This study used 1-methyl-4-phenyl-1,2,3,6,-tetrahydropyridine (MPTP) in mice to determine if exercise improves behavior and dopamine (DA) and serotonin (<em>5HT</em>) content. Male C57BL/6 mice received MPTP (4 x 20mg/kg) or saline. They remained sedentary or exercised by treadmill or voluntary running wheel for 6 weeks (n=8/group). Saline-treated mice ran significantly faster on running wheels (22.8+/-1.0m/min) than on treadmill (8.5+/-0.5m/min), and MPTP lesion did not reduce voluntary exercise (19.3+/-1.5m/min, p>0.05). There was a significant effect of both lesion and exercise on overall Rotarod performance (ORP): MPTP lesion reduced ORP, while treadmill exercise increased ORP vs sedentary mice (p<0.05). MPTP increased anxiety in the marble-burying test: sedentary lesioned mice buried more marbles (74.0+/-5.2%) than sedentary controls (34.8+/-11.8%, p<0.05). Conversely, exercise reduced anxiety on the elevated plus maze. Among saline-treated mice, those exposed to voluntary wheel-running showed an increased percent of open arm entries (49.8+/-3.5%, p<0.05) relative to sedentary controls (36.2+/-4.0%, p<0.05). Neither MPTP nor exercise altered symptoms of depression measured by sucrose preference or tail suspension. MPTP significantly reduced DA in striatum (in sedentary lesioned mice to 42.1+/-3.0% of saline controls), and lowered <em>5HT</em> in amygdala and striatum (in sedentary lesioned mice to 86.1+/-4.1% and 66.5+/-8.2% of saline controls, respectively); exercise had no effect. Thus, exercise improves behavior in a model of DA depletion, without changes in DA or <em>5HT</em>.

Second generation antipsychotics (SGAs), such as clozapine, olanzapine, risperidone and quetiapine, are among the most effective therapies to stabilize symptoms schizophrenia (SZ) spectrum disorders. In fact, clozapine, olanzapine and risperidone have improved the quality of life of billions SZ patients worldwide. Based on the broad spectrum of efficacy and low risk of extrapyramidal symptoms displayed by SGAs, some regulatory agencies approved the use of SGAs in non-schizophrenic adults, children and adolescents suffering from a range of neuropsychiatric disorders. However, increasing number of reports have shown that SGAs are strongly associated with accelerated weight gain, insulin resistance, diabetes, dyslipidemia, and increased cardiovascular risk. These metabolic alterations can develop in as short as six months after the initiation of pharmacotherapy, which is now a controversial fact in public disclosure. Although the percentage of schizophrenic patients, the main target group of SGAs, is estimated in only 1% of the population, during the past ten years there was an exponential increase in the number of SGAs users, including millions of non-SZ patients. The scientific bases of SGAs metabolic side effects are not yet elucidated, but the evidence shows that the activation of transcriptional factor SRBP1c, the D1/D2 dopamine, GABA2 and <em>5HT</em> neurotransmitions are implicated in the SGAs cardiovascular toxicity. Polypharmacological interventions are either non- or modestly effective in maintaining low cardiovascular risk in SGAs users. In this review we critically discuss the clinical and molecular evidence on metabolic alterations induced by SGAs, the evidence on the efficacy of classical antidiabetic drugs and the emerging concept of antidiabetic polyphenols as potential coadjutants in SGA-induced metabolic disorders.

The superficial dorsal horn of the spinal cord (SDH; laminae I and II) receives strong input from thin primary afferent fibres and is involved in nociception, pain, temperature sensing and other experiences. The SDH also is the target of serotonergic and adrenergic projections from the brain stem. The interaction between descending pathways that utilize particular mediators and the neurone population of the SDH is poorly understood. To explore this issue, in rat spinal cord slices during whole-cell recordings from identified SDH neurones, noradrenaline (NA) or serotonin (<em>5HT</em>) were briefly applied in the superfusing artificial cerebrospinal fluid. The action of these agents proved specifically related to the type of SDH neurone and its dorsal-root afferent input. Vertical, radial and tonic central lamina II cells consistently expressed outward current to both NA and <em>5HT</em>, but transient central and Substance P (SP)-insensitive lamina I cells were unaffected directly by either NA or <em>5HT</em>. Extended islet cells responded with outward current to NA and inward current to <em>5HT</em>. Lamina I SP-sensitive cells expressed an outward current regularly to NA. <em>5HT</em> had inhibitory effects on Adelta and C fibre input to all types of SDH neurones. NA inhibited C fibre input to transient central neurones. The present results support the idea that descending systems may have multiple functions, including but not limited to nociceptive modulation.

