Control of cytochrome P-450 in rat testis mitochondria by human chorionic gonadotrophin

Purvis, John L.; Canick, Jacob A.; Rosenbaum, J.; Hologgitas, Joanne; Latif, Syed A.

doi:10.1016/0003-9861(73)90426-8

Cited by 36 publications

(14 citation statements)

References 12 publications

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“…No similar studies have been conducted in porcine testes to our knowledge, however, microsomal and mitochondrial P450 spectra have been measured in subcellular fractions isolated from rat and mouse (75,76). Purvis and colleagues (77,78) demonstrated that levels of mitochondrial P450 were 40 -80 times lower than microsomal P450 levels in rat testes, but were increased many fold in response to human chorionic gonadotropin (hCG) stimulation. Testicular cytochrome b 5 levels were changed very little by hCG treatment in comparison to either microsomal or mitochondrial P450 (77), consistent with the observations for the neonatal pig reported here.…”

Section: Discussionmentioning

confidence: 96%

Regulation of Microsomal P450, Redox Partner Proteins, and Steroidogenesis in the Developing Testes of the Neonatal Pig

et al. 2002

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Testicular growth and plasma androgen concentrations increase markedly in the first weeks of neonatal life of pigs. The regulation of steroidogenesis through this period was examined by measuring total microsomal cytochromes P450 (P450), 17alpha-hydroxylase/17,20-lyase P450 (P450c17) and aromatase P450 (P450arom) enzyme activities, and the redox partner proteins nicotinamide adenine dinucleotide phosphate, reduced form (NADPH)-cytochrome P450 reductase (reductase) and cytochrome b(5) in testicular microsomes. Testes were collected from 1-24 d of age, and testicular development was suppressed by a GnRH antagonist in some animals from d 1-14. Both 17/20-lyase and aromatase activities increased from d 1-7 but not thereafter, and 17-20-lyase activity was always at least 200-fold higher than aromatase activity. Reductase decreased in wk 1, then increased to d 24. No changes were seen in cytochrome b(5) expression. GnRH antagonist treatment suppressed plasma LH, testosterone and testes growth to d 14. 17,20-Lyase and aromatase activities in testicular microsomes were reduced by 20% and 50%, respectively. Total microsomal P450 concentration was reduced by 50% on d 7, but there was no effect of treatment on reductase or cytochrome b(5) expression. These data support the hypothesis that the rise in neonatal testicular androgen secretion is more likely due to gonadotropin-stimulated gonadal growth, rather than specific P450c17 expression. Neither P450c17 nor P450arom can account for the decline in total microsomal P450. Reductase and cytochrome b(5) expression appears to be constitutive, but reductase levels saturate both P450c17 and P450arom.

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Section: Discussionmentioning

confidence: 96%

Regulation of Microsomal P450, Redox Partner Proteins, and Steroidogenesis in the Developing Testes of the Neonatal Pig

et al. 2002

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“…The fact that the stimulatory effect of cGTH can be almost completely abolished by glutethemide indicates that the conversion of cholesterol to pregnenolone is necessary for expression of cGTH effect on androgen synthesis. The regulatory role of LH on the conversion of cholesterol to pregnenolone has been well demonstrated in mammals (Bakker et al, 1978;Cigorraga et al, 1978;Hall and EikNes, 1964;Hall and Young, 1968;Purvis et al, 1973;van der Vusse et al, 1975). Whether the conversion of cholesterol to pregnenolone in carp testis is also under the control of cGTH is currently being investigated in this laboratory.…”

Section: Discussionmentioning

confidence: 92%

“…The testis or its dispersed Leydig cells has been used by many investigators as a model system to probe the mode of action of LH on steroidogenesis (Bakker et al, 1978;Cigorraga et al, 1978;Cooke et al, 1975Cooke et al, , 1979Hall and Eik-Nes, 1964;Hall and Young, 1968;Mendelson et al, 1975;Purvis et al, 1973;van der Vusse et al, 1975). Recently, we have demonstrated that fish GTH can stimulate carp testis to produce androgen in vitro (Huang and Chang, 1980), therefore attempts have been made to use this newly developed system as a model to investigate the mode of action of fish GTH.…”

