1
|
Mota CMD, Branco LGS, Morrison SF, Madden CJ. Systemic serotonin inhibits brown adipose tissue sympathetic nerve activity via a GABA input to the dorsomedial hypothalamus, not via 5HT 1A receptor activation in raphe pallidus. Acta Physiol (Oxf) 2020; 228:e13401. [PMID: 31599481 DOI: 10.1111/apha.13401] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 10/04/2019] [Accepted: 10/05/2019] [Indexed: 12/18/2022]
Abstract
AIM Serotonin (5-hydroxytryptamine, 5-HT), an important neurotransmitter and hormone, modulates many physiological functions including body temperature. We investigated neural mechanisms involved in the inhibition of brown adipose tissue (BAT) sympathetic nerve activity (SNA) and BAT thermogenesis evoked by 5-HT. METHODS Electrophysiological recordings, intravenous (iv) injections and nanoinjections in the brains of anaesthetized rats. RESULTS Cooling-evoked increases in BAT SNA were inhibited by the intra-rostral raphé pallidus (rRPa) and the iv administration of the 5-HT1A receptor agonist, 8-OH-DPAT or 5-HT. The intra-rRPa 5-HT, the intra-rRPa and the iv 8-OH-DPAT, but not the iv 5-HT-induced inhibition of BAT SNA were prevented by nanoinjection of a 5-HT1A receptor antagonist in the rRPa. The increase in BAT SNA evoked by nanoinjection of NMDA in the rRPa was not inhibited by iv 5-HT, indicating that iv 5-HT does not inhibit BAT SNA by acting in the rRPa or in the sympathetic pathway distal to the rRPa. In contrast, under a warm condition, blockade of 5HT1A receptors in the rRPa increased BAT SNA and BAT thermogenesis, suggesting that endogenous 5-HT in the rRPa contributes to the suppression of BAT SNA and BAT thermogenesis. The increases in BAT SNA and BAT thermogenesis evoked by nanoinjection of NMDA in the dorsomedial hypothalamus (DMH) were inhibited by iv 5-HT, but those following bicuculline nanoinjection in the DMH were not inhibited. CONCLUSIONS The systemic 5-HT-induced inhibition of BAT SNA requires a GABAergic inhibition of BAT sympathoexcitatory neurones in the DMH. In addition, during warming, 5-HT released endogenously in rRPa inhibits BAT SNA.
Collapse
Affiliation(s)
- Clarissa M. D. Mota
- Department of Neurological Surgery Oregon Health and Science University Portland OR USA
- Department of Physiology School of Medicine of Ribeirão Preto University of São Paulo Ribeirão Preto Brazil
| | - Luiz G. S. Branco
- Department of Physiology School of Medicine of Ribeirão Preto University of São Paulo Ribeirão Preto Brazil
- Department of Morphology, Physiology, and Basic Pathology School of Dentistry of Ribeirão Preto University of São Paulo Ribeirão Preto Brazil
| | - Shaun F. Morrison
- Department of Neurological Surgery Oregon Health and Science University Portland OR USA
| | - Christopher J. Madden
- Department of Neurological Surgery Oregon Health and Science University Portland OR USA
| |
Collapse
|
2
|
Sattin JA, Login IS. Buspirone Challenge is not a valid Probe of Central 5-HT1A Receptor Function. Cephalalgia 2016; 24:510; author reply 511-2. [PMID: 15154863 DOI: 10.1111/j.1468-2982.2004.715_1.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|
3
|
|
4
|
O'Mahony S, Chua ASB, Quigley EMM, Clarke G, Shanahan F, Keeling PWN, Dinan TG. Evidence of an enhanced central 5HT response in irritable bowel syndrome and in the rat maternal separation model. Neurogastroenterol Motil 2008; 20:680-8. [PMID: 18194152 DOI: 10.1111/j.1365-2982.2007.01065.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Efforts to define either a biomarker for irritable bowel syndrome (IBS) or a valid animal model have proven disappointing. The aims of this study were to determine if buspirone stimulates prolactin release through the 5-hydroxytryptamine (5HT)1a receptor and whether this response is altered in patients with IBS and in the rat maternal separation model. Buspirone (30 mg) was used to stimulate prolactin release in 40 patients with IBS and in 40 healthy controls. In study 1, 10 IBS patients and 10 controls underwent pretreatment with pindolol (5HT1a antagonist) or placebo followed by buspirone. In study 2, 30 patients with IBS and 30 healthy controls had prolactin release stimulated by buspirone. Maternally separated and nonseparated rats were also treated with buspirone and prolactin monitored. Serotonin metabolites were measured together with the expression of the 5HT1a and serotonin transporter (SERT) gene. Pindolol produced a dose-dependent decrease in the buspirone prolactin response. Patients with IBS and maternally separated rats showed an exaggerated release of prolactin in response to buspirone. In the animal model, an increased turnover of 5HT was found in the brainstem together with a trend toward increased activity of the SERT gene. In conclusion altered central serotonin responses are found in both IBS and in an animal model.
Collapse
Affiliation(s)
- S O'Mahony
- Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
| | | | | | | | | | | | | |
Collapse
|
5
|
Zuideveld KP, Van der Graaf PH, Peletier LA, Danhof M. Allometric Scaling of Pharmacodynamic Responses: Application to 5-Ht1A Receptor Mediated Responses from Rat to Man. Pharm Res 2007; 24:2031-9. [PMID: 17541734 DOI: 10.1007/s11095-007-9336-y] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Accepted: 05/03/2007] [Indexed: 11/26/2022]
Abstract
PURPOSE The aim of the present study was to assess whether two widely used biomarkers for 5-HT(1A)-receptor mediated responses in the rat (hypothermia and corticosterone increase) could be scaled to man using allometric principles. MATERIALS AND METHODS Mechanism-based pharmacokinetic-pharmacodynamic (PK-PD) models were developed and characterized in rats for the standard 5-HT(1A)-receptor agonists, buspirone and flesinoxan. Allometric scaling was investigated on the basis of simulation taking into account the inter-individual variability and clinical study design. The model-predicted effects of both flesinoxan and buspirone were compared to those published in the literature. RESULTS The main finding of this analysis was that for both hypothermia and cortisol increase, the model could predict the extent of the pharmacological response in man adequately. For the hypothermic response, the time course of the response was also predicted with a high degree of accuracy. In contrast, in the case of the cortisol response, the observed time lag was, despite the fact that it fell within the model uncertainty, not predicted. CONCLUSIONS Based on these analyses, it is concluded that allometrically scaled mechanism based PK-PD models are promising as a means of predicting the pharmacodynamic responses in man. This approach provides for a novel way of interpreting and scaling pre-clinical pharmacological responses and ultimately facilitates the understanding and prediction of pharmacological responses in man.