Psychedelic agents have a long history of use by humans for their capacity to induce profound modifications in perception, emotion and cognitive processes. Despite increasing knowledge of the neural mechanisms involved in the acute effects of these drugs, the impact of sustained psychedelic use on the human brain remains largely unknown. Molecular pharmacology studies have shown that psychedelic 5-hydroxytryptamine (<em>5HT</em>)2A agonists stimulate neurotrophic and transcription factors associated with synaptic plasticity. These data suggest that psychedelics could potentially induce structural changes in brain tissue. Here we looked for differences in cortical thickness (CT) in regular users of psychedelics. We obtained magnetic resonance imaging (MRI) images of the brains of 22 regular users of ayahuasca (a preparation whose active principle is the psychedelic <em>5HT</em>2A agonist N,N-dimethyltryptamine (DMT)) and 22 controls matched for age, sex, years of education, verbal IQ and fluid IQ. Ayahuasca users showed significant CT differences in midline structures of the brain, with thinning in the posterior cingulate cortex (PCC), a key node of the default mode network. CT values in the PCC were inversely correlated with the intensity and duration of prior use of ayahuasca and with scores on self-transcendence, a personality trait measuring religiousness, transpersonal feelings and spirituality. Although direct causation cannot be established, these data suggest that regular use of psychedelic drugs could potentially lead to structural changes in brain areas supporting attentional processes, self-referential thought, and internal mentation. These changes could underlie the previously reported personality changes in long-term users and highlight the involvement of the PCC in the effects of psychedelics.

The manipulation of the enteric microbiota with specific prebiotics and probiotics, has been shown to reduce the host's inflammatory response, alter brain chemistry, and modulate anxiety behaviour in both rodents and humans. However, the neuro-immune and behavioural effects of prebiotics on sickness behaviour have not been explored. Here, adult male CD1 mice were fed with a specific mix of non-digestible galacto-oligosaccharides (Bimuno®, BGOS) for 3 weeks, before receiving a single injection of lipopolysaccharide (LPS), which induces sickness behaviour and anxiety. Locomotor and marble burying activities were assessed 4h after LPS injection, and after 24h, anxiety in the light-dark box was assessed. Cytokine expression, and key components of the serotonergic (5-Hydroxytryptamine, 5-HT) and glutamatergic system were evaluated in the frontal cortex to determine the impact of BGOS administration at a molecular level. BGOS-fed mice were less anxious in the light-dark box compared to controls 24h after the LPS injection. Elevated cortical IL-1β concentrations in control mice 28 h after LPS were not observed in BGOS-fed animals. This significant BGOS×LPS interaction was also observed for <em>5HT</em>2A receptors, but not for <em>5HT</em>1A receptors, <em>5HT</em>, 5HIAA, NMDA receptor subunits, or other cytokines. The intake of BGOS did not influence LPS-mediated reductions in marble burying behaviour, and its effect on locomotor activity was equivocal. Together, our data show that the prebiotic BGOS has an anxiolytic effect, which may be related to the modulation of cortical IL-1β and 5-HT2A receptor expression. Our data suggest a potential role for prebiotics in the treatment of neuropsychiatric disorders where anxiety and neuroinflammation are prominent clinical features.

The mechanism controlling the development of dopaminergic (DA) and serotonergic (<em>5HT</em>) neurons in vertebrates is not well understood. Here we characterized a zebrafish mutant--too few (tof)--that develops hindbrain <em>5HT</em> and noradrenergic neurons, but does not develop hypothalamic DA and <em>5HT</em> neurons. tof encodes a forebrain-specific zinc finger transcription repressor that is homologous to the mammalian Fezl (forebrain embryonic zinc finger-like protein). Mosaic and co-staining analyses showed that fezl was not expressed in DA or <em>5HT</em> neurons and instead controlled development of these neurons non-cell-autonomously. Both the eh1-related repressor motif and the second zinc finger domain were necessary for tof function. Our results indicate that tof/fezl is a key component in regulating the development of monoaminergic neurons in the vertebrate brain.

