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Voronova IP. 5-HT Receptors and Temperature Homeostasis. Biomolecules 2021; 11:1914. [PMID: 34944557 PMCID: PMC8699715 DOI: 10.3390/biom11121914] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/11/2021] [Accepted: 12/16/2021] [Indexed: 12/28/2022] Open
Abstract
The present review summarizes the data concerning the influence of serotonin (5-HT) receptors on body temperature in warm-blooded animals and on processes associated with its maintenance. This review includes the most important part of investigations from the first studies to the latest ones. The established results on the pharmacological activation of 5-HT1A, 5-HT3, 5-HT7 and 5-HT2 receptor types are discussed. Such activation of the first 3 type of receptors causes a decrease in body temperature, whereas the 5-HT2 activation causes its increase. Physiological mechanisms leading to changes in body temperature as a result of 5-HT receptors' activation are discussed. In case of 5-HT1A receptor, they include an inhibition of shivering and non-shivering thermogenesis, as well simultaneous increase of peripheral blood flow, i.e., the processes of heat production and heat loss. The physiological processes mediated by 5-HT2 receptor are opposite to those of the 5-HT1A receptor. Mechanisms of 5-HT3 and 5-HT7 receptor participation in these processes are yet to be studied in more detail. Some facts indicating that in natural conditions, without pharmacological impact, these 5-HT receptors are important links in the system of temperature homeostasis, are also discussed.
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Affiliation(s)
- Irina P. Voronova
- Department of Thermophysiology, Scientific Research Institute of Neurosciences and Medicine, 630117 Novosibirsk, Russia
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Blessing W, McAllen R, McKinley M. Control of the Cutaneous Circulation by the Central Nervous System. Compr Physiol 2016; 6:1161-97. [PMID: 27347889 DOI: 10.1002/cphy.c150034] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The central nervous system (CNS), via its control of sympathetic outflow, regulates blood flow to the acral cutaneous beds (containing arteriovenous anastomoses) as part of the homeostatic thermoregulatory process, as part of the febrile response, and as part of cognitive-emotional processes associated with purposeful interactions with the external environment, including those initiated by salient or threatening events (we go pale with fright). Inputs to the CNS for the thermoregulatory process include cutaneous sensory neurons, and neurons in the preoptic area sensitive to the temperature of the blood in the internal carotid artery. Inputs for cognitive-emotional control from the exteroceptive sense organs (touch, vision, sound, smell, etc.) are integrated in forebrain centers including the amygdala. Psychoactive drugs have major effects on the acral cutaneous circulation. Interoceptors, chemoreceptors more than baroreceptors, also influence cutaneous sympathetic outflow. A major advance has been the discovery of a lower brainstem control center in the rostral medullary raphé, regulating outflow to both brown adipose tissue (BAT) and to the acral cutaneous beds. Neurons in the medullary raphé, via their descending axonal projections, increase the discharge of spinal sympathetic preganglionic neurons controlling the cutaneous vasculature, utilizing glutamate, and serotonin as neurotransmitters. Present evidence suggests that both thermoregulatory and cognitive-emotional control of the cutaneous beds from preoptic, hypothalamic, and forebrain centers is channeled via the medullary raphé. Future studies will no doubt further unravel the details of neurotransmitter pathways connecting these rostral control centers with the medullary raphé, and those operative within the raphé itself. © 2016 American Physiological Society. Compr Physiol 6:1161-1197, 2016.
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Affiliation(s)
- William Blessing
- Human Physiology, Centre for Neuroscience, Flinders University, Adelaide, S.A., Australia
| | - Robin McAllen
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Vic., Australia
| | - Michael McKinley
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Vic., Australia
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Yadav PN, Abbas AI, Farrell MS, Setola V, Sciaky N, Huang XP, Kroeze WK, Crawford LK, Piel DA, Keiser MJ, Irwin JJ, Shoichet BK, Deneris ES, Gingrich J, Beck SG, Roth BL. The presynaptic component of the serotonergic system is required for clozapine's efficacy. Neuropsychopharmacology 2011; 36:638-51. [PMID: 21048700 PMCID: PMC3055689 DOI: 10.1038/npp.2010.195] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Clozapine, by virtue of its absence of extrapyramidal side effects and greater efficacy, revolutionized the treatment of schizophrenia, although the mechanisms underlying this exceptional activity remain controversial. Combining an unbiased cheminformatics and physical screening approach, we evaluated clozapine's activity at >2350 distinct molecular targets. Clozapine, and the closely related atypical antipsychotic drug olanzapine, interacted potently with a unique spectrum of molecular targets. This distinct pattern, which was not shared with the typical antipsychotic drug haloperidol, suggested that the serotonergic neuronal system was a key determinant of clozapine's actions. To test this hypothesis, we used pet1(-/-) mice, which are deficient in serotonergic presynaptic markers. We discovered that the antipsychotic-like properties of the atypical antipsychotic drugs clozapine and olanzapine were abolished in a pharmacological model that mimics NMDA-receptor hypofunction in pet1(-/-) mice, whereas haloperidol's efficacy was unaffected. These results show that clozapine's ability to normalize NMDA-receptor hypofunction, which is characteristic of schizophrenia, depends on an intact presynaptic serotonergic neuronal system.
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Affiliation(s)
- Prem N Yadav
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | - Atheir I Abbas
- Department of Biochemistry, Case Western Reserve University Medical School, Cleveland, OH, USA
| | - Martilias S Farrell
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | - Vincent Setola
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA,National Institute of Mental Heath Psychoactive Drug Screening Program, University of North Carolina, Chapel Hill, NC, USA
| | - Noah Sciaky
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | - Xi-Ping Huang
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA,National Institute of Mental Heath Psychoactive Drug Screening Program, University of North Carolina, Chapel Hill, NC, USA
| | - Wesley K Kroeze
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC, USA
| | - LaTasha K Crawford
- Department of Anesthesiology, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA, USA
| | - David A Piel
- Department of Anesthesiology, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA, USA
| | - Michael J Keiser
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - John J Irwin
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Brian K Shoichet
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA, USA
| | - Evan S Deneris
- Department of Neurosciences, Case Western Reserve University Medical School, Cleveland, OH, USA
| | - Jay Gingrich
- Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY, USA
| | - Sheryl G Beck
- Department of Anesthesiology, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA, USA,Department of Anesthesiology, Children's Hospital of Philadelphia Research Institute, Philadelphia, PA 19104, USA. Tel: +1 215 590 0651; Fax: +1 215 590 4107; E-mail:
| | - Bryan L Roth
- National Institute of Mental Heath Psychoactive Drug Screening Program, University of North Carolina, Chapel Hill, NC, USA,Departments of Pharmacology, Medicinal Chemistry and Psychiatry, Lineberger Cancer Center, University of North Carolina, Chapel Hill, NC, USA,Department of Pharmacology, University of North Carolina, National Institute of Mental Heath Psychoactive Drug Screening Program, Chapel Hill, NC, 27516, USA. Tel: +1 919 966 7535; Fax: +1 919 843 5788; E-mail:
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Zhang G, Tao R. Enhanced responsivity of 5-HT(2A) receptors at warm ambient temperatures is responsible for the augmentation of the 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI)-induced hyperthermia. Neurosci Lett 2010; 490:68-71. [PMID: 21172407 DOI: 10.1016/j.neulet.2010.12.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Revised: 12/10/2010] [Accepted: 12/11/2010] [Indexed: 10/18/2022]
Abstract
Warm ambient temperature facilitates hyperthermia and other neurotoxic responses elicited by psychogenic drugs such as MDMA and methamphetamine. However, little is known about the neural mechanism underlying such effects. In the present study, we tested the hypothesis that a warm ambient temperature may enhance the responsivity of 5-HT(2A) receptors in the central nervous system and thereafter cause an augmented response to 5-HT(₂A) receptor agonists. This hypothesis was tested by measuring changes in body-core temperature in response to the 5-HT(2A) receptor agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) administered at four different ambient temperature levels: 12 °C (cold), 22 °C (standard), 27 °C (thermoneutral zone) and 32 °C (warm). It was found that DOI only evoked a small increase in body-core temperature at the standard (22 °C) or thermoneutral ambient temperature (27 °C). In contrast, there was a large increase in body-core temperature when the experiments were conducted at the warmer ambient temperature (32 °C). Interestingly, the effect of DOI at the cold ambient temperature of 12 °C was significantly reduced. Moreover, the ambient temperature-dependent response to DOI was completely blocked by pretreatment with the 5-HT(₂A) receptor antagonist ketanserin. Taken together, these findings support the hypothesis that 5-HT(₂A) receptors may be responsible for some neurotoxic effects of psychogenic drugs in the central nervous system, the activity of which is functionally inhibited at cold but enhanced at warm ambient temperature in contrast to that at standard experimental conditions.
