Kristen B. Eik-Nes

The action of gonadotropic hormones upon rabbit testis in vitro.

1. Slices of rabbit testis have been shown to incorporate [1-14C]acetate into [14C]testosterone in vitro. This incorporation is variable but is increased by interstitial cell-stimulating hormone and follicle-stimulating hormone added in vitro or by interstitial cell-stimulating hormone and human gonadotropin administered in vivo. 2. Interstitial cell-stimulating hormone did not stimulate the conversion of [4-14C]cholesterol to [14C]testosterone by homogenate of testis but reduced TPN was shown to increase this conversion. 3. The response of slices of testis to interstitial cell-stimulating hormone in vitro was inhibited by chloramphenicol and puromycin. 4. Interstitial cell-stimulating hormone increased the incorporation of [1-14C]-valine and [1-14C]tryptophan into protein by slices of testis when the hormone was administered in vivo or added in vitro. 5. These findings suggest that interstitial cell-stimulating hormone stimulates proteins synthesis by testis and raise the possibility that this hormone may share with ACTH a mechanism of action based on increased provision of reduced TPN although it is not at present possible to conclude that both hormones produced this effect by the same means.

Concentration of tritium in brain tissue of dogs given [1,2-3H2] cortisol intravenously

Abstract A technique for removing discrete hypothalamic nuclei in the dog is described. Following the intravenous administration of [1,2- 3 H 2 ]cortisol to normal dogs the amount of radioactivity present per mg tissue in the hypothalamic nuclei was higher than in the hypophysis or in cortex cerebri. Hypothalamus showed a fast uptake and a slow release of free cortisol and its free metabolites. The hypophysis, cortex cerebri, the mammillary body, a median eminence and a nucleus supraopticus area all converted cortisol to cortisone in vitro . It is postulated that cortisol inhibition of the adrenal-pituitary axis primarily occurs at a hypothalamic level.

Determination of free estrone in blood plasma by gas-phase chromatography with electron capture detection☆

Abstract A method for the estimation of free estrone in plasma has been developed using gas-phase chromatography with electron capture detection. As little as 0.00014 μg pure estrone can be measured, but at least 0.001 μg of the hormone is needed in the original sample for adequate quantitation. Prior to gas-phase chromatography, plasma estrone is purified by thinlayer chromatography and converted to its 3-methyl ether 17-pentafluorophenylhydrazone. Plasma estrone values in pregnant women (9th to 40th week) ranged from 0.5 to 9.8 μg/liter and in normal women during midpoint of the menstrual cycle from 0.18 to 1.25 μg/liter. These data are in good agreement with estrone concentrations found by other, more time-consuming, methods. The sensitivity, specificity, accuracy, and precision of the method have been discussed.

METABOLISM IN VIVO OF STEROIDS BY THE CANINE TESTES.

Abstract The formation of testosterone in vivo has been investigated in anesthetized dogs by infusing radioactive steroids via the left spermatic artery and isolating radioactive testosterone in venous blood obtained from the left spermatic vein. The data from such experiments indicate that the formation of 17α-hydroxypregnenolone and the metabolism of this steroid to testosterone is a major route in the biosynthesis in vivo of testosterone from pregnenolone by the canine testis. 1. 1. When an equal amount of [4 −14 C]progesterone and 17α-hydroxy[7α- 3 H]pregnenolone were infused at a constant rate by the spermatic artery, the concentration of 3 H in isolated spermatic vein testosterone was from 3–8 times that of 14 C. 2. 2. When [7α- 3 H]prenenolone was infused by the left spermatic artery for 5 min, more [ 3 H]17α-hydroxypregnenolone than [ 3 H]progesterone was found in the left testis at the end of this infusion. 3. 3. The problem of preferred metabolism to testosterone in vivo by testicular tissue is discussed.

Testosterone synthesis by the two-day-old chick testis in vitro ☆

The effect of interstitial cell-stimulating hormone, follicle-stimulating hormone, human chorionic gonadotrophin, and pregnant mare serum gonadotrophin on the incorporation of acetate-1-14C into testosterone-14C by the 2-day-old chick testis in vitro has been investigated. All gonadotrophins tested stimulated this incorporation. Incubations at various temperatures indicate that 41°C is the optimal temperature for this conversion. The isolation and identification of testosterone-14C, biosynthesized from acetate-1-14C by the normal 2-day-old chick testis in vitro, clearly shows that birds of this young age can synthesize this androgen. In addition, the presence of dehydroepiandrosterone in a nonmammalian testis has been demonstrated.

