Avaliação da expressão do mRNA do GLUT 4 em corpo lúteo de cadelas sadias ao longo do diestro / Evaluation of the expression of GLUT4 mRNA in canine corpus luteum during diestrus

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The canine estral cycle differs from other domestic species. Some studies demonstrated that the increase of the plasmatic concentration of progesterone during canine luteinic phase can lead to metabolic alterations, such as insulinic resistance and may cause complications such as Diabetes mellitus. Glucose is a molecule that is transported in most cells by transporting proteins. The process of installation of the insulinic resistance is characterized by tissue alterations of the expression of some glucose transporting proteins, as GLUT4. Currenly, 13 isoforms of transporting proteins were sequenced (GLUT1 to GLUT13). GLUT4 is present mainly in muscle and fat tissue. In order to assess if GLUT4 expression is present in luteal cells, and if this expression is related to P4 and E2 production, 28 bitches were divided into 7 groups, in accordance with the days after the ovulation -p.o. (from 10 to 70 days, n=4 for group). The ovaries were dissected and frozen in liquid nitrogen. The RNA was extracted and the cDNA was made and submitted to real time PCR. GAPDH gene was used as endogenous conntrol to standardization of target gene expression. Blood was collected to glycemia, insulinemia, P4, and E2β dosage. To assess the positive regulation of GLUT4, we also assessed HIF-1α mRNA expression of the same bitches. GLUT4 expression showed a tendency to increase the expression on the twentieth day (p.o.), when compared to the 10th, 30th, and 40th days, expression top on the 50 th day (p.o.) , and then, it showed a tendency to foll on the 60th and 70th days p.o. HIF-1α expression was very similar over the days, tending to fall on the 10th and 40th days post ovulation, when compared to other groups. P4 and E2β dosage results varied according to thr expectations in diestrus and have not shown correlation with GLUT4 expression; glycemia and insulin, here expressed by HOMA index (insulin x glucose % 22,5) showed crest (highest point) on the 40 th day. It is knows that the higher the HOMA index, the less sensitive this animal is to insulin, it is, more resistant to it. It was observed that HOMA index was higher on the 40th day, associated to small values of the GLUT4 expression. Otherwise, the got the top of GLUT4 expression on the 50th day, when HOMA index showed low values. It has been suggested that P4 fall associated to the plasmatic E2 increase may influence HOMA index. We may conclude that GLUT4 expression into the corpus luteum of bitches follows the standard observed in insulin-sensitive tissues, in which there is a higher expression over the phase of higher sensitiveness to insulin and remarkable decrease in pre or even installed insulinic resistance.

ASSUNTO(S)

corpus luteum diestro bitches glut4 pcr tempo real glut4 diestrus real time pcr cadelas

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