Effects of GABA receptor blockade on stimulation-induced feeding and self-stimulation

Frequency thresholds for eating elicited by electrical stimulation of the lateral hypothalamus of rats decreased in a dose-dependent manner after intraperitoneal (IP) administration of picrotoxin, a gamma-aminobutyric acid (GABA) antagonist that blocks GABA-mediated synaptic inhibition. Strychnine IP, a glycine antagonist that blocks glycine-mediated synaptic inhibition, had no effect. By contrast, frequency thresholds for self-stimulation at the same electrode site significantly increased after picrotoxin. Again, strychnine had no effect. These findings indicate that GABAergic mechanisms are involved in both electrically-elicited feeding and self-stimulation. They also suggest a dissociation of the neural substrates which subserve these behaviors.