Lack of release of ACTH from the denervated rat pars intermedia in vivo.

The purpose of this study was to ascertain whether the pars intermedia of the rat adenohypophysis, isolated from direct innervation via the infundibular stem, could maintain adrenal cortical weight and plasma corticosterone levels. We compared the adrenal cortical response of rats 40 days after either complete hypophysectomy, hypophysectomy with reinsertion of only the pars distalis, or hypophysectomy with reinsertion of only the nervosa-intermedia. Adrenal weight and plasma corticosterone levels were partially maintained in the group with reinserted pars distalis. These parameters were not different from the complete hypophysectomy group in the animals with reinserted nervosa-intermedia. Thus, the pars intermedia, with its nerve supply disrupted, cannot maintain adrenal cortical function.