Relação dos constituintes do sistema IGF, receptores esteroidais no útero e hormônios esteroides séricos de cadelas no diestro cíclico

Abstract

In bitches, endocrine modifications denote different hormonal moments during diestrus. At 20 days after ovulation, a progesterone peak (P4) was observed and at 40 days estrogen elevation (E2). IGFs (insulin-like growth factors) are growth factors produced in most organs and tissues of the body and their regulatory mechanisms involve receptor availability, abundance of IGFBPs (IGF-binding proteins) and protease activity. This study was divided into two chapters, first a literature review on the topic (Chapter 1) and then a scientific article (Chapter 2) to verify the correlation of hormonal variations in gene expression of IGF1 system members and estradiol and progesterone receptors in the uterus of nonpregnant bitches during diestrus. The uterus of 29 bitches, was used after elective ovariohysterectomy at 10, 20, 30, 40, 50 and 60 (n = 4 or 5 per group) days after ovulation. Tissue was analyzed by RT-qPCR for relative mRNA abundance for IGF1, IGFR1, IGFBP3, IGFBP4, PAPPA, PGR, ERS1 and