Prolonged effects of intraventricular galanin on a 5-hydroxytryptamine(1A)receptor mediated function in the rat

Galanin (3 nmol/rat), 2 h after its intracerebroventricular (i.c.v.) admini stration to male rats, attenuated the passive avoidance (PA) retention defi cit induced by the 5-hydroxytryptamine (HT)(1A) receptor agonist 8-hydroxy- 2-(di-N-propylamino)tetraline (8-OH-DPAT) (0.2 mg/kg) The reduction in the postjunctional 5-HT1A receptor-mediated response after i.c.v. galanin was n ot associated with changes in the mRNA levels and agonist binding propertie s of cortical limbic 5-HT1A receptors, believed to be the target receptors mediating the PA deficit caused by 8-OH-DPAT. These results suggest that ac ute increases of galanin transmission in vivo even after 2 h can counteract limbic 5-HT1A receptor-mediated responses of relevance for affective disor ders without significantly affecting gene expression and binding characteri stics of cortical limbic 5-HT1A receptors. (C) 2001 Elsevier Science Irelan d Ltd. AII rights reserved.