BACKGROUND

Recurrent abdominal pain is reported by a third of patients with diverticulosis, particularly those with previous episodes of acute diverticulitis. The current understanding of the etiology of this pain is poor. Our aim was to assess visceral sensitivity in patients with diverticular disease and its association with markers of previous inflammation and neuropeptides.

METHODS

Patients with asymptomatic and symptomatic diverticular disease underwent a flexible sigmoidoscopy and biopsy followed 5-10 days later by visceral sensitivity testing with barostat-mediated rectal distension. Inflammation was assessed by staining of serotonin (<em>5HT</em>) and CD3 positive cells. mRNA levels of tumor necrosis factor alpha (TNF α) and interleukin-6 (IL-6) were quantitated using RT-PCR. Neuropeptide expression was assessed from percentage area staining with substance P (SP) and mRNA levels of the neurokinin 1 & 2 receptors (NK1 & NK2), and galanin 1 receptor (GALR1).

RESULTS

Thirteen asymptomatic and 12 symptomatic patients were recruited. The symptomatic patients had a lower first reported threshold to pain (28.4 mmHg i.q.r 25.0-36.0) than the asymptomatic patients (47 mmHg i.q.r 36.0-52.5, P < 0.001). Symptomatic patients had a higher median overall pain rating for the stimuli than the asymptomatic patients (P < 0.02). Symptomatic patients had greater median relative expression of NK1 and TNF alpha mRNA compared with asymptomatic patients. There was a significant correlation between barostat VAS pain scores and NK 1 expression (Figure 4, r(2) 0.54, P < 0.02).

CONCLUSIONS

Patients with symptomatic diverticular disease exhibit visceral hypersensitivity, and this may be mediated by ongoing low grade inflammation and upregulation of tachykinins.

1. Intracellular recordings were made from neurones in the myenteric plexus of the ileum isolated from adult guinea-pigs.2. Three synaptic potentials were evoked in different myenteric neurones by focal stimulation of the ganglion surface at a distance of up to 100 mum from the cell body from which the recording was made. These were the fast cholinergic excitatory post-synaptic potential (e.p.s.p.), the slow e.p.s.p. and the slow inhibitory post-synaptic potential (i.p.s.p.).3. 5-hydroxytryptamine and substance P were applied to the neurones by superfusion (10 nm-1 mum) or by electrophoresis within 5 mum of the neurone cell body. 5-HT depolarized, hyperpolarized or had no effect on approximately equal numbers of neurones, whereas substance P depolarized 90% of neurones.4. Many neurones with a depolarizing slow e.p.s.p. were hyperpolarized by superfusion or electrophoretic application of 5-HT.5. Superfusion with 5-HT reversibly depressed the fast e.p.s.p., slow e.p.s.p. and slow i.p.s.p. Superfusion with substance P depressed the slow e.p.s.p.6. Methysergide (10-30 mum) reduced the amplitude of the fast e.p.s.p., the slow e.p.s.p. and the slow i.p.s.p.7. Chymotrypsin (200 mug/ml.) reversibly reduced the amplitude of the slow e.p.s.p., but had no effect on membrane potential, the action potential or the fast e.p.s.p. Chymotrypsin reduced or abolished the depolarization caused by electrophoretic application of substance P, but had no effect on the depolarization or hyperpolarization caused by <em>5HT</em>.8. The results provide evidence that 5-HT is not the transmitter which mediates the slow e.p.s.p. in myenteric neurones. The slow e.p.s.p. may be caused by substance P or another similar peptide.

Glucocorticoid administration to preterm infants is associated with neurodevelopmental disorders. We treated developing rats with dexamethasone (Dex) at 0.05, 0.2, or 0.8 mg/kg, doses below or spanning the range in clinical use, testing the effects of administration during three different stages: gestational days 17-19, postnatal days 1-3 or postnatal days 7-9. In adulthood, we assessed the impact on synaptic biomarkers for serotonin (5-hydroxytryptamine (<em>5HT</em>)) systems. Across all three regimens, Dex administration evoked upregulation of cerebrocortical <em>5HT</em>1A and <em>5HT</em>2 receptors and the presynaptic <em>5HT</em> transporter, greatest for <em>5HT</em>1A receptors. The effects were fully evident even at the lowest dose. In contrast, <em>5HT</em> levels in the cerebral cortex and hippocampus showed disparate patterns of temporal sensitivity, with no change after gestational treatment, an increase with the early postnatal regimen, and a decrease with the later postnatal exposure. None of the changes in <em>5HT</em> concentrations were offset by adaptive changes in the fractional <em>5HT</em> turnover rate. Furthermore, the critical period of sensitivity seen for <em>5HT</em> levels differed from that of dopamine even within the same brain region. These findings suggest that developmental exposure to Dex during the critical neurodevelopmental period corresponding to its use in preterm infants, elicits selective changes in <em>5HT</em> and dopaminergic synaptic function over and above its effects on general aspects of neural cell development, below the threshold for somatic growth impairment, and even at doses below those used clinically. Accordingly, adverse neurobehavioral consequences may be inescapable in glucocorticoid therapy of preterm infants.