Collapse
Affiliation(s)
- Klaas P Zuideveld
- Leiden/Amsterdam Center for Drug Research, Division of Pharmacology, Gorlaeus Laboratory, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
| | | | | | | |
Collapse
|
6
|
Cassidy EM, Hardiman O, Dinan T, O'Keane V. Authors' reply. Cephalalgia 2004. [DOI: 10.1111/j.1468-2982.2004.715_2.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
7
|
Pitchot W, Wauthy J, Legros JJ, Ansseau M. Hormonal and temperature responses to flesinoxan in normal volunteers: an antagonist study. Eur Neuropsychopharmacol 2004; 14:151-5. [PMID: 15013031 DOI: 10.1016/s0924-977x(03)00108-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2002] [Revised: 07/01/2003] [Accepted: 07/01/2003] [Indexed: 11/22/2022]
Abstract
RATIONALE Flesinoxan is a highly potent and selective 5-HT1A agonist. In a recent study, in normal volunteers, flesinoxan induced a significant and dose-dependent increase in adrenocorticotropic hormone (ACTH), cortisol, prolactin (PRL), growth hormone (GH) and a decrease in body temperature. OBJECTIVES In order to better define the role of 5-HT receptor subtypes in response to flesinoxan, we assessed the influence of 5-HT1A and 5-HT2 antagonists on hormonal and temperature responses to flesinoxan. METHODS Hormonal and temperature responses were studied in 6 volunteers with or without pretreatment with pindolol (30 mg p.o.), a 5-HT1A antagonist, or ritanserin (10 mg p.o.), a selective 5-HT2 antagonist, using a double-blind crossover design. RESULTS Pindolol significantly antagonized ACTH, PRL, GH and temperature responses to flesinoxan and ritanserin exhibited similar activity on PRL and ACTH responses. CONCLUSIONS These results show the role of 5-HT1A mechanisms in the PRL, ACTH, GH, and temperature responses to flesinoxan, and the role of 5-HT2 mechanisms in PRL and ACTH responses. Therefore, they confirm the interest of flesinoxan as a 5-HT neuroendocrine probe.
Collapse
|
8
|
Bridge MW, Weller AS, Rayson M, Jones DA. Responses to exercise in the heat related to measures of hypothalamic serotonergic and dopaminergic function. Eur J Appl Physiol 2003; 89:451-9. [PMID: 12684806 DOI: 10.1007/s00421-003-0800-z] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2003] [Indexed: 12/01/2022]
Abstract
We have studied 12 recreationally active men to measure their responses to exercise in the heat and relate these to measures of hypothalamic function explored with a buspirone [5-hydroxytryptamine 1A (5-HT(1A)) agonist, dopaminergic D(2) antagonist] neuroendocrine challenge, with and without pretreatment with pindolol (5-HT(1A) antagonist). Pindolol treatment allowed the serotonergic and non-serotonergic components of prolactin release to be distinguished. Subjects exercised at 73 (5)% maximal rate of oxygen uptake (VO(2max)) until volitional fatigue at 35 degrees C (relative humidity, 30%). On another two occasions they underwent a buspirone challenge [0.5 mg (kg body mass)(-1)], once with, and once without, pindolol [0.5 mg (kg body mass)(-1)] pretreatment and the circulating plasma concentrations of prolactin were measured for the next 2.5 h. Rectal temperature increased throughout exercise, whilst mean skin temperature remained constant. There was a wide inter-subject variation in prolactin response to the neuroendocrine challenges. The proportion of the prolactin response to buspirone attributable to a non-serotonergic component (most likely dopaminergic) correlated both with exercise duration (r=0.657, P=0.028), rectal temperature at fatigue (r=0.623, P=0.041) and the rate of temperature rise (r=-0.669, P=0.024). Our results suggest that high activity of the dopaminergic pathways in the hypothalamus is a predictor of exercise tolerance in the heat.
Collapse
Affiliation(s)
- Mathew W Bridge
- School of Sport and Exercise Sciences, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | | | | | | |
Collapse
|
9
|
McAllister-Williams RH, Massey AE. EEG effects of buspirone and pindolol: a method of examining 5-HT1A receptor function in humans. Psychopharmacology (Berl) 2003; 166:284-93. [PMID: 12589521 DOI: 10.1007/s00213-002-1339-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2002] [Accepted: 11/05/2002] [Indexed: 10/20/2022]
Abstract
RATIONALE An involvement of 5-HT(1A) receptors is postulated in the pathophysiology of affective disorders and mechanism of action of antidepressants. Methods for studying their functional integrity in humans are, however, limited. Preliminary data suggests that activation of somatodendritic 5-HT(1A) receptors cause a negative shift in the EEG frequency spectrum. Animal research suggests that pindolol is an agonist at these receptors but an antagonist at postsynaptic 5-HT(1A) receptors. OBJECTIVE We postulated that while pindolol would antagonise known postsynaptic mediated neuroendocrine responses to the 5-HT(1A) agonist buspirone, both drugs would have a similar effect on the EEG frequency spectrum. METHODS Fourteen healthy men were administered placebo or pindolol (20 mg orally) 90 min before placebo or buspirone (30 mg orally) in a double blind cross-over study. Plasma prolactin and growth hormone were assayed and EEGs recorded before and after drug administration. RESULTS A significant negative shift in the EEG frequency spectrum was found for both buspirone and pindolol, with the combination producing a similar effect to each drug alone. In contrast, the neuroendocrine response to buspirone was significantly attenuated by pindolol. CONCLUSIONS The data obtained are consistent with the EEG effects of buspirone and pindolol being mediated by somatodendritic 5-HT(1A) receptors, in contrast to the neuroendocrine response, which is known to be mediated by postsynaptic receptors. The development of this novel method of assessing somatodendritic 5-HT(1A) receptors in humans is a potentially important advance which may allow the testing of hypotheses of its involvement in depression and response to antidepressants.
Collapse
Affiliation(s)
- R H McAllister-Williams
- Psychobiology Research Group, School of Neurology, Neurobiology and Psychiatry, University of Newcastle, NE1 4LP, Newcastle upon Tyne, UK.
| | | |
Collapse
|
10
|
Cassidy EM, Tomkins E, Sharifi N, Dinan T, Hardiman O, O'Keane V. Differing central amine receptor sensitivity in different migraine subtypes? A neuroendocrine study using buspirone. Pain 2003; 101:283-290. [PMID: 12583871 DOI: 10.1016/s0304-3959(02)00335-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Despite the importance of the 5HT1A receptor in regulating central serotonergic tone, there is a dearth of research examining its role in migraine. In this study, we examined the hypothesis that there would be altered neuroendocrine responses to a 5HT1A agonist challenge in different migraine subtypes. Prolactin (PRL) responses to the 5HT1A receptor agonist drug buspirone were compared in 30 female subjects with migraine (ten migraine with aura, MA; ten migraine without aura, MO and ten chronic/transformed migraine, CM), and ten healthy controls matched for age, gender and menstrual status. None of the subjects were taking psychotropic medication or migraine prophylactic treatment and those with formal psychiatric disorder were excluded. Endocrine responses were determined by measuring differences between baseline PRL and maximum increases post-buspirone (deltaPRL). There was no difference in baseline PRL between groups. MA subjects did not differ in their PRL responses to buspirone compared to healthy controls. The MO group had a four-fold increase in mean deltaPRL responses compared to healthy controls. Mean deltaPRL was also increased in the CM group compared to controls, but the difference was less exaggerated. This study indicates that there is supersensitive central amine receptor function in MO and CM, but not in MA. These findings support the hypothesis that central 5HT function differs among the migraine subtypes. The results also suggest that migrainous 'transformation' may be associated with adaptive changes in central 5HT receptor sensitivity. The relative contribution of 'state' and 'trait' receptor function to these findings as well as the possible role of dopamine receptors is discussed.
