Sexual differentiation in litter-bearing mammals: influence of sex of adjacent fetuses in utero

In rodents and swine, individual differences in a broad range of characteristics correlate with intrauterine position during fetal life. By identifying the intrauterine position of mice at cesarean delivery, we can predict reliably postnatal reproductive traits such as genital morphology, timing of puberty, length of estrous cycles, timing of reproductive senescence, sexual attractiveness, sexual behavior, aggressiveness, daily activity level, body weight and tissue enzyme activity in females; in males we can predict genital and brain morphology, sexual behavior, aggressiveness, daily activity level, body weight, and tissue enzyme activity. In mice, as in all mammals, male fetuses have greater concentrations of testosterone than do females. In addition, female mouse fetuses have greater circulating concentrations of estradiol than do male fetuses, a condition not found in all mammals. A mouse fetus positioned between males has greater concentrations of testosterone than does a fetus of the same sex positioned between females, and a fetus positioned between females has greater concentrations of estradiol than does a fetus of the same sex positioned between males. Gonadal steroids regulate differentiation of secondary sexual characteristics. Studies in which the effects of intrauterine position have been eliminated by exposing fetuses to steroid receptor blockers reveal the critical role of steroids in mediating this phenomenon. The intrauterine position phenomenon provides the only mammalian model for relating postnatal traits to concentrations of endogenous hormones to which individuals are exposed during fetal life. Results from studies using this naturally occurring experimental system in litter-bearing species have given insights concerning the consequences of individual differences in steroid concentrations during sexual differentiation that likely apply to all mammals. One specific hypothesis is that circulating estradiol may interact with testosterone in mediating some aspects of sexual differentiation in rodents and, thus, possibly in other mammals.

Endocrine-Disrupting Activities In Vivo of the Fungicides Tebuconazole and Epoxiconazole

The triazole fungicides tebuconazole and epoxiconazole were investigated for reproductive toxic effects after exposure during gestation and lactation. Rats were dosed with epoxiconazole (15 or 50 mg/kg bw/day) or tebuconazole (50 or 100 mg/kg bw/day) during pregnancy from gestational day (GD) 7 and continued during lactation until postnatal day (PND) 16. Some dams were randomly chosen for cesarean section at GD 21 to evaluate effects on sexual differentiation in the fetuses. Other dams delivered normally, and the pups were examined (e.g., anogenital distance [AGD] and hormone levels) at birth, at PND 13 or PND 16, and semen quality was assessed in adults. Both tebuconazole and epoxiconazole affected reproductive development in the offspring after exposure in utero. Both compounds virilized the female offspring as shown by an increased AGD PND 0. Furthermore, tebuconazole had a feminizing effect on male offspring as shown by increased nipple retention. This effect was likely caused by the reduced testosterone levels seen in male fetuses. Tebuconazole increased the testicular concentrations of progesterone and 17alpha-hydroxyprogesterone in male fetuses, indicating a direct impact on the steroid synthesis pathway in the Leydig cells. The high dose of epoxiconazole had marked fetotoxic effects, while the lower dose caused increased birth weights. The increased birth weights may be explained by a marked increase in testosterone levels in dams during gestation. Common features for azole fungicides are that they increase gestational length, virilize female pups, and affect steroid hormone levels in fetuses and/or dams. These effects strongly indicate that one major underlying mechanism for the endocrine-disrupting effects of azole fungicides is disturbance of key enzymes like CYP17 involved in the synthesis of steroid hormones.

Rapid signalling by androgen receptor in prostate cancer cells

Androgens are important growth regulators in prostate cancer. Their known mode of action in target cells requires binding to a cytoplasmic androgen receptor followed by a nuclear translocation event and modulation of the expression of specific genes. Here, we report another mode of action of this receptor. Treatment of androgen responsive prostate cancer cells with dihydrotestosterone leads to a rapid and reversible activation of mitogen-activated protein kinases MAPKs (also called extracellular signal-regulated kinases or Erks). Transient transfection assays demonstrated that the androgen receptor-mediated activation of MAP kinase results in enhanced activity of the transcription factor Elk-1. This action of the androgen receptor differs from its known transcriptional activity since it is rapid and insensitive to androgen antagonists such as hydroxyflutamide or casodex. Biochemical studies as well as analyses with dominant negative mutants showed the involvement of kinases such as MAPK/Erk kinase, phosphatidyl-inositol 3-kinase and protein kinase C in the androgen receptor-mediated activation of MAP kinase. These results demonstrate a novel regulatory action of the androgen receptor and prove that in addition to its known transcriptional effects, it also uses non-conventional means to modulate several cellular signalling processes.

Sustained drug delivery systems. I. The permeability of poly(epsilon-caprolactone), poly(DL-lactic acid), and their copolymers

The maximum steady state flux, diffusion coefficients, and solubilities of five contraceptive steroids in homopolymers and copolymers of epsilon-caprolactone and DL-lactic acid were determined. The permeabilities of polymers of epsilon-caprolactone were comparable to silicone rubber and, by inference, are suitable for the construction of drug delivery devices. Poly(DL-lactic acid) was 10(4) times less permeable, although its permeability was significantly enhanced by additives.

