Localization and quantitation of beta-endorphin in human brain and pituitary

The concentration of human beta-endorphin (beta h-EP)) was measured in various hypothalamic nuclei, in extrahypothalamic brain regions and in the anterior and posterior lobes of the pituitary using a specific radioimmunoassay (RIA) The beta h-EP concentrations in the arcuate nucleus (169 +/- 35 pg/100 micrograms protein, n = 7) and median eminence (163 +/- 32 pg/100 micrograms protein, n = 6) were among the highest in the 17 brain areas examined. The immunoreactive beta h-EP in the hypothalamus corresponded to authentic beta h-EP, as determined by gel exclusion chromatography. By chromatography and RIA the beta h-EP concentrations in anterior (1.53 X 10(5) +/- 0.51 X 10(5) pg/100 micrograms protein, n = 3) and posterior (1.41 X 10(5) +/- 0.38 X 10(5) g/100 micrograms protein, n - 5) pituitary were found to be approximately 1,000-fold higher than in hypothalamus. Within the pituitary beta h-EP was localized throughout the anterior lobe, in the pars intermedia and in that part of the posterior lobe nearest the pars intermedia, as judged by immunocytochemistry. Dense immunocytochemical staining was found along the perimeter of many blood vessels. Beta h-EP and adrenocorticotropin (ACTH) were co-localized in the same pituitary cells. The present data represent the first unequivocal localization and quantitation of beta h-EP in human brain and in the separate lobes of the human pituitary.