Browsing by Author "Cortés, PP"

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    Estrogen receptor, cyclic adenosine monophosphate, and protein kinase A are involved in the nongenomic pathway by which estradiol accelerates oviductal oocyte transport in cyclic rats
    (2003) Orihuela, PA; Parada-Bustamante, A; Cortés, PP; Gatica, C; Croxatto, HB
    This investigation examined the role of estrogen receptor (ER) on the stimulatory effect of estradiol (E) on protein phosphorylation in the oviduct as well as on E-2-induced acceleration of oviductal oocyte transport in cyclic rats. Estrous rats were injected with E-2 s.c. and with the ER antagonist 10 182 780 intrabursally (i.b.), and 6 h later, oviducts were excised and protein phosphorylation was determined by Western blot analysis. ICI 182780 inhibited the E-2-induced phosphorylation of some oviductal proteins. Other estrous rats were treated with E-2 s.c. and ICI 182 780 i.b. The number of eggs in the oviduct, assessed 24 h later, showed that ICI 182 780 blocked the E-2-induced egg transport acceleration. The possible involvement of adenylyl cyclase, protein kinase A (PK-A), protein kinase C (PK-C), or tyrosine kinases on egg transport acceleration induced by E-2 was then examined. Selective inhibitors of adenylyl cyclase or PK-A inhibited the E-2-induced egg transport acceleration, whereas PK-C or tyrosine kinase inhibitors had no effect. Furthermore, forskolin, an adenylyl cyclase activator, mimicked the effect of E-2 on ovum transport and E, increased the level of cAMP in the oviduct of cycling rats. Finally, we measured PK-A activity in vitro in the presence of E-2 or E-2-ER complex. Activity of PK-A in the presence of E-2 or E-2-ER was similar to PK-A alone, showing that E-2 or E-2-ER did not directly activate PK-A. We conclude that the nongenomic pathway by which E-2 accelerates oviductal egg transport in the rat requires absolute participation of ER and cAMP and partial participation of PK-A signaling pathways in the oviduct.