Beta-endorphin: stimulation of growth hormone release in vivo.

Abstract

Two micrograms of .beta.-endorphin (.beta.-lipotropin61-91) injected intraventricularly in rats treated with antiserum [rabbit] against somatostatin [ovine] led to a 6- and 10-fold stimulation of the concentration of plasma growth hormone (somatotropin) measured 10 and 20 min after injection of the peptide, whereas 400 .mu.g of methionine-enkephalin led to a 4- to 6-fold increase of levels of plasma growth hormone at 10 min with a rapid return to basal levels at later time intervals. At doses of 5 and 25 .mu.g, .beta.-endorphin led to a 20- to 30-fold stimulation of levels of plasma growth hormone, the maximal effect being measured between 20-30 min after injection. A possible role of the endogenous opiate-like peptides in the control of growth hormone secretion is suggested.