Neuropeptide Y attenuates the effect of locus coeruleus denervation by DSP-4 treatment on social behaviour in the rat

Noradrenaline (NA) has been implicated in both increase and reduction of an xiety. Selective destruction of nerve endings of the locus coeruleus projec tions by DSP-4 has been shown to reduce active behaviour in novel situation s by enhancing anxiety. In the present study, DSP-4 (50 mg/kg) treatment re duced locomotor activity and time spent in social interaction in rats place d into a novel environment together with an unfamiliar rat, indicating an a nxiogenic-like effect. The effect of DSP-4 on time spent in social interact ion was completely antagonized by intracerebroventricular administration of neuropeptide Y (NPY) (1 mu g) which had no effect of its own on this measu re. The present study thus supports the idea that DSP-4 pretreatment is anx iogenic in novel situations and suggests a functional relationship of NA- a nd NPY-using neural mechanisms in the regulation of social behaviour. (C) 2 000 Harcourt Publishers Ltd.