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Affiliation(s)
- Gongliang Zhang
- Department of Basic Science, Charles E. Schmidt College of Medicine, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-3091, USA.
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Ding Z, Cowan A, Rawls SM. 5-HT reuptake and 5-HT2 receptors modulate capsaicin-evoked hypothermia in rats. Neurosci Lett 2008; 430:191-6. [DOI: 10.1016/j.neulet.2007.10.033] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 10/25/2007] [Accepted: 10/30/2007] [Indexed: 10/22/2022]
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Cortés EC, Cornejo ALV, de Cortés OGM. New derivatives of dibenzo[b,e][1,4]diazepin-1-ones by an efficient synthesis and spectroscopy. J Heterocycl Chem 2007. [DOI: 10.1002/jhet.5570440128] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Chang CP, Chen SH, Lin MT. IPSAPIRONE AND KETANSERIN PROTECTS AGAINST CIRCULATORY SHOCK, INTRACRANIAL HYPERTENSION, AND CEREBRAL ISCHEMIA DURING HEATSTROKE. Shock 2005; 24:336-40. [PMID: 16205318 DOI: 10.1097/01.shk.0000175894.18168.66] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We assess the effects of ipsapirone (a 5-HT1A receptor agonist), ketanserin (a 5-HT2A receptor antagonist), (-)-pindolol (a 5-HT1A receptor antagonist), and DOI (a 5-HT2A receptor agonist) on heatstroke in a rat model. Animals, under urethane anesthesia, were exposed to high ambient temperature of 42 degrees C until mean arterial pressure and local cerebral blood flow in the striatum began to decrease, which was arbitrarily defined as the onset of heatstroke. Normothermic controls were exposed to room temperature of 24 degrees C. In rats treated with normal saline immediately before the initiation of heat stress, the values for survival time were found to be 21 to 25 min. Systemic administration of ipsapirone (10 mg/kg) or ketanserin (2 mg/kg) immediately before the initiation of heat stress significantly increased the survival time to new values of 92 to 104 min. Combined treatment with ipsapirone and ketanserin had additive effects (survival time of 156-194 min). In contrast, systemic administration of (-)-pindolol (2 mg/kg) or DOI (2 mg/kg) significantly decreased the survival time to new values of 2 to 3 min. In vehicle-treated heatstroke rats, the values for core temperature, intracranial pressure, and the extracellular levels of cellular ischemia (e.g., glutamate and lactate/pyruvate ratio) or damage (e.g., glycerol) markers and neuronal damage scores in striatum were significantly higher than those of normothermic controls. On the other hand, the values for mean arterial pressure, cerebral perfusion pressure, cerebral blood flow, and brain partial pressure of O2 were significantly lower than those of normothermic controls. The heatstroke-induced hyperthermia, arterial hypotension, intracranial hypertension, cerebral hypoperfusion and hypoxia, and increased levels of cellular ischemia and damage markers in striatum were all significantly attenuated by prior administration of ipsapirone or ketanserin. The present results strongly suggest that previous activation of 5-HT1A receptors or antagonism of 5-HT2A receptors protects against heatstroke by reducing circulatory shock and cerebral ischemia, whereas prior antagonism of 5-HT1A receptors or activation of 5-HT2A receptors exacerbates heatstroke.
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Affiliation(s)
- Ching-Ping Chang
- Department of Biotechnology, Southern Taiwan University of Technology, Tainan, Taiwan 710
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Blessing WW. Clozapine increases cutaneous blood flow and reduces sympathetic cutaneous vasomotor alerting responses (SCVARs) in rats: comparison with effects of haloperidol. Psychopharmacology (Berl) 2005; 181:518-28. [PMID: 15986198 DOI: 10.1007/s00213-005-0012-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Accepted: 03/30/2005] [Indexed: 10/25/2022]
Abstract
RATIONALE Clozapine inhibits sympathetic outflow to the cutaneous vascular bed. Clozapine reverses hyperthermia and cutaneous vasoconstriction induced by 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) or by lipopolysaccharide (LPS). Clozapine also reverses cutaneous vasoconstriction elicited by exposure to cold. These actions distinguish clozapine from haloperidol. Clozapine could also inhibit sympathetic cutaneous vasomotor alerting responses (SCVARs), vasoconstrictor episodes that reflect emotional/psychological function, and this property might also distinguish clozapine from haloperidol. OBJECTIVES Experiments in rats determined whether clozapine and haloperidol inhibit SCVARs, and whether SR46349B (a 5HT2A receptor antagonist), 8-OH-DPAT (a 5-HT1A agonist), L741,626 (a dopamine D2 antagonist) or SCH23390 (a dopamine D1 antagonist) have clozapine-like effects on SCVARs. METHODS Mean level and pulse amplitude of the tail artery Doppler flow signal were recorded in conscious freely moving rats before and after alerting stimuli (e.g. tapping the cage), and expressed as a SCVAR index (fall to zero flow implies SCVAR index of 100%, no fall implies 0%). RESULTS Clozapine (0.0625-1.0 mg/kg, s.c.) dose-dependently increased resting tail blood flow. After 1 mg/kg, the SCVAR index was 18+/-1%, compared with 83+/-2% after vehicle. SR46349B (0.01-1.0 mg/kg) and 8-OH-DPAT (0.25 mg/kg) had similar but less potent effects on cutaneous blood flow and on SCVARs. Haloperidol (0.005-0.5 mg/kg) and L741,626 (1 mg/kg) had no or little effect on these variables. SCH23390 mildly inhibited SCVARs. CONCLUSIONS Clozapine, but not haloperidol, increases resting cutaneous blood flow and decreases SCVARs. Antagonism at 5-HT2A receptors and agonism at 5-HT1A receptors could contribute to these actions.
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Affiliation(s)
- William Walter Blessing
- Department of Physiology, Centre for Neuroscience, Flinders University, Adelaide, Australia.
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Chio CC, Tsai SM, Wang JJ, Lin MT. 5-HT2A-mu opioid receptor mechanisms in the hypothalamus mediate interleukin-1beta fever in rats. Neurosci Lett 2005; 381:6-11. [PMID: 15882780 DOI: 10.1016/j.neulet.2005.01.074] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Revised: 01/10/2005] [Accepted: 01/25/2005] [Indexed: 12/01/2022]
Abstract
Direct administration of interleukin-1beta (IL-1beta) into the lateral cerebral ventricle of rat brain, in addition to inducing febrile responses, upregulated the immunoreactivity of tryptophan hydroxylase in the preoptic anterior hypothalamus. The fever induced by IL-1beta was significantly attenuated by pretreatment with intracerebroventricular injection of 5-HT2A receptor antagonists including cyproheptadine, ketanserin, or mianserin. In addition, the IL-1beta-induced fever was mimicked by intracerebroventricular administration of a 5-HT2A receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-amionpropane (DOI). The DOI-induced (present results) or IL-1beta-induced (previous results) fever was further attenuated by pretreatment with an intracerebroventricular dose of mu-opioid receptor antagonists (e.g., buprenorphine or cyclic d-phe-cys-Try-d-Arg-Thr-pen-Thr-NH2) or 5-HT receptor antagonists (e.g., ketanserin or cyproheptadine). These findings suggest that a 5-HT2A-mu opioid receptor mechanism in the hypothalamus may mediate the IL-1beta fever.
