Eric Bloch

Effects of cannabinoids on reproduction and development.

Publisher Summary This chapter discusses the effects of cannabinoids on reproduction and development. The potential importance of the effects of marihuana on reproduction and development has been recognized. This recognition has led to an increasing number of studies and reports on the action of marihuana and its purified cannabinoid fractions on reproductive capacity and events and on embryonic and fetal development. Cannabinoids exert a direct inhibitory action on testicular androgen synthesis and cell metabolism. This is in contrast to the variable weight changes but explains in part the drop in plasma testosterone levels following cannabinoid intake. The addition of tetrahydrocannibinol (Δ 9 -THC) or cannabinol to mouse testes minces in incubation medium inhibited endogenous testosterone production by more than 50%. The acute administration of marihuana by smoking usually leads to a decrease in circulating testosterone and luteinizing hormone levels. The effect of cannabinoids on maternal physiology during pregnancy and lactation is also elaborated in the chapter.

Reproductive toxicity of 2,4-dinitrotoluene in the rat☆

The present study was undertaken to evaluate the effects of the chemosterilant 2,4-dinitrotoluene (DNT) on the rat testis. Adult male rats were fed control, or 0.1%, or 0.2% DNT for 3 weeks. An ultrastructural study of the testes was performed, serum was assayed for testosterone and gonadotropins, and sperm reserve count was determined. A marked change in Sertoli cell morphology was found after 3 weeks of 0.2% DNT exposure. Varying sized vesicles associated with swollen mitochondria and distended endoplasmic reticulum were visible in cells from DNT-treated animals. Circulating levels of follicle stimulating hormone and luteinizing hormone were increased in 0.2% DNT-treated animals. Reduced weights of the epididymides and decreased epididymal sperm reserves were observed in DNT-treated animals. These results indicate that DNT is capable of inducing testicular injury, of directly or indirectly disturbing pituitary function, and of exerting a toxic effect at the late stages of spermatogenesis. These findings suggest that a locus of DNT action is the Sertoli cell, resulting in both inhibition of spermatogenesis and changes in testicular-pituitary endocrine activity.

The conversion of 7-3H-pregnenolone and 4-14C-progesterone to testosterone and androstenedione by mammalian fetal testes in vitro

Abstract Homogenates of testes from fetal rats, armadillos, guinea-pigs and dogs converted 7-3H-pregnenolone and 4-14C-progesterone to testosterone (major product) and androstenedione during in vitro incubations. Except with canine testes, conversion was efficient. These results, in conjunction with data obtained from studies with human and rabbit testes, establish the capacity of fetal testes of a range of mammalian species to synthesize testosterone from steroidal precursors. It is suggested that the capacity of the adult mammalian testes to synthesize C19 steroids, particularly testosterone, is established during fetal development.

The effect of mono(2-ethylhexyl) phthalate on Sertoli cell transferrin secretion in vitro

We have examined the effect of mono(2-ethylhexyl) phthalate (MEHP) on the secretion of rat transferrin (rTf) by Sertoli cells (SC) in the presence and absence of FSH. Significant decreases in rTf secretion were observed in SC cultures exposed to 50 and 75 microM MEHP, in the absence of FSH. Treatment of SC with FSH (300 ng/ml) obviated this suppression of rTf secretion by MEHP. These findings indicate an effect of MEHP on rTf secretion by SC in vitro which could account for the testicular toxicity of MEHP in vivo.

Endogenous Estradiol and Progesterone Concentrations in Smokers on Oral Contraceptives

The simultaneous effects of cigarette smoking and oral contraceptives on serum estradiol and progesterone levels were investigated in 114 premenopausal women. Serum 17 beta-estradiol and progesterone levels were measured by radioimmunoassay. In smokers, estradiol and progesterone levels were significantly lower (p less than 0.025). In smokers using oral contraceptives, estradiol and progesterone levels were the lowest (p less than 0.001 and p less than 0.01, respectively). The findings suggest that smoking and oral contraceptives independently lower serum estradiol and progesterone concentrations in premenopausal women and that the effects may be additive.

Reproductive toxicity of 2,4-toluenediamine in the rat. 1. Effect on male fertility

Effects of 2,4-toluenediamine (TDA) on reproduction in adult male Sprague-Dawley rats were evaluated. Diets containing 0, 0.01 and 0.03% TDA were fed ad libitum to experimental animals for 10 wk. No signs of toxicity were found. Exposure to the high dose resulted in decreased mating frequency and an increase in infertile matings. Light-microscopic examination of the testes revealed reduced numbers of sperm in the seminiferous tubules and cauda epididymides. These results indicate that TDA is capable of reducing fertility and of exerting an inhibitory or toxic effect on spermatogenesis in the rat.

Comparative placental steroid synthesis. II. C19 steroid metabolism by guinea-pig placentas and fetal adrenals in vitro

Placental homogenates from guinea-pigs at 16, 20, 35 and 55 days gestation were incubated with 7α-3H-dehydroepiandrosterone and 4-14C-androstenedione and analyzed for conversion products by reverse isotope dilution methods. 14C-3α-Hydroxy-5α-androstan-17-one, 14C-androstane-3α, 17β-diol and 3Handrost-5-ene-3β, 17β-diol were isolated from homogenates incubated with substrates for 2 hours. 3H, 14C-Testosterone was isolated from preparations incubated for 15 minutes or with high substrate: tissue ratios. Androst-4-ene-3, 17-dione, 5α-androstane-3, 17-dione, 5β-androstanedione derivative and C18 steroid formation could not be demonstrated. These results demonstrate the capacity of guinea-pig placentas to convert dehydroepiandrosterone and androstenedione to testosterone and to derivatives reduced in ring A (5α) and at carbon 17. The activity of the Δ5-3β-hydroxysteroid dehydrogenase enzyme system appears to have been rate limiting. Homogenates of adrenals from 44–55 day old fetuses converted 4-14C-pregnenolone to androst-4-ene-3, 17-dione and 6β- and 11β-hydroxyandrostenedione. A guineapig fetal-placental unit is postulated, with steroid metabolic characteristics different from the human unit. Both permit reduction of fetal adrenal cortisol production and placental removal of C19 steroids.