Progesterone metabolism by testicular tissue of the English sparrow (Passer domesticus)

Homogenates of testes from the English sparrow (Passer domesticus) were incubated with progesterone-4-C14. The pathway of androgen formation from progesterone as well as the requirements for cofactors in this in vitro system were similar to those reported for mammalian testes. The sparrow testes possessed a greater capacity for 20-ketone reduction of progesterone than the mammalian testes hitherto investigated. These enzymatic processes may tend to inactivate progesterone if this steroid hormone is permitted to accumulate in the testicular tissue. It is likely that four enzymes are present in the testes of the English sparrow which will reduce the 20-ketone function of progesterone and 17α-hydroxyprogesterone.

Determination of deoxycorticosterone and aldosterone in biological samples by gas chromatography with electron capture detection

Abstract Gas chromatography with electron capture detection was used for quantitation of deoxycorticosterone and aldosterone from biological samples. Purification of samples prior to final quantitation on the gas chromatograph was done by paper chromatography, derivative formation, and then thin-layer chromatography. The derivatives used which were sensitive to electron capture detection were deoxycorticosterone acetae and aldosterone γ-lactone. As little as 0.02 μg of either deoxycorticosterone or aldosterone in the original sample could be quantitated. The methods were applied to simulated samples, rabbit adrenal venous blood. and adrenal incubates. Specific activities of deoxycorticosterone and aldosterone from adrenals incubated with progesterone-4-C 11 were obtainable with the methods developed.

The influence of gonadotropins in vivo upon the biosynthesis of androgens by homogenate of rat testis

Treatments of rabbits with gonadotropins in vivo failed to produce demonstrable stimulation of the conversion of [4-14C]cholesterol to [14C]testosterone by homogenate of testis. Short-term treatment (1–12 h) of hypophysectomized rats with human chorionic gonadotropin or interstitial cell-stimulating hormone also failed to increase the conversion of cholesterol to androgens by homogenate of testis. However, 24 h after a single injection of human chorionic gonadotropin or interstitial cell-stimulating hormone an increase in the conversion of cholesterol to androgens by homogenate of testis from hypophysectomized rats was observed.

Progesterone metabolism by testicular tissue of the English sparrow (Passer domesticus) during the annual reproductive cycle

Abstract By incubating cell-free testicular tissue homogenates in vitro with 4-C 14 -progesterone, an attempt has been made to determine the levels of the 17 α-hydroxylase, 20 α-hydroxysteroid dehydrogenase, and 20 β-hydroxysteroid dehydrogenase activities in tissue from English sparrows in different stages of the annual testicular cycle of size and activity. Per milligram testicular protein the 17 α-hydroxylase decreased by a factor of 10 with an increase in testicular weight from 7.2 to 480 mg, whereas the 20-hydroxysteroid dehydrogenases remained relatively constant or decreased by only a factor of 2 over similar testicular weight changes. Calculated on a basis of enzyme content per bird the total testicular 17 α-hydroxylase increased by a factor of 3–4, while the 20-hydroxysteroid dehydrogenases increased by a factor of 20–40 when the mean testicular weight increased from 7 to about 500 mg. Administration of human chorionic gonadotropin stimulated both the 17 α-hydroxylase and 20-hydroxysteroid dehydrogenases, but had a greater effect on the former enzyme. The changes in enzyme activities correlated histologically and suggested that the 20 α- and 20 β-hydroxysteroid dehydrogenases may be located in the cellular elements of the germinal tissue whereas the 17 α-hydroxylase is of interstitial cell origin. Of the different progesterone metabolites identified from these incubations, only the known androgens, testosterone and androstenedione, promoted blackening of the sparrow beak.

Biosynthesis in vivo of testosterone and Δ4-androstenedione from dehydroepiandrosterone-sodium sulfate by the canine testis and ovary

Abstract Dehydroepiandrosterone-sodium sulfate (DHEA-sodium sulfate) labeled with tritium in 7α position has been infused at a constant rate by the left ovarian or spermatic artery in anesthetized dogs pretreated with human chorionic gonadotropin for 10 days. Testosterone and Δ 4 -androstenedione were isolated in the venous blood from the gonads in both sexes, while free dehydroepiandrosterone was isolated only in the female animal. 1. 1. The canine ovary and testis are able to convert DHEA-sodium sulfate to testosterone and Δ 4 -androstenedione in vivo . 2. 2. No conversion from DHEA-sodium sulfate to estrogens could be detected. 3. 3. The significance of this reaction is discussed.