Activation of GABA A receptor in the brain suppresses neostigmine or histamine-induced central nervous system-mediated hyperglycemia

Abstract

We investigated the effect of GABA receptor agonists on the central nervous system (CNS)-mediated hyperglycemia induced by neostigmine or histamine in anesthetized fed rats. The injection of muscimol, GABA A receptor agonist (1, 2.5 nmol) into the third cerebral ventricle suppressed the hyperglycemia induced by intraventricular injection of neostigmine (1×10 −8 mol) or histamine (5×10 −7 mol). Baclofen, GABA B receptor agonist (1, 2.5 nmol), however, did not suppress these hyperglycemia. Neither muscimol nor baclofen (2.5 nmol) affected plasma glucose levels. These findings suggest that activation of GABA A receptor in the CNS suppresses the hyperglycemia induced by the stimulation of cholinoceptive neuron or histaminergic neuron, but activation of GABA B receptor does not affect them.