Atrial natriuretic peptide in trout ovarian follicles

An immunocytochemical study on atrial natriuretic peptide (ANP) was carried out in trout ovaries using an antiserum raised against human atrial natriuretic peptide (hANP). Weakly immunoreactive material was observed both in the ooplasm of the previtellogenic and the early vitellogenic oocytes and in the follicular cells of the late vitellogenic oocytes. Binding sites for hANP have been located using 125I-ANP and light-microscopic autoradiography. These studies provide evidence of specific binding of ANP-like material in both early and advanced vitellogenic oocytes. Autoradiograms indicated that the ANP-like binding sites were localized to a subpopulation of follicles. The presence of ANP-like immunoreactive material and its specific binding sites in the ovary suggest a role for atrial natriuretic peptide as a regulator of the fish ovarian function.