Activity of the steroid 5α-reductase in pulmonary alveolar macrophages from adult male rats has been investigated in vitro. Intratracheal instillation of 3.4 μmol K2Cr2O7 lowered the enzyme activity within 6 h, and the reduction was significant on the subsequent 2, 4 and 7 days. The activity of this enzyme was significantly decreased only 6 and 24 h after instillation when measured in the 800 g supernatant fraction of whole lung. Instillation of 3.4 μmol K2Cr2O7 increased serum levels of corticosterone. Serum levels of triiodothyronine and thyroxine decreased except for a transient increase 3 h after the K2Cr2O7 instillation. Subcutaneous administration of 200 μg dexamethasone/100g b.wt, 200 μg/100 gb.wt of testosterone, 17β-hydroxy-5α-androstane-3-one (5α-DHT), dehydroepiandrosterone or corticosterone had no effect on the 5α-reductase activity of the pulmonary alveolar macrophages within 12h. The combined treatment with dexamethasone s.c. and intratracheal instillation of 3.4 μmol K2Cr2O7 reduced the steroid 5α-reductase activity in the pulmonary alveolar macrophages to about 25% of controls. Measurement of the steroid 5α-reductase activity in pulmonary alveolar macrophages as an index of lung damage when exposed to toxic material is discussed.

The effect of inhaled methanol, ethanol, n-propanol and n-butanol on male reproductive function as measured by the serum concentration of circulating T (testosterone) and LH (luteinizing hormone) has been investigated. The animals were exposed to concentrations of these alcohols equal to the current threshold limit values in industry (methanol: 200 ppm, ethanol: 1000 ppm, n-propanol, n-butanol: 50 ppm) 6 h a day for up to 1 week. A significant depression in the concentration of circulating T was found after the first 6 h exposure to the respective alcohols with restoration after a recovery period of 18 h, except in rats exposed to n-butanol where a depression of 48% could still measured. The concentration of LH was within the normal range in all experimental groups whereas corticosterone was increased after exposure to n-butanol. Exposure for 1 week was not associated with any significant inability of the rat testis to produce T.

Male mature rats were examined for alterations in circulating free testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) after inhalation of methanol vapour in a dynamic system for up to 6 weeks at doses ranging 200 ppm to 10,000 ppm. The most extensive effects were observed after exposure to 200 ppm of methanol for 6 weeks with serum testosterone concentrations being 32% of the controls. A significant change in LH concentration after exposure to 10,000 ppm of methanol for 6 weeks was also demonstrated. FSH remained unchanged throughout these experiments. Such exposure did not change the elimination rate of testosterone from blood which indicated effects on the testicular synthesis of testosterone.

The effects of 6 alpha-methyl-17 alpha-acetoxy-4-pregnene 3,20-dione (MPA) on the activity of different steroid metabolizing enzymes in vitro were investigated in several organs in the rat. MPA seems to be a potent inhibitor of 3 alpha-reduction of 17 beta-hydroxy-5 alpha-androstan-3-one (Dht) in homogenates of the testis, ovary, epididymis, prostate, kidney and the adrenal glands. In testicular homogenates MPA acts like a competitive inhibitor of the 3 alpha-reduction of Dht, with Ki of 0.42 [microM]. MPA seems to be a selective inhibitor of 3 alpha-hydroxysteroid oxidoreductase in numerous organs. Steroid metabolizing enzymes like 5 alpha-reductase, 7 alpha-hydroxylase, 3 beta-hydroxysteroid oxidoreductase and 17 beta-hydroxysteroid oxidoreductase were not inhibited by MPA under the conditions of incubation employed in these studies.

The human cell line NHIK 3025 has a cytoplasmic dexamethasone receptor. When these cells are exposed to glucocorticoids, the cell cycle time is prolonged. The structural requirements for this effect were investigated by measuring cell number after 4 days exposure to different glucocorticoid analogues at concentrations of 10−6M and 10−7 M. Growth inhibition at 10−7 M required the 4–5 double bond, the 3,20 ketone—and the 11β, 17α and 21 hydroxygroups of the glucocorticoid structure, e.g. cortisol, dexamethasone and prednisolone. Other synthetic glucocorticoids like bimetrazol and triamcinolone acetonide were also active at this dose whereas corticosterone, lacking the 17α hydroxygroup, was only active at 10−6 M. The effect was steroid specific and could be inhibited by anti-cortisol antiserum or by glucocorticoid antagonists.

