IMMUNOREACTIVE BETA-ENDORPHIN AND ACTH IN THE SAME NEURONS OF THE HYPOTHALAMIC ARCUATE NUCLEUS IN THE RAT

Immunoreactive ACTH and β‐endorphin (β‐End) were localized in the brain and pituitaries of normal and colchicine‐treated rats, using the immunoperoxidase method at the light microscopic level. On adjacent serial 5‐μm paraffin sections of anterior pituitaries, both ACTH and β‐End could be found in the same cells. On adjacent 5‐μm paraffin sections of brains of colchicine‐treated rats, both ACTH and β‐End could be found in the same perikarya of hypothalamic arcuate nucleus neurons. It appeared that all perikarya containing β‐End contained ACTH as well, suggesting that neurons producing β‐End also produce ACTH. Pathways of ACTH fibers corresponded to pathways of β‐End fibers. These findings suggest that the synthesis, and transport, of ACTH and β‐End are linked in the brain as well as in the pituitary, possibly through a common precursor. Copyright © 1979 Wiley‐Liss, Inc.