Collapse
Affiliation(s)
- Eugene M Cassidy
- Migraine/Headache Clinic, Department of Neurology, Royal College of Surgeons in Ireland, Beaumont hospital, Dublin 9, Ireland Department of Psychiatry, Royal College of Surgeons in Ireland, Beaumont hospital, Dublin 9, Ireland Department of Endocrinology, Royal College of Surgeons in Ireland, Beaumont hospital, Dublin 9, Ireland Department of Clinical Pharmacology, Cork University hospital, Cork, Ireland
| | | | | | | | | | | |
Collapse
|
11
|
Cassidy EM, Tomkins E, Dinan T, Hardiman O, O'Keane V. Central 5-HT receptor hypersensitivity in migraine without aura. Cephalalgia 2003; 23:29-34. [PMID: 12534577 DOI: 10.1046/j.1468-2982.2003.00441.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Serotonin has long been implicated as a key neurotransmitter in migraine. There is a dearth of research specifically examining 5-HT1A receptor sensitivity in migraine despite the importance of this receptor in regulating central serotonergic tone. In this study we examined the hypothesis that migraine without aura is associated with hypersensitivity of central 5-HT1A receptors, using a 5-HT1A neuroendocrine challenge drug and comparing serum prolactin responses between a test group with migraine and a matched group of healthy controls. Twelve female subjects fulfilling International Headache Society (IHS) criteria for migraine without aura were evaluated. Following an overnight fast, subjects presented for testing at 9am. An intravenous canula was inserted and serum prolactin was assessed at baseline and every 30 min for 3 h following a single dose of 30 mg oral buspirone, a 5-HT1A-receptor agonist. Subjects were assessed during the first 5 days of the menstrual cycle. No subjects were taking psychotropic medication or migraine prophylactic treatment. Patients with current or previous psychiatric disorder, daily headache or analgesic overuse were excluded. 16 healthy female volunteers matched for age and menstrual status were also evaluated and served as controls. There was no difference in baseline prolactin between groups. There was a significant rise in prolactin following buspirone in both groups. Subjects with migraine had a significantly increased prolactin response to buspirone (delta max) compared to controls (P < 0.001). This study supports the hypothesis that migraine without aura is associated with a relative hypersensitivity of central 5-HT1A receptors. This is of relevance given the role of the 5-HT1A receptor in controlling raphe 5-HT tone and in the possible association between migraine and anxiety and depression.
Collapse
Affiliation(s)
- E M Cassidy
- Migraine/Headache Clinic, Department of Neurology, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin, Ireland.
| | | | | | | | | |
Collapse
|
12
|
Sobczak S, Honig A, van Duinen MA, Riedel WJ. Serotonergic dysregulation in bipolar disorders: a literature review of serotonergic challenge studies. Bipolar Disord 2002; 4:347-56. [PMID: 12519094 DOI: 10.1034/j.1399-5618.2002.01217.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVES Serotonin (5-hydroxytryptamine; 5-HT) and endocrine abnormalities have been repeatedly reported in bipolar disorders (BD). Useful methods to investigate 5-HT responsivity, and the interaction with neuroendocrine functioning, are provided by acute 5-HT challenge and depletion paradigms. In this review 5-HT challenges are limited to paradigms that stimulate 5-HT activity in BD. METHODS Literature was searched for in electronic libraries: MEDLINE and PSYCHLIT, period 1966-2001. Papers describing effects of an acute 5-HT challenge on neuroendocrine functioning in BD patients were selected. RESULTS Review of the literature revealed 15 studies: five papers described the effects of 5-HT challenges in manic BD patients, four papers in euthymic BD and seven in depressed BD patients. The reviewed 5-HT challenge paradigms are acute administration of oral and intravenous (i.v.) dosage of d,l-fenfluramine, tryptophan, 5-hydroxytryptophan, ipsapirone and buspirone. There were no papers which investigated neuroendocrine effects of m-chlorophenylpiperazine, clomipramine and citalopram in BD patients and were therefore not reviewed. CONCLUSIONS The literature on 5-HT challenge procedures in BD shows evidence for a blunted prolactin (PRL) in mania and depression as well as a blunted cortisol in euthymic BD patients. This suggests that in both mania and depression similar changes in the 5-HT system are involved. It is speculated that blunting of cortisol responses in euthymic BD patients may be a result of chronically altered 5-HT functioning, whereas changes in PRL release following 5-HT challenges reflect more state-dependent changes in 5-HT activity. The 5-HT responsivity in BD patients has also been associated with pharmacological treatment, suicidal behaviour, weight loss and age. Recommendations for future research are given.
Collapse
Affiliation(s)
- S Sobczak
- Brain and Behavior Institute, Department of Psychiatry, Academic Hospital Maastricht (AZM), University of Maastricht, The Netherlands
| | | | | | | |
Collapse
|
13
|
Grasby PM, Friston KJ, Bench CJ, Frith CD, Paulesu E, Cowen PJ, Liddle PF, Frackowiak RS, Dolan R. The effect of apomorphine and buspirone on regional cerebral blood flow during the performance of a cognitive task-measuring neuromodulatory effects of psychotropic drugs in man. Eur J Neurosci 2002; 4:1203-12. [PMID: 12106383 DOI: 10.1111/j.1460-9568.1992.tb00145.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Psychopharmacological activation, in conjunction with positron emission tomographic measurements of regional cerebral blood flow (rCBF), was used to investigate the neurotransmitter basis of a specific cognitive function in man. Monoaminergic neurotransmission was pharmacologically manipulated during performance of auditory - verbal memory tasks. Statistical parametric mapping was used to identify the brain sites of interaction between memory-induced increases in rCBF and active drugs. Memory task-induced increases in rCBF in the left prefrontal cortex were attenuated by apomorphine, a non-selective dopamine agonist, whilst buspirone, a serotonin1A partial agonist, augmented rCBF increases in this area. In addition, apomorphine and buspirone augmented memory-induced increases in rCBF centred in the posterior cingulate cortex, whilst buspirone alone attenuated rCBF increases in the retrosplenial cortex and posterior parahippocampal gyrus. These regionally selective interactions may represent neuromodulatory effects of monoaminergic neurotransmission on a specific cognitive function in man.
Collapse
Affiliation(s)
- P M Grasby
- MRC Cyclotron Unit, Hammersmith Hospital, DuCane Road, London W12 0HS, UK
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Zuideveld KP, Maas HJ, Treijtel N, Hulshof J, van der Graaf PH, Peletier LA, Danhof M. A set-point model with oscillatory behavior predicts the time course of 8-OH-DPAT-induced hypothermia. Am J Physiol Regul Integr Comp Physiol 2001; 281:R2059-71. [PMID: 11705793 DOI: 10.1152/ajpregu.2001.281.6.r2059] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Agonists for the 5-hydroxytryptamine (HT)(1A) receptor induce a hypothermic response that is believed to occur by lowering of the body's set-point temperature. We have developed a physiological model that can be used to predict the complex time course of the hypothermic response after administration of 5-HT(1A) agonists to rats. In the model, 5-HT(1A) agonists exert their effect by changing heat loss through a control mechanism with a thermostat signal that is proportional to the difference between measured and set-point temperature. Agonists exert their effect in a direct concentration-dependent manner, with saturation occurring at higher concentrations. On the basis of simulations, it is shown that, depending on the concentration and the intrinsic efficacy of a 5-HT(1A) agonist, the model shows oscillatory behavior. The model was successfully applied to characterize the complex hypothermic response profiles after administration of the reference 5-HT(1A) agonists R-8-hydroxy-2-(di-n-propylamino)tetralin (R-8-OH-DPAT) and S-8-OH-DPAT. This analysis revealed that the observed difference in effect vs. time profile for these two reference agonists could be explained by a difference in in vivo intrinsic efficacy.