The median cell cycle of synchronized NHIK3025 cells grown in Eagle's MEM with 10% foetal calf serum was 23.6 h, compared to 18 h observed earlier in Puck's E2a medium with 30% serum (20% human and 10% horse). This difference is due to prolongation of both G1 and G2 in the MEM type medium. Testosterone and 4-androstene-3 beta, 17 beta-diol reduced the cell cycle of synchronized populations of NHIK3025 cultured in MEM type medium. Dexamethasone gave cell cycle prolongation while estradiol had no effect. These results are in accordance with steroid-induced changes in growth of asynchronous cell populations observed earlier. The androgen growth stimulation was partly due to a shortening of G2 but was not exclusively located in one particular phase of the cell cycle.

Publisher Summary Human chorionic gonadotropin (HCG) is produced in the placenta and is thus a gonadotropin of strictly female origin. While in the pregnant woman, this mixed function gonadotropin is of major significance, its trophic activity in the male is restricted to the intra-uterine period of life. Addition of HCG to sliced testicular tissue leads to increased testosterone production. The processes leading to the production and secretion of testicular testosterone in vivo are rapid. The fact that the HCG increases production and secretion of all steroid intermediates of testosterone may be a part of an androgen regulatory mechanism in the testicular tissue. The HCG shares similarity with the pituitary gonadotropins in terms of high concentration of sugars, in particular, in sialic acid. In a number of biological assays, it has been shown that the removal of sialic acid from the HCG is associated with marked reduction in biological activity. Desialylated HCG has a shorter plasma half-life than native HCG but shows increased affinity for gonadal binding sites and considerable steroidogenic activity when added to testicular tissue in vitro.

5α—Dihydrotestosterone (DHT) was extracted, separated and identified from testes of mature rats. When teased preparations of testicular tissue, levator ani or thigh muscle were incubated with 3H—testosterone (T) and an NADPH generating system, 3H—DHT could be detected. Teased testicular tissue produced more 3H—DHT from 3H—T than homogenized tissue and the rates of this conversion in teased testicular tissue were the same in incubations carried out at 33 C or at 37 C. Testes of immature rats formed larger quantities of 3H—DHT and other 5a—reduced metabolites of 3H—T than testes of mature animals. FSH tended to stimulate testicular production of 3H-DHT from 3H—T only when administered to the rats prior to removal of the testes. Testes from rats injected with hCG formed less 3H—DHT from 3H—T than testes from control animals. This effect was also observed when hCG was added to the incubation medium. LH (ICSH) did not have an effect on synthesis of DHT from T at the doses tested. When testicular tissue was incubated with 3H—DHT as the substrate, the main 3H—metabolite was androstanediol. (Endocrinology91: 702, 1972)

Over the past ten years data have been published on the biosynthesis of androgens and estrogens from Δ5-pregnenolone in vertebrate gonads via two metabolic pathways—one pathway (A) using progesterone and 17α-hydroxyprogesterone as intermediates and another pathway (B) biotransforming Δ5-pregnenolone to androgens and estrogens via 17α-hydroxypregnenolone, dehydroepiandrosterone, and Δ5-androstenediol. We have investigated these problems in the canine testis and in the canine ovary in experiments in vivo. Since 17α-hydroxypregnenolone can be metabolized to 17α-hydroxyprogesterone in the gonads from both sexes, metabolic pathway B and metabolic pathway A may overlap. Thus, testosterone can be produced in the canine testis bypassing the formation of the steroid hormone progesterone.

In two different ovarian preparations in vivo, androstenedione-C14 was infused via the left ovarian artery of the dog. In such animals, estradiol-C14 and estrone-C14 could be isolated from the venous blood of the infused organ. If clomiphene was infused via the left ovarian artery concomitant with androstenedione-C14, the rate of conversion of androstenedione-C14 to estradiol-C14 and to estrone-C14 increased. Clomiphene, moreover, increased the ovarian production of estradiol from non-radioactive precursors. The data are discussed with regard to possible mechanism of action of clomiphene on endocrine organs.

Testosterone production by rabbit testis slices has been studied. It has been demonstrated that interstitial cell stimulating hormone, follicle stimulating hormone, and the nucleotide, adenosine-3′,5′- monophosphate will increase the production of testosterone in this system. Theophylline, a competitive inhibitor of the phosphodiesterase enzyme, also will cause an increased production of testosterone by rabbit testis slices thus suggesting that the adenyl cyclase-phosphodiesterase system may be a functional unit in the rabbit testis.

A method of steroid elution from Silica Gel G after thin-layer chromatography is presented. The method is based on the principle of column chromatography. This technique gives adequate and reproducible recoveries and a high state of compound purity.

which had been added bovine serum albumin.The latter has been shown to aid in the preservation of Neurospora mitochondria capable of coupling oxidation to phosphorylation.4It would seem then that the inclusion of bovine serum albumin in the medium has allowed us to isolate mitochondrial preparations capable of demon- strating substrate-independent amino acid production.Summary.-The mitochondria of Neurospora, or a particulate fraction with the same density, have been shown to produce several amino acids in the presence of ATP and manganous ion.The process seems to be synthetic.