PubMed · 10778091
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Y Shimizu, T Yanaihara. 1999. [17 alpha-Hydroxyprogesterone].. https://pubmed.ncbi.nlm.nih.gov/10778091/
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To assess whether induced vitellogenesis in longfinned eels mimics that in naturally maturing conspecifics, female eels were artificially matured and steroid hormone status and oocyte cytology during oogenesis were evaluated. Successful induction of vitellogenesis was evident from the presence of yolk granules in the ooplasm of salmon pituitary homogenate (SPH)-injected, but not saline-, 17-hydroxyprogesterone-, and/or gonadotropin-releasing hormone-treated fish. In SPH-treated females, the migratory nucleus stage was reached after 33-53 days, followed by ovulation around 30 hours after induction of final maturation and ovulation. Only a portion of the germ cells matured, although resumption of vitellogenesis was seen in the majority of oocytes. In contrast, in ovaries of saline-injected controls, the most advanced oocytes were early vitellogenic. Atretic follicles were observed in ovaries of all eels, but abundance was greater in controls than in SPH-treated fish. SPH injections elevated plasma levels of estradiol-17beta and androgens, but not pregnenes, from within three days of treatment. Our results indicate that sex steroid levels in midvitellogenic hormone-treated females are similar to those in wild midvitellogenic females. In contrast, differences in yolk morphology of midvitellogenic follicles were seen between SPH-treated and wild females, especially in the second crop of midvitellogenic-sized oocytes measuring 300-400 microm in diameter. We discuss whether the observed differences affect egg quality, and perhaps explain the short life span of captive-bred eel larvae. J. Exp. Zool. 289:119-129, 2001.
OBJECTIVE: To evaluate adrenal sex hormone concentrations in neutered dogs with hypercortisolemia. DESIGN: Case series. ANIMALS: 11 neutered dogs with hypercortisolemia. PROCEDURE: Serum samples obtained before and 1 hour after administration of ACTH were evaluated for concentrations of cortisol, progesterone, testosterone, dehydroepiandrosterone sulfate or androstenedione or both, and 17-hydroxyprogesterone. RESULTS: For all dogs, concentrations of 1 or more adrenal sex hormones were substantially greater than reference range values before or after administration of ACTH. Testosterone concentration was not greater than reference range values in any of the dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Results emphasize the importance of ruling out hypercortisolemia before measuring adrenal sex hormone concentrations as a means of diagnosing adrenal hyperplasia syndrome (alopecia X) in dogs.
Adrenal cytochrome P450 C21 in a membrane-reconstituted system catalyzed 21-hydroxylation of 17alpha-hydroxyprogesterone at a rate higher than that for progesterone in the steady state at 37 degrees C. The rate of product formation in the steady state increased with the concentration of the complex between P450 C21 and the reductase in the membranes. The complex formation was independent of the volume of the reaction, showing that the effective concentrations of the membrane proteins should be defined with the volume of the lipid phase. The rates of conversion of progesterone and 17alpha-hydroxyprogesterone to the product in a single cycle of the P450 C21 reaction were measured with a reaction rapid quenching device. The first-order rate constant for the conversion of progesterone by P450 C21 was 4.3 +/- 0.7 s(-)1, and that for 17alpha-hydroxyprogesterone was 1.8 +/- 0.5 s(-)1 at 37 degrees C. It was found from the analysis of kinetic data that the rate-determining step in 21-hydroxylation of progesterone in the steady state was the dissociation of product from P450 C21, whereas the conversion to deoxycortisol was the rate-determining step in the reaction of 17alpha-hydroxyprogesterone. The difference in the rate-determining steps in the reactions for the two substrates was clearly demonstrated in the pre-steady-state kinetics.