Procaine inhibits cyclic AMP-induced steroidogenesis in isolated bovine adrenocortical cells

Inhibition of adrenal cortical steroid formation by procaine is mediated by reduction of the cAMP-induced 3-hydroxy-3-methylglutaryl-coenzyme A reductase messenger ribonucleic acid levels

Elevated glucocorticoid levels are associated with many diseases, including age-related depression, hypertension, Alzheimer's disease, and acquired immunodeficiency syndrome. Cortisol-lowering agents could provide useful complementary therapy for these disorders. We examined the effect of procaine and procaine in a pharmaceutical formulation on adrenal cortical steroid formation. Procaine inhibited dibutyryl cyclic AMP (dbcAMP)-induced corticosteroid synthesis by murine Y1 and human H295R adrenal cells in a dose-dependent manner without affecting basal steroid formation. Treatment of rats with the procaine-based formulation reduced circulating corticosterone levels. This steroidogenesis-inhibiting activity of procaine was not observed in Leydig cells, suggesting that the effect was specific to adrenocortical cells. In search of the mechanism underlying this inhibitory effect on cAMP-induced corticosteroidogenesis, procaine was found to affect neither the cAMP-dependent protein kinase activity nor key proteins involved in cholesterol transport into mitochondria, cytochrome P450 side chain cleavage enzyme expression, and enzymatic activities associated with cholesterol metabolism to final steroid products. However, procaine reduced in a dose-dependent manner the 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA) activity and the dbcAMP-induced HMG-CoA reductase mRNA levels by affecting mRNA stability. These data suggest that the inhibitory effect of procaine on cAMP-induced corticosteroid formation is due to the reduced synthesis of cholesterol. This modulatory effect of procaine on HMG-CoA reductase mRNA expression was also seen in dbcAMP-stimulated Hepa1-6 mouse liver hepatoma cells. Taken together, these results suggest that procaine may provide a pharmacological means for the control of hormone-induced HMG-CoA reductase mRNA expression and hypercortisolemia.

Effects of 3-MeSO2-DDE and some CYP inhibitors on glucocorticoid steroidogenesis in the H295R human adrenocortical carcinoma cell line

The formation of steroids in the H295R human adrenocortical carcinoma cell line was analysed by HPLC or RIA, and based on these data the apparent catalytic activities of CYP11A, CYP17, CYP21 and CYP11B1 in this cell line were calculated. The environmental pollutant 3-methylsulfonyl-DDE (3-MeSO2-DDE) and the cytochrome P450 (CYP) inhibitors ketoconazole, metyrapone and aminoglutethimide were studied for their effects on the steroid formation. Metyrapone (IC50) of 1 microM) and 3-MeSO2-DDE (10 microM: 66 +/- 10% of control) were found to inhibit the apparent CYP11B1 activity. Ketoconazole inhibited all enzymes examined with the greatest effects on CYP11B1 (IC50) of 2.5 microM). Aminoglutethimide was examined only for effects on CYP11A activity and was shown to inhibit pregnenolone formation (20 microM: 61 +/- 4% of control). The possibility of studying all CYP enzymes in the corticosteroidogenesis makes this cell line a valuable test system to examine effects of chemicals, such as suspected endocrine disruptors, on the human glucocorticoid hormone synthesis. The inhibition of cortisol formation by 3-MeSO2-DDE supports an interaction with the active site of CYP11B1, as previously reported in mouse adrenocortical Y1 cells. In mice, this interaction led to metabolic activation and a high adrenotoxicity of 3-MeSO2-DDE. Therefore studies on the adrenotoxicity of 3-MeSO2-DDE in humans are needed.

Comparison of the effects of the K(+)-channel openers cromakalim and minoxidil sulphate on vascular smooth muscle

1 The actions of the potassium channel openers, cromakalim and minoxidil sulphate, were compared in a range of isolated blood vessel preparations. 2 Cromakalim and minoxidil sulphate inhibited spontaneous mechanical activity of the guinea-pig portal vein and relaxed the noradrenaline precontracted rat aorta with similar potency. In contrast, minoxidil sulphate was less potent than cromakalim in inhibiting spontaneous activity in the rat portal vein and was essentially inactive in the noradrenaline precontracted rat mesenteric artery and rabbit aorta. 3 Minoxidil sulphate did not antagonize the effects of cromakalim in the rabbit aorta indicating it was not acting as a partial 'agonist'. 4 Charybdotoxin, noxiustoxin and rubidium failed to discriminate between cromakalim and minoxidil sulphate indicating that the apparently selective effects of minoxidil sulphate were not mediated by either Ca(2+)-activated potassium channels, delayed rectifiers or rubidium impermeable potassium channels. 5 Glibenclamide antagonized the effects of cromakalim in an apparently competitive manner whereas the effects of minoxidil sulphate were antagonized in a non-competitive manner. The involvement of subtypes of ATP-sensitive potassium channels is discussed.