BACKGROUND

The functional polymorphism of the serotonin transporter gene (5HTTLPR) has been earlier associated with affective disorders. No research has however been carried out to identify the relationship between this polymorphism and depressive traits and subclinical depressive symptoms within a psychiatrically healthy population.

METHODS

One hundred and twenty-eight female subjects with no lifetime or current history of DSM-IV Axis I disorders participated in the study. All subjects completed the Zung Self-Rating Depression Scale and were genotyped for the 5HTTLPR polymorphism.

RESULTS

Significant differences were found on the Zung SDS and also on the physical-vegetative subscale of the Zung SDS according to both phenotype and genotype. Subjects carrying the s allele scored significantly higher on the Zung SDS and had also significantly higher scores on the physical-vegetative symptom subscale. Furthermore, subjects carrying the ss genotype scored highest and subjects carrying the ll genotype scored the lowest on both scales.

CONCLUSIONS

Subclinical depressive symptoms (i.e. DSM-IV subthreshold depression) are associated with the functional polymorphism of the serotonin transporter gene. The main association between this polymorphism and subclinical depression is primarily carried by the physical symptoms of depression. The s allele of the 5HTTLPR gene is associated with a "low mood endophenotype".

Platelets activated by ADP become refractory to restimulation, but the mechanism of this process is not well understood. A normal platelet response to ADP requires coactivation of the P2Y(1) receptor responsible for shape change and the P2cyc receptor, responsible for completion and amplification of the response. The aim of the present study was to characterize the desensitization of platelets to ADP and to determine whether or not these two receptors are desensitized simultaneously through identical pathways when platelets become refractory to ADP. It was found that full inhibition of platelet aggregation in response to restimulation by ADP required the presence of ADP in the medium or use of a high concentration (1 mM) of its non-hydrolysable analogue ADPbetaS. Platelets incubated for 1 h at 37 degrees C with 1 mM ADPbetaS and resuspended in Tyrode's buffer containing apyrase displayed a stable refractory state characterized by the inability to aggregate or change shape in response to ADP. ADPbetaS treated platelets loaded with fura-2/AM showed complete blockade of the calcium signal in response to ADP, whereas the capacity of ADP to inhibit PGE1 stimulated cAMP accumulation in these platelets was only diminished. Consequently, serotonin was able to promote ADP induced aggregation through activation of the Gq coupled <em>5HT</em>(2A) receptor while adrenaline had no such effect. These results suggested that the refractory state of ADPbetaS treated platelets was entirely due to desensitization of the P2Y(1) receptor, the P2cyc receptor remaining functional. Binding studies were performed to determine whether the P2Y(1) and/or P2cyc binding sites were modified in refractory platelets. Using selective P2Y(1) and P2cyc antagonists (A3P5P and AR-C66096 respectively), we could demonstrate that the decrease in [33P]2MeSADP binding sites on refractory platelets corresponded to disappearance of the P2Y(1) sites with no change in the number of P2cyc sites, suggesting internalization of the P2Y(1) receptor. This was confirmed by flow cytometric analysis of Jurkat cells expressing an epitope-tagged P2Y(1) receptor, where ADPbetaS treatment resulted in complete loss of the receptor from the cell surface. We conclude that the P2Y(1) and P2cyc receptors are differently regulated during platelet activation.

