[Effect of peptides introduced into the central nucleus of amygdala on the hypothalamic self-stimulation in...

The reinforcing properties of neuropeptides (substance P, corticoliberin, leu-enkephalin, alaptide) and 70 kDa heat shock protein (HSP) administered into the extended amygdala were studied on the hypothalamic self-stimulation model in rats reared in community or social isolation since the 17th day after birth. Since that time (17th day) half of rats were given 5 - 15 % ethanol solution instead of water (semiforced alcoholization). In the age of 90 - 100 days, all rats were implanted electrodes into lateral hypothalamus and cannulas into the central nucleus of amygdala. In the group of alcohol-dependent rats, the alcohol administration was continued. In rats reared in community, corticoliberin, leu-enkephalin and substance P increased the reinforcing properties of self-stimulation in dose-dependent manner, but alaptide and HSP decreased self-stimulation moderately. In rats reared in social isolation, the vector of neuropeptide effects was retained, although the magnitude of the effects was lower. Therefore, the neuropeptides differently participate in the reinforcing mechanisms of hypothalamus. It is suggested that the extended amygdala modulates the reinforcing properties of lateral hypothalamus, probably by means of extrahypothalamic corticoliberin-containing neurons.