Radioactive myo-inositol was injected intraperitoneally into nephrectomized rats. The radioactive material present in liver, spleen, brain, heart, diaphragm, seminal vesicle, coagulating gland, prostate, epididymis, vas deferens and testis was shown to consist exclusively of myo-inositol and its derivatives, as shown by paper chromatography of hydrolysates and trichloroacetic acid extracts of these tissues. Radioactive myo-inositol was accumulated rapidly within 1 h by the thyroid, coagulating gland and seminal vesicle. Other tissues, such as the pituitary, prostate gland, liver and spleen, concentrated myo-inositol less actively. The muscle tissues studied (diaphragm and heart) concentrated little inositol, whereas brain, testis, and epididymal fat-pad did not concentrate it at all. The lipid fraction of liver contained most of the radio-labelled myo-inositol. In the other organs most of the radioactivity was found in the aqueous trichloroacetic acid extract, largely as free myo-inositol.
Cholesterol side chain cleavage reaction has been studied in ovaries of immature female rats pretreated with pregnant mare serum gonadotrophin and human chorionic gonadotrophin. The cleavage enzymes were found to be in the mitochondria and to have the characteristics of a mixed function oxidase requiring NADPH and oxygen. Using [4-14C]cholesterol as substrate the main product obtained was progesterone while pregnenolone and 2Qa-hydroxypregn-4-en-3-one, were formed in smaller amounts. This shows that ovarian mitochondria contains a d5-3P-hydroxysteroid-dehydrogenase, a A 5-614-5 isomerase and a 2 0~h y d r o x y steroid dehydrogenase. The proposed intermediates in cholesterol side chain cleavage (20a-hydroxy cholesterol and 20a, 22~-clihyciroxy cholesterol) were not detected.Mitochondria1 production of progesterone in the presence of NADPH was further stimulated by succinate while fumarate was without effect. I n the presence of NADPH, NADH was found to be inhibitory while NAD' gave rise to an increase in pregnenolone, the overall reaction being unaffected. Excess of NADPH causes an accumulation of pregnenolone and slightly decreases the overall reaction. The action of reduced glutathione (GSH) and ascorbic acid-like reducing agents of physiological occurrence has been studied. It was found that GSH in small amounts stimulates and in larger amounts inhibits the side chain cleavage reaction. Ascorbic acid in physiological amounts produced an inhibitory effect.The action of adenosine 3',5'-cyclic-monophosphoric acid (3'5'AMP) and other nucleotides (AMP, ADP, ATP) was tested. 3'5'AMP markedly stimulates the conversion of cholesterol to pregnenolone and decreases the synthesis of progesterone. The action of AMP shows some similarities with that of 3'5'AMP but the action of ADP and ATP was found to be different.There is a considerable amount of experimental evidence to support the contention that most of the steroid hormones are formed in steroidogenic tissue from cholesterol, and that pregnenolone occupies a central place in the formation of
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.