Histological characterization and immunolocalization of caspase 3 in corpus luteum of bovine females treated with Dinoprost tromethamine or cloprostenol sodium, with whole or half dose, during metaestrus or diestrus
Prostaglandin F2 alpha (PGF2 alpha) analogs are widely used in estrous cycle control, promoting luteolysis and, consequently, apoptosis. One of the main participants of the apoptosis cascade in the bovine corpus luteum (CL) is caspase 3. Although there is knowledge about the ultrasonographic aspects, CL morphology and progesterone profile, there are few reports regarding the histological pattern of luteal cells and expression of caspases in CL. Thus, in the present work the objective is to evaluate the luteolytic efficiency of PGF2± analogs, dinoprost tromethamine or sodium cloprostenol, in full or half dose, at the moment of metestrus or diestrus (4 or 11 days after ovulation, respectively) by histological characterization and caspase 3 labeling by the immunohistochemical technique. For this purpose, CL from 26 Bos indicus or crossed cows, previously synchronized for the days proposed in the study will be used. CLs will be included in paraffin and mounted on slides to be stained with hematoxylin-eosin (HE) and will also be submitted to immunohistochemistry (IHC) preparation with the use of the primary anti-caspase 3 antibodies. Three cuts from each slide will be evaluated for counting large and small luteal cells in HE staining, and for intensity of the immunoreaction for caspase 3 (categorizing 1 to 5) in IHC. Histology data will be described as mean and SEM, submitted to analysis of variance and t-test and the intensity of the reaction will be analyzed by the Kruskal-Wallis test, with a significance of 5%. It is expected to elucidate the luteolysis mechanisms according to the proposed conditions.
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