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Affiliation(s)
- Chung-Ching Chio
- Department of Surgery, Chi-Mei Medical Center, Tainan 710, Taiwan
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Blessing WW. Clozapine and olanzapine, but not haloperidol, reverse cold-induced and lipopolysaccharide-induced cutaneous vasoconstriction. Psychopharmacology (Berl) 2004; 175:487-93. [PMID: 15083260 DOI: 10.1007/s00213-004-1850-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
RATIONALE Reduction of body temperature is used as predictor of psychotropic drug action. The cutaneous circulation functions as a heat-loss component of temperature regulation. Clozapine and olanzapine reverse hyperthermia and sympathetically-mediated cutaneous vasoconstriction induced by MDMA (3,4-methylenedioxymethamphetamine, ecstasy), suggesting that these drugs might reverse other forms of sympathetically mediated cutaneous vasoconstriction. OBJECTIVES Clozapine and olanzapine were compared with haloperidol with respect to their ability to reverse cold-induced and LPS (lipopolysaccharide)-induced cutaneous vasoconstriction in rabbits. METHODS Cutaneous blood flow was measured in conscious rabbits by Doppler ultrasonic flow probe implanted around the central ear artery, and body temperature was measured telemetrically. After control observations, animals were transferred from 26 to 10 degrees C, or LPS (0.5 microLg/kg IV) was administered. After 30 min, clozapine, olanzapine or haloperidol was administered and ear pinna blood flow and body temperature were measured for another 30 min. RESULTS Clozapine, in a dose responsive manner (1, 2.5 and 5 mg/kg IV), substantially reversed cold-induced ear pinna vasoconstriction and reduced body temperature. Clozapine (1 mg/kg IV) reversed LPS-induced cutaneous vasoconstriction and reduced the LPS-induced rise in body temperature. Olanzapine had generally similar effects. Haloperidol (1 mg/kg IV in cold experiments and 0.2 mg/kg IV in LPS experiments) did not reverse ear pinna vasoconstriction, or affect body temperature. CONCLUSIONS Both clozapine and olanzapine, but not haloperidol, reverse physiologically induced cutaneous sympathetic vasomotor discharge. Because of the close link between psychological function and sympathetic regulation of cutaneous blood flow, similar neuropharmacological mechanisms might underly the cutaneous vasodilating action and the psychotropic actions of atypical antipsychotic drugs.
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Affiliation(s)
- William Walter Blessing
- Department of Physiology, Centre for Neuroscience, Flinders University, Bedford Park, SA, 5042, Australia.
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Cortéas EC, Baños MA, De Cortés OGM. Efficient synthesis and spectral determination of 11-[(o-m- andp-substituted)-phenyl]-8-chloro-3,3-dimethyl-2,3,4,5,10,11-hexahydro-1H-dibenzo[b,e][1,4]diazepin-1-ones. J Heterocycl Chem 2004. [DOI: 10.1002/jhet.5570410221] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Chueh FS, Chang CP, Chio CC, Lin MT. Puerarin Acts Through Brain Serotonergic Mechanisms to Induce Thermal Effects. J Pharmacol Sci 2004; 96:420-7. [PMID: 15599109 DOI: 10.1254/jphs.fp0040424] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The present study was attempted to investigate the effect of puerarin, an isoflavone compound isolated from Pueraria lobata, on both the basal body temperature and pyrogenic fever in unanesthetized, restrained rats. Intraperitoneal administration of puerarin or crude extracts of Pueraria lobata elicited hypothermia. Direct administration of a small amount of puerarin into the lateral cerebral ventricle produced the same extent of hypothermia. Systemic or central administration of puerarin causes a decrease in both colonic temperature and hypothalamic 5-HT efflux in rats. The puerarin-induced hypothermia and decreased 5-HT efflux in the hypothalamus were attenuated by selective depletion of hypothalamic 5-HT produced by intracerebroventricular injection of 5,7-dihydroxytryptamine. Furthermore, the puerarin-induced hypothermia was almost completely abolished by treatment with a 5-HT2A-receptor agonist (DOI or quipazine) or a 5-HT1A-receptor antagonist [(-)-pindolol]. A 5-HT2A-receptor antagonist (ketanserin) or a 5-HT1A-receptor agonist (8-OH-DPAT) had additive effects with puerarin. Intracerebroventricular administration of interleukin-1 caused an increase in both colonic temperature and hypothalamic 5-HT efflux. The interleukin-1-induced hyperthermia and increased 5-HT efflux in the hypothalamus were attenuated by treatment with systemic administration of puerarin. The data indicate that puerarin exerts its hypothermic and antipyretic effects by activating 5-HT1 receptor and/or antagonizing 5-HT2A receptors in the hypothalamus.
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Affiliation(s)
- Fu-Shin Chueh
- Department of Applied Life Science, Taichung Healthcare and Management University, Taichung, Taiwan 413
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Clozapine reverses hyperthermia and sympathetically mediated cutaneous vasoconstriction induced by 3,4-methylenedioxymethamphetamine (ecstasy) in rabbits and rats. J Neurosci 2003. [PMID: 12867524 DOI: 10.1523/jneurosci.23-15-06385.2003] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Life-threatening hyperthermia occurs in some individuals taking 3,4-methylenedioxymethamphetamine (MDMA, ecstasy). In rabbits, sympathetically mediated vasoconstriction in heat-exchanging cutaneous beds (ear pinnae) contributes to MDMA-elicited hyperthermia. We investigated whether MDMA-elicited cutaneous vasoconstriction and hyperthermia are reversed by clozapine and olanzapine, atypical antipsychotic agents. Ear pinna blood flow and body temperature were measured in conscious rabbits; MDMA (6 mg/kg, i.v.) was administered; and clozapine (0.1-5 mg/kg, i.v.) or olanzapine (0.5 mg/kg, i.v.) was administered 15 min later. One hour after MDMA, temperature was 38.7 +/- 0.5 degrees C in 5 mg/kg clozapine-treated rabbits and 39.0 +/- 0.2 degrees C in olanzapine-treated rabbits, less than untreated animals (41.5 +/- 0.3 degrees C) and unchanged from pre-MDMA values. Ear pinna blood flow increased from the MDMA-induced near zero level within 5 min of clozapine or olanzapine administration. Clozapine-induced temperature and flow responses were dose-dependent. In urethane-anesthetized rabbits, MDMA (6 mg/kg, i.v.) increased ear pinna postganglionic sympathetic nerve discharge to 217 +/- 33% of the pre-MDMA baseline. Five minutes after clozapine (1 mg/kg, i.v.) discharge was reduced to 10 +/- 4% of the MDMA-elicited level. In conscious rats made hyperthermic by MDMA (10 mg/kg, s.c.), body temperature 1 hr after clozapine (3 mg/kg, s.c.) was 36.9 +/- 0.5 degrees C, <38.6 +/- 0.3 degrees C (Ringer's solution-treated) and not different from the pre-MDMA level. One hour after clozapine, rat tail blood flow was 24 +/- 3 cm/sec, greater than both flow in Ringer's solution-treated rats (8 +/- 1 cm/sec) and the pre-MDMA level (17 +/- 1 cm/sec). Clozapine and olanzapine, by interactions with 5-HT receptors or by other mechanisms, could reverse potentially fatal hyperthermia and cutaneous vasoconstriction occurring in some humans after ingestion of MDMA.
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Abstract
Effects of melatonin on both thermoregulatory responses and hypothalamic serotonin release were assessed in unanesthetized rats at three different ambient temperatures (Ta). Systemic administration of melatonin (30-120 mg/kg, i.p) caused a decrease in both colonic temperature and hypothalamic serotonin (5-HT) release in rats at both Ta 8 and 22 degrees C. The hypothermia was brought about by a decrease in metabolic rate at Ta 8 degrees C, whereas at Ta 22 degrees C the hypothermia was produced by both a decrease in metabolic rate and an increase in cutaneous temperature. However, in the heat (Ta 31 degrees C), neither thermoregulatory responses nor hypothalamic 5-HT release was affected by the same amount of administered melatonin. The melatonin-induced hypothermia and decreased 5-HT release in the hypothalamus were attenuated by selective depletion of brain 5-HT produced by intracerebroventricular injection of 5,7-dihydroxytryptamine. Furthermore, the melatonin-induced hypothermia was almost completely abolished by treatment with a 5-HT2A receptor agonist (DOI) or a 5-HT1A receptor antagonist [(-)-pindolol]. The data indicate that melatonin potentiates the 5-HT1A receptor activation in the hypothalamus and results in hypothermic effects which can be antagonized by the expected hyperthermic effect of DOI.