Collapse
Affiliation(s)
- K P Zuideveld
- Sylvius Laboratory, Division of Pharmacology, Leiden/Amsterdam Center for Drug Research, 2300 RA Leiden, The Netherlands
| | | | | | | | | | | | | |
Collapse
|
15
|
Rabiner EA, Gunn RN, Wilkins MR, Sargent PA, Mocaer E, Sedman E, Cowen PJ, Grasby PM. Drug action at the 5-HT(1A) receptor in vivo: autoreceptor and postsynaptic receptor occupancy examined with PET and [carbonyl-(11)C]WAY-100635. Nucl Med Biol 2000; 27:509-13. [PMID: 10962259 DOI: 10.1016/s0969-8051(00)00120-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Serotonin(1A) (5-HT(1A)) receptors have been implicated in the pathophysiology and treatment of anxiety and depression and are a target for novel drug development. In this qualitative study, positron emission tomography (PET) and [carbonyl-(11)C]WAY-100635 were used to assess 5-HT(1A) autoreceptor and postsynaptic receptor occupancy in man in vivo by five different compounds with nanomolar affinity for this site. Occupancy by pindolol, penbutolol, buspirone, EMD 68843, and S 15535 was compared to test-retest data from 10 healthy volunteers. All drugs, apart from buspirone, displayed occupancy at the 5-HT(1A) receptor site. Pindolol demonstrated a preferential occupancy at the autoreceptor compared to the postsynaptic receptor over a plasma range of about 10-20 ng/mL. Differential occupancy may be an important component of novel drug action. The level of autoreceptor or postsynaptic occupancy needed to achieve significant physiological effects is not known, although it is of note that none of the drugs in this study achieved occupancies beyond 60%. Overall this study demonstrates the utility of PET in aiding novel drug development.
Collapse
Affiliation(s)
- E A Rabiner
- MRC Cyclotron Unit, Hammersmith Hospital, Imperial College School of Medicine, London, United Kingdom.
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Abstract
Selective serotonin (5-HT) reuptake inhibitors (SSRIs) are effective drugs for the treatment of several neuropsychiatric disorders associated with reduced serotonergic function. Serotonergic neurons play an important role in the regulation of neuroendocrine function. This review will discuss the acute and chronic effects of SSRIs on neuroendocrine function. Acute administration of SSRIs increases the secretion of several hormones, but chronic treatment with SSRIs does not alter basal blood levels of hormones. However, adaptive changes are induced by long-term treatment with SSRIs in serotonergic, noradrenergic and peptidergic neural function. These adaptive changes, particularly in the function of specific post-synaptic receptor systems, can be examined from altered adrenocorticotrophic hormone (ACTH), cortisol, oxytocin, vasopressin, prolactin, growth hormone (GH) and renin responses to challenges with specific agonists. Neuroendocrine challenge tests both in experimental animals and in humans indicate that chronic SSRIs produce an increase in serotonergic terminal function, accompanied by desensitization of post-synaptic 5-HT1A receptor-mediated ACTH, cortisol, GH and oxytocin responses, and by supersensitivity of post-synaptic 5-HT2A (and/or 5-HT2C) receptor-mediated secretion of hormones. Chronic exposure to SSRIs does not alter the neuroendocrine stress-response and produces inconsistent changes in alpha2 adrenoceptor-mediated GH secretion. Overall, the effects of SSRIs on neuroendocrine function are dependent on adaptive changes in specific neurotransmitter systems that regulate the secretion of specific hormones.
Collapse
Affiliation(s)
- D K Raap
- Department of Pharmacology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153, USA
| | | |
Collapse
|
17
|
Olivier B, Soudijn W, van Wijngaarden I. The 5-HT1A receptor and its ligands: structure and function. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1999; 52:103-65. [PMID: 10396127 DOI: 10.1007/978-3-0348-8730-4_3] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
An overview is presented on progress made in research on 5-HT1A receptors and their ligands since their discovery in 1983. Molecular biology has offered new tools, for example cloned 5-HT1A receptors, their mutants and chimeras to study structure and function. Many compounds, belonging to different chemical classes, display high affinity and selectivity for 5-HT1A receptors. The majority of these compounds are agonists or partial agonists, full antagonists are still scarce. Agonists and partial agonists are active in various animal models of anxiety and depression. Partial receptor agonists have been proven to be effective in general anxiety disorder and depression in man. Potential therapeutic applications for 5-HT1A receptor antagonists are evaluated, for example, in cognition disorders.
Collapse
Affiliation(s)
- B Olivier
- Dept. of Psychopharmacology, Faculty of Pharmacy, Utrecht University, The Netherlands
| | | | | |
Collapse
|
18
|
Schwartz PJ, Turner EH, Garcia-Borreguero D, Sedway J, Vetticad RG, Wehr TA, Murphy DL, Rosenthal NE. Serotonin hypothesis of winter depression: behavioral and neuroendocrine effects of the 5-HT(1A) receptor partial agonist ipsapirone in patients with seasonal affective disorder and healthy control subjects. Psychiatry Res 1999; 86:9-28. [PMID: 10359479 DOI: 10.1016/s0165-1781(99)00017-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Winter depressions in seasonal affective disorder (SAD) are associated with central serotonergic (5-HT) dysfunction. SAD patients demonstrate rather specific, state-dependent, abnormal increases in 'activation-euphoria' ratings following intravenous infusion of the 5-HT receptor agonist meta-chlorophenylpiperazine (m-CPP). Several studies are also consistent with abnormal serotonergic regulation of the hypothalamic-pituitary-adrenal (HPA) axis in SAD. Here, we investigated the effects of the 5-HT1A receptor partial agonist ipsapirone, which produces behavioral effects and HPA-axis activation, to further characterize the 5-HT receptor subtype-specificity of these disturbances in SAD. Eighteen SAD patients and 18 control subjects completed two drug challenges (ipsapirone 0.3 mg/kg and placebo) separated by 3-5 days in randomized order. We measured behavioral responses with the NIMH self-rating scale, and plasma ACTH, cortisol, and prolactin concentrations. Compared with placebo, ipsapirone was associated with significant increases in self-rated 'functional deficit' and 'altered self-reality', and in each of the hormones. There were no differences between groups on any measures. The level of depression in SAD patients was inversely correlated with their ipsapirone-induced cortisol responses. There were significant drug x order effects on baseline 'anxiety' scores, ACTH and cortisol concentrations, such that subjects were significantly more stressed (higher 'anxiety', ACTH and cortisol) prior to their first challenge compared with their second. In conclusion, post-synaptic 5-HT1A receptors appear to function normally in SAD. The previously observed m-CPP-induced behavioral abnormality may be mediated by either 5-HT2C or 5-HT7 receptors.
Collapse
Affiliation(s)
- P J Schwartz
- University of Cincinnati College of Medicine, Department of Psychiatry and VAMC, OH, USA.
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Pecins-Thompson M, Bethea CL. Ovarian steroid regulation of serotonin-1A autoreceptor messenger RNA expression in the dorsal raphe of rhesus macaques. Neuroscience 1999; 89:267-77. [PMID: 10051234 DOI: 10.1016/s0306-4522(98)00326-1] [Citation(s) in RCA: 120] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
It is widely hypothesized that ovarian steroids act on serotonin neurons to modulate mood and alter neuroendocrine function in women. However, information is needed on the molecular consequences of estrogen and progesterone action in serotonin neurons. This study examined the effect of estrogen, with and without progesterone, on the expression of messenger RNA for the serotonin-1A autoreceptor in monkeys using in situ hybridization and a 432-bp serotonin-1A probe generated with polymerase chain reaction. Monkeys were spayed/ovariectomized (control; n=4), estrogen treated (28 days, n=4) and estrogen+progesterone treated (14 days estrogen+14 days estrogen+progesterone, n=4). Perfusion-fixed midbrain sections containing the dorsal raphe (10 microm) were hybridized at 60 degrees C with 35S antisense complementary RNA. After a final wash in 0.1 x standard saline citrate at 70 degrees C, sections were apposed to betamax film for four days and then emulsion fixed. Adjacent sections were immunostained for serotonin to confirm the location of the dorsal raphe. Densitometric analysis of autoradiographs with gray level thresholding was performed at five levels of the dorsal raphe. The number of pixels exceeding background in defined areas was obtained (pixel number), as well as the mean optical density. In the estrogen- and the estrogen+progesterone-treated groups compared to the control group, there was a 38% and 43% decrease in serotonin-1A messenger RNA signal, respectively, represented by pixel number (P<0.05). Mean optical density for serotonin-1A was significantly decreased by estrogen treatment (21%; P<0.05) and then further decreased with the addition of progesterone treatment (45%; P<0.01). Also, the number of positive cells and the grains/cell were counted. There were significantly fewer serotonin-1A messenger RNA-positive cells in the serotonergic neurons of the dorsal raphe in estrogen- and estrogen+progesterone-treated groups (P<0.001) than controls. There were significantly lower single-cell levels of serotonin-1A messenger RNA in serotonergic neurons of the dorsal raphe only in the estrogen+progesterone-treated group (P<0.05). These results suggest that estrogen reduces serotonin-1A gene expression and that the addition of progesterone further reduces serotonin-1A gene expression in non-human primates. If the changes in gene expression are manifested by alterations in protein expression, then, together, these actions of estrogen and progesterone could increase serotonin neurotransmission, thereby elevating mood and/or altering neuroendocrine functions.
