Evidence for central alpha sub(2)-adrenergic modulation of rat pineal melatonin synthesis

This study was performed to distinguish central and peripheral alpha sub(2)-adrenoceptors in the inhibition of rat pineal melatonin synthesis. The rats received lipo- or hydrophilic alpha sub(2)-adrenoceptor ligand injections at middark; after 1 or 2 h the pineal melatonin contents were measured. Th...

Full description

Saved in:
Bibliographic Details
Published in:Brain research 2000-12, Vol.887 (1), p.174-177
Main Authors: Mustanoja, S M, Hatonen, T, Alila-Johansson, A, Laakso, M L
Format: Article
Language:English
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:This study was performed to distinguish central and peripheral alpha sub(2)-adrenoceptors in the inhibition of rat pineal melatonin synthesis. The rats received lipo- or hydrophilic alpha sub(2)-adrenoceptor ligand injections at middark; after 1 or 2 h the pineal melatonin contents were measured. The lipophilic agonist medetomidine (100 mu g/kg s.c.) suppressed the melatonin contents significantly, while the hydrophilic agonists ST-91 and p-aminoclonidine (10 or 100 mu g/kg i.v.) did not. The suppression by medetomidine was counteracted by the lipophilic antagonist yohimbine (0.3-3.0 mg/kg i.p.) but not by the hydrophilic antagonist L-659,066 (1-10 mg/kg i.v.). In conclusion, the suppression of nocturnal melatonin synthesis by alpha sub(2)-adrenoceptor agonists is mainly of central origin.
ISSN:0006-8993