EVIDENCE FOR AXONAL SPROUTING IN THE ANTERIOR-PITUITARY FOLLOWING ADRENALECTOMY IN THE RAT

Our recent studies have demonstrated the presence of peptidergic nerve fibers in the anterior pituitary of the rat. They were found to incre ase in number following adrenalectomy and the present study was aimed at investigating whether axonal sprouting could account for this incre ase. Antibody against the neuronal growth-associated protein GAP-43 wa s used as the probe. Four days following adrenalectomy GAP-43-like imm unoreactivity was found to increase dramatically, mostly as varicositi es surrounding the gland cells. The results suggest an active axonal s prouting following this hormone manipulation and strongly support our hypothesis of neural-humoral dual regulation of the mammalian anterior pituitary.