Alterations in Glial Fibrillary Acidic Protein (GFAP) mRNA Levels in the Hamster Facial Motor Nucleus: Effects of Axotomy and Testosterone

Testosterone propionate (TP) administered at the time of facial nerve injury in the hamster accelerates the rate of regeneration. In this study, we tested the hypothesis that the mechanism by which TP augments peripheral nerve regeneration involves regulation of glial fibrillary acidic protein (GFAP) mRNA in the facial motor nucleus. Castrated male hamsters were subjected to right facial nerve transection, with half the animals implanted subcutaneously with Silastic capsules containing exogenous TP and the remainder sham implanted. Postoperative survival times were 0.25, 1, 2, 4, 7, and 14 d. Qualitative/quantitative analyses of both film and emulsion autoradiograms were accomplished. Axotomy, with or without TP, resulted in a dramatic increase in GFAP mRNA levels by 1 d postoperative on the axotomized side, relative to controls. GFAP mRNA levels remained elevated throughout all postoperative times in both the nonhormone- and TP-treated animals. Qualitative examination of the film autoradiograms indicated a generalized decrease in the amount of GFAP mRNA in the control and axotomized nuclei of TP-treated animals when compared to the control and axotomized nuclei, respectively, of nonhormone-treated animals. Statistical comparison of the values obtained for both the film and emulsion autoradiograms confirmed this impression. Thus, while the injury-induced increases in GFAP mRNA expression were not blocked by TP, the overall extent of the increase was significantly tempered by steroid treatment. These data suggest that hormonal modulation of the astrocytic response to peripheral nerve injury may be a contributing factor in the ability of steroids to enhance the regenerative capacities of injured motor neurons.     

Role of AMPK in mammals reproduction: Specific controls and whole-body energy sensing

AMP-activated protein kinase (AMPK) is a key enzyme involved in linking the energy sensing to metabolic pathways. As such, it plays a central role at the whole-body level to translate endocrine communications into adapted responses aimed either at saving energy when food is scarce or at allocating it to various functions, particularly reproduction, when food is available. AMPK also plays major roles in the energy individual cells use in order to realize their specific functions. This is of course especially true for all cells involved in the reproductive function (gonads, gametes) or in its control (hypothalamus, pituitary). In the present review, I report a survey of the various roles of AMPK functions in reproduction, either directly in reproductive organs, or indirectly in organs controlling reproduction, particularly at hypothalamus level.     

True hermaphroditism with 46,X,+22p/46,XY and gonadal mosaicism detected by fluorescence in situ hybridization

A Japanese girl was diagnosed as true hermaphroditism with 46,X,+mar/46,XY and the marker chromosome was determined on the short arm of chromosome 22 without alpha-satellite by fluorescence in situ hybridization (FISH) and spectral karyotyping (SKY) methods. At birth, she showed intersexual external genitalia, urethral-vaginal fistula and right inguinal hernia. The right gonad was revealed as an ovotestis, and the left was as an undifferentiated testis. The gonadal mosaicism was demonstrated directly in gonadal tissue by interphase FISH.     

Effects of the aromatase inhibitor fadrozole on plasma sex steroid secretion,spermatogenesis and epididymis morphology in the lizard,Podarcis sicula

