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 anxiety. Selective destruction of nerve endings of the locus coeruleus projections by DSP-4 has been shown to reduce active behaviour in novel situations by enhancing anxiety. In the present study, DSP-4 (50 mg/kg) treatment reduced locomotor activity and time spent in social interaction in rats placed into a novel environment together with an unfamiliar rat, indicating an anxiogenic-like effect. The effect of DSP-4 on time spent in social interaction was completely antagonized by intracerebroventricular administration of neuropeptide Y (NPY) (1 microg) which had no effect of its own on this measure. The present study thus supports the idea that DSP-4 pretreatment is anxiogenic in novel situations and suggests a functional relationship of NA- and NPY-using neural mechanisms in the regulation of social behaviour.