Influence of anterior pituitary on avoidance learning and escape behavior

Adenohypophysectomized rats were subjected to an avoidance learning procedure. Only 6 of 21 adenohypophysectomized rats achieved the conditioning criterion against 14 of 18 sham-operated controls. The treatment with a long-acting ACTH preparation (ACTH(A1)Zn) during avoidance training resulted in an improvement in the rate of conditioning, which was most optimal following the administration of 1.5 IU. The injection of replacement therapy with cortisone, testosterone, and thyroxine also improved the ability of adenohypophysectomized rats to acquire an avoidance response. The speed with which adenohypophysectomized rats escaped a noxious stimulus in a runway was significantly lower than that of sham-operated controls, indicating that the motor and sensory capacities of this animal were seriously impaired. Administration of ACTH (A1)Zn or of the replacement therapy restored the escape speed toward normal. Accordingly, the deficiency in learning capacity of adenohypophysectomized rats does not seem to depend on the absence of ACTH but on a general debilitation of the adenohypophysectomized organism.

A reconstituted cell-free system for the specific transfer of steroid--receptor complexes into nuclear chromatin isolated from the rat ventral prostate gland

1. A system has been developed for the specific transfer of [(3)H]dihydrotestosterone-receptor complexes into prostatic chromatin in vitro. 2. Under optimum conditions the overall transfer of [(3)H]dihydrotestosterone into purified chromatin in this reconstituted system is entirely consistent with the results obtained in whole tissue both in vivo and in vitro. 3. The transfer of [(3)H]dihydrotestosterone into chromatin is tissue-specific and maximal into chromatin isolated from androgen-dependent tissues. 4. The tissue specificity is maintained at two levels: first, in the presence of specific cytoplasmic androgen-receptor proteins; secondly, by the nature and composition of the chromatin itself. 5. Evidence is presented that androgenic steroids in vivo may maintain the tissue-specific nature of chromatin in androgen-dependent tissues by the selective induction of nuclear protein synthesis. 6. The relevance of these findings to the mechanism of action of androgenic steroids is discussed.

The emerging risk of exposure to nano(micro)plastics on endocrine disturbance and reproductive toxicity: From a hypothetical scenario to a global public health challenge

Humans are potentially exposed to nano(micro)plastics, however their interaction with tissues and cells in humans remains largely unknown. This premise is particularly notable with nano-sized plastic particulates, a potentially most pernicious form of plastic pollution. In this study, even in a hypothetical scenario in terms of dose (1, 3, 6 and 10 mg/kg-day) and exposure time (five weeks), the potential endocrine disturbances with particular reference to reproductive toxicity of polystyrene nanoplastics (PS NPs, average size = 38.92 nm) was studied in male rats considering biomarkers of semen quality, changes in hormonal milieu and molecular signatures of endocrine disruption. Sperm DNA integrity and its chromatin structure were also analyzed. There observed significant inverse associations between exposure to PS NPs and serum concentrations of testosterone, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Tissue and cell impairments were also noticed even at the lowest tested dosage, though the severity of lesions followed a clear dose-response pattern. DNA damage as well as alterations in sperm morphology and viability were evident, again proportionally with the amount of exposure dosage. RT-qPCR data were in accordance with the results of physio-histological alterations and fluorescence imaging, as significant down-regulation of PLZF, DAZL, FSH and LH gene expressions were noticed in the testis of exposed animals, suggesting that exposure interferes with spermatogenesis and also with HPT-axis. However, among those with highest exposure dosage, expressions of FSH and LH were significantly increased. ABP modulation further revealed evidence of a nonlinear dose response. The association between PS NPs exposure and GnRH was indeed in an unexpected positive direction, though these end-points were less sensitive at higher doses. Although additional evidence is warranted, the present work provides new insights into the possible risks of plastic nanoparticles exposure in humans, especially since the problem is growing and will persist for a long time.

Measurement of specific radioactivities in labelled hormones by self-displacement analysis

A graphical method is described that allows the determination of specific radioactivities of radioactively labelled hormones. This method combines the self-displacement technique, plotting bound/free ratios versus mass of unlabelled hormone or total radioactivity of labelled preparation added to the receptor preparation, and the maximal binding capacity of the labelled hormone. The procedure presented herein provides a more realistic specific radioactivity for use in all binding experiments. Application of the method is demonstrated for 125I-labelled ovine prolactin, and data are presented for 125I-labelled human choriogonadotropin and [3H]testosterone.

Obesity and prostate cancer: making sense out of apparently conflicting data

Both obesity and prostate cancer are epidemic in Western society. Although initial epidemiologic data appeared conflicting, recent studies, especially large prospective studies published in the past 6-12 months, have clarified the association between obesity and prostate cancer. The aim of this paper is to review the epidemiologic data linking obesity and prostate cancer, with an emphasis on new data published since 2005. A PubMed search was done on the keywords, "prostate cancer" and "obesity." Relevant articles and their references were reviewed for data on the association between obesity and prostate cancer. Recent data suggest that obesity is associated with reduced risk of nonaggressive disease but increased risk of aggressive disease. This may in part be explained by an inherent bias in our ability to detect prostate cancer in obese men (lower prostate-specific antigen values and larger sized prostates making biopsy less accurate for finding an existing cancer). Ultimately, this leads to increased risk of cancer recurrence after primary therapy and increased risk of prostate cancer mortality. The biologic causes of these associations are likely multifactorial, although the lower testosterone levels among obese men appear to be one of the most promising explanations. The association between obesity and prostate cancer is complex. Emerging data suggest a differential effect of obesity by disease aggressiveness: obesity may reduce the risk of nonaggressive disease while it may promote aggressive disease.