Vasoactive intestinal peptide stimulation modulates the expression of Bcl-2 family members in the adrenal gland of the lizard Podarcis sicula

The adrenal gland of the lizard Podarcis sicula is formed by a dorsal ribbon of chromaffin cells, generally defined as medullary tissue, arranged along a central part of steroidogenic cells considered as cortical tissue. These two tissues produce catecholamines and steroids as part of the hypothalamo-hypophyseal-adrenal gland axis. Recent studies have demonstrated that Podarcis sicula adrenal gland is not only under hypothalamo-hypophyseal axis control but that several peptides may influence the physiological activity of the gland; among these, vasoactive intestinal peptide is able to enhance strongly both catecholamine and steroid hormone production. The aim of the present study was to verify whether vasoactive intestinal peptide administration could become deleterious. For this reason, we monitored the pattern of expression of two members of the Bcl-2 family, Bcl-2 and Bax, in control and vasoactive intestinal peptide treated specimens. Furthermore, we also tested if peptide treatment induces apoptosis by TUNEL assay.