Section: Discussionmentioning

confidence: 99%

“…The stimulatory effect of LH on androgen production is dependent on de wvo protein synthesis since ribonucleic acid (RNA) and protein synthesis inhibitors can inhibit the stimulatory effect of LH (Cigorraga et al, 1978;Cooke et al, 1975Cooke et al, , 1979Dufau et al, 1974;Mendelson et al, 1975;Moyle et al, 1971;Shin and Sato, 1971). The effect of LH on androgen production is mainly due to its promotion of the conversion of cholesterol to pregnenolone (Bakker et al, 1978;Cigorraga et al, 1978;Hall and Eik-Nes, 1964;Hall and Young, 1968;Purvis et al, 1973;van der Vusse et al, 1975).…”

mentioning

confidence: 99%

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The mode of action of carp gonadotropin on the stimulation of androgen production by carp testis in vitro

Chang

Huang

1982

General and Comparative Endocrinology

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Carp gonadotropin (cGTH) can stimulate carp testis to produce androgen in vitro. This action can be mimicked by dibutyryl CAMP (Bt, CAMP) and prostaglandins (PG). Btp CAMP can enhance the androgen production when submaximal doses of cGTH are used but cannot do so when maximal dose of cGTH is used. PG F,,is more effective than PG E, and E,. Both the inhibitors of RNA and protein synthesis can interfere the stimulatory effect of cGTH. Actinomycin D has 87% while cycloheximide has 100% inhibition. The stimulatory effect of cGTH is much more dependent on de nova protein synthesis than on RNA synthesis. In addition, steroidogenesis inhibitors, glutethemide, metyrapone, and spirocyanoketone, can also inhibit the stimulatory effect of cGTH on androgen production.

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“…The liver tissue was homogenized in an all-glass Duall homogenizer, and the subcellular components (nuclei, mitochondria, light mitochondria, microsomes and cytosol) were isolated from the liver homogenate by differential centrifugation (DeDuve et al, 1955). Microsomal contamination of the nuclei, mitochondria, and light mitochondria (as defined by DeDuve et al, 1955) was determined by measurement of the cytochrome P-450 content in these fractions by optical difference spectroscopy using a Cary 219 spectrophotometer (Purvis et al, 1973). Subcellular components were assayed colorimetrically for carboxylesterase activity after a modification of the method by Talcott (1979) using a Beckman 25 spectrophotometer.…”

Section: Subcellular Distribution Of Hepatic Carboxylesterasesmentioning

confidence: 99%

Inhibition of rat liver and plasma carboxylesterases by impurities present in technical phenthoate

1982

Journal of Toxicology and Environmental Health

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Phenthoate [O,O-dimethyl S-(α-ethoxycarbonyl)benzyl phosphorodithioate] was rapidly hydrolyzed by rat liver and plasma carboxylesterases to the corresponding nontoxic metabolite, phenthoate acid. A partially purified enzyme isolated from rat liver microsomes was sevenfold more effective in hydrolyzing phenthoate than the microsomal fraction. O,S,S-Trimethyl phosphorodithioate (TMPDT) and O,O,Strimethyl phosphorothioate (TMPT), two impurities present in technical formulations of phenthoate, were examined for their inhibiting effects on the esterase degradation of [phenyl-14 C] phenthoate in vitro. Incubation of [ 14 C]phenthoate with rat liver and plasma carboxylesterases in the presence of these impurities greatly diminished the amount of phenthoate acid formed. TMPDT was superior in its inhibitory action against rat liver carboxylesterase to that of TMPT. TMPDT was equipotent in inhibiting crude rat liver and plasma carboxylesterases, and TMPT was more effective in inhibiting plasma carboxylesterase than rat liver carboxylesterases.

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Control of cytochrome P-450 in rat testis mitochondria by human chorionic gonadotrophin

Cited by 36 publications

References 12 publications

Regulation of Microsomal P450, Redox Partner Proteins, and Steroidogenesis in the Developing Testes of the Neonatal Pig

Regulation of Microsomal P450, Redox Partner Proteins, and Steroidogenesis in the Developing Testes of the Neonatal Pig

The mode of action of carp gonadotropin on the stimulation of androgen production by carp testis in vitro

Inhibition of rat liver and plasma carboxylesterases by impurities present in technical phenthoate

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