Effect of procaine injection into the ventromedial hypothalamic area (VMH) of the rat on serum insulin, glucose and corticosterone and gastric emptying rate.

Bilateral injection of procaine into the VMH resulted in a decrease in serum glucose and immunoreactive insulin levels in both food-deprived rats and meal-fed rats. Corticosterone levels and gastric emptying rate were unaffected by these VMH procaine injections. Since it is likely that the procaine disrupted only those neurons whose cell bodies and synapses lay in the region of the VMH, the results suggest that the two major factors in the etiology of the 'VMH syndrome' following electrolytic lesions, rapid emptying and insulin hyperresponsivity, are dependent upon destruction of fibers of passage through the VMH. Finally, the results further support the proposal that the VMH exerts tonic excitatory control over liver glucose output.