title: Stress-induced hyperthermia and basal body temperature are mediated by different 5-HT(1A) receptor populations: a study in SERT knockout rats.
abstract: Disturbances in the serotonergic system are implicated in many central nervous system disorders. The serotonin transporter (SERT) regulates the serotonin homeostasis in the synapse. We recently developed a rat which lacks the serotonin transporter (SERT(-/-)). It is likely that adaptive changes take place at the level of pre- and postsynaptic 5-HT receptors. Because autonomic responses are often used to measure 5-HT(1A) receptor function, we analysed these responses by examining the effects of a 5-HT(1A) receptor agonist and antagonist under in vivo conditions in the SERT(-/-) rat. Moreover, we studied the effect of a mild stressor on the body temperature (stress-induced hyperthermia) because of the known involvement of 5-HT(1A) receptors in this phenomenon. Results show that core body temperature did not differ between genotypes under basal, non-stressed conditions. Compared to SERT(+/+) rats, stress-induced hyperthermia was reduced in SERT(-/-) rats. The 5-HT(1A) receptor agonist [R(+)-N-(2[4-(2,3-dihydro-2-2-hydroxy-methyl-1,4-benzodioxin-5-yl)-1-piperazininyl]ethyl)-4-fluorobenzoamide HCl (flesinoxan) reduced stress-induced hyperthermia in both genotypes. The flesinoxan-induced hypothermia in SERT(+/+) rats was blocked by the 5-HT(1A) receptor antagonist [N-(2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl)-N-(2-pyridinyl) cyclohexane carboxamide 3HCl (WAY100635). Moreover, WAY100635-induced hyperthermia in SERT(-/-), but not in SERT(+/+) rats. In SERT(-/-) rats, WAY100635 completely blocked the flesinoxan-induced reduction of stress-induced hyperthermia. Interestingly, flesinoxan-induced hypothermia was absent in SERT(-/-) rats. It is concluded that the SERT knockout rat reveals that 5-HT(1A) receptors modulating stress-induced hyperthermia belong to a population of receptors that differs from that involved in hypothermia.
authors.affiliation: Department Cognitive Neuroscience: Psychoneuropharmacology, Radboud University Nijmegen Medical Center, Nijmegen, The Netherlands. j.olivier@cns.umcn.nl
authors.forename: Jocelien D A
authors.initials: JD
authors.lastname: Olivier
authors.forename: Alexander R
authors.initials: AR
authors.lastname: Cools
authors.forename: Berend
authors.initials: B
authors.lastname: Olivier
authors.forename: Judith R
authors.initials: JR
authors.lastname: Homberg
authors.forename: Edwin
authors.initials: E
authors.lastname: Cuppen
authors.forename: Bart A
authors.initials: BA
authors.lastname: Ellenbroek
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001831:Body Temperature; D002940:Circadian Rhythm; D005334:Fever / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D010879:Piperazines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D044282:Receptor, Serotonin, 5-HT1A / Q000502:physiology*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000502:physiology*; D013315:Stress, Psychological / Q000503:physiopathology*; D013610:Tachycardia / Q000503:physiopathology
chemical_list: D010879:Piperazines; D011725:Pyridines; D050486:Serotonin Plasma Membrane Transport Proteins; D044282:Receptor, Serotonin, 5-HT1A; C056895:flesinoxan; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide