In addition to control of adrenal cortical steroidogenesis by adrenocorticotropic hormone (ACTH) and angiotensin 11, the intact rat adrenal gland is extensively innervated by a variety of nerve fibers that have been implicated in modulating adrenal cortical function (reviewed in 1). Adrenal autotransplantation has been used widely to investigate the neural modulation of adrenal cortical function. Following autotransplantation to an ectopic site, adrenal cortical tissue regenerates, while the medulla does not regenerate. It is widely accepted that adrenal transplants are not reinnervated (2-4), thereby providing a model to investigate adrenal function in the absence of neural modulation. However, we have recently shown that adrenal capsules transplanted beneath the kidney capsule are extensively reinnervated by TH-, NPY-, and VIP-positive nerve fibers by 14d post-transplantation (5). In addition, there is marked recovery of steroidogenic function and steroidogenic enzyme expression through 30d post-transplantation (5). The finding that nerve fibers are present in the transplants during the reestablishment of steroidogenic function and enzyme expression suggests that innervation modulates the regeneration and functional recovery of adrenal transplants. However, the hypothesis that the reinnervation of transplants modulates regeneration has not been directly tested. In the present studies, in an