Inhibition of ACTH-stimulated steroidogenesis in isolated rat adrenal cells treated with neuraminidase

The possible role of membrane sialic acid in the action of ACTH was investigated in rat adrenal cells. After treatment with neuraminidase, the cells showed a diminished steroidogenic response to ACTH while the response to cyclic AMP and dibutyryl cyclic AMP was unaffected. 11β-hydroxylation of deoxycorticosterone (DOC) was also not impaired. Dose response curves for three ACTH peptides (ACTH_1–39′, ACTH_1–24 and ACTH_1–10) with neuraminidase treated cells suggest that sialic acid residues on the glycoproteins of the plasma membrane may either impart affinity to the plasma membrane for ACTH molecule or facilitate transmission of the signal arising from ACTH-receptor interaction to the catalytic site of adenyl cyclase.