The metabolism of 7-3H-pregnenolone and 4-14C-progesterone by adrenal homogenates of fetal guinea-pigs and other mammalian fetuses

Abstract Adrenal tissue homogenates from fetal guinea-pigs were incubated with 7- 3 H-pregnenolone or 4- 14 C-progesterone and analyzed for conversion products by reverse isotope dilution procedures. Cortisol and 11β-hydroxyandrostenedione were synthesized from both substrates; corticosterone was formed only from progesterone. The results indicated a similarity in the metabolism of pregnenolone and progesterone by adrenal cortical tissue of late gestation guinea-pig fetuses with that of adult guinea-pigs. The isolation of 11β-hydroxy-androstenedione demonstrates C 19 steroid synthesis by fetal adrenal tissue in a species other than the human, and suggested two pathways of pregnenolone metabolism in this tissue. Fetal armadillo and rat adrenals converted pregnenolone or progesterone to corticosterone or cortisol; canine adrenal preparations showed limited metabolic activity. Steroid synthesis in the adrenal cortex of the human fetus is characterized by the production of 3β-hydroxy-5-steroids including the C 19 steroid, dehydroepiandrosterone-sulfate 3 , and by an inhibition of corticosteroid synthesis (1, 2). In contrast, cortisol or corticosterone are the major products of adrenal steroidogenesis in fetal rats (3), armadillos (4), and sheep (5). 3β-Hydroxy-5-steroids or androgenic C 19 steroids have not been reported as products of adrenal steroidogenesis in these species. Price and Ortiz reported that adrenal glands of fetal guinea-pigs maintained in organ culture together with fragments of rat prostatic tissue prevented regression of these fragments (6). They further found 3β-hydroxy-5-steroid dehydrogenase activity in the adrenal glands, leading to the conclusion that the capacity for secreting steroidal androgens existed in the adrenal cortex of fetal guinea-pigs (7). The observations of Price and Ortiz prompted the experiments reported here, i.e., in vitro incubations of fetal guinea-pig adrenals with labeled pregnenolone or progesterone. In addition, evidence was sought for 3β-hydroxy-5 -steroid and C 19 steroid formation in adrenals of fetal rats, armadillos and dogs.

Reproductive toxicity of 2,4‐toluenediamine in the rat. 2. Spermatogenic and hormonal effects

The present study was undertaken to evaluate the endocrinologic and spermatogenic effects of 2,4-toluenediamine (TDA) in the rat. Adult male rats were fed 0,0.01, and 0.03% TDA ad libitum for 10 wk. At the end of wk 10 and at 11 wk post TDA treatment, the animals were killed, and cauda epididymal sperm counts and reproductive organ weights were determined. Blood samples were obtained for analyses of testosterone and gonadotropins. Treatment with 0.03% TDA for 10 wk reduced the weight of the seminal vesicles and epididymides and reduced serum testosterone levels. Cauda epididymal sperm counts were decreased in animals treated with 0.03% TDA for 10 wk and in TDA-treated animals placed on normal diet for 11 wk. Serum luteinizing hormone (LH) concentrations were increased and weights of epididymides and testes were reduced in 0.03%-TDA-treated animals placed on normal diet for 11 wk. The results indicate that TDA exerts a toxic effect on spermatogenesis and appears to affect androgen action and production in the male rat. Since the males exhibited reduced cauda epididymal sperm counts 11 wk after 0.03% TDA treatment, it appears that TDA induced damage to the germinal components of the testes.

Gonadotropin stimulation of steroid synthesis and metabolism in the Rana pipiens ovarian follicle : Sequential changes in endogenous steroids during ovulation, fertilization and cleavage stages

Steroid synthesis and metabolism have been followed in Rana pipiens ovarian follicles, denuded oocytes and eggs during ovulation, fertilization and cleavage stages (blastula formation). Under physiological conditions, gonadotropin stimulation of the fully grown follicle leads to progesterone synthesis from [(3)H]acetate as well as formation of much smaller amounts of 17alpha-hydroxyprogesterone, androstenedione, pregnanedione and pregnanediol. Progesterone levels increase during completion of the first meiotic division, but by ovulation progesterone disappears from the egg. Plasma membrane-bound progesterone is taken up into the oocyte cortical granules and is largely metabolized to 5alpha-pregnane-3alphaol,20-one and 5beta-pregnane-3alpha,17alpha,20beta-triol coincident with internalization of 60% of the oocyte surface (and >90% of bound progesterone) by the end of the hormone-dependent period. The principal steroid in the ovulated egg is 5beta-pregnane-3alpha,17alpha,20beta-triol. There is a rapid efflux of 5beta-pregnane-3alpha,17alpha,20beta-triol into the medium immediately following fertilization and residual steroid levels remain low in the developing blastula. Dissociated blastulae cells prepared from stage 9 1/2 embryos concentrate both pregnenolone and progesterone from the medium with minimal metabolism. The results indicate that the ovarian follicle has the ability to synthesize and metabolize progesterone but that this ability disappears in the ovulated egg. The progesterone metabolites formed during meiosis are largely released at fertilization.