Endocrine control of hypothalamic and pituitary met-enkephalin and beta-endorphin contents

This review summarizes the recent findings on the effects of endocrine manipulation on the hypothalamic and pituitary contents of met-enkephalin and beta-endorphin. In the pituitary, gonadectomy decreases beta-endorphin content in both the anterior lobe and neuro-intermediate lobe. Orchidectomy results in a decrease while ovariectomy leads to an increase in anterior lobe met-enkephalin contents. Adrenalectomy only lead to an increase in beta-endorphin contents in the anterior pituitary lobe. Hypothyroidism induced by propylthiouracil treatment is accompanied by a decrease of beta-endorphin in the neuro-intermediate lobe and a decrease in met-enkephalin in the anterior lobe while thyroidectomy entails a decrease in met-enkephalin in the anterior lobe only. Chemically induced diabetes mellitus results in a decrease in beta-endorphin content in the hypothalamus and the neuro-intermediate lobe, and a reduction in met-enkephalin level in the anterior and neuro-intermediate lobes. All these changes are reversible with appropriate hormone treatments. These results indicate the importance of hormones in the regulation of the synthesis and/or release of the opioid peptides in the hypothalamus and the pituitary.