Effects of delta 9-tetrahydrocannabinol on testosterone production in vitro: influence of Ca++, Mg++ or glucose

The major psychoactive component of marihuana, delta 9-tetrahydrocannabinol (THC), influences testicular function. In the present experiments, the addition of THC to incubations of whole decapsulated mouse testes altered testosterone (T) production differentially, depending on the specific gonadotropin used, the dose of THC and/or the amount of divalent cation present in the media. In the presence of luteinizing hormone (LH; 10 ng/ml), and a dose of 25 micrograms THC/ml, T production was significantly decreased, compared to that by testes incubated with LH and vehicle at all Ca++ levels, except at 0.127 or 1.0 mM Ca++. The production of T by these paired testes exposed to either THC or vehicle (ethanol; ETOH), increased as Ca++ concentration approached physiological levels. In contrast, in the presence of follicle-stimulating hormone (FSH; 1 microgram/ml), THC-induced suppression of T production was significant in the absence of Ca++ from the media, and at 12.7 mM Ca++. However, it appeared that the levels of Ca++ did not differentially affect T production in the presence of FSH, whether or not THC was also added. In the presence of human chorionic gonadotropin (hCG; 12.5 mIU/ml), a lower dose of THC (25 ng/ml), stimulated T production at 0.25 to 1 mM Ca++, but had no effect as Ca++ reached 2.5 mM. Without additional Ca++ in the media, this dose of THC significantly reduced T secretion. In contrast, in the presence of hCG, a higher THC dose (25 micrograms/ml), suppressed T accumulation at 0.127, and from 1.0 to 12.7, but had no effect at 0.25 mM, or in the absence of Ca++. In the presence of hCG, the high 25 micrograms/ml dose of THC stimulated T production, in the absence of additional Mg++, and at 0.01 mM Mg++, but THC had no effect at 0.1 mM Mg++, but inhibited T production at 1.1 mM Mg++. In the presence of hCG, 25 micrograms THC/ml produced a consistent suppression of T production across glucose concentrations examined. These findings suggest that the mechanisms by which THC effects testicular steroidogenesis may involve Ca++- and/or Mg++-dependent processes. Differential requirements for these divalent cations by the gonadotropins may explain the interactive effects of THC with LH, hCG or FSH.     

Adrenalectomy does not prevent the hyperprolactinemic, induced sexual behavior deficits in CDF male rats

Inbred male CDF rats were bilaterally adrenalectomized and received either two pituitaries under each kidney capsule or were sham operated. They were tested at approximately four, seven and eight weeks after surgery. Between the first and second behavioral test, the animals received corticosterone replacement therapy. In each of the three tests, grafted animals exhibited deficits in male sexual behavior as compared to sham-grafted controls. These results suggest that, at least in CDF inbred rats, the adrenal gland is not necessary for the reduction in male sex behavior resulting from chronic hyperprolactinemia.     

Homologues of catalytic domains of Cellulomonas glucanases found in fungal and Bacillus glycosidases

We demonstrate homology between the catalytic domains of exoglucanase (1,4-beta-D-glucan cellobiohydrolase, EC 3.2.1.91) from Cellulomonas fimi and those of endoxylanases (1,4-beta-D-xylan xylanohydrolases, EC 3.2.1.8) from Bacillus sp. strain C-125 and the fungus Cryptococcus albidus; and between the catalytic domains of endoglucanase (1,4-(1,3:1,4)-beta-D-glucan 4-glucanohydrolase, EC 3.2.1.4) from Cellulomonas fimi and exoglucanase II from Trichoderma reesei. These five enzymes apparently evolved by reshuffling of two catalytic domains and several substrate-binding domains.     

Increased plasma corticosterone levels in bovine growth hormone (bGH) transgenic mice: Effects of ACTH,GH and IGF-I onin vitro adrenal corticosterone production

Previous work from our laboratory provided evidence for increased plasma corticosterone levels in mice transgenic for human and bovine growth hormone (GH). Corticosterone was elevated in both sexes, under both basal and ether-induced stress conditions. The objectives of the present study were to investigate thein vitro adrenal sensitivity to ACTH, GH and/or IGF-I in normal and bGH transgenic mice, to examine plasma corticosterone levels at different times of the day, and to determine plasma levels of ACTH in these animals. For the measurement of plasma corticosterone and ACTH levels, transgenic and normal siblings were housed 2 per cage and decapitated simultaneously within 20 seconds of the first disturbance of the cage. The corticosterone production byin vitro adrenal incubations did not differ between adrenals from normal and transgenic mice at the basal level or in the presence of different doses of ACTH. Growth hormone or IGF-I did not have any effect on corticosterone productionin vitro when given alone, and did not modify the effects of ACTH on the accumulation of corticosterone in the media. Plasma corticosterone concentrations were higher in transgenic than in normal animals in both morning and evening. Plasma concentrations of ACTH in animals killed in the morning were sharply increased in transgenic males as compared with their normal siblings. The results indicate that increased circulating levels of corticosterone in transgenic mice are not due to a potentiation of ACTH actions by GH or IGF-I, but rather to a chronic increase in plasma ACTH levels. The increase in ACTH is presumably a reflection of GH actions in the hypothalamic-pituitary system.     

