interaction with channels in the resting state. The major metabolite of trazodone, m-chlorophenylpiperazine, showed comparable potency on Ca(v)3.3 channels (IC(50)=35 microM) and was less active on Ca(v)3.1 channels (IC(50)=317 microM). We also demonstrate trazodone's inhibitory effects on native T-type calcium currents recorded from subthalamic neurons in a patch-clamp rat brain slice assay (approximately 30% inhibition at 100 microM). Our data suggest that T-type calcium channel antagonism may contribute to the pharmacology of trazodone and its reported neurological effects.

Although evidence suggests that 5-HT(2A) and muscarinic M1/M4 receptors are implicated in the pathology of schizophrenia, the results are not conclusive. In the present study we tested the hypothesis that binding of 5-HT(2A) and M1/M4 receptors is altered in the postmortem brain of schizophrenia subjects. Quantitative autoradiography was employed to measure [(3)H]ketanserin binding to 5-HT(2A) receptors and [(3)H]pirenzepine binding to both M1 and M4 receptors in Brodmann's area 9 (BA9), caudate/putamen, and the hippocampal formation from six schizophrenic and six control subjects. A significant reduction in the density of <em>5HT</em>(2A) receptors in BA 9 of schizophrenic subjects was observed (p=0.036). No significant difference was observed in the density of <em>5HT</em>(2A) receptors in the hippocampus or caudate/putamen between the two groups. No significant changes in the density of M1/M4 receptors was observed in these three regions between the two groups. These findings support a possible involvement of the serotonergic system in the pathology of schizophrenia.

The peripheral serotonergic system has been implicated in the modulation of an array of pain states, from migraine to fibromyalgia; however, the mechanism by which serotonin (<em>5HT</em>) induces pain is unclear. Peripherally released <em>5HT</em> induces thermal hyperalgesia, possibly via modulation of the transient receptor potential V1 (TRPV1) channel, which is gated by various noxious stimuli, including capsaicin. We previously reported in vitro that <em>5HT</em> increases calcium accumulation in the capsaicin-sensitive population of sensory neurons with a corresponding increase in proinflammatory neuropeptide release, and both are antagonized by pretreatment with <em>5HT</em>(2A) and <em>5HT</em>(3) antagonists, as well as the anti-migraine drug sumatriptan. In the current study, we extended these findings in vivo using the rat hind paw thermal assay to test the hypothesis that peripheral <em>5HT</em> enhances TRPV1-evoked thermal hyperalgesia that can be attenuated with <em>5HT</em>(2A) and <em>5HT</em>(3) receptor antagonists, as well as sumatriptan. Thermal hyperalgesia and edema were established by <em>5HT</em> injection (0.1-10 nmol/100 μl) into the rat hind paw, and the latency to paw withdrawal (PWL) from noxious heat was determined. Rats were then pretreated with either <em>5HT</em> before capsaicin (3 nmol/10 μl), the <em>5HT</em>(2A) receptor antagonist ketanserin or the <em>5HT</em>(3) receptor antagonist granisetron (0.0001-0.1 nmol/100 μl) before <em>5HT</em> and/or capsaicin, or the <em>5HT</em>(1B/1D) receptor agonist sumatriptan (0.01-1 nmol/100 μl) before capsaicin, and PWL was determined. We report that <em>5HT</em> pretreatment enhances TRPV1-evoked thermal hyperalgesia, which is attenuated with local pretreatment with ketanserin, granisetron, or sumatriptan. We also report that peripheral <em>5HT</em> induced a similar magnitude of thermal hyperalgesia in male and female rats. Overall, our results provide in vivo evidence supporting an enhancing role of <em>5HT</em> on TRPV1-evoked thermal hyperalgesia, which can be attenuated by peripheral serotonergic intervention.

L-5-Hydroxytryptophan (<em>5HT</em>P) was administered to 20 patients suffering from panic disorder and to 20 healthy controls. Subjects received 60 mg <em>5HT</em>P in 300 ml saline solution. Before, during, and up to 2 hours after <em>5HT</em>P administration, symptoms of anxiety and depression were assessed. In addition, plasma <em>5HT</em>P, 3-methoxy-4-hydroxyethylglycol (MHPG), cortisol, beta-endorphin, and melatonin levels were measured at several time points, and the kinetics of 5-hydroxytryptamine (<em>5HT</em>) in blood platelets were measured. During and after the infusion of <em>5HT</em>P, none of the patients showed an increase in anxiety or depressive symptoms, despite the presence of severe side effects. Some patients even experienced the <em>5HT</em>P infusion as a relief. In contrast to the patients, nine control subjects reported depressed mood, although no increases in anxiety were noted. In both patients and controls, the <em>5HT</em>P infusion led to substantial increases in plasma cortisol and beta-endorphin levels, while the plasma MHPG level was unchanged. Plasma melatonin increased significantly after <em>5HT</em>P administration, suggesting that increasing <em>5HT</em> availability in man might affect melatonin synthesis. The results of this study are at odds with the hypothesis that there is a supersensitivity of <em>5HT</em>2 receptors in panic disorder.