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Affiliation(s)
- Mao-Tsun Lin
- Department of Medical Research, Chi-Mei Medical Center, Yung-Kang City, Tainan Hsien, Taiwan.
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Sumiyoshi T, Matsui M, Yamashita I, Nohara S, Kurachi M, Uehara T, Sumiyoshi S, Sumiyoshi C, Meltzer HY. The effect of tandospirone, a serotonin(1A) agonist, on memory function in schizophrenia. Biol Psychiatry 2001; 49:861-8. [PMID: 11343682 DOI: 10.1016/s0006-3223(00)01025-8] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND The purpose of this study was to test the hypothesis that the addition of tandospirone, a 5-HT(1A) partial agonist, to ongoing treatment with typical antipsychotic drugs, would improve memory function in patients with schizophrenia. METHODS Eleven outpatients (male/female = 7/4) with schizophrenia who had been on stable doses of haloperidol and biperiden were given tandospirone, 30 mg/day, for 4 weeks. The Wechsler Memory Scale-Revised (WMS-R) was administered at baseline and 4 weeks after the addition of tandospirone. The Brief Psychiatric Rating Scale (BPRS; Total, Positive, and Negative subscale scores) and the Simpson-Angus Scale for Extrapyramidal Symptoms (SAS) were also completed on the two occasions. To exclude the possibility of a practice effect on the WMS-R test, 11 age-matched patients with schizophrenia (M/F = 7/4) were tested at baseline and after a 4-week interval. RESULTS Repeated measures analysis of variance revealed a significant time by group (patients with or without tandospirone) effect for the Verbal-, but not the Visual Memory composite scores of the WMS-R test; no significant change was observed in patients without tandospirone, whereas improvement in the Verbal Memory score was noted in patients receiving tandospirone. Moreover, there was improvement in the Inclusion score, an index of memory organization as measured by the Logical Memory subtest of WMS-R, only in patients with tandospirone. Scores on the BPRS and SAS were improved during treatment with tandospirone, but the effects did not reach statistical significance. CONCLUSIONS The results suggest that adjunctive treatment with 5-HT(1A) agonists may improve some types of memory function in schizophrenia.
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Affiliation(s)
- T Sumiyoshi
- Department of Neuropsychiatry, Toyama Medical and Pharmaceutical University, School of Medicine, Toyama, Japan
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16
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Cortes E, Becerra MI, Osornio YM, Díaz E, Jankowski K. 2D NMR analysis of highly restricted internal rotation in 2-methylthio-3H-4-p-bromophenyl)-7-[(ortho- and para-substituted)-phenylthio]-1, 5-benzodiazepines. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2000; 56A:1661-1673. [PMID: 10952128 DOI: 10.1016/s1386-1425(00)00242-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The complete assignments of twelve 4-aryl-7-thioaryl-1,5-benzodiazepines 1H and 13C spectra, performed with the use of high resolution variable solvent and temperature 1D and 2D techniques (e.g. HOMOCOSY, NOESY, HMQC and HMBC), lead to the determination of conformational equilibria between two rotamers having the aromatic ring of the thioaryl oriented in a perpendicular or helical orientation toward the benzodiazepine ring. The restricted rotation was evaluated from the population of these conformers.
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Affiliation(s)
- E Cortes
- Instituto de Química, Universidad Nacional Autonoma de Mexico, UNAM Circuito Exterior, CU Mexico DF
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17
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Salmi P, Ahlenius S. Evidence for functional interactions between 5-HT1A and 5-HT2A receptors in rat thermoregulatory mechanisms. PHARMACOLOGY & TOXICOLOGY 1998; 82:122-7. [PMID: 9553989 DOI: 10.1111/j.1600-0773.1998.tb01410.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The present study was designed to examine 1) functional interactions between 5-HT1A and 5-HT2A/C receptors in thermoregulation in rats and 2) the specific involvement of 5-HT2A and 5-HT2C receptors in such interactions. The 5-HT2A/C receptor agonist DOI (0.025 1.6 mg kg-1, subcutaneously) produced a dose-dependent hyperthermia in rats, which was enhanced by addition of either of two 5-HT1A receptor antagonists, (-)-pindolol (0.5-1.0 mg kg-1, subcutaneously) or WAY-100,635 (0.1-0.4 mg kg-1, subcutaneously). Furthermore, the DOI-induced hyperthermia was counteracted by pretreatment with the 5-HT1A receptor agonist 8-OH-DPAT (0.05 mg kg-1, subcutaneously). The hyperthermia produced by DOI, alone or in combination with WAY-100,635, was fully antagonized by pretreatment with the 5-HT2A/C receptor antagonist ritanserin (1.0 mg kg-1, subcutaneously), as well as with the selective 5-HT2A receptor antagonist amperozide (2.0 mg kg-1, subcutaneously). The present results provide evidence for functional interactions between 5-HT1A and 5-HT2A receptors in temperature regulation in rats, and also suggest an important role for postsynaptic 5-HT2A receptors in the mediation of DOI-induced hyperthermia.
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Affiliation(s)
- P Salmi
- Department of Psychology, Stockholm University, Sweden
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18
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Busatto GF, Kerwin RW. Perspectives on the role of serotonergic mechanisms in the pharmacology of schizophrenia. J Psychopharmacol 1997; 11:3-12. [PMID: 9097883 DOI: 10.1177/026988119701100102] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In recent years, a number of research findings has renewed interest in the possible role of serotonin (5-HT) in the pharmacology of schizophrenia. Atypical antipsychotics that potently block 5-HT receptors have been shown to be at least as effective as classical antipsychotics as well as producing fewer extrapyramidal side-effects. In addition, molecular biological studies have suggested that allelic variations of 5-HT receptor genes may affect both susceptibility to schizophrenia and clinical response to atypical antipsychotics. Building on these findings, this article proposes that 5-HT receptors are critical sites of antipsychotic action, and examines the implications of this to the treatment and pathophysiology of schizophrenia. Possible pharmacological mechanisms underlying the clinical efficacy of 5-HT blocking antipsychotics are discussed, and the potential of functional neuroimaging techniques to further elucidate these mechanisms is emphasized.
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Affiliation(s)
- G F Busatto
- Department of Psychological Medicine, Institute of Psychiatry, DeCrespigny Park, Denmark Hill, London, UK
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19
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Sebens JB, Koch T, Korf J. Lack of cross-tolerance between haloperidol and clozapine towards Fos-protein induction in rat forebrain regions. Eur J Pharmacol 1996; 315:269-75. [PMID: 8982664 DOI: 10.1016/s0014-2999(96)00649-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We investigated whether the acute effects of haloperidol and clozapine on Fos expression in the rat forebrain are mediated by the same receptors through evaluation of cross-tolerance, particularly in the commonly affected areas. Acutely administered haloperidol (1 mg/kg. i.p.) and clozapine (20 mg/kg, i.p.) induce regionally different (e.g., the striatum, the hypothalamic paraventricular and supraoptic nuclei, and the central amygdala) and overlapping (e.g., the nucleus accumbens and the lateral septum) patterns of Fos-protein distribution in the rat forebrain. After long-term treatment, part of the acute effects of these drugs disappears in most brain areas, except in the lateral septum, the hypothalamic paraventricular and supraoptic nuclei and the amygdala following haloperidol administration. Cross-tolerance between haloperidol and clozapine was determined by administering a challenge dose of the one antipsychotic, following a 21-day pretreatment with the same or the other drug or saline. In none of the investigated brain regions was cross-tolerance towards Fos-protein induction found after haloperidol challenge in the clozapine-treated rats. Conversely, a competitive dose of clozapine in long-term haloperidol-treated rats showed cross-tolerance in the lateral septum, while the common effect of the drugs in both the dorsomedial and the dorsolateral parts of the striatum was very small. These findings indicate that, for the major part, the responses to haloperidol and clozapine are mediated by different receptors, even in brain areas that are affected by both drugs.
