Browsing by Author "Croxatto, HB"

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    Basic aspects of oviduct function
    (PARTHENON PUBLISHING GROUP LTD, 1997) Croxatto, HB; Ortiz, ME; Villalon, M; Cardenas, H; Imarai, M; Hermoso, M; Velasquez, L; Orihuela, P; Coutifaris, C; Mastroianni, L
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    In vivo expression of β-galactosidase by rat oviduct exposed to naked DNA or messenger RNA
    (2002) Rios, M; Venegas, A; Croxatto, HB
    Intra-oviductal administration of RNA obtained from oviducts of estradiol-treated rats resulted in accelerated egg transport (Rios et al., 1997). It is probable that estradiol-induced messenger RNA (mRNA) entered oviductal cells and was translated into the proteins involved in accelerated egg transport. In order to test this interpretation we deposited in vivo 50 mug of pure beta-galactosidase (beta-gal) mRNA, 50 mug of pure DNA from the reporter gene beta-gal under SV40 promoter or the vehicle (control oviducts) into the oviductal lumen of rats. Twenty four hours later the beta-gal activity was assayed in oviductal tissue homogenates using o-nitrophenyl-beta-D-galactopyranoside as a substrate. The administration of beta-gal mRNA and pSVBgal plasmid increased beta-gal activity by 71% and 142%, respectively, over the control oviducts. These results indicate that naked DNA and mRNA coding for beta-gal can enter oviductal cells and be translated into an active enzyme. They are consistent with the interpretation that embryo transport acceleration caused by the injection of estradiol-induced RNA in the oviduct involves translation of the injected mRNA.
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    Inositol triphosphate participates in an oestradiol nongenomic signalling pathway involved in accelerated oviductal transport in cycling rats
    (2006) Orihuela, PA; Parada-Bustamante, A; Zuñiga, LM; Croxatto, HB
    Oestradiol (E,) accelerates oviductal transport of oocytes in cycling rats through a nongenomic pathway that involves the cAMP-PKA signalling cascade. Here we examined the role of the inositol triphosphate (IP3) and mitogen-activated protein kinase (MAPK) signalling cascades in this nongenomic pathway. Oestrous rats were injected with E-2 s.c. and intrabursally (i.b) with the selective inhibitors of phospholipase C (PLC) ET-18OCH(3) or MAPK PD98059. The number of eggs in the oviduct assessed 24 h later showed that ET-18-OCH3 blocked E-2-induced egg transport acceleration, whereas PD980559 had no effect. Other oestrous rats were treated with E-2 s.c. and 1, 3 or 6 h later oviducts were excised and the levels of IP3 and phosphorylated MAPK p44/42 (activated) were determined by radioreceptor assay and Western blot, respectively. Oestradiol administration increased IP3 level at 1 and 6 h after treatment, whereas activated MAPK p44/42 level was unchanged. Finally, e 0 1 we explored whether cAMP-PKA and PLC-IP3 signalling cascades are coupled. Inhibition of adenylyl cyclase by i.b. injection of SQ 22536 blocked the increase of IP3 levels induced by E, while inhibition of PLC by ET-18OCH(3) had no effect on E(2-)induced PKA activity. Furthermore, activation of adenylyl cylase by Forskolin increased oviducral IP3 levels. Thus, activation of PLC-IP3 by E, requires previous stimulation of cAMP-PKA. We conclude that the nongenomic pathway utilised by E, to accelerate oviductal transport of oocytes in cycling rats involves Successive activation of the cAMP-PKA and PLC-IP3 signalling cascades and does not require activation of MAPK. These findings clearly illustrate a non-genomic pathway triggered by E-2 that regulates a complex physiologic process accomplished by in entire organ.
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    The expression of αv and β3 integrin subunits in the normal human Fallopian tube epithelium suggests the occurrence of a tubal implantation window
    (1998) Sülz, L; Valenzuela, JP; Salvatierra, AM; Ortiz, ME; Croxatto, HB
    The co-expression of alpha(1)beta(1), alpha(4)beta(1) and alpha(nu)beta(3) integrins in the human endometrium coincides with the implantation window The alpha(nu)beta(3) integrin is expressed in the apical surface of the luminal epithelium and may serve to anchor trophoblast cells in the adhesion phase of implantation. Using immunohistochemistry, we compared the expression of alpha, alpha(1), alpha(4) and beta(3) integrin subunits in samples of normal human Fallopian tube and endometrium obtained from five women in the non-receptive period (luteal phase days 2-4) and from another five women in the receptive period (luteal phase days 6-8), The staining was quantified visually on a scale of 0 to ++, according to the intensity and density of stained cells. The alpha(nu) subunit is expressed in the Fallopian tube epithelium during both periods in a pericellular distribution. The beta(3) subunit is also expressed in the same location, but it is up-regulated during the period of endometrial receptivity, The other subunits are expressed in localizations which are not relevant to trophoblast adhesion and exhibit little or no difference in the level of expression between the non-receptive and receptive periods. Based on these results we postulate that the expression of the beta(3) subunit in the human tubal epithelium is under the same systemic controlling signals as in the endometrium and that the normal tubal epithelium may have an implantation window, at about the same time as the endometrium, that affords the opportunity for trophoblast attachment should a 5-7 day embryo be unduly retained in the tube.