Expression of melanocortin receptors mRNA, and direct effects of ACTH on steroid secretion in the bovine ovaryReportar como inadecuado




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Resumen

Melanocortin receptors MCRs are involved in physiological responses to ACTH, as well as to - - and -melanocytestimulatinghormone - - and -MSH. Their expression has previously been analyzed in various bovine tissues; however, thereare apparently no reports regarding their localization in the ovaries. In the present study, the expression of MCR mRNA in variousbovine ovarian structures was characterized with reverse transcription polymerase chain reaction RT-PCR. Furthermore, whetherACTH affected follicular components by affecting steroid secretion in fragments of ovarian follicular wall of medium and largeantral follicles cultured in serum free medium with 1, 10, and 100 nM ACTH, was also determined. Melanocortin receptorsmRNA was localized in the theca cells of various follicular stages, whereas only MC3R mRNA was weakly evident in granulosacells. Melanocortin receptors 1, 2, and 3 mRNA were present in the CL, whereas in stroma, only MC2R mRNA was expressed.There were significant increases in estradiol and cortisol concentrations in response to ACTH in medium follicles, as well asincreased concentrations of testosterone and cortisol in large follicles. These results confirmed earlier reports in other species, anddemonstrated that MCRs were present in bovine ovaries. Since ACTH induced steroid secretion from the ovary in vitro, weinferred that melanocortin peptides could be involved in regulatory mechanisms related to ovarian functions, e.g. ovulation,steroidogenesis, and luteal function.



Autor: Amweg, A. N.; - Paredes, A.; - Salvetti, N. R.; - Lara Peñaloza, Hernán; - Ortega, H. H.; -

Fuente: http://repositorio.uchile.cl/



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