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Affiliation(s)
- J B Sebens
- Department of Biological Psychiatry, University of Groningen, Netherlands
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20
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Cortés EC, Islas PM, García MM, Romero MOZ. Synthesis and spectral properties of isomeric [(12-N-methyl) and (10-N-methyl)]-11-(o, andp-substituted-anilino)-5H-dibenzo[b,e][1,4]diazepines. J Heterocycl Chem 1996. [DOI: 10.1002/jhet.5570330629] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Hemrick-Luecke SK, Fuller RW. Involvement of 5-HT2A receptors in the elevation of rat serum corticosterone concentrations by quipazine and MK-212. Eur J Pharmacol 1996; 311:207-11. [PMID: 8891601 DOI: 10.1016/0014-2999(96)00439-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The possible involvement of 5-HT2A or 5-HT2C receptors in the elevation of serum corticosterone in rats by quipazine (2-(1-piperazinyl)quinoline maleate) and MK-212 (6-chloro-(1-piperazinyl)pyrazine), direct-acting 5-HT receptor agonists, was investigated by the use of two newly available receptor antagonists, SB 200646A (N-(1-methyl-5-indolyl)-N'-(3-pyridyl)urea) and MDL 100,907 (R-(+)-alpha-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]- 4-piperidinemethanol). MDL 100,907 blocked the increase in serum corticosterone elicited by quipazine and MK-212 with ED50 values of 0.0028 and 0.0027 mg/kg, s.c., respectively. In contrast, SB 200646A only partially antagonized the serum corticosterone concentration increases by quipazine and MK-212 even at the highest dose tested, 40 mg/kg, i.p. Because published data show the affinities of MDL 100,907 and SB 200646A for 5-HT2C receptors to be nearly identical, whereas the affinity of MDL 100,907 for 5-HT2A receptors is 17500-fold higher than that of SB 200646A, our findings suggest that 5-HT2A receptors rather than 5-HT2C receptors mediate the serum corticosterone increases by both quipazine and MK-212.
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Affiliation(s)
- S K Hemrick-Luecke
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN 46285, USA
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22
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Adityanjee, Pandurangi AK, Lindenmayer JP, Jampala VC. m-CPP Challenge Test as Predictor of Response to Clozapine in Schizophrenia. Psychiatr Ann 1996. [DOI: 10.3928/0048-5713-19960701-08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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23
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Klint T, Larsson K. Clozapine acts as a 5-HT2 antagonist by attenuating DOI-induced inhibition of male rat sexual behaviour. Psychopharmacology (Berl) 1995; 119:291-4. [PMID: 7675963 DOI: 10.1007/bf02246293] [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: 01/26/2023]
Abstract
Evidence has been reported that clozapine may derive part of its therapeutic effects in treatment-resistant schizophrenic patients by interacting with the serotonin system. Among the few behavioural models available to test the hypothesis of an interaction of clozapine with 5-HT2 receptors, male rat sexual behaviour is particularly useful, since in this behaviour 5-HT1A and 5-HT2 receptors have opposite functions. Stimulation of 5-HT1A receptors facilitates ejaculatory behaviour and stimulation of 5-HT2 receptors inhibit ejaculation. In the present study, male rat sexual behaviour was depressed by treatment with DOI (1.0 mg/kg), a selective 5-HT2 receptor agonist. The depressive effect of DOI was attenuated by the administration of clozapine (0.1-1.0 mg/kg) in doses that by themselves did not significantly affect sexual behaviour. It was concluded that clozapine in the male rat sexual behaviour model may be interpreted as serving as a 5-HT2 antagonist.
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Affiliation(s)
- T Klint
- Department of Psychology, University of Göteborg, Sweden
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24
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Curtis VA, Wright P, Reveley A, Kerwin R, Lucey JV. Effect of clozapine on d-fenfluramine-evoked neuroendocrine responses in schizophrenia and its relationship to clinical improvement. Br J Psychiatry 1995; 166:642-6. [PMID: 7620750 DOI: 10.1192/bjp.166.5.642] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
BACKGROUND Clozapine is an effective antipsychotic that has high affinity for serotonin type 2 (5-HT2) receptors. The importance of 5-HT antagonism in the overall clinical efficacy of clozapine is unclear. Using a neuroendocrine strategy we tested the hypothesis that clinical response to clozapine is related to alteration in 5-HT function. METHOD Ten treatment-resistant schizophrenic subjects were treated with clozapine for a mean of 10.3 (s.e. 0.9) weeks; d-fenfluramine (DFEN) challenge tests were performed before and after treatment with concurrent clinical ratings (BPRS, SAPS, SANS) made at the time of testing. RESULTS All patients showed clinical improvement following treatment with clozapine. In addition, clozapine produced a significant attenuation of prolactin (PRL) and cortisol (CRT) response to DFEN challenge. Change in symptom ratings correlated significantly with reduction in PRL response to DFEN challenge. CONCLUSIONS These data show that functional alterations occur in the 5-HT system following response to clozapine and lend support to studies suggesting that 5-HT is an important component to the spectrum of action of clozapine.
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25
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Harada H, Igarashi M, Sugae S, Okamoto K, Tsuji M, Nakajima T. A schizophrenic patient who developed extreme hypothermia after an increase in the dose of haloperidol: a case report. THE JAPANESE JOURNAL OF PSYCHIATRY AND NEUROLOGY 1994; 48:595-8. [PMID: 7891424 DOI: 10.1111/j.1440-1819.1994.tb03020.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A patient with chronic schizophrenia, who had been treated for a long time with chlorpromazine, haloperidol, levodopa, benserazide hydrochloride, diazepam and biperiden, developed extreme hypothermia (about 32 degrees C) when the dose of haloperidol was increased because of a deterioration of the patient's mental symptoms. No other physical manifestations were observed, except bradycardia. The turnover of noradrenaline in the cerebrospinal fluid and blood was increased in association with the hypothermia in this patient. A hypothesis about the involvement of monoamine imbalance in changes in body temperature is discussed.
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Affiliation(s)
- H Harada
- Department of Psychiatry, Reinan Hospital, Fukui, Japan
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26
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Kahn RS, Davidson M, Siever LJ, Sevy S, Davis KL. Clozapine treatment and its effect on neuroendocrine responses induced by the serotonin agonist, m-chlorophenylpiperazine. Biol Psychiatry 1994; 35:909-12. [PMID: 8080889 DOI: 10.1016/0006-3223(94)91236-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The effects of clozapine treatment on neuroendocrine responses induced by the serotonin agonist, m-chlorophenylpiperazine (mCPP) were examined. mCPP and placebo were administered after a 2-week drug-free period and again after 5 weeks of clozapine treatment in nine schizophrenic inpatients. Adrenocorticotropic hormone (ACTH), prolactin, and mCPP levels were measured. Clozapine treatment completely blocked mCPP-induced ACTH and prolactin release suggesting that clozapine blocks serotonin receptors that mediate these hormone responses.
