THE INTRA-ADRENAL DISTRIBUTION OF INTRINSIC AND EXTRINSIC NITRERGIC NERVE-FIBERS IN THE RAT

The intra-adrenal distribution of nitric oxide synthase (NOS)-immunoreactive nerve fibres was studied in rats subjected to various denervations. Splanchnic nerve section eliminated the NOS-immunoreactive nerve fibres which innervate adrenal chromaffin and neuronal cells. It did not affect those innervating blood vessels and zona glomerulosa, which instead were affected by adrenal demedullation. Guanethidine, 6-hydroxydopamine (6-OHDA) and capsaicin treatments, however, did not produce any change. These results suggest that nitrergic nerves which innervate adrenal medullary cells are extrinsic (largely preganglionic sympathetic), whilst those innervating the zona glomerulosa and the majority of adrenal vessels are intrinsic, and that they do not belong to nerves sensitive to the sympathetic nerve neurotoxins, guanethidine and 6-OHDA, or the sensory neurotoxin, capsaicin.