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 increase in number following adrenalectomy and the present study was aimed at investigating whether axonal sprouting could account for this increase. Antibody against the neuronal growth-associated protein GAP-43 was used as the probe. Four days following adrenalectomy GAP-43-like immunoreactivity was found to increase dramatically, mostly as varicosities surrounding the gland cells. The results suggest an active axonal sprouting following this hormone manipulation and strongly support our hypothesis of neural-humoral dual regulation of the mammalian anterior pituitary.