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M Vigier

Publications and source records attributed to M Vigier.

29 records · Page 2Linked to original sources
PubMed1988

Steroidogenesis expression depends on negative control(s): analysis in Leydig X adrenal intraspecific cell hybrids.

Hybrids constructed by fusing mouse Leydig cells with mouse adrenal Y1 cells were able to randomly express all the parental specific traits but for the response to gonadotropin (hCG) and corticotropin (ACTH): three of them, YDYL 14, 17 and 19, metabolized both progesterone and dehydroepiandrosterone into testosterone accounting for 17 alpha-hydroxylase, 17-20-lyase, 17-ketoreductase and 3 beta-hydroxysteroid dehydrogenase activities. Under basal conditions, 17 alpha-hydroxylase and 17-20-lyase activities were high in the three clones as compared to parental Leydig cells, and were no longer stimulated by cAMP in YDYL 17 and 19. The hybrids responded to various hormones such as prostaglandin E2 (PGE2), vasoactive intestinal peptide (VIP) and prolactin (PRL) which are not directly implicated in the expression of steroidogenesis; they generally retained the Y1 morphological response to 8-bromo cAMP. On extended culture, reexpression of ACTH sensitivity occurred in one clone, YDYL 9. This reexpression was correlated with a Robertsonian translocation between mouse chromosomes 2 and 11, while extinction required the presence of an intact mouse chromosome 11.

17-alpha-Hydroxyprogesterone↗
PubMed1987

Transforming growth factor beta inhibits Leydig cell functions.

The role of transforming growth factor beta (TGF-beta) on the functions of pig Leydig cells cultured in a chemically defined medium was investigated. TGF-beta reduced the number of hCG receptors, without modification of the binding affinity, and reduced the cAMP and testosterone response to this hormone. These effects were dose-dependent. The minimal effective dose was 10 pg/ml (4 X 10(-13) M) and half-maximal inhibition for the three effects was observed at about 100 pg/ml. At maximal effective concentration (1 ng/ml), the inhibitory effect was time-dependent, the first effects were observed after a lag period of 12 h and the maximal effect after 72 h. At maximal concentrations TGF-beta reduced by 70% the number of hCG receptors and the steroidogenic response to this hormone and reduced by 50% the cAMP response to hCG. Moreover, TGF-beta also reduced the cAMP response to forskolin and the steroidogenic effects of this diterpene and 8-Bromo-cAMP. In contrast, the conversion of exogenous pregnenolone to testosterone was increased in TGF-beta-treated cells. The inhibition of Leydig cell steroidogenesis can be dissociated from any effect on cell proliferation and is related to modifications located at the membrane level and beyond cAMP formation, but before pregnenolone formation. The results suggest that in the testis, as in other steroidogenic tissues, TGF-beta may play a role in the development and maintenance of differentiated function.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1975

[Influence of the pituitary-adrenal axis on the brown fat tissue of the rat and golden hamster].

The suppression or reduction of the adrenal secretion in the Rat and in the golden Hamster results in a reduction of the weight of brown adipose tissue and of the volume of intra cytoplasmic vacuoles. When corticotropin is given to normal and hypophysectomized animals, the intra cytoplasmic vacuolar system and the corticosterone concentration of brown fat increase. After sham hypophysectomy and short ether intake, a considerable lipidic depletion and a high level of corticosterone are observed. The authors speculate that the by adrenaline. The morphologic responses are much more intense and rapid lipid content of brown adipose tissue is increased by corticotropin and reduced by adrenaline. The morphologic responses are much more intense and rapid in brown adipose tissue than in white adipose tissue.

Adipose Tissue, Brown↗
PubMedDate not supplied

[In vitro murine spermatogenesis: cytologic study of the meiosis stage].

Spermatogenesis is a complex process of cellular multiplication and differentiation, the regulation of which is only partially understood. This may be due; 1) to the redundancy of the mechanisms of local regulation; 2) to the ubiquitous character of those growth factors and cytokines present in the testis; 3) to the lack of long term culture systems allowing male germ cell development. We describe herein two culture systems associating Sertoli cells and germ cell in which part of the meiotic step can occur in vitro. In the first system, pachytene spermatocytes prepared by centrifugal elutriation are cultured on a layer of Sertoli cells. In the second system small fragments of seminiferous tubules are seeded in bicameral chambers. The cytological and immunocytochemical studies presented show that pachytene spermatocytes of stages IV-VI differentiate into spermatids of steps 1 to 5.

Animals↗