Collapse
Affiliation(s)
- M Pecins-Thompson
- Division of Reproductive Science, Oregon Regional Primate Research Center, Beaverton 97006, USA
| | | |
Collapse
|
20
|
Clifford EM, Gartside SE, Umbers V, Cowen PJ, Hajós M, Sharp T. Electrophysiological and neurochemical evidence that pindolol has agonist properties at the 5-HT1A autoreceptor in vivo. Br J Pharmacol 1998; 124:206-12. [PMID: 9630361 PMCID: PMC1565357 DOI: 10.1038/sj.bjp.0701796] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
1. It has been hypothesized that 5-HT1A autoreceptor antagonists may enhance the therapeutic efficacy of SSRIs and other antidepressants. Although early clinical trials with the beta-adrenoceptor/5-HT1 ligand, pindolol, were promising, the results of recent more extensive trials have been contradictory. Here we investigated the actions of pindolol at the 5-HT1A autoreceptor by measuring its effect on 5-HT neuronal activity and release in the anaesthetized rat. 2. Pindolol inhibited the electrical activity of 5-HT neurones in the dorsal raphe nucleus (DRN). This effect was observed in the majority of neurones tested (10/16), was dose-related (0.2-1.0 mg kg(-1), i.v.), and was reversed by the 5-HT1A receptor antagonist, WAY 100635 (0.1 mg kg(-1), i.v.), in 6/7 cases tested. 3. Pindolol also inhibited 5-HT neuronal activity when applied microiontophoretically into the DRN in 9/10 neurones tested. This effect of pindolol was current-dependent and blocked by co-application of WAY 100635 (3/3 neurones tested). 4. In microdialysis experiments. pindolol caused a dose-related (0.8 and 4 mg kg(-1), i.v.) fall in 5-HT levels in dialysates from the frontal cortex (under conditions where the perfusion medium contained 1 microM citalopram). In rats pretreated with WAY 100635 (0.1 mg kg(-1), i.v.), pindolol (4 mg kg(-1), i.v.) did not decrease, but rather increased 5-HT levels. 5. We conclude that, under the experimental conditions used in this study, pindolol displays agonist effects at the 5-HT1A autoreceptor. These data are relevant to previous and ongoing clinical trials of pindolol in depression which are based on the rationale that the drug is an effective 5-HT1A autoreceptor antagonist.
Collapse
Affiliation(s)
- E M Clifford
- University Department of Clinical Pharmacology, Radcliffe Infirmary, Oxford
| | | | | | | | | | | |
Collapse
|
21
|
Sharpe M, Clements A, Hawton K, Young AH, Sargent P, Cowen PJ. Increased prolactin response to buspirone in chronic fatigue syndrome. J Affect Disord 1996; 41:71-6. [PMID: 8938208 DOI: 10.1016/0165-0327(96)00075-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We studied the endocrine and subjective responses that followed acute administration of the 5-HT1A receptor agonist buspirone (0.5 mg/kg orally) in 11 male patients with chronic fatigue syndrome (CFS) and a group of matched healthy controls. Patients with CFS had significantly higher plasma prolactin concentrations and experienced more nausea in response to buspirone than did controls. However, the growth hormone response to buspirone did not distinguish CFS patients from controls. Our data question whether the enhancement of buspirone-induced prolactin release in CFS is a consequence of increased sensitivity of post-synaptic 5-HT1A receptors. It is possible that the increased prolactin response to buspirone in CFS could reflect changes in dopamine function.
Collapse
Affiliation(s)
- M Sharpe
- University Department of Psychiatry, Warneford and Littlemore Hospitals, Oxford, UK
| | | | | | | | | | | |
Collapse
|
22
|
Meltzer HY, Maes M. Effect of pindolol on hormone secretion and body temperature: partial agonist effects. J Neural Transm (Vienna) 1996; 103:77-88. [PMID: 9026379 DOI: 10.1007/bf01292618] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Pindolol has been shown to be a partial agonist at 5-HT1A receptors in preclinical studies. It has also been reported to inhibit the effects of other 5-HT1A partial agonists such as ipsapirone and buspirone on hormone secretion and body temperature in man, indicating its antagonist action at 5-HT1A receptors in man. To determine if pindolol has 5-HT1A agonist as well as antagonist effects in man, pindolol, 30 mg, p.o. and placebo, were given single blind in random order to 23 normal men with indwelling venous catheters and its effects on hormone secretion and body temperature noted. Pindolol significantly increased basal plasma cortisol concentrations, whereas it decreased plasma prolactin (PRL) concentrations and body temperature. The increase in plasma cortisol due to pindolol suggests a 5-HT1A agonist action and is consistent with a 5-HT1A partial agonist mechanism in man whereas the PRL effects are consistent with an antagonist action at 5-HT1A receptors. The effects of pindolol on plasma cortisol concentration and body temperature were significantly negatively correlated. Furthermore, these results indicate significant differences in the 5-HT1A-dependent regulation of PRL and the hypothalamo-pituitary-adrenal (HPA) axis and body temperature, and suggest that human basal PRL secretion is tonically stimulated by 5-HT1A mechanism whereas the HPA axis and body temperature are not. Since rodent studies suggest differences in 5-HT1A receptor sensitivity between males and females, the results reported here need to be replicated in females. These differences in the effect of pindolol are discussed in terms of receptor reserve theory.
Collapse
Affiliation(s)
- H Y Meltzer
- Department of Psychiatry, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | | |
Collapse
|
23
|
Meltzer HY, Maes M. Pindolol pretreatment blocks stimulation by meta-chlorophenylpiperazine of prolactin but not cortisol secretion in normal men. Psychiatry Res 1995; 58:89-98. [PMID: 8570772 DOI: 10.1016/0165-1781(95)02701-w] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Previous reports from this laboratory have shown that pindolol, a partial serotonin1A receptor agonist, inhibited prolactin, but not cortisol secretion induced by administration of the serotonin (5-HT) precursor L-5-hydroxytryptophan or the direct-acting 5-HT2A/5HT2C receptor agonist MK-212. The findings suggest additive or interactive effects of 5-HT1A and 5-HT2A/5-HT2C receptors in modulating 5-HT-related prolactin, but not cortisol, responsivity. To examine further the role of 5-HT1A and 5-HT2A/5-HT2C receptors in prolactin and cortisol secretion in healthy men, the effects of meta-chlorophenylpiperazine (mCPP), a potent 5-HT receptor agonist, on the above hormones were studied in eight healthy men with and without pindolol pretreatment. It has previously been demonstrated that ketanserin, a 5-HT2A antagonist, and ritanserin, a 5-HT2A/5-HT2C antagonist, block the prolactin and attenuate the hypothalamic-pituitary-adrenal axis responses to mCPP in man or rodents. Administration of mCPP induced a significant increase in plasma concentrations of prolactin and cortisol. The mCPP-induced prolactin concentrations were significantly blocked by pretreatment with pindolol, whereas mCPP-stimulated cortisol levels were not diminished by pindolol pretreatment. Thus, mCPP-induced prolactin secretion appears to require the availability of both 5-HT2C and 5-HT1A receptor activation, since blockade of either of these receptors may diminish the mCPP-induced prolactin response. Cortisol secretion stimulated by mCPP may occur following 5-HT2C receptor stimulation in the presence of 5-HT1A receptor blockade.
