Exp Clin Endocrinol Diabetes 1994; 102(4): 299-306
DOI: 10.1055/s-0029-1211295
Original

© J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart · New York

Regulation of interrenal secretion in the axolotl, Ambystoma mexicanum

O. P. Gupta, W. Hanke
  • Department of Zoology, Karlsruhe University, Karlsruhe, Germany
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Publication History

Publication Date:
15 July 2009 (online)

Summary

The regulation of corticosteroid secretion of the adrenal cortex (interrenal tissue) of axolotl (Ambystoma mexicanum) was studied using in vitro preparations of kidney containing interrenal tissue. Normally, 0.3 – 0.65 ng/5 min corticosterone and 0.15 – 0.3 ng/5 min aldosterone were released from the tissue. Regulatory peptides were effective in the following range: ACTH = arginine vasotocin > urotensin II > angiotensin II. They stimulate an elevation of corticosterone (plus 0.2 – 1 ng/5 min) and of aldosterone (plus 0.05 – 0.15 ng/5 min).

The three primary effector systems leading to second messengers, adenylate cyclase (forming cAMP), phos-pholipase C (forming InsP3 + DAG), and phospholipase A2 (liberating arachidonic acid) are involved in stimulation of biosynthesis. It can be suggested that the second messengers stimulate the biosynthesis at the level of the steps between pregnenolone and corticosterone ('3ß-hydroxysteroid-dehydrogenase etc.), because the release of corticosterone is more stimulated than aldosterone. This is different than the regulation of anuran interrenal tissue.

Ca++ ions are involved in corticosterone secretion. Verapamil inhibits immediately the secretion of corticosteroids and elevation of external Ca++ stimulates the release. It is suggested that Ca++ mediates the secretion process itself. Metamorphosis does not change the response of the interrenal gland compared with the neo-tenic animal.

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