Stress-induced learned helplessness in animals serves as a model of behavioral depression and other stress-related disorders. Our recent report that repeated stress prolongs the duration of learned helplessness behavior in rats may be important since acute and recurrent disorders may have different responsive mechanisms. To examine the role of serotonergic (<em>5HT</em>) mechanisms in such behavior, we studied the expression of <em>5HT</em>2A receptors in different brain areas of rats, and further investigated whether the alterations in expression of <em>5HT</em>2A receptors are similar after single versus repeated stress. Rats exposed to inescapable shock once on day 1, or twice, on day 1 and day 7, were tested for escape latency on days 2 and 4, or day 14, respectively. Higher escape latencies were observed on day 2 after single, and on day 14 after repeated shock. Whereas the single-stress paradigm produced a significant decrease of <em>5HT</em>2A receptor mRNA and protein expression in hippocampus of non-learned helpless and learned helpless rats as compared with tested controls, repeated stress resulted in increase in frontal cortex but decrease in hippocampus and hypothalamus of learned helpless rats only, as compared with tested control rats. These results demonstrate differential regulation of <em>5HT</em>2A receptors in LH rats after single and repeated stress, which may be critical in the pathophysiology of depression/other stress-related disorders.

In the present study we have examined the effects of the serotonin3 (5-HT3) agonist 2-methylserotonin (2-Me-<em>5HT</em>) on the dopamine (DA) release in the nucleus accumbens (NAc) of rats using in vivo chronocoulometric recording. The intraventricular (i.c.v.) administration of 2-Me-<em>5HT</em> dose-dependently increased the DA release in the NAc. This effect was blocked by the selective 5-HT3 antagonist BRL-43694 (granisetron), but not by the 5-HT1/5-HT2 antagonist metergoline. The i.c.v. injection of 8-hydroxydipropylaminotetraline (8-OHDPAT, a selective 5-HT1a agonist) or (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI, a 5-HT2/5-HT1c agonist) failed to alter the DA release in the NAc. The increase in the DA release produced by 2-Me-<em>5HT</em> was abolished in animals that had received acute bilateral injections of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle. Our results suggest that the 2-Me-<em>5HT</em>-induced DA release in the NAc is mediated by 5-HT3 receptors. In addition, 2-Me-<em>5HT</em> induced effect is dependent upon the impulse flow of DA cells.

Transplantation of neural stem cells (NSC) into lesioned spinal cord offers the potential to increase regeneration by replacing lost neurons or oligodendrocytes. The majority of transplanted NSC, however, typically differentiate into astrocytes that may exacerbate glial scar formation. Here we show that blocking of ciliary neurotrophic factor (CNTF) with anti-CNTF antibodies after NSC transplant into spinal cord injury (SCI) resulted in a reduction of glial scar formation by 8 weeks. Treated animals had a wider distribution of transplanted NSC compared with the control animals. The NSC around the lesion coexpressed either nestin or markers for neurons, oligodendrocytes, or astrocytes. Approximately 20% fewer glial fibrillary acidic protein-positive/bromodeoxyuridine (BrdU)-positive cells were seen at 2, 4, and 8 weeks postgrafting, compared with the control animals. Furthermore, more CNPase(+)/BrdU(+) cells were detected in the treated group at 4 and 8 weeks. These CNPase(+) or Rip(+) mature oligodendrocytes were seen in close proximity to host corticospinal tract (CST) and <em>5HT</em>(+) serotonergic axon. We also demonstrate that the number of regenerated CST fibers both at the lesion and at caudal sites in treated animals was significantly greater than that in the control animals at 8 weeks. We suggest that the blocking of CNTF at the beginning of SCI provides a more favorable environment for the differentiation of transplanted NSC and the regeneration of host axons.

The involvement of dopamine (DA) in conditioned taste aversion (CTA) learning was studied with saccharin or sucrose as the conditioned stimulus (CS) and intraperitoneal lithium as the unconditioned stimulus (US). The dopamine D(1) antagonist R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH 23390) (12.5-50 microg/kg, s.c.), given 5 min after the CS, impaired the acquisition of CTA in a paradigm consisting of three or a single CS-lithium association. SCH 23390 failed to impair CTA acquisition given 45 min after, 30 min before, or right before the CS. (-)-trans-6,7,7a,8,9,13b-hexahydro-3-chloro-2-hydroxy-N-methyl-5a-benzo-(d)-naphtho-(2,1b) azepine (SCH 39166) (12.5-50.0 microg/kg, s.c), a SCH 23390 analog that does not bind to <em>5HT</em>(2) receptors, also impaired CTA. No significant impairment of CTA was obtained after administration of the specific D(2)/D(3) antagonist raclopride (100 and 300 microg/kg, s.c.). The ability of SCH 23390 to impair CTA learning was confirmed by its ability to reduce the conditional aversive reactions to a gustatory CS (sweet chocolate) as estimated in a taste reactivity paradigm. SCH 39166 impaired CTA also when infused in the nucleus accumbens (NAc) shell 5 min after the CS. No impairment was obtained from the NAc core or from the bed nucleus stria terminalis. The results indicate that D(1) receptor blockade impairs CTA learning by disrupting the formation of a short-term memory trace of the gustatory CS and that endogenous dopamine acting on D(1) receptors in the NAc shell plays a role in short-term memory processes related to associative gustatory learning.

