The function of the anterior pituitary hormone beta-LPH is still unknown, although it is now known to share a common precursor molecule with ACTH and to be itself a potential precursor of the endogenous morphine-like peptides alpha, beta, and gamma-endorphin and Met-enkaphalin. We have begun, and will continue an investigation of plasma beta-LPH response to typical physiological events (physical exercise, food intake, stress) to manipulation of plasma free fatty acids levels, to administration of opiate receptor agonists and antagonists, hypothalamic releasing hormones and drugs affecting neurotransmitter function. Beta-LPH will be measured in plasma and cerebrospinal fluid of patients with pituitary tumors both before and after alpha particle pituitary irradiation. The molecular heterogeneity of beta-LPH-like immunoreactive material in plasma and cerebrospinal fluid will be examined and radioimmunoassays for endorphins and enkephalins will be developed to investigate the relationship of these peptides to beta-LPH in biological fluids.