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Affiliation(s)
- R S Kahn
- Department of Psychiatry, Mount Sinai School of Medicine/Bronx Veterans Administration Hospital, New York, NY
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27
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Nomikos GG, Iurlo M, Andersson JL, Kimura K, Svensson TH. Systemic administration of amperozide, a new atypical antipsychotic drug, preferentially increases dopamine release in the rat medial prefrontal cortex. Psychopharmacology (Berl) 1994; 115:147-56. [PMID: 7862887 DOI: 10.1007/bf02244765] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The putative atypical antipsychotic drug amperozide (APZ) shows high affinity for serotonin 5-HT2 receptors but only low affinity for dopamine (DA) D2 receptors. By employing microdialysis, we examined the effects of APZ on extracellular concentrations of DA in the nucleus accumbens (NAC), the dorsolateral striatum (STR) and the medial prefrontal cortex (MPC) of awake rats. A 5.0 mg/kg (SC) dose of APZ failed to affect DA concentrations in the NAC, while it increased DA outflow in the STR (by 46%) and the MPC (by 207%). A higher dose of APZ (10 mg/kg, SC) enhanced dialysate DA from the NAC and the STR by 30%, and from the MPC by 326%. Similarly, clozapine (2.5 and 10 mg/kg, SC) produced a greater release of DA in the MPC (+ 127 and + 279%) than in the NAC (+ 52 and + 98%). The selective 5-HT2 receptor antagonist ritanserin (1.5 and 3.0 mg/kg, SC) also produced a slightly higher increase of DA output in the MPC (+ 25 and + 47%) compared with the NAC (+ 19 and + 21%). In contrast, the selective D2 receptor antagonist raclopride (0.5 and 2.0 mg/kg, SC) increased DA release in the NAC (+ 65 and + 119%) to a greater extent than in the MPC (+ 45 and + 67%). These data suggest that the 5-HT2 receptor antagonistic properties of APZ and clozapine may contribute to their preferential effects on DA transmission in the MPC. Infusion of low doses (1, 10 microM, 40 min) of APZ through the probe in the DA terminal areas did not affect significantly DA outflow, while infusion of high doses (100, 1000 microM, 40 min) resulted in a more pronounced elevation of DA levels in the NAC (up to 961%) and the STR (up to 950%) than in the MPC (up to 316%). These findings indicate that the selective action of systemically administered APZ on DA in the MPC is most likely mediated at a level other than the terminal region. Taken together, the present results provide support for the notion that 5-HT2 receptor antagonism may be of considerable significance for the action of atypical antipsychotic drugs on mesolimbocortical dopaminergic neurotransmission.
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Affiliation(s)
- G G Nomikos
- Department of Pharmacology, Karolinska Institutet, Stockholm, Sweden
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28
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Salmi P, Karlsson T, Ahlenius S. Antagonism by SCH 23390 of clozapine-induced hypothermia in the rat. Eur J Pharmacol 1994; 253:67-73. [PMID: 7912199 DOI: 10.1016/0014-2999(94)90758-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Clozapine (7.5-30.0 mumol kg-1 s.c.) produced a decrease in core temperature in the rat. The temperature decrease caused by clozapine (7.5 mumol kg-1 s.c.) was fully antagonized by the selective dopamine D1 receptor antagonist SCH 23390 (0.3 mumol kg-1) s.c.) and a partial antagonism was obtained by the selective dopamine D2 receptor antagonist raclopride (1.6 mumol kg-1 s.c.). On the other hand, the hypothermia was not antagonized by alpha-adrenoceptor antagonists (idazoxan and prazosin), 5-HT receptor antagonists ((-)-pindolol and ritanserin) or by the muscarinic M1 receptor antagonist scopolamine. The hyperthermia produced by the 5-HT1C/2 receptor agonist DOI (0.75 mumol kg-1) was blocked by clozapine (3.0 mumol kg-1 s.c.). Clozapine did not antagonize hypothermia produced by selective dopamine D1 and D2 receptor agonists (A 68930 and quinpirole), the alpha 2-adrenoceptor agonist clonidine, the 5-HT1A receptor agonist 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino)tetralin) or the muscarinic M1 receptor agonist oxotremorine. The present results suggest that clozapine may be a partial agonist at brain dopamine D1 receptors.
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Affiliation(s)
- P Salmi
- Department of Behavioural Pharmacology, Astra Arcus AB, Södertälje, Sweden
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29
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Albinsson A, Lundstedt T, Andersson G. Use of neuroendocrine effects in discrimination between CNS-active drugs in the rat. Drug Dev Res 1993. [DOI: 10.1002/ddr.430290310] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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30
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Kahn RS, Siever L, Davidson M, Greenwald C, Moore C. Haloperidol and clozapine treatment and their effect on M-chlorophenylpiperazine-mediated responses in schizophrenia: implications for the mechanism of action of clozapine. Psychopharmacology (Berl) 1993; 112:S90-4. [PMID: 7831445 DOI: 10.1007/bf02245012] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Since clozapine is, in contrast to conventional neuroleptics, effective in treatment refractory schizophrenic patients its mechanism of action may be different from that of typical neuroleptics. Clozapine has been shown to display the highest binding affinity of all neuroleptics to one of the serotonin (5-hydroxytryptamine, 5HT) receptor subtypes, i.e., the 5HT1c receptor. Furthermore, clozapine, in contrast to conventional neuroleptics, blocks the effect of 5HT agonists on ACTH and corticosterone release in animals. This study hypothesized that clozapine, but not haloperidol would block ACTH and prolactin release induced by the 5HT agonist, m-chlorophenylpiperazine (MCPP). MCPP (0.35 mg/kg PO) was administered after a 3-week drug-free period, after 5 weeks of haloperidol treatment (20 mg/day) and finally after 5 weeks of clozapine treatment (> 400 mg/day) in ten male schizophrenic patients. Clozapine, but not haloperidol, blocked the effect of MCPP on ACTH and prolactin release. These results suggest that clozapine, in contrast to haloperidol, is a functional 5HT antagonist. Since MCPP-induced ACTH and prolactin release may be (partially) 5HT1c mediated, these results suggest that clozapine is a potent antagonist at the 5HT1c receptor.
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Affiliation(s)
- R S Kahn
- Department of Psychiatry, Mount Sinai School of Medicine/Bronx Veterans Administration Hospital, New York, NY 10468
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31
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Affiliation(s)
- H Y Meltzer
- Department of Psychiatry, Case Western Reserve University School of Medicine, Cleveland, OH 44106
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32
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Meltzer HY, Maes M, Lee MA. The cimetidine-induced increase in prolactin secretion in schizophrenia: effect of clozapine. Psychopharmacology (Berl) 1993; 112:S95-104. [PMID: 7831446 DOI: 10.1007/bf02245013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
There is considerable interest in the role of serotonin (5-HT) in the pathophysiology of schizophrenia and in the mechanism of action of clozapine, an atypical antipsychotic agent and a potent dopamine (DA), 5-HT2/5-HT1C and histamine (H) antagonist. Cimetidine, an H2 antagonist, produces robust, transient increase in plasma prolactin (PRL) levels in man following intravenous administration. This effect has been attributed, in part, to indirect central serotonergic mechanisms involving 5-HT2 receptors in the hypothalamus, but the evidence is inconclusive. This study investigated the effects of cimetidine on plasma PRL levels in unmedicated schizophrenic patients versus normal controls and the effect of chronic treatment with clozapine on the cimetidine-induced PRL response. The PRL response to cimetidine was significantly blunted in male but not female schizophrenic patients. The PRL response in male schizophrenic patients was inversely related to psychopathology. Chronic treatment with clozapine completely suppressed the plasma PRL response following cimetidine. These data are consistent with the hypothesis of an abnormality of serotonergic activity, including downregulation of 5-HT2 receptors, in male but not female schizophrenic patients. The role of antagonism of 5-HT2 receptors in the action of clozapine is discussed.
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Affiliation(s)
- H Y Meltzer
- Department of Psychiatry, Case Western Reserve University, School of Medicine, Cleveland, OH
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Gudelsky GA, Nwajei EE, Defife K, Nash JF. Interaction of amfonelic acid with antipsychotic drugs on dopaminergic neurons. Synapse 1992; 12:304-11. [PMID: 1361248 DOI: 10.1002/syn.890120407] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The effects of two inhibitors of dopamine (DA) reuptake, amfonelic acid and GBR 12909, on the clozapine- and haloperidol-induced increases in DA synthesis, release, and metabolism were investigated in the rat. In the striatum, as well as in the nucleus accumbens, the haloperidol-induced increase in tissue concentrations of dihydroxyphenylacetic acid (DOPAC) or the accumulation of dihydroxyphenylalanine (DOPA) was potentiated or unaltered, respectively, in rats treated with amfonelic acid. In contrast, amfonelic acid attenuated the stimulatory effects of clozapine on DOPAC concentrations and DOPA accumulation in both brain regions. GBR 12909 also differentially affected the haloperidol- and clozapine-induced increases in DOPAC concentrations. However, the clozapine-induced increase in DOPA accumulation in the median eminence was not significantly altered by treatment with amfonelic acid. The haloperidol-induced increase in the extracellular concentrations of DA and DOPAC in the striatum also was potentiated by amfonelic acid, whereas the increase elicited by clozapine was suppressed. The increase in extracellular DA produced by the administration of morphine or the coadministration of ritanserin, a 5-HT2 antagonist, and haloperidol also was potentiated by amfonelic acid. The ability of amfonelic acid to distinguish between the actions of clozapine and haloperidol on nigrostriatal and mesocorticolimbic DA neurons does not appear to be related to differences in the effects of the drugs on DA autoreceptors or 5-HT2 receptors. Moreover, the mechanism through which clozapine activates tuberoinfundibular DA neurons may differ from that which is involved in the activation of nigrostriatal or mesocorticolimbic DA neurons.
