Effects of L-thyrosyl-L-arginine (kyotorphin) on the behavior of rats and goldfish

The effects of kyotorphin (KTP), a dipeptide (L-Tyr-L-Arg), on the level of sensory attention to stimuli of different modalities in rats and the explo ratory behavior in goldfish were investigated. In both cases KTP was found to suppress the exploratory activity. When 5-HTP, a precursor of seroronin synthesis, is activated the inhibitory effects of KTP increased. It is assu med that the regulatory effect of KTP on the exploratory behavior of animal s is mediated by the monoaminergic (neurotransmitting) brain systems, as di stinct from its analgetic effects, which are mediated by the opioid brain s ystems. (C) 2000 Elsevier Science Inc. All rights reserved.