8-Hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) elicits eating in free-feeding rats by acting on central serotonin neurons.

A subcutaneous injection of 0.5 mg/kg 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), a drug with high affinity for 5-hydroxytryptamine (5-HT1A) binding sites, substantially increased eating in non-deprived rats. Intraventricular injections of 5,7-dihydroxytryptamine (5,7-DHT), a neurotoxin for 5-HT neurons, also significantly increased eating in rats and antagonized the effect of 8-OH-DPAT. Microinjections of 8-OH-DPAT (0.5 and 1 microgram) in the nuclei dorsalis and medianus raphe also significantly increased eating in rats. 8-OH-DPAT appears to stimulate eating by acting on 5-HT-containing neurons. These results are compatible with the hypothesis that a decrease in central 5-HT function disinhibits feeding.