Collapse
Affiliation(s)
- H Y Meltzer
- Department of Psychiatry, Case Western Reserve University, School of Medicine, University Hospitals of Cleveland, OH 44106, USA
| | | |
Collapse
|
24
|
Meltzer HY, Maes M. Effect of pindolol pretreatment on MK-212-induced plasma cortisol and prolactin responses in normal men. Biol Psychiatry 1995; 38:310-8. [PMID: 7495925 DOI: 10.1016/0006-3223(95)00301-v] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Previous reports based on studies with serotonin (5-HT) precursors or direct acting agonists have suggested that postsynaptic 5-HT1A and 5-HT2A/5-HT2C receptors may stimulate cortisol and prolactin (PRL) secretion in man. To further clarify the role of these receptors in the regulation of cortisol and PRL secretion in man, the effects of 6-chloro-2-(1-piperazinyl) pirazine (MK-212), a centrally acting direct 5-HT2A/5-HT2C agonist, on the above hormones were studied in 11 normal men with and without pretreatment with pindolol, a 5-HT1A partial agonist. MK-212 induced a significant increase in plasma concentrations of cortisol and PRL. The MK-212-induced response in plasma cortisol was not diminished by pindolol pretreatment, whereas the MK-212-induced PRL response was significantly inhibited by pindolol pretreatment. These data suggest that the MK-212-induced cortisol response may be mediated by 5-HT2A or 5-HT2C receptor activation, or both, despite 5-HT1A inhibition; however, PRL secretion by MK-212 requires 5-HT1A receptor availability as well as 5-HT2A/5-HT2C receptor activation, since blockade of the former appears to blunt the PRL responses to MK-212. These findings may be explained by postulating a cooperativity between 5-HT1A and 5-HT2A/5-HT2C receptors with regard to the 5-HT-dependent stimulation of PRL secretion.
Collapse
Affiliation(s)
- H Y Meltzer
- Department of Psychiatry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | | |
Collapse
|
25
|
Maskall DD, Zis AP, Lam RW, Clark CM, Kuan AJ. Prolactin response to buspirone challenge in the presence of dopaminergic blockade. Biol Psychiatry 1995; 38:235-9. [PMID: 8547445 DOI: 10.1016/0006-3223(94)00264-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Buspirone-stimulated prolactin release has been employed as an indirect measure of central serotonin activity; however, it is not clear whether serotonergic or dopaminergic systems are responsible for this response. In an attempt to further elucidate the mechanism, we studied the prolactin response to buspirone in eight subjects in the presence of maximal dopaminergic receptor blockade with metoclopramide under placebo-controlled, double-blind conditions. The prolactin response to buspirone in the presence of metoclopramide was not statistically different from that to placebo under the same conditions. The demonstration of further prolactin release by a bolus of thyrotropin-releasing hormone under maximal dopaminergic receptor blockade provided evidence against potential pituitary prolactin depletion by metoclopramide. These results lend further support to a dopaminergic mechanism in buspirone-induced prolactin secretion; therefore, further caution is warranted in interpreting the results of this challenge test as a measure of serotonergic activity in the brain.
Collapse
Affiliation(s)
- D D Maskall
- Department of Psychiatry, University of British Columbia, Vancouver
| | | | | | | | | |
Collapse
|
26
|
Berlin I, Chalon S, Payan C, Schöllnhammer G, Cesselin F, Varoquaux O, Puech AJ. Evaluation of the alpha 2-adrenoceptor blocking properties of buspirone and ipsapirone in healthy subjects. Relationship with the plasma concentration of the common metabolite 1-(2-pyrimidinyl)-piperazine. Br J Clin Pharmacol 1995; 39:243-9. [PMID: 7619663 PMCID: PMC1364998 DOI: 10.1111/j.1365-2125.1995.tb04443.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
1. Because the 5-HT1A agonist anxiolytic azapirones have a common alpha 2-adrenoceptor antagonist metabolite, 1-(2-pyrimidinyl)-piperazine (1PP), we measured central and peripheral alpha 2-adrenoceptor dependent responses before and after intravenous administration of 0.15 mg clonidine when healthy subjects were taking buspirone (30 mg day-1 for 4 days and 10 mg on day 5), ipsapirone (15 mg day-1 for 4 days and 5 mg on day 5) or placebo. 2. Clonidine decreased blood pressure, heart rate, oral body temperature, salivary excretion, plasma noradrenaline, 3,4-dihydroxyphenylglycol (DHPG) concentrations, increased plasma growth hormone but did not modify plasma insulin and C-peptide concentrations. Treatments tended to modify only the effect of clonidine on growth hormone (P = 0.07). 3. The azapirones reduced clonidine induced prolongation of choice reaction time (P = 0.015) and tended to antagonise clonidine induced fall in critical flicker fusion frequency (P = 0.066). 4. Only buspirone reduced total reaction time and increased critical flicker fusion threshold measured 12 h after the evening dose and these effects were correlated with the residual plasma 1PP concentration which was higher on buspirone than on ipsapirone (2.76 micrograms l-1, 95% CI:1.3-4.22 vs 0.65 microgram l-1, 95% CI: 0.32-0.98, P = 0.006). 5. Mean AUC of the 1PP plasma concentrations after the last dose of treatments were 3.7 times greater with buspirone than with ipsapirone (P = 0.0011). The AUC ipsapirone/AUC 1PP ratio was 6.45 and the AUC buspirone/AUC 1PP ratio was 0.076.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- I Berlin
- Département de Pharmacologie Clinique, Hôpital Pitié-Salpêtrière, Paris, France
| | | | | | | | | | | | | |
Collapse
|
27
|
Goodall EM, Whittle M, Cookson J, Cowen PJ, Silverstone T. Menstrual cycle effects on the action of buspirone on food intake in healthy female volunteers. J Psychopharmacol 1995; 9:307-12. [PMID: 22298394 DOI: 10.1177/026988119500900403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
We studied the effect of single doses of the 5-HT(1A) agonist buspirone (10 mg and 20 mg) on food intake during the menstrual cycle of nine healthy women, none of whom were on a contraceptive pill. In a double-blind placebo-controlled trial, subjects were tested over three cycles, receiving one treatment per cycle. Within each cycle, they were tested at two time points; mid-follicular and late luteal. Food intake following 20 mg buspirone was significantly higher in the luteal phase, suggesting the possibility of pre-menstrually enhanced 5-HT receptor sensitivity.
Collapse
Affiliation(s)
- E M Goodall
- Formerly Academic Unit of Human Psychopharmacology, Department of Psychological Medicine, Medical College of St Bartholomew's Hospital, London EC1A 7BE, Psychopharmacology Research Unit, Littlemore Hospital, Oxford OX4 4XN, UK
| | | | | | | | | |
Collapse
|
28
|
Young AH, Sharpley AL, Campling GM, Hockney RA, Cowen PJ. Effects of hydrocortisone on brain 5-HT function and sleep. J Affect Disord 1994; 32:139-46. [PMID: 7829766 DOI: 10.1016/0165-0327(94)90072-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The effects of hydrocortisone administration (20 mg, orally, twice daily) on the sensitivity of brain 5-HT1A receptors in healthy volunteers were studied using a buspirone challenge paradigm. The effects of hydrocortisone administration on sleep architecture were also studied. Hydrocortisone treatment significantly attenuated the hypothermic and cortisol responses to buspirone; however, the prolactin and growth hormone responses were unchanged. Hydrocortisone also decreased the amount of rapid eye movement sleep (REM). The ability of hydrocortisone to attenuate 5-HT1A receptor mediated hypothermia and decrease REM sleep is shared by certain antidepressant treatments and may be related to the effects of corticosteroids on mood.
