Manganese superoxide dismutase activity in the rat adrenal

Abstract

In the light of studies suggesting that transcription of the gene coding for manganese superoxide dismutase (MnSOD) is induced by ACTH in the rat adrenal gland, northern blot analysis was used to determine its mRNA distribution. It was found that mRNA coding for MnSOD is primarily present in the inner zones of the rat adrenal cortex, and not the glomerulosa. To investigate the functional relationships between MnSOD activity and expression and adrenocortical function, adrenals and blood were taken from animals pretreated with corticotrophin or betamethasone (Betnesol), or subjected to a low-sodium diet. MnSOD activity in inner zone mitochondrial fractions was enhanced by corticotrophin and by a low-sodium diet, but suppressed by betamethasone. Apparent cytosolic MnSOD activity, total cytosolic MnSOD and CuZnMn-SOD, and glomerulosa mitochondrial MnSOD all were unaffected. Steroid assays showed a clear correlation between circulating corticosterone and inner zone mitochondrial MnSOD, but none between aldosterone and glomerulosa MnSOD.Immunoblot analysis of MnSOD showed two apparent isoforms, at approximately 25 kDa and 75 kDa. There was a partial relationship between expression of the 75 kDa isoform and MnSOD activity, in that it was induced by corticotrophin. However, there was also a slight induction with betamethasone, and a low-sodium diet had no effect. The 25 kDa MnSOD isoform was unaffected by the treatments. The results suggest that MnSOD may have a specific role in the steroidogenic function of the fasciculata/reticularis of the rat adrenal, but not in that of the glomerulosa.

Eph receptors and zonation in the rat adrenal cortex

“…To determine which of these are relevant to zonation, glands were taken from animals subjected to different treatments known to affect specifically the glomerulosa/fasciculata phenotypes in the rat. Thus, a low-sodium diet, which provokes angiotensin II generation, is widely used to stimulate the zona glomerulosa and aldosterone secretion (Aguilera & Catt 1983, Lehoux et al 1997, Raza et al 2005, while the ACE inhibitor captopril suppresses it (McEwan et al 1996, van Kats et al 2005. Similarly, ACTH treatment suppresses aldosterone secretion, and quickly initiates the transformation of glomerulosa into fasciculata cells (Aguilera et al 1981, Pudney et al 1984, Abayasekara et al 1989: prolonged treatment may result in the elimination of the glomerulosa altogether (Vinson 2003).…”

“…Similarly, ACTH treatment suppresses aldosterone secretion, and quickly initiates the transformation of glomerulosa into fasciculata cells (Aguilera et al 1981, Pudney et al 1984, Abayasekara et al 1989: prolonged treatment may result in the elimination of the glomerulosa altogether (Vinson 2003). Betamethasone, by contrast, suppresses circulating ACTH, and hence fasciculata function and glucocorticoid secretion (Buckingham & Hodges 1976, Cam & Bassett 1983, Raza et al 2005.…”

“…These were low-sodium diet or ACTH treatment, which enhance glomerulosa and fasciculata expression respectively, and treatment with the angiotensin converting enzyme (ACE) inhibitor captopril or betamethasone, which reduce the circulating levels of the major stimulants of the glomerulosa and fasciculata, namely angiotensin II and ACTH (e.g. Vinson et al 1992, Raza et al 2005.…”

Synthesis, crystal structure and superoxide dismutase activity of [pyrrolidinium][Co(sulfathiazole)3(pyrrolidine)]

“…The mechanism believed to be operating in the metalloproteins involves one-electron reduction of a metal ion by superoxide followed by re-oxidation of the reduced metal ion by a second superoxide anion [1,2]. Metal complexes that can undergo such redox cycling can function as superoxide scavengers; copper is the active metal center in the best studied SOD and many copper complexes have been synthesized and tested for SOD-like activity [3][4][5][6][7][8][9][10][11][12][13]. The other two classes of SODs that contain iron or manganese have received less attention and their structures have only been recently described [14][15][16].…”

“…The other two classes of SODs that contain iron or manganese have received less attention and their structures have only been recently described [14][15][16]. However, some iron [4,17,18], manganese [4,17,19], ruthenium [20] and cobalt [21] SOD mimics have been reported and some show marked SOD activity and seem to retain it in living cells [22,23].…”