Expressão das aquaporinas 1 e 9 durante o desenvolvimento folicular em ratas

• Ano de defesa: 2013
• Autor(a) principal: Carina de Oliveira Dumont Horta
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Fisiologia e Farmacologia; Ovários; Fase folicular; Fisiologia; Aquaporinas
• Link de acesso: http://hdl.handle.net/1843/BUOS-9KWHLZ

Aquaporins (AQPs) constitute a family of integral membrane proteins with a wide distribution in different physiological systems. The AQPs are present in several organs of the female genital tract as placenta, uterus, fallopian tubes, cervix, vagina and ovaries. In ovaries, AQPs may play an important role during folliculogenesis, contributing for the antral cavity expansion through the water transport into the follicle. The AQP1 and AQP9 may be especially important in folliculogenesis. AQP1 is associated with angiogenesis and gonadal steroids seems to regulate AQP9 expression. The aim of this study was to evaluate the expression of Aquaporins 1 and 9 during follicular development and ovulatory process induced by gonadotropins in the rat ovary. Prepubertal female Wistar rats (24-26 days old) received subcutaneous injection of 20UI of pregnant mare serum gonadotropin (PMSG - NHPP, Torrance, CA, USA) to induce the development of multiple follicles. After 48 hours, half of them received 20UI of human chorionic gonadotropin (hCG - Choragon, Ferring Pharmaceuticals, Wittland, Germany) for ovulation induction. The control rats received saline injections. The messenger RNA (mRNA) expression for the AQPs was determined by real time - PCR (RT-PCR). The distribution of AQPs in the ovaries was evaluated by immunohistochemistry. The data were analyzed by one-way analysis of variance, followed by Newman - Keuls test using the GraphPad Prism version 5.00. The rats treated with PMSG showed increased expression of AQP9 mRNA compared to controls (2.05 ± 0.71 vs. 1.02 ± 0.18, p<0.05) . The results of PMSG + hCG treated group were similar to the PMSG treated group (2.70 ± 1.16 vs. 2.05 ± 0.71). In ovaries of prepubertal control rats, the AQP9 protein expression was observed in granulosa cells from primary follicles. In antral follicles, the positive staining was found in the theca and granulosa cells. Interstitial cells present in the stroma were negative for AQP9. Oocytes showed weak labeling for AQP9. Treatment with PMSG resulted in increased immunostaining for AQP9 in the theca cells of antral and pre-ovulatory follicles. Positive staining was also observed in interstitial cells of the stroma. The rats treated with PMSG + hCG showed the same staining pattern induced by treatment with PMSG. On the other side, positive labeling for AQP1 was restricted to the endothelium of ovarian vessels. Increase of AQP1 gene expression was observed in ovaries treated with PMSG compared with controls (0.290 ± 0.115 vs. 0.048 ± 0.004; p<0.05). Treatment with PMSG (0,36 ± 0,07) e PMSG/hCG (0,46 ± 0,06) decreased the AQP1 mRNA expression compared to control group (1,01 ± 0,07). Quantification of vessels in preovulatory and antral follicles was performed by morphometry. The PMSG+hCG treatment increased vascularity in the theca layer of antral and preovulatory follicles (0.57 ± 0.05) compared to the control (0.45 ± 0.08) and PMSG (0.46 ± 0,06) groups. In addition, our results showed changes in the immunostaining profile of follicular vessels. The area negative for AQP1 was lower in the PMSG + hCG treated group compared to PMSG and control groups (0.09 ± 0.06, 0.28 ± 0.11; 0.29 ± 0.05, respectively). The hCG treatment enhanced imunostaining for AQP1, which resulted in the increase of staining vessel area for AQP1 (0.48 ± 0.05) compared to the control group and PMSG (0.16 ± 0.03, 0.17 ± 0.03). Progesterone seems to be important for the preovulatory process and is enhanced by LH/hCG. To evaluate the role of progesterone in the regulation of AQP1 expression, we administrated the progesterone receptor antagonist, RU 486 (5mg/rat). RU-486 injection did not affect the AQP1 protein expression, indicating that progesterone is not involved in the increase of vascularization and AQP1 expression induced by LH/hCG. Taken together, our results indicate that major changes in the expression of AQP1 and AQP9 occur during follicular development and early ovulatory process, and expand the knowledge about the involvement of AQPs in the reproductive process.