Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The sexually differentiated microsomal enzyme steroid 5 alpha-reductase (NADPH: delta 4-3-oxosteroid 5 alpha-oxido-reductase, EC 1.3.99.5) catalyzes the NADPH-dependent conversion of testosterone to 5 alpha-dihydrotestosterone, a more potent androgen. In rat liver, this enzyme is expressed at a 10-fold higher level in adult females as compared to adult males. The pituitary regulation of this enzyme and its mRNA was studied in untreated and hypophysectomized rats and in rats rendered hypothyroid by treatment with the antithyroid drug methimazole. Hepatic 5 alpha-reductase activity was elevated 8-fold, to 85% of adult female levels, in adult male rats given growth hormone by continuous infusion. This same treatment was only partially effective in restoring 5 alpha-reductase in rats depleted of endogenous growth hormone by hypophysectomy, indicating that other pituitary-dependent factors contribute to the elevation observed in the inact animals. Further analysis revealed that thyroxine, but not adrenocorticotropic hormone (ACTH) or chorionic gonadotropin, could elevate 5 alpha-reductase activity and mRNA when given to the hypophysectomized rats and that this effect was enhanced by the presence of growth hormone. This thyroid hormone dependence was confirmed by the decrease in hepatic 5 alpha-reductase expression in hypothyroid rats and by its substantial restoration following thyroxine replacement. Thyroxine also stimulated expression of another female-predominant hepatic mRNA, encoding the steroid 16 alpha-hydroxylase cytochrome P-450f (IIC7), in a manner that was independent of the stimulatory effect of growth hormone on this transcript. In contrast, thyroid hormone did not significantly affect protein or mRNA levels of the growth hormone-stimulated, female-specific steroid sulfate 15 beta-hydroxylase P-450 2d (IIC12). These findings establish that thyroid hormones act at a pretranslational level to modulate the expression of some, but not all, growth hormone-stimulated hepatic mRNAs and demonstrate that both thyroxine and growth hormone can independently contribute to the sex-dependent expression of hepatic enzymes of steroid metabolism.
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PMID:Pretranslational control by thyroid hormone of rat liver steroid 5 alpha-reductase and comparison to the thyroid dependence of two growth hormone-regulated CYP2C mRNAs. 217 47

The metabolism of testosterone and 5 alpha-dihydrotestosterone has been studied in vitro in preputial glands of posterior hypophysectomized, totally hypophysectomized and control sham-operated rats. The level of C19 steroid 5 alpha-reductase activity/unit of preputial gland DNA did not fall after removal of the neurointermediate lobe and rose after total hypophysectomy. It was concluded from this that the androgen unresponsiveness of the preputial glands of hypophysectomized rats was not due to a near-total lack of 5 alpha-reductase and hence that the combined synergistic action of testosterone and alpha-melanocyte-stimulating hormone (alpha-MSH) on preputial gland activity was unlikely to be due to an alpha-MSH-mediated restoration of 5 alpha-reductase levels in hypophysectomized rats. Levels of 3 alpha and 3 beta-hydroxysteroid dehydrogenase but not of 17 beta-hydroxysteroid dehydrogenase appeared to be altered by hypophysectomy.
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PMID:Mechanism of action of alpha-melanocyte-stimulating hormone in rat preputial glands: the role of androgen metabolism. 710 14