Recently, increasing importance has been attached to the role of estrogens and their receptors in male reproduction, since they have been found to be abundant in the male reproductive tract. In the lizard, Podarcis sicula, a seasonal breeder, estrogens seem to be involved in the regulation of testicular activity. Particularly, it has been hypothesized that the block of spermatogenesis and the complete regression of the epididymis and other secondary sexual characters (SSCs) in autumn might be due to high estrogen levels. To investigate the role of estrogens in the reproductive process of male lizards, we utilized Fadrozole ((AI) [4-(5,6,7,8-tetrahydroimidazole [1,5-a] pyridin-5-yl)-benzonitrile monohydrochloride] (CGS 16949A)), a nonsteroidal inhibitor of aromatase, the enzyme involved in the aromatization of androgens to estrogens, evaluating its effects on plasma sex-hormone release, spermatogenesis and epididymis morphology. For this purpose, adult male lizards, captured during the autumnal recrudescence, were intraperitoneally injected with 0.5 microg and 5 microg/g/body weight of AI for 15 and 30 days. In the animals treated with the higher AI dose, estrogen levels decreased if compared to the control groups, whereas androgen levels increased. Furthermore, histologic sections of testes and epididymes showed that the 30-day treatment with AI-induced spermatogenesis resumption with release of sperms into the large lumen of the seminiferous tubules, and the epididymes appeared more developed with moderately secreting columnar canal cells. Therefore, it is proposed that failure of spermatogenesis in autumn might be due to high estrogen levels.     

Number of somatic and germ cells during early stages of gonadal development in frog larvae treated with zinc sulphate

Summary ZnSO₄ treatment of early frog tadpoles resulted, initially, in a mitotic stimulation of primordial germ cells. In later larval stages, ZnSO₄ was responsible for the atresy of gonads in which germ cell and medullary cell numbers sharply decreased. At the same time, very few germ cells entered the meiotic prophase, while the degeneration of some of them was observed. Our results are discussed in connection with previous findings about the influence of Zn on cellular proliferation.     

Estrogen mitogenic action. I. Demonstration of estrogen-dependent MTW9/PL2 carcinogen-induced rat mammary tumor cell growth in serum-supplemented culture and technical implications

Summary The MTW9/PL cell line was established by our laboratory in culture from the carcinogen-induced hormone-responsive MT-W9A rat mammary tumor of a Wistar-Furth (W/Fu) rat. This tumor formed estrogen, androgen, and progesterone responsive tumors in W/Fu rats (Sirbasku, D. A., Cancer Res. 38:1154–1165; 1978). It was later used to derive the MTW9/PL2 cell population which was also estrogen-responsive in vivo (Danielpour, D., et al., In Vitro Cell. Dev. Biol. 24∶42–52; 1988). In the study presented here, we describe serum-supplemented culture conditions in which the MTW9/PL2 cells demonstrate≥80-fold steroid hormone growth responses. All sera used were steroid hormone-depleted by charcoal-dextran treatment at 34°C. The studies were done with horse serum as well as serum from other mammalian species. The growth of the MTW9/PL2 cells was biphasic in response to hormone-depleted serum. Concentrations of ≤5% (v/v) promoted optimum growth. Above this concentration, serum was inhibitory. Concentrations ≥40% (v/v) inhibited growth altogether. Addition of 1.0×10⁻¹³−1.0×10⁻⁸ M 17β-estradiol (E₂) reversed the inhibition completely. At 1.0×10⁻⁸ M, estrone, estriol and diethylstilbestrol promoted growth as well as E₂. Testosterone and dihydrotestosterone promoted growth only at ≥10⁻⁷ M. Progesterone was effective only at≥10⁻⁶ M. Cortisol was ineffective. Labeled-hormone-binding analysis and Western immunoblotting documented that MTW9/PL2 cells had estrogen and progesterone receptors but not androgen or cortisol receptors. Estrogen treatment of MTW9/PL2 cells induced a concentration and time dependent increase in progesterone receptors. We conclude (1) the MTW9/PL2 population is the first highly steroid hormone-responsive rat mammary tumor cell line to be established in culture from a carcinogen-induced tumor, and (2) sera from a number of species including horse, rat and human contain an inhibitor which mediates estrogen sensitive MTW9/PL2 cell growth in culture.     