Serum estradiol, testosterone and dihydrotestosterone in male monkeys treated with testosterone propionate.

Serum estradiol (E2), testosterone (T) and dihydrotestosterone (DHT) were measured in juvenile (pre-pubertal) male rhesus monkeys injected with either 8 mg or 80 mg of testosterone propionate (TP). After one week, the three steroids were elevated and remained essentially unchanged for the duration of the study. There was little difference in serum E2 or DHT when comparing the two groups of steroid-treated monkeys. In contrast, T levels were consistently greater in the animals given the high dosage of TP.     

Differential effects of two alleles of the dy locus on the pituitary-testicular axis of mice.

Testicular function was studied in vivo and in vitro in adult male dy/dy and dy2J/dy2J dystrophic mice. The results demonstrate that testicular function in dy/dy mice is more affected. The basal levels of pituitary hormones measured were normal in dystrophic mice, except for the presence of hyperprolactinemia in dy/dy mice. In dy/dy mice testicular weight was diminished and a deficient transduction of the gonadotropic signal is present in vivo, accompanied by reduced efficiency of 17-hydroxylase and 17-hydroxysteroid dehydrogenase. In dy2J/dy2J mice the signal transduction is normal and the reduction in enzyme efficiency is limited to 17-hydroxysteroid dehydrogenase. The in vitro HCG-induced increases in production of testosterone (T) and estradiol (E2) were reduced in dy/dy/mice, and the data indicate a reduction of enzyme activity rather than in efficiency. In dy21/dy21/mice, HCG-induced T synthesis was increased, HCG-induced E2 synthesis was normal, but basal media E2 levels were reduced, with the in vitro efficiency of aromatase being suppressed under both basal and HCG-stimulated conditions, when compared to their normal littermates.     

The estrous cycle of captive woodchucks (Marmota monax)

Changes in vaginal cytology were assessed and correlated with temporal changes in circulating concentrations of progesterone (P) and estradiol-17 beta (E2) during the breeding season (February to March) in a seasonally breeding rodent, the woodchuck (Marmota monax). Ten individually caged adult females, maintained under laboratory conditions for 3-11 mo, were studied. Vaginal smears were taken each morning for 2 consecutive months beginning 1 February 1990. Seven of 10 females exhibited readily identifiable estrus, characterized by a clear predominance (83%) of cornified cells. The earliest estrous smear was recorded on 3 February and the latest on 12 March. These animals were monoestrous and remained in a prolonged estrous period during their brief breeding season. The average duration of estrus was 18.1 +/- 2.1 days, ranging from 12-27 days. Levels of P and E2 were determined in serum samples taken before, during, and after estrus from 7 females who exhibited estrus. No changes in the circulating levels of P were apparent during the estrous cycle. However, there was a consistent pattern of estradiol secretion characterized by elevated levels of E2 before and during estrus, followed by a significant (p less than 0.05) decline in E2 levels one week after the end of estrus. Elevated levels of E2 preceded and coincided with maximal degree of vaginal cornification. Thus, the termination, but not the onset, of estrus in woodchucks reflected closely the temporal pattern of changes in serum E2 levels during the breeding season.     

Developing testicular microvasculature in the golden hamster, Mesocricetus auratus: a model for angiogenesis under physiological conditions.

The ultrastructure of the developing testicular microvasculature in the testes of immature (3, 5, 8, 10, 12, 16, 20, 25, 30 and 35 days old) golden hamsters was examined and compared to the testicular microvasculature of adult (3 months old) hamsters. In addition, in 16- to 35-day-old hamsters vascular permeability was studied after localization of injected horseradish peroxidase (HRP). Angiogenic processes were present in the testes of all examined immature hamsters and were most conspicuous between 8 and 25 days of age. These processes were absent in the testes of 3-month-old hamsters. On days 3 and 5, few undifferentiated blood vessels with activated endothelium were present in the interstitial spaces. Endothelial cell migration started from these 'mother vessels' and led to invasion of intertubular spaces by vascular sprouts, before vascularization of peritubular spaces occurred (after day 12). Sprouting endothelial cells were identified by the presence of a basal lamina and characterized by abundant cytoplasm and cell organelles. HRP-positive slits were seen in developing vessels, which opened to form the vascular lumen. HRP exited the vascular lumen through unspecialized endothelial contacts and micropinocytotic vesicles. By day 16, the blood-testis barrier prevented HRP from entering the seminiferous tubules beyond the basal compartment. By days 30 and 35 most testicular microvessels and at the age of 3 months all testicular microvessels were of the mature type, with narrow inactive endothelium and specialized cell contacts (including tight junctions). These results demonstrate that the postnatal vascularization of the testis in the golden hamster is a timed complex process. Due to high permeability, vascular sprouts are likely to influence the metabolic situation and thus the maturation processes of the testis. Angiogenesis in the golden hamster testis shares typical morphological features with angiogenic processes in other organs and species under various pathological and physiological conditions. We therefore conclude that the postnatal testis can be viewed as a physiological model of angiogenesis.