RESUMO
The tumor necrosis factor-alpha (TNF-alpha) plays an important role in ovarian follicular development and ovulation process and acts through its receptor (TNFRI). The present investigation describes the expression of mRNAs encoding TNF-alpha and TNFRI in relation to glyceraldehyde-3-phosphate dehydrogenase (G3PDH) and beta-actin as control genes, using RT-PCR, in granulosa cells, intact follicles and luteal tissues from buffalo ovary. There was significant higher expression of mRNAs encoding TNF-alpha in granulosa cells from medium follicles and TNFRI expression increased with increase in size of follicles. Post-ovulatory structures (corpus luteum and corpus albicans) exhibited significantly higher expression of TNFRI mRNAs as compared to that obtained in intact follicles suggesting its immediate and critical role just after ovulation, for mediating TNF-alpha action on these tissues. Though the expression of TNF-alpha mRNA was stimulated by treatment of granulosa cells with FSH during culture, the expression of TNFRI mRNA did not change. The FSH alongwith IGF-I did not exert any effect. These results suggested an important role of TNF-alpha and its receptor in buffalo ovarian functions.
Assuntos
Actinas/genética , Animais , Búfalos/crescimento & desenvolvimento , Corpo Lúteo/metabolismo , Feminino , Hormônio Foliculoestimulante/farmacologia , Gliceraldeído-3-Fosfato Desidrogenases/genética , Células da Granulosa/efeitos dos fármacos , Fator de Crescimento Insulin-Like I/farmacologia , Folículo Ovariano/efeitos dos fármacos , Ovário/efeitos dos fármacos , RNA Mensageiro/análise , Receptores Tipo I de Fatores de Necrose Tumoral/genética , Fator de Necrose Tumoral alfa/genéticaAssuntos
Humanos , Feminino , Corpo Lúteo/fisiopatologia , Endométrio/fisiologia , Fase Luteal , Corpo Lúteo/metabolismoRESUMO
To examine the electrophysiological properties of luteal cells and the relationship between membrane potential and luteal steroidogenic capacity, the membrane potential of luteal cells and the luteal steroidogenesis were measured under different ionic conditions following treatment with various drugs and gonadotropins. The membrane potential of luteal cells did not vary throughout the estrous cycle and was -55 +/- 1 mV. The membrane potential was highly dependent upon the external K+ concentration and was depolarized by the deprivation of external Ca2+, however) there seemed to be a lower K+ permeability in luteal membranes as the presence of 10-9 M valinomycin, a K+ ionophore Caused hyperpolarization from -55 to -91 mV. Luteal progestin production was increased in a high K+ solution but not m a Ca2+-free solution indicating that Ca2+ may be essential for steroid synthesis and/or secretion by luteal cells. Gonadotropins and ouabain induced a depolarization of the membrane potential and stimulated luteal steroidogenesis; however; prostaglandin F2alpha stimulated only steroidogenesis without any changes in membrane potential. These results suggest that the relationship between steroidogenesis and the changes in membrane potential by drugs and gonadotropins is still obscure and remains to be eluridated. The relationship between membrane potential and steroidogenesis in the luteal cell may be dependent upon the availability of intracelluar Ca2+.