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Evidence for postsynaptic mediation of the hypothermic effect of 5‐HT 1A receptor activation

Evidence for postsynaptic mediation of the hypothermic effect of 5‐HT 1A receptor activation 1 The 5‐HT1A ligand BMY 7378 (8‐(2(4‐(2‐methoxyphenyl)‐1‐piperazinyl)ethyl)8‐azaspirol (4,5)‐decane‐7,9‐dione dihydrochloride, 0.032–2 mg kg−1, s.c.) caused hyperphagia, a response to the activation of presynaptic 5‐HT1A receptors. 2 BMY 7378 (8 mg kg−1, s.c.) and the 5‐HT1A agonist (8‐hydroxy‐2‐(di‐n‐propylamino) tetralin (8‐OH‐DPAT), 0.10 and 0.25 mg kg−1 s.c.) also caused hypothermia. This was inhibited by (−)‐pindolol (1 mg kg−1, i.p.) and not prevented by pretreatments with p‐chlorophenylalanine which grossly depleted 5‐hydroxytryptamine (5‐HT) from terminal regions. The hypothermic effects are explicable by activation of postsynaptic 5‐HT1A receptors. Infusion of BMY 7378 (8–64 μg) into the dorsal raphe was without convincing hypothermic effect. 3 BMY 7378 (8 mg kg−1, s.c.) inhibited another effect of activation of postsynaptic 5‐HT1A receptors, i.e., the induction of components of the 5‐HT syndrome by 8‐OH‐DPAT (0.5, 1.0 mg kg−1, s.c.) which suggests that BMY 7378 has antagonistic as well as agonistic effects at these sites. 4 Partial agonist properties of BMY 7378 at postsynaptic sites were also indicated by doses for hypothermia being much greater than those for hyperphagia i.e., ED50 (hypothermia) > 2 mg kg−1, ED50 (hyperphagia) = 0.010 mg kg−1. This contrasts with the similar ED50 values for both the hypothermic (ED50 = 0.08–0.10 mg kg−1) and hyperphagic (ED50 = 0.06–0.10 mg kg−1) effects of 8‐OH‐DPAT. 5 The evidence obtained for mediation of the hypothermic response to 5‐HT1A agonists by postsynaptic sites is relevant to the interpretation of the effects on it of antidepressant treatments and depressive illness. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png British Journal of Pharmacology Wiley

Evidence for postsynaptic mediation of the hypothermic effect of 5‐HT 1A receptor activation

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References (63)

Publisher
Wiley
Copyright
1992 British Pharmacological Society
ISSN
0007-1188
eISSN
1476-5381
DOI
10.1111/j.1476-5381.1992.tb14382.x
Publisher site
See Article on Publisher Site

Abstract

1 The 5‐HT1A ligand BMY 7378 (8‐(2(4‐(2‐methoxyphenyl)‐1‐piperazinyl)ethyl)8‐azaspirol (4,5)‐decane‐7,9‐dione dihydrochloride, 0.032–2 mg kg−1, s.c.) caused hyperphagia, a response to the activation of presynaptic 5‐HT1A receptors. 2 BMY 7378 (8 mg kg−1, s.c.) and the 5‐HT1A agonist (8‐hydroxy‐2‐(di‐n‐propylamino) tetralin (8‐OH‐DPAT), 0.10 and 0.25 mg kg−1 s.c.) also caused hypothermia. This was inhibited by (−)‐pindolol (1 mg kg−1, i.p.) and not prevented by pretreatments with p‐chlorophenylalanine which grossly depleted 5‐hydroxytryptamine (5‐HT) from terminal regions. The hypothermic effects are explicable by activation of postsynaptic 5‐HT1A receptors. Infusion of BMY 7378 (8–64 μg) into the dorsal raphe was without convincing hypothermic effect. 3 BMY 7378 (8 mg kg−1, s.c.) inhibited another effect of activation of postsynaptic 5‐HT1A receptors, i.e., the induction of components of the 5‐HT syndrome by 8‐OH‐DPAT (0.5, 1.0 mg kg−1, s.c.) which suggests that BMY 7378 has antagonistic as well as agonistic effects at these sites. 4 Partial agonist properties of BMY 7378 at postsynaptic sites were also indicated by doses for hypothermia being much greater than those for hyperphagia i.e., ED50 (hypothermia) > 2 mg kg−1, ED50 (hyperphagia) = 0.010 mg kg−1. This contrasts with the similar ED50 values for both the hypothermic (ED50 = 0.08–0.10 mg kg−1) and hyperphagic (ED50 = 0.06–0.10 mg kg−1) effects of 8‐OH‐DPAT. 5 The evidence obtained for mediation of the hypothermic response to 5‐HT1A agonists by postsynaptic sites is relevant to the interpretation of the effects on it of antidepressant treatments and depressive illness.

Journal

British Journal of PharmacologyWiley

Published: Jul 1, 1992

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