Changes in adrenal neuropeptides content [peptide 7B2, neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP)] induced by pharmacological and hormonal manipulations

Abstract

A novel pituitary peptide, designated 7B2, was shown to be present in the adrenal gland. 7B2-like immunoreactivity was mainly localized in the adrenal medulla, similarly to NPY and VIP. In order to elucidate the neural and humoral regulation of adrenal 7B2, NPY and VIP content, Wister rats were treated with reserpine (RES), ranitidine (RANT) or chlorpheniramine maleate (CPhM) for 7-10 days. The thyroid hormone excess and deficient states were experimentally produced with thyroxine (T4) treatment for 2 weeks, methylmercaptoimidazole (MMI) for 4 weeks, or a thyroidectomized state (Tx) for 4 weeks. Orchiectomy or neonatal monosodium glutamate (MSG) treatment was also done. 7B2, NPY and VIP contents were measured by specific radioimmunoassays. RES and RANT treatments caused significant 7B2 reduction (p less than 0.01) and adrenal NPY was significantly decreased by RES (p less than 0.05), while CPhM induced a VIP decreased (p less than 0.05). Orchiectomy did not affect the peptides concentrations, though MSG treatment did cause a reverse change in VIP and NPY. Although T4 administration did not cause any significant change, MMI treatment and Tx induced significant increase (p less than 0.05 or p less than 0.01) in these peptides. Gel or high performance liquid chromatographic analysis revealed the majority of each immunoreactivity coeluted with each standard. These results suggested that adrenal NPY seemed to be coregulated with catecholamine, while VIP was mainly affected by histaminergic control. Furthermore 7B2 might be modulated by both catecholaminergic and histaminergic nervous control. Thyroid hormone deficiency may also affect the amount of these peptides.