Intraventricular galanin produces a time-dependent modulation of 5-HT1A receptors in the dorsal raphe of the rat

Galanin given i.c.v. increased the K-D values of 5-HT1A receptors in the DR by 100% 10 min after administration. This effect had disappeared 2 h and 5 h after galanin administration. In contrast, i.c.v. galanin caused a 40% i ncrease in the B-max values at 2 h without affecting the B-max values 10 mi n and 5 h after i.c.v. galanin. The mRNA levels of 5-HT1A receptors and of galanin in the DR were significantly decreased by 33% and 56% respectively 2 h but not 5 h after i.c.v. galanin. These results suggest that in vivo ga lanin can modulate somatodendritic 5-HT1A receptors in the DR in a time-dep endent manner via galanin-5-HT1A receptor interactions. The findings implic ate a potential role of galanin in affective disorders. NeuroReport 11:3943 -3948 (C) 2000 Lippincott Williams & Wilkins.