MHC genotype predicts mate choice in the ring-necked pheasant Phasianus colchicus

Females of several vertebrate species selectively mate with males on the basis of the major histocompatibility complex (MHC) genes. As androgen-mediated maternal effects have long-lasting consequences for the adult phenotype, both mating and reproductive success may depend on the combined effect of MHC genotype and exposure to androgens during early ontogeny. We studied how MHC-based mate choice in ring-necked pheasants (Phasianus colchicus) was influenced by an experimental in ovo testosterone (T) increase. There was no conclusive evidence of in ovo T treatment differentially affecting mate choice in relation to MHC genotype. However, females avoided mating with males with a wholly different MHC genotype compared with males sharing at least one MHC allele. Females also tended to avoid mating with MHC-identical males, though not significantly so. These findings suggest that female pheasants preferred males with intermediate MHC dissimilarity. Male MHC heterozygosity or diversity did not predict the expression of ornaments or male dominance rank. Thus, MHC-based mating preferences in the ring-necked pheasant do not seem to be mediated by ornaments' expression and may have evolved mainly to reduce the costs of high heterozygosity at MHC loci for the progeny, such as increased risk of autoimmune diseases or disruption of coadapted gene pools.     

Seasonal dynamics of agonistic behavior and hormones in an ex situ all‐male colony of large flying foxes

Large flying foxes (Pteropus vampyrus) are a socially complex species. In situ colonies typically comprise thousands of individuals in small harems of one male to many females. In ex situ environments, all‐male colonies are becoming more common due to a surplus of males in the population. There is limited information describing the hormonal and behavioral patterns of all‐male colonies during the breeding season. We assessed seasonal changes in hormones and behavior in an all‐male colony of 12 large flying foxes at Disney's Animal Kingdom^®. We validated hormone assays using morning urine and fecal samples to assess seasonal changes in excreted immunoreactive testosterone and glucocorticoid metabolites. We collected behavior data using an all‐occurrence method, recording agonistic behaviors related to territorial defense (hooking, biting, wing flexing, vocalizing, and wrestling), and sexual behavior (mounting and frontal grabbing). Results indicated that (i) we could reliably measure testosterone and glucocorticoid metabolites concentrations from fecal and urine samples collected from individual bats; (ii) there were distinct relationships between changes in levels of agonism and hormone concentrations throughout the year; and (iii) three agonistic behaviors (chasing, wrestling, and open‐mouth threat) peaked prior to the increase in testosterone and glucocorticoid hormones measured during the breeding season. These three behaviors could potentially be used as early indicators to signal the onset of the breeding season and allow time to implement ex situ management changes to reduce the incidence of agonism between individuals.     

Sex differences in adrenocortical structure and function

Summary Adrenal glands of adult female rats are heavier than the glands of corresponding male rats. Postpubertal orchiectomy increases the adrenal weight, an effect restored by testosterone replacement. Under the same conditions ovariectomy of 8 weeks duration does not change the adrenal weight while estradiol replacement enhances the relative adrenal weight.Karyometric studies have shown that nuclei in the female zona fasciculata cells are larger (app. 18%) than those of the male. Similar but only slight differences (2%) were observed in the zona reticularis. Orchiectomy results in enlargement of cell nuclei within all zones of the adrenal cortex; testosterone replacement has the opposite effect. Ovariectomy of 8 weeks duration slightly enhances the volume of nuclei of the zona glomerulosa cells, has no effect on the nuclei of the zona fasciculata and reduces the volume of nuclei in the zona reticularis. Estradiol replacement reduces the volume of nuclei of the zona glomerulosa cells but increases nuclear volume in the zona fasciculata and in the zona reticularis.Thus testosterone has an inhibitory effect on the adrenal cortex of the rat while the physiologic effect of estradiol on the morphology of this gland, particularly on the zona fasciculata cells is rather dubious.The author wishes to thank Mrs. B. Westerska and Miss K. Siejak for excellent technical assistance.This research was supported in part by a grant from the Zoological Committee, 2nd Department, Polish Academy of Sciences.This paper is dedicated to the memory of late Kazimierz Mietkiewski, M.D., Ph.D. whose encouragements and suggestions were most stimulating for my work.