Developmental exposure of rats to the organophosphate (OP) pesticides leads to altered neurobehavioral function in juvenile and young adult stages. The current study was conducted to determine whether effects of neonatal parathion exposure on cognitive performance persist in older adult and aged rats, and the relationship of behavioral changes to underlying cholinergic and serotonergic mechanisms. We administered parathion to rat pups on postnatal days 1-4, at doses spanning the threshold for the initial signs of systemic toxicity and for barely detectable cholinesterase inhibition (0.1 or 0.2 mg/kg/day). Beginning at 14 months of age and continuing until 19 months, the rats were trained in the 16-arm radial maze. Controls showed the normal sex difference in this spatial learning and memory task, with the males committing significantly fewer working memory errors than females. Neonatal parathion exposure eliminated the sex difference primarily by causing impairment in males. In association with the effects on cognitive performance, neonatal parathion exposure elicited widespread abnormalities in indices of serotonergic (<em>5HT</em>) and cholinergic synaptic function, characterized by upregulation of <em>5HT</em>(2) receptors and the <em>5HT</em> transporter, deficits in choline acetyltransferase activity and nicotinic cholinergic receptors, and increases in hemicholinium-3 binding to the presynaptic choline transporter. Within-animal correlations between behavior and neurochemistry indicated a specific correlation between working memory performance and hippocampal hemicholinium-3 binding; parathion exposure eliminated this relationship. Like the behavioral effects, males showed greater effects of parathion on neurochemical parameters. This study demonstrates the sex-selective, long-term behavioral alterations caused by otherwise nontoxic neonatal exposure to parathion, with effects increasingly expressed with aging.

BACKGROUND

The organophosphate chlorpyrifos (CPF) is a pesticide largely used worldwide. Studies from animal models indicate that CPF exposure during development at low doses can target different neurotransmitter systems in the absence of overt cholinergic effects.

METHODS

Late gestational exposure (gestational days 14-17) to CPF at the dose of 6 mg/kg was evaluated in CD-1 mice at adulthood. Neurobehavioural effects likely involving serotonin (5-hydroxytryptamine, <em>5HT</em>) transmission were assessed both in males and females, through the light-dark exploration test to assess CPF effects on anxiety profiles and the forced swimming test to evaluate the response to the <em>5HT</em> transporter (<em>5HT</em>T) inhibitor fluvoxamine (30 mg/kg). In females only, we evaluated the effects of gestational exposure to CPF on maternal aggression, under basal condition or after injection of fluvoxamine.

RESULTS

Gestational CPF exposure increased anxiety levels only in female mice, as shown by the augmented thigmotaxis behaviour and the lower latency to enter in the dark compartment. In the forced swimming test, no differences between CPF and control mice were found when assessed under basal condition (saline administration), but both male and female CPF mice missed to show the typical behavioural effects of the <em>5HT</em>T inhibitor fluvoxamine. During maternal aggression, CPF females showed lower propensity to and intensity of aggressive behaviour, together with mild decreased responsiveness to fluvoxamine administration.

CONCLUSIONS

Overall, the present results confirm a specific and sex-dependent vulnerability of affective/emotional domains to developmental CPF exposure. Furthermore, data provide clear indication on the disrupting effects of prenatal CPF on serotoninergic transmission.