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Affiliation(s)
- G A Gudelsky
- Department of Psychiatry, Case Western Reserve University, Cleveland, Ohio 44106
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Lee HS, Bastani B, Friedman L, Ramirez L, Meltzer HY. Effect of the serotonin agonist, MK-212, on body temperature in schizophrenia. Biol Psychiatry 1992; 31:460-70. [PMID: 1581424 DOI: 10.1016/0006-3223(92)90258-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The effects of 6-chloro-2-(1-piperaziny)pyrazine (MK-212), a centrally acting 5-HT1C/5-HT2 agonist, on body temperature and behavior were assessed using a single-blind cross-over design in 23 schizophrenic patients and 22 normal controls. Body temperature was assessed before drug administration and at 30-min intervals for 3 hr. Each subject was administered placebo or MK-212. MK-212 significantly elevated temperature in normal controls. There was no overall MK-212-induced increase in temperature compared to placebo in the schizophrenic patients; however, 13 of 23 (56.5%) patients had a larger increase in temperature after MK-212 than placebo, 3 of 23 (13.1%) had no change, whereas the temperature change after placebo was greater than after MK-212 in 7 of 23 (30.4%) patients. MK-212 produced significant increases in nausea, feeling strange, and arousal but these effects did not differ between groups. These results are consistent with decreased 5-HT2 receptor responsivity in some patients with schizophrenia.
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Affiliation(s)
- H S Lee
- Laboratory of Biological Psychiatry, Case Western Reserve University, University Hospitals of Cleveland, OH 44106
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35
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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.
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Affiliation(s)
- A D Levy
- Department of Pharmacology, Loyola University of Chicago, Stritch School of Medicine, Maywood, IL 60153
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Abstract
The arrival of clozapine has been one of the most significant developments in antipsychotic drug treatment since the advent of chlorpromazine ushered in the psychopharmacologic era. However, its utilization has been significantly limited and complicated by its potential to cause adverse effects and agranulocytosis in particular. It must be emphasized that clozapine has a side effect profile that is in many ways distinct from standard typical antipsychotic drugs. Side effects with clozapine are common and range from the benign to the potentially lethal. The most common side effects include sedation, dizziness, and sialorrhea during sleep; the most serious are agranulocytosis, seizures and respiratory depression. Although side effects from clozapine are not necessarily preventable, they are for the most part manageable. Even with the most serious adverse effects, proper knowledge of the medication's actions, clinical vigilance, and prompt intervention can prevent the occurrence of significant morbidity and mortality as a consequence of clozapine treatment.
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Affiliation(s)
- J A Lieberman
- Hillside Hospital, Long Island Jewish Medical Center, Glen Oaks, NY 11004
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Robertson GS, Fibiger HC. Neuroleptics increase C-FOS expression in the forebrain: Contrasting effects of haloperidol and clozapine. Neuroscience 1992; 46:315-28. [PMID: 1347406 DOI: 10.1016/0306-4522(92)90054-6] [Citation(s) in RCA: 369] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The mechanisms by which the atypical neuroleptic clozapine produces its therapeutic effects in the treatment of schizophrenia without causing the extrapyramidal side effects that are characteristic of most antipsychotic drugs remain unclear. Recently, a single injection of the typical antipsychotic haloperidol has been shown to increase c-fos expression in the striatum [Dragunow et al. (1990) Neuroscience 37, 287-294]. C-fos is a proto-oncogene that encodes a 55,000 mol. wt phosphoprotein, Fos, which is thought to assist in the regulation of "target genes" containing an AP-1 binding site. Because a wide variety of physiological and pharmacological stimuli increase c-fos expression, it has been proposed that Fos immunohistochemistry might be useful in mapping functional pathways in the central nervous system. The present experiments examined some potential neuroanatomical differences in the actions of clozapine and haloperidol by comparing their effects on c-fos expression in the medial prefrontal cortex, nucleus accumbens, striatum and lateral septum. The effects of the selective dopamine receptor antagonists SCH 23390 (D1) and raclopride (D2) were also examined. Haloperidol (0.5, 1 mg/kg) and raclopride (1, 2 mg/kg) produced large increases in the number of Fos-containing neurons in the striatum and nucleus accumbens. SCH 23390 (0.5, 1 mg/kg) reduced the number of Fos-positive neurons in the nucleus accumbens and striatum, and had no effect in the other regions. Neither haloperidol nor raclopride increased the number of Fos-positive neurons in the medial prefrontal cortex. Haloperidol, but not raclopride, produced a modest increase in c-fos expression in the lateral septal nucleus. Clozapine (10, 20 mg/kg) was without effect in the striatum; however, it significantly increased the number of Fos-positive neurons in the nucleus accumbens, medial prefrontal cortex and lateral septal nucleus. Destruction of mesotelencephalic dopaminergic neurons with 6-hydroxydopamine abolished the increase in Fos expression in the nucleus accumbens and striatum produced by haloperidol and raclopride, and also blocked the clozapine-induced increase in the nucleus accumbens. However, the inductive effects of clozapine and haloperidol on c-fos expression in the lateral septal nucleus and of clozapine in the medial prefrontal cortex were not affected by the 6-hydroxydopamine lesions. These results suggest that clozapine's unique therapeutic profile may be related to its failure to induce Fos in the striatum as well as its idiosyncratic actions in the lateral septum and medial prefrontal cortex. The effects of clozapine in these latter regions do not appear to be mediated by dopaminergic mechanisms.
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Affiliation(s)
- G S Robertson
- Department of Psychiatry, University of British Columbia, Vancouver, Canada
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Lemus CZ, Lieberman JA, Johns CA, Mayerhoff DI, Pollack S, Cooper TB, Novacenko H. Hormonal response to fenfluramine challenges in clozapine-treated schizophrenic patients. Biol Psychiatry 1991; 29:691-4. [PMID: 2054440 DOI: 10.1016/0006-3223(91)90141-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- C Z Lemus
- Hillside Hospital, Research Department, Glen Oaks, NY 11004
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Lee MA, Nash JF, Barnes M, Meltzer HY. Inhibitory effect of ritanserin on the 5-hydroxytryptophan-mediated cortisol, ACTH and prolactin secretion in humans. Psychopharmacology (Berl) 1991; 103:258-64. [PMID: 1851310 DOI: 10.1007/bf02244213] [Citation(s) in RCA: 42] [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: 12/29/2022]
Abstract
Oral administration of the serotonin (5-HT) precursor L-5-hydroxytryptophan (5-HTP), 200 mg, significantly increased plasma cortisol levels in man. L-5-HTP had no significant effect on the plasma prolactin levels. A borderline effect of 5-HTP on plasma ACTH levels was found. Pretreatment with the 5-HT2/5-HT1c antagonist ritanserin (5 mg, PO, b.i.d. for 2 days) significantly inhibited 5-HTP-induced cortisol secretion. Ritanserin had no effect on the basal plasma cortisol or prolactin levels. These data are suggestive that 5-HTP stimulates cortisol secretion in man via 5-HT2/5-HT1c receptor mechanisms.
