Inhibition of pentobarbital-induced release of growth hormone by thyrotropin releasing hormone.

TRH antagonized the GH releasing effect of pentobarbital anesthesia as well in normal as in thyroidectomized rats, and significantly increased plasma B levels in normal animals. This effect was also observed when TRH was administered into a lateral ventricle of the brain in ug amounts, and was suppressed by the beta-adrenergic receptor blocker propranolol. T3 also antagonized the pentobarbital-induced release of GH; however, plasma B levels were not modified, and the effect on plasma GH levels was not suppressed by propranolol.