Collapse
Affiliation(s)
- A H Young
- Department of Psychiatry, Oxford University, Littlemore Hospital, UK
| | | | | | | | | |
Collapse
|
29
|
Meltzer HY, Maes M. Effect of pindolol on the L-5-HTP-induced increase in plasma prolactin and cortisol concentrations in man. Psychopharmacology (Berl) 1994; 114:635-43. [PMID: 7855226 DOI: 10.1007/bf02244995] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Previous studies with direct-acting serotonin (5-HT) agonists and antagonists have demonstrated that stimulation of 5-HT1A, 5-HT1C and 5-HT2 receptors may promote cortisol and prolactin (PRL) secretion in man. There is also evidence that 5-HT1C/2 receptor stimulation contributes to the cortisol and PRL responses following administration of the 5-HT precursor, L-5-hydroxytryptophan (L-5-HTP), in man. To clarify the possible contribution of 5-HT1A receptor stimulation to the ability of L-5-HTP to stimulate cortisol and PRL secretion in man, the effect of pindolol, a beta adrenoceptor antagonist that is also a 5-HT1A partial agonist, on the L-5-HTP-induced increases in cortisol and PRL secretion, was examined in 12 normal male volunteers. Pretreatment with pindolol, 30 mg orally, significantly inhibited the PRL but not the cortisol response to L-5-HTP, 200 mg PO. Pindolol alone decreased basal plasma PRL levels and increased basal plasma cortisol levels, possibly due to 5-HT1A antagonist and agonists effects, respectively. These data, coupled with observations from other studies, suggest that the L-5-HTP-induced increase in PRL but not cortisol secretion requires 5-HT1A receptor activation. PRL secretion due to 5-HT formed from exogenous L-5-HTP may require the availability of both intact 5-HT1A and 5-HT2/5-HT1C receptors, since blockade of either receptor type inhibited the PRL response to L-5-HTP. The implication of this synergistic effect for interpretation of neuroendocrine studies involving the serotonergic system in man is discussed.
Collapse
Affiliation(s)
- H Y Meltzer
- Laboratory of Biological Psychiatry, Case Western Reserve University, Cleveland, OH 44106
| | | |
Collapse
|
30
|
Meltzer HY, Maes M. Effects of buspirone on plasma prolactin and cortisol levels in major depressed and normal subjects. Biol Psychiatry 1994; 35:316-23. [PMID: 8011800 DOI: 10.1016/0006-3223(94)90035-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The cortisol response to ipsapirone (a 5-HT1A-partial agonist that produces a dose-dependent increase in plasma cortisol secretion in man) is blunted in major depression. Buspirone is another 5-HT1A agonist that increases cortisol secretion in man. This study investigated cortisol and prolactin (PRL) responses to buspirone (30 mg orally) in 45 major depressed subjects and 28 normal controls. Buspirone administration yielded a significant increase in cortisol and PRL levels in both normal controls and depressed subjects. No differences in buspirone-induced hormone responses were found either between major depressives and normal controls or between melancholic and nonmelancholic depressives. There were no significant relationships between severity of depression and any of the hormonal responses to buspirone. PRL responses to buspirone were significantly higher in women than in men.
Collapse
Affiliation(s)
- H Y Meltzer
- Department of Psychiatry, University Hospitals of Cleveland, OH 44106
| | | |
Collapse
|
31
|
Cowen PJ, Power AC, Ware CJ, Anderson IM. 5-HT1A receptor sensitivity in major depression. A neuroendocrine study with buspirone. Br J Psychiatry 1994; 164:372-9. [PMID: 8199791 DOI: 10.1192/bjp.164.3.372] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The hypothermic, growth hormone and corticotrophin (ACTH) responses to the 5-HT1A receptor agonist buspirone (30 mg orally) were measured in 20 unmedicated patients with major depression and 20 healthy controls. Compared with the controls, the hypothermic responses of the depressed patients to buspirone were significantly attenuated, particularly in patients with melancholic depression. In contrast, the responses of growth hormone and ACTH to buspirone were unchanged. The data suggest that major depression may be associated with impaired sensitivity of 5-HT1A autoreceptors but that the function of the post-synaptic 5-HT1A receptors that mediate growth hormone and ACTH release is unaltered. Within the limitations that attend the use of buspirone as a 5-HT1A probe, our data suggest that the decrement in serotonin neurotransmission at post-synaptic 5-HT1A receptors in depression is due to decreased serotonin release rather than impaired responsivity of post-synaptic 5-HT1A receptors.
Collapse
Affiliation(s)
- P J Cowen
- Psychopharmacology Research Unit, Littlemore Hospital, Oxford
| | | | | | | |
Collapse
|
32
|
Kahn RS, Trestman R, Lawlor BA, Gabriel S, Davidson M, Siever L. Effects of ipsapirone in healthy subjects: a dose-response study. Psychopharmacology (Berl) 1994; 114:155-60. [PMID: 7846198 DOI: 10.1007/bf02245457] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A dose-response study of ipsapirone (IPS), a 5HT1a partial agonist, was conducted in healthy male subjects. IPS was administered in doses of 5, 10 and 20 mg PO in a placebo-controlled, double-blind design to 15 subjects on 4 test days separated by at least 3 days. Oral temperature, ACTH, cortisol, prolactin, blood pressure, pulse rate and behavioral variables were assessed every 30 min for 3 h after administration of tablets (at 10:00 A.M.). IPS at 20 mg significantly decreased temperature and increased cortisol levels. Although IPS increased ACTH levels at 20 mg, this effect was variable and not significant. IPS did not affect prolactin levels nor did it have any behavioral effects. Although 20 mg IPS decreased blood pressure and pulse rate in one subject, overall it had no significant effect on these parameters. IPS at 20 mg PO appears a useful probe to test 5HT1a function when temperature and cortisol are used as response variables. These results replicate earlier studies on the effect of IPS in healthy human subjects.
Collapse
Affiliation(s)
- R S Kahn
- Department of Psychiatry, Bronx Veterans Affairs Medical Center/Mount Sinai School of Medicine, NY 10468
| | | | | | | | | | | |
Collapse
|
33
|
Lucey JV. BAP/SKB Young Psychopharmacologist Award Towards a neuroendocrinology of obsessive-compulsive disorder. J Psychopharmacol 1994; 8:250-7. [PMID: 22298631 DOI: 10.1177/026988119400800408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Neuroendocrine research has made an important contribution to the understanding of psychiatric illness in vivo. This review is a summary of the recent neuroendocrine studies on obsessive-compulsive disorder (OCD) patients carried out at the Departments of Psychiatry at Trinity College Medical School and St. Patrick's Hospital, Dublin, Ireland. We found that both serotonergic and cholinergic abnormalities were present in OCD, while noradrenergic responsivity and hypothalmic-pituitary axis function were normal. The data suggests that OCD may have a unique neuroendocrinology.
