Emprego tópico de prostaglandina da família E ou de análogo com o intuito de acelerar a migração de embriões eqüinos para o útero e imunolocalização dos respectivos receptores / Topic application of prostaglandin E family or analogous aiming the acceleration of the migration of equine embryos to the uterus and immunolocalization of the respective receptors

Karen Regina Peres

Differently of any other ways of occurrence among the domestic animals, concerning mares, their embryos migrate in a delayed lapse of time to their uterus due to a correlation to the PGE2. Consequently, one extracts embryos which are already into some more advanced phase of their development (blastocyst and expanded blastocyst) normally exceeding 300 micrometers when their extraction is performed after the 6th day. This fact results into a failure concerning the protocols of embryonic cryopreservation. Regarding this problem, the effectiveness of applying PGE2 using two different methods (experiment I) and the effectiveness of PGE1 and the analogous misoprostol (experiment II) for promoting the anticipated extraction of the embryos, were evaluated. Both experiments were carried on some superstimulated mares using Equine Pituitary Extract. Experiment I: after the 4th day after the ovulation (D4), two mares were submitted to laparoscopy through the flank for depositing 0.2mg of PGE2 gel on the oviduct; to three other mares PGE2 was topically applied on the uterus-tube junction (UTJ) with the aid of a flexible pipette (not-surgical method). Twenty and four hours after the gel disposal (D5) regarding both methods, a first attempt for extracting the embryos was unsuccessfully performed. Another attempt was performed between the D6-6.5, and this time two embryos were extracted from the five mares (40%), one of each group. Experiment II: two applications of 0.2mg of PGE1 gel 100% (n=5) or misoprostol gel 1% (n=5) were accomplished on the UTJ region, at D4, through the not-surgical method. There werent any extracted embryos at D5 from the mares which had received PGE1 (0/5) and there were just two embryos extracted from a mare at D6-6.5. From the group which had received misoprostol three embryos from different mares were extracted at D5 (3/5), being a morula and two embryos aged seven days, from not-synchronous ovulations. However, at D6, eight embryos were extracted from all of the mares (5/5) which have received misoprostol, a significantly superior result (P=0.0048) comparing to the group which received PGE1 (1/5). Although the small number of animals, there were extracted eleven embryos from the twelve ovulations into the group which received misoprostol, all of them with a diameter 300 micrometers. In the last experiment it was qualitatively detected by immunohistochemistry the different receptor subtypes (EP1 to EP4) for the PGEs in the uterus, on the UTJ and in the different segments of the oviduct, in all stages of the estrous cycle and during two periods of gestation; however, there is a smaller amount (P<0.0001) of the receptor subtype EP1 in comparison to the other subtypes. The obtained results by immunohistochemistry genuinely indicate that the topical application of PGE on the UTJ through a not-surgical method seems effective and the obtained results in the first two experiments show that even though it doesnt anticipate the embryos migration to the uterus, the protocol using misoprostol 1% in superstimulated mares was significantly effective for increasing the extraction of embryos aged six days with desirable characteristics for the cryopreservation.

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