ABSTRACT
The opioids have been shown to exert effects on the rates of secretion of all hormones of the anterior pituitary gland. The effect of acute morphine administration on adrenal cortical hormone secretion appears to be species dependent. The acute administration of morphine to rats produces a marked increase in plasma radioimmunoassayable growth hormone. The investigations of E. E. Muller and A. Pecile suggest that morphine enhances growth hormone secretion. Although the effects of chronic administration of morphine on growth hormone secretion have not yet been studied, there is some indication that long-term injections may inhibit its release. Acute administration of morphine has been reported to stimulate lactation, an index of increased prolactin secretion. Since acute morphine administration increases lactation and adrenocorticotrophic hormones secretion while inhibiting follicle-stimulating hormone and luteinizing hormone secretion, it seems valid to assume that acute administration facilitates release of prolactin.
