Pentagastrin modulation of sensitivity of neurons of the lateral hypothalamus to noradrenaline and dopamine.

The chemical sensitivity of neurons of the lateral hypothalamus of hungry and fed rabbits to pentagastrin (PG) and to the mediators, noradrenaline (NA) and dopamine (DA), was investigated utilizing indices which permit the assessment of the structural-functional organization of the impulse stream of nerve cells. It was demonstrated that the neurons of the lateral hypothalamus possess varied chemical sensitivity in the presence of alimentary motivation and during the satisfaction of the corresponding need. The microiontophoresis of PG changes the sensitivity of cells in hungry animals to a higher degree to DA (60%) than to NA (30%), while in fed animals, to a higher degree to NA (48%) than to DA (23%). The administration of NA against the background of the action of PG to fed rabbits decreased the percent of neurons with spike train complex activity. The number of cells in the deprived animals with impulse activity of a similar character decreased following the microiontophoresis of DA alone and DA against the background of the action of PG. It is concluded that PG exerts a modulating influence on the effects of NA and DA on the impulse activity of the neurons, and that the character of the effect of PG depends on the initial state of the animal.