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Affiliation(s)
- M A Lee
- Department of Psychiatry, Case Western Reserve University, School of Medicine, Cleveland, Ohio
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Canton H, Verrièle L, Colpaert FC. Binding of typical and atypical antipsychotics to 5-HT1C and 5-HT2 sites: clozapine potently interacts with 5-HT1C sites. Eur J Pharmacol 1990; 191:93-6. [PMID: 1982659 DOI: 10.1016/0014-2999(90)94100-c] [Citation(s) in RCA: 129] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We determined the affinity of several typical and atypical antipsychotics for the 5-HT1C and 5-HT2 sites using radioligand binding assays. Most of the antipsychotics tested appeared to bind to 5-HT2 sites with affinities that were fairly high (i.e. pKi values between 7 and 9) and significantly higher than for 5-HT1C sites. In contrast, clozapine was found to have a significantly higher affinity for 5-HT1C than for 5-HT2 sites. Clozapine had the highest affinity for 5-HT1C sites of all the compounds tested. These findings are consistent with the hypothesis that an interaction with 5-HT2 receptors may be relevant to the clinical activity of typical antipsychotics. The findings also suggest, however, that an interaction with 5-HT1C sites may be relevant to the mechanism of clinical action of clozapine and, perhaps, of other atypical antipsychotics.
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Affiliation(s)
- H Canton
- Neurobiology Division, FONDAX-Groupe de Recherche Servier, Puteaux, France
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Chapter 1. Novel Antipsychotic Agents. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 1990. [DOI: 10.1016/s0065-7743(08)61577-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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44
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Clozapine: Mechanism of Action in Relation to its Clinical Advantages. INTERNATIONAL PERSPECTIVES SERIES: PSYCHIATRY, PSYCHOLOGY, AND NEUROSCIENCE 1990. [DOI: 10.1007/978-1-4612-3248-3_11] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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Meltzer HY, Koenig JI, Nash JF, Gudelsky GA. Melperone and clozapine: neuroendocrine effects of atypical neuroleptic drugs. Acta Psychiatr Scand Suppl 1989; 352:24-9. [PMID: 2573238 DOI: 10.1111/j.1600-0447.1989.tb06432.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effects of atypical neuroleptics within the neuroendocrine axis of rodents can be distinguished from those of typical neuroleptics by the production of: 1) a shortlived increase in serum PRL concentrations, 2) an acute increase in the activity of TIDA neurons, and 3) a marked increase in serum corticosterone concentrations. It is of interest to speculate that the pharmacological properties of atypical neuroleptics which mediate the unique neuroendocrine responses are of relevance to an understanding of the mechanisms which underlie the clinical profile of these antipsychotic agents.
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Affiliation(s)
- H Y Meltzer
- Department of Psychiatry, School of Medicine, Case Western Reserve University, Cleveland
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Meltzer HY, Bastani B, Ramirez L, Matsubara S. Clozapine: new research on efficacy and mechanism of action. EUROPEAN ARCHIVES OF PSYCHIATRY AND NEUROLOGICAL SCIENCES 1989; 238:332-9. [PMID: 2569975 DOI: 10.1007/bf00449814] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Clozapine can produce greater clinical improvement in both positive and negative symptoms than typical antipsychotic drugs in neuroleptic-resistant schizophrenic patients. The clinical response may occur rapidly in some patients but is delayed in others. Clozapine has also been reported to produce fewer parkinsonian symptoms, to involve a lower risk of producing tardive dyskinesia, and to produce no serum prolactin elevations in man. It seems likely that these effects are the result of a common biological mechanism or related mechanisms, rather than unrelated effects. Other atypical antipsychotic drugs, such as melperone and fluperlapine, share at least some of these properties. A relatively low affinity for the D-2 dopamine (DA) receptor and high affinity for the 5-HT2 receptor, producing a high 5-HT2/D-2 ratio, best distinguishes atypical antipsychotics like clozapine from typical antipsychotic drugs. Through its weak antagonist action on D-2DA receptors and a potent inhibitory effect on 5-HT2 receptors, as well as its ability to increase DA and 5-HT2 release, clozapine may be able to permit more normal dopaminergic function in the anterior pituitary, the mesostriatal, mesolimbic and mesocortical regions. The numerous advantages of clozapine over typical neuroleptics are consistent with the primary importance of DA to the pathophysiology of schizophrenia. The secondary but still significant role of 5-HT in the action of clozapine may either be direct or via the effect of 5-HT on dopaminergic mechanisms. Some aspects of schizophrenia could be due to a dysregulation of the interaction between serotonergic and dopaminergic neurotransmission.
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Affiliation(s)
- H Y Meltzer
- Department of Psychiatry, Case Western Reserve University, School of Medicine, Cleveland, OH 44106
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Meltzer HY. Clinical studies on the mechanism of action of clozapine: the dopamine-serotonin hypothesis of schizophrenia. Psychopharmacology (Berl) 1989; 99 Suppl:S18-27. [PMID: 2682729 DOI: 10.1007/bf00442554] [Citation(s) in RCA: 363] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Clozapine administration to schizophrenic patients was found to produce dopamine2 (D-2) and serotonin2 (5-HT2) receptor blockade, as evidenced by the ability to block the increases in growth hormone and cortisol secretion produced by apomorphine and MK-212, respectively, direct acting dopamine (DA) and 5-HT2 agonists. Clozapine did not increase plasma prolactin (PRL) levels nor did it block the apomorphine-induced decrease in plasma PRL concentration, as would be expected from a D-2 receptor antagonist. These PRL results are consistent with the observation that clozapine may increase DA release. Clozapine also decreased plasma tryptophan, plasma homovanillac acid (HVA) and basal plasma cortisol levels. Rodent studies suggest clozapine also increases 5-HT release. We hypothesize that antagonism of D-2 and 5-HT2 receptors and enhancement of DA and 5-HT release are critical elements in the action of clozapine to minimize both positive and negative symptoms without producing significant extrapyramidal symptoms or plasma PRL increases. It is proposed that schizophrenia may also involve a dysregulation of 5-HT2- and D-2-mediated neurotransmission, and that a more normal balance in serotonergic and dopaminergic neurotransmission is at least partially restored by clozapine.
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Affiliation(s)
- H Y Meltzer
- Case Western Reserve University School of Medicine, Cleveland, OH 44106
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Matsubara S, Meltzer HY. Effect of typical and atypical antipsychotic drugs on 5-HT2 receptor density in rat cerebral cortex. Life Sci 1989; 45:1397-406. [PMID: 2571912 DOI: 10.1016/0024-3205(89)90027-1] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effect of acute treatment with seven atypical antipsychotic drugs and four typical antipsychotic drugs on serotonin2 (5-HT2) receptor binding sites in rat cerebral cortex was studied. Among the atypical antipsychotic drugs examined, clozapine, fluperlapine, RMI-81582 and setoperone decreased the density of 5-HT2 receptors, but ticspirone, amperozide and melperone did not. None of the drugs affected the Kd value. Among the typical antipsychotic drugs, loxapine decreased Bmax and increased the Kd of 5-HT2 receptor binding sites, whereas chlorpromazine and cis-flupenthixol had no effect. Clothiapine, a typical antipsychotic drug of the same chemical class as clozapine, decreased Bmax without increasing Kd. The downregulation of 5-HT2 receptor binding sites following a single injection of clozapine, 20 mg/kg, remained almost unchanged during the first 72 hrs and was still significantly decreased for up to 120 hrs. There was no relationship between the affinity for the downregulation of rat cortical 5-HT2 receptor binding site and 5-HT2 receptor density. Coadministration of the D1 dopamine agonist, SKF-38393, did not affect the clozapine-induced downregulation. It is suggested that rapid and prolonged downregulation of 5-HT2 receptor sites is characteristic of some but not all atypical antipsychotic drugs and is not specific to atypical antipsychotic drugs. Dibenzo-epines (clozapine, loxapine, amoxapine, chlothiapine) consistently downregulate 5-HT2 receptors in frontal cortex after acute treatment.
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Affiliation(s)
- S Matsubara
- Department of Psychiatry, Case Western Reserve University School of Medicine, Cleveland, OH 44106
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