The Conus peptides alpha-conotoxin ImI (alpha-ImI) and ImII (alpha-ImII) differ by only three of 11 residues in their primary sequences and yet are shown to inhibit the human alpha7 nicotinic acetylcholine receptor (nAChR) by targeting different sites. Mutations at both faces of the classical ligand binding site of the alpha7 nAChR strongly affect antagonism by alpha-ImI but not alpha-ImII. The effects of the mutations on alpha-ImI binding and functional antagonism are explained by computational docking of the NMR structure of alpha-ImI to a homology model of the ligand binding domain of the alpha7 nAChR. A distinct binding site for alpha-ImII is further demonstrated by its weakened antagonism for a chimeric receptor in which the membrane-spanning domains and intervening linkers of the alpha7 nAChR are replaced with the corresponding sequence from the serotonin type-3 receptor (<em>5HT</em>(3)). The two toxins also discriminate between different subtypes of human nicotinic receptors; alpha-ImII most strongly blocks the human alpha7 and alpha1beta1deltaepsilon receptor subtypes, while alpha-ImI most potently blocks the human alpha3beta2 subtype. Collectively, the data show that while alpha-ImI targets the classical competitive ligand binding site in a subtype selective manner, alpha-ImII is a probe of a novel inhibitory site in homomeric alpha7 nAChRs.

Nutrient delivery to the gut activates neuroendocrine mechanisms that control digestion and energy intake and utilisation. These include the release from enteroendocrine cells of mediators including <em>5HT</em>, CCK, GLP-1, PYY and ghrelin that act on vagal afferent neurons regulating food intake and autonomic reflexes controlling motility, secretion, inflammatory responses and mucosal defence. The mediators may act locally on vagal afferent fibres running close to their cell of origin, or distally after delivery in the circulation. Recent work indicates that the signalling mechanisms are strongly influenced by nutrient status. Thus, both food withdrawal and diet-induced obesity alter the sensitivity of vagal afferent neurons to stimulation as well as their patterns of expression of receptors and neuropeptide transmitters. Normally, leptin potentiates vagal afferent stimulation by CCK but this is lost in obesity. Recent studies suggest changes in the gut microbiota in obesity lead to increased LPS which suppresses leptin effects on vagal afferent neurons. There are obvious limitations to direct studies of vagal afferent signalling in man but recent work indicates fMRI brain imaging of CNS responses to CCK and ghrelin is feasible, informative and provides opportunities for future progress in human studies of gut-brain signalling.

OBJECTIVE

To test the hypothesis that allelic variation in <em>5HT</em>T gene-linked polymorphic region (5-HTTLPR) genotype was associated with sleep quality (Pittsburgh Sleep Quality Index, PSQI) as a main effect and as moderated by the chronic stress of caregiving. Serotonin (<em>5HT</em>) is involved in sleep regulation and the <em>5HT</em> transporter (<em>5HT</em>T) regulates <em>5HT</em> function. A common 44-base pair deletion (s allele) polymorphism in the 5-HTTLPR is associated with reduced <em>5HT</em>T transcription efficiency and <em>5HT</em> uptake in vitro.

METHODS

Subjects were 142 adult primary caregivers for a spouse or parent with dementia and 146 noncaregiver controls. Subjects underwent genotyping and completed the PSQI.

RESULTS

Variation in 5-HTTLPR genotype was not related to sleep quality as a main effect (p>> .36). However, there was a caregiver X 5-HTTLPR interaction (p < .009), such that the s allele was associated with poorer sleep quality in caregivers as compared with controls.

CONCLUSIONS

Findings suggest that the s allele may moderate sleep disturbance in response to chronic stress.

A comparison of 5-hydroxytryptamine (<em>5HT</em>)-induced contractions was made on cocaine-treated strips of bovine pulmonary arteries and large coronary arteries. The affinities of the <em>5HT</em>2 antagonist ketanserin, its metabolite ketanserinol, yohimbine and rauwolscine were estimated for both arteries. Ketanserin was a competitive antagonist of the effects of <em>5HT</em> in both arteries. The KB values (-log mol/l) were 9.5 for large coronary arteries and 9.4 for pulmonary arteries. Ketanserinol was also a competitive antagonist of the effects of <em>5HT</em> in both arteries. The KB values (-log mol/l) were 6.5 for large coronary arteries and 6.4 for pulmonary arteries. A combination of ketanserin with ketanserinol antagonized the <em>5HT</em> effects as expected from competition of the 3 drugs for a single class of receptor in both arteries. Yohimbine and rauwolscine were competitive antagonists of the effects of <em>5HT</em> in pulmonary artery. The KB-values (-log mol/l) were 6.8 for yohimbine and 6.5 for rauwolscine. A combination of ketanserin with either yohimbine or rauwolscine antagonized the <em>5HT</em> effects as expected from competition of all 4 drugs for a single class of receptors in pulmonary arteries. The evidence is consistent with the assumption that smooth muscle <em>5HT</em> receptors of both pulmonary artery and large coronary artery are of the <em>5HT</em>2 class. The reduction of the ketone of ketanserin to alcohol (i.e. ketanserinol) causes an approximately 1000-fold decrease in affinity for arterial <em>5HT</em>2 receptors. Reported peak plasma levels of ketanserinol are too low (less than or equal to 10(-7) mol/l) in humans to account for a contribution of the metabolite to the blockade of <em>5HT</em> effects by ketanserin.

Acetylcholine binding protein (AChBP) is widely considered as a functional and structural homologue of the ligand binding domain of Cys-loop receptors. We report the use of AChBP as template to identify ligands for the nicotinic receptors (nAChRs). An in silico screening protocol was set up and applied to crystal structures of AChBP. Several ligands containing a dibenzosuberyl moiety were identified and shown to bind with high affinity to AChBP and alpha7 nAChRs. Two high affinity ligands were cocrystallized with AChBP, revealing the binding mode in the orthosteric site. Functional studies revealed that these two ligands caused inhibition of the alpha7, alpha4beta2, and <em>5HT</em>(3) receptors. The noncompetive blockade of the receptors suggests that these compounds act by steric hindrance of the channel. The analysis of the dual binding mode of these dibenzosuberyl-containing compounds can lead to better understanding of the complex mode of action of similar tricyclic ligands on Cys-loop receptors.

The management of the irritable bowel syndrome (IBS) remains unsatisfactory. For abdominal pain, antispasmodics are, at best, of only modest efficacy. Tricyclic antidepressants in low dose are useful (with the number needed to treat being three), but side effects and patient concerns regarding use of a centrally acting agent for depression remain limitations. Selective serotonin reuptake inhibitors are of uncertain efficacy in IBS. Opioid agonists, especially loperamide, are useful for diarrhea but not for pain in IBS; rebound constipation also remains a problem. Bile salt sequestering agents are not of established value in IBS but seem to be useful clinically in a small group of IBS patients with diarrhea. Aloestron, a <em>5HT</em>(3) antagonist, should be reserved, if available, for women with severe diarrhea predominant IBS who have failed to respond to conventional therapy, and started at a low dose. Fiber and bulking agents may help constipation in some trials, but the evidence that they are efficacious in IBS is equivocal; they are frequently prescribed as first-line drugs for IBS regardless of the primary bowel disturbance but often increase bloating, gas, and pain. Laxatives are not of established value in IBS but are often taken by patients with constipation predominant IBS. Tegaserod, a partial <em>5HT</em>(4) agonist, is now available in the United States and other countries for use in women with IBS whose primary bowel symptom is constipation; its efficacy in men and in those with alternating bowel habits is unknown. Probiotics are of uncertain efficacy. Chinese herbal medicine data are insufficient. Other new drugs in development include the cholecystokinin antagonists and novel visceral analgesics. Both current and potential therapies for IBS are reviewed in this article.

1. Experiments were carried out in conscious, chronically instrumented, male, Sprague-Dawley rats to delineate the regional haemodynamic effects of the putative endogenous cannabinoid, anandamide, (0.075 - 3 mg kg(-1)), and to dissect some of the mechanisms involved. 2. At all doses of anandamide, there was a significant, short-lived increase in mean arterial blood pressure associated with vasoconstriction in renal, mesenteric and hindquarters vascular beds. 3. The higher doses (2.5 and 3 mg kg(-1)), caused an initial, marked bradycardia accompanied, in some animals, by a fall in arterial blood pressure which preceded the hypertension. In addition, after the higher doses of anandamide, the hindquarters vasoconstriction was followed by vasodilatation. 4. Although some of the effects described above resembled those of 5-HT (25 microg kg(-1)), the bradycardia and hypotensive actions of the latter were abolished by the <em>5HT</em>(3)-receptor antagonist, azasetron, whereas those of anandamide were generally unaffected. 5. None of the cardiovascular actions of anandamide were influenced by the CB(1)-receptor antagonist, AM 251, but its bradycardic effect was sensitive to atropine, and its hindquarters vasodilator action was suppressed by the beta(2)-adrenoceptor antagonist, ICI 118551. 6. The results differ, in several aspects, from those previously reported in anaesthetized animals, and underscore the important impact anaesthesia can have on responses to anandamide.