DIFFERENTIATED METABOLIC STIMULATION OF RAT PITUITARY LOBES BY PERIPHERAL AND CENTRAL ENDOTHELIN-1

Intravenous infusion (14 nmol/min) and lateral cerebral ventricular injection (9 pmol) of endothelin-1 increased rates of glucose utilization (quantitative autoradiographic [C-14]deoxyglucose method) by 75-219% in pars intermedia and distalis of the rat pituitary gland. In rats given intraventricular endothelin, glucose metabolism was also increased significantly in pars nervosa (+92%). Metabolic activation by central endothelin in pars intermedia and distalis was inhibited by intraventricular pretreatment with the dihydropyridine, nimodipine, indicating that endothelin stimulates energy metabolism and probably hormone secretion in melanotrophs and pars distalis cells via L-type calcium channels.