Effects of idazoxan on 5-hydroxytryptamine-mediated behaviour in the mouse and rat.

Abstract

The α(2)-adrenoceptor antagonists idazoxan and RX811059 induced reciprocal forepaw treading, a component of the 5-HT-behavioural syndrome in rats. This response is independent of 'non-α(2)-adrenoceptor idazoxan binding sites' (NAIBS) at which RX811059 is inactive. Idazoxan pre-treatment, in rats, enhanced forepaw treading, head weaving and tremor induced by the 5-HT agonist 5-methoxy-N,N dimethyltryptamine (5-MeODMT), increased head twitches (but decreased hindlimb abduction) induced by the 5-HT releaser p- chloroamphetamine (pCA), but did not clearly alter head twitches induced by the 5-HT precursor L-5-hydroxytryptophan in mice. The α(1)-antagonist prazosin did not alter behaviour induced by either 5-MeODMT or pCA in rats. The α( 2)-agonist, guanoxabenz, did not alter 5-MeODMT-induced behaviour in rats. St587, an α(1)-agonist, selectively potentiated tremor induced by 5-MeODMT, but no other behaviour. A possible mechanism for these interactions could be through enhanced, α(2)-adrenoceptor-mediated, 5-HT release in specific brain areas. Other possibilities, e.g. direct action at subtypes of 5-HT receptors and the importance of these NA-5-HT interactions in the treatment of resistant depression, are discussed.

• Authors: S L Dickinson, I F Tulloch, B Gadie
• Journal: Journal of psychopharmacology (Oxford, England) (J Psychopharmacol) Vol. 5 Issue 3 Pg. 187-95 (Jan 1991) ISSN: 0269-8811 [Print] United States
• PMID: 22282554 (Publication Type: Journal Article)