Melatonin potentiates 5-HT1A receptor activation in rat hypothalamus and results in hypothermia

Mao Tsun Lin, Jih Ing Chuang

Research output: Contribution to journalArticle

25 Citations (Scopus)

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°C. The hypothermia was brought about by a decrease in metabolic rate at Ta 8°C, whereas at Ta 22°C the hypothermia was produced by both a decrease in metabolic rate and an increase in cutaneous temperature. However, in the heat (Ta 31°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.

Original languageEnglish
Pages (from-to)14-19
Number of pages6
JournalJournal of Pineal Research
Volume33
Issue number1
DOIs
Publication statusPublished - 2002 Jan 1

All Science Journal Classification (ASJC) codes

  • Endocrinology

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