Collapse
Affiliation(s)
- J V Lucey
- Lecturer and Wellcome Fellow, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London SE5 8AF, UK
| |
Collapse
|
34
|
Affiliation(s)
- A H Young
- Department of Psychiatry, Littlemore Hospital, Oxford, United Kingdom
| | | | | | | |
Collapse
|
35
|
Herdman JR, Cowen PJ, Campling GM, Hockney RA, Laver D, Sharpley AL. Effect of lofepramine on 5-HT function and sleep. J Affect Disord 1993; 29:63-72. [PMID: 8254146 DOI: 10.1016/0165-0327(93)90121-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We studied the effect of the tricyclic antidepressant lofepramine (140-210 mg daily for 16 days) on 5-hydroxytryptamine 1A (5-HT1A) receptor sensitivity in healthy volunteers, using a buspirone neuroendocrine challenge paradigm (30 mg orally). We also studied the effect of lofepramine on platelet 5-HT content and sleep architecture. Lofepramine treatment did not alter the hypothermic, endocrine or amnesic effects of buspirone but significantly lowered platelet 5-HT content and decreased rapid eye movement sleep. Our findings suggest that at clinically used doses, lofepramine inhibits the uptake of 5-HT and produces changes in sleep architecture characteristic of tricyclic antidepressants. However, lofepramine does not appear to alter the sensitivity of 5-HT1A receptors.
Collapse
Affiliation(s)
- J R Herdman
- MRC Unit of Clinical Pharmacology, Littlemore Hospital, Oxford, UK
| | | | | | | | | | | |
Collapse
|
36
|
Young AH, Dow RC, Goodwin GM, Fink G. The effects of adrenalectomy and ovariectomy on the behavioral and hypothermic responses of rats to 8-hydroxy-2(di-n-propylamino)tetralin (8-OH-DPAT). Neuropharmacology 1993; 32:653-7. [PMID: 8361580 DOI: 10.1016/0028-3908(93)90078-h] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The aim of this study was to determine the effects of sex, corticosterone and oestradiol-17 beta on the hypothermia and motor behavioural syndrome induced by the 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) in the rat. The hypothermia, but not the behavioural syndrome induced by 8-OH-DPAT was significantly greater in female compared with male rats. Adrenalectomy in male rats enhanced the hypothermic response, an effect prevented by corticosterone implants. Ovariectomy significantly attenuated the hypothermia induced by 8-OH-DPAT, an effect prevented by oestradiol-17 beta implants. Neither type of steroid manipulation affected the behavioural syndrome. These results show that sex, corticosterone and oestradiol-17 beta modulate the hypothermic response to 8-OH-DPAT in the rat, with corticosterone and oestradiol-17 beta having opposing effects.
Collapse
|
37
|
Abstract
Neuroendocrine probes of serotonergic function are based on the premise that serotonin (5-HT) exhibits an excitory influence on the release of certain anterior pituitary hormones and that the extent of release of these hormones following a challenge with a 5-HT agonist would provide an index of central 5-HT activity. This paper critically reviews studies published to date on healthy volunteers to assess the validity of tests of serotonergic function. Using standardized criteria, it is concluded that although extensive data is available on 5-HT-neuroendocrine probes, there is no test that is currently available that would fulfil all the proposed requirements for a test to be acceptable, although ipsapirone, m-chlorophenylpiperazine (m-CPP), and possibly fenfluramine challenge tests come very close. The rapid development and availability of more specific and stereo-selective 5-HT agonists/antagonists seem to indicate that it will not be too long before a valid neuroendocrine test for the assessment of serotonergic function emerges.
Collapse
|
38
|
Anderson I. Serotonin, gastric emptying, and dyspepsia. BMJ (CLINICAL RESEARCH ED.) 1992; 305:1295. [PMID: 1301036 PMCID: PMC1883743 DOI: 10.1136/bmj.305.6864.1295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
39
|
Gardosi J. Outcome of breech delivery at term. West J Med 1992. [DOI: 10.1136/bmj.305.6864.1294-b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
40
|
Chua A, Keeling PWN, Dinan TG. Serotonin, gastric emptying, and dyspepsia: Authors' reply. West J Med 1992. [DOI: 10.1136/bmj.305.6864.1295-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
41
|
Grasby PM, Friston KJ, Bench C, Cowen PJ, Frith CD, Liddle PF, Frackowiak RS, Dolan RJ. Effect of the 5-HT1A partial agonist buspirone on regional cerebral blood flow in man. Psychopharmacology (Berl) 1992; 108:380-6. [PMID: 1523287 DOI: 10.1007/bf02245127] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Repeated measurements of regional cerebral blood flow (rCBF) were made in normal volunteers before, and after, the administration of the 5-HT1A partial agonist, buspirone, or placebo. The difference in rCBF, before and after drug, (buspirone versus placebo) was used to identify brain areas affected by buspirone. Buspirone-induced changes in rCBF were studied under two behavioural conditions (5 word-list learning and 15 word-list learning). Compared to placebo, buspirone increased blood flow in the cuneus during both behavioural states. However, decreases in blood flow, centred in the left dorso-lateral prefrontal cortex and posterior cingulate cortex, were only observed under one of the two behavioural conditions. It is concluded that buspirone-induced alterations in regional cerebral blood flow are better understood, not in relation to the known distribution of monoamine neurotransmitter systems (particularly ascending 5-HT projections), but rather in relation to putative neuronal circuits possibly many synapses "downstream" of buspirone's pharmacological site of action.
Collapse
Affiliation(s)
- P M Grasby
- MRC Cyclotron Unit, Hammersmith Hospital, London, UK
| | | | | | | | | | | | | | | |
Collapse
|
42
|
Levy AD, Van de Kar LD. Endocrine and receptor pharmacology of serotonergic anxiolytics, antipsychotics and antidepressants. Life Sci 1992; 51:83-94. [PMID: 1352027 DOI: 10.1016/0024-3205(92)90001-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Several classes of drugs that modify serotonin (5-HT) neurotransmission are either currently used, or are being evaluated for their potential use in the treatment of anxiety, schizophrenia, and depression. 5-HT1A agonists are considered potential anxiolytics, while some atypical antipsychotics are potent 5-HT2 antagonists (and also have modest dopamine D2 affinity). Furthermore, there is a diverse group of serotonergic drugs that may be effective antidepressants. Secretion of ACTH, corticosterone/cortisol, prolactin, renin, oxytocin and vasopressin are stimulated by activation of different 5-HT receptor subtypes, while other neurotransmitter receptors also influence the secretion of these hormones. We compared the receptor binding profiles of 5-HT anxiolytics, antipsychotics and antidepressants with their endocrine effects. These comparisons could aid in understanding both the therapeutic and side effects of these drugs.
Collapse
Affiliation(s)
- A D Levy
- Department of Pharmacology, Loyola University of Chicago, Stritch School of Medicine, Maywood, IL 60153
| | | |
Collapse
|
43
|
Best NR, Rees MP, Barlow DH, Cowen PJ. Effect of oestradiol treatment on 5-HT and dopamine-mediated neuroendocrine responses. J Psychopharmacol 1992; 6:483-8. [PMID: 22291396 DOI: 10.1177/026988119200600403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We assessed the effect of oestradiol treatment in women on the endocrine responses to the 5-hydroxytryptamine (5-HT) precursor, L-tryptophan (LTP) (5 g i.v.) and the dopamine agonist, apomorphine (0.005 mg/kg s.c.). Following oestradiol implant (100 mg s.c.) the prolactin (PRL) response to LTP was significantly enhanced but there was no change in the growth hormone (GH) response to apomorphine. There was, however, a significant correlation between post-implant oestradiol concentrations and post-implant apomorphine-induced GH release. The results indicate that oestrogen treatment may facilitate 5-HT-mediated PRL release and could also influence the regulation of dopamine-mediated GH responses. However, further studies are needed to exclude direct effects of oestradiol on the pituitary release of PRL and GH.
Collapse
Affiliation(s)
- N R Best
- MRC Unit of Clinical Pharmacology and University Department of Psychiatry, Littlemore Hospital, Oxford
| | | | | | | |
Collapse
|