Plasma growth hormone in the anesthetized rat. Effects of dibutyryl cyclic AMP, prostaglandin E 1 , adrenergic agents, vasopressin, chlorpromazine, amphetamine and L-dopa.

Abstract

Plasma rat growth hormone (GH) responses to various stimuli were studied under urethane anesthesia (150 mg/100 g body wt). Intravenous injections of dibutyryl cyclic AMP (0.5 mg/100 g body wt) or prostaglandin E1 (5 μg/100 g body wt) caused significant increments in plasma rat GH. Increments in plasma rat GH were also caused by isoproterenol (10 μg/100 g body wt) or phentolamine (100 μg/100 g body wt), and these effects were suppressed by concurrent administration of propranolol or phenylephrine, respectively. Synthetic arginine vasopressin (100 mU/100 g body wt) significantly increased plasma rat GH, and this effect was inhibited by the simultaneous administration of propranolol. Intravenous injections of chlorpromazine (50 μg–1 mg/100 g body wt) produced marked doserelated increments in plasma growth hormone in these studies. The peak response appeared 20 to 40 min after injection of chlorpromazine. This effect was partially inhibited by simultaneous injection of L-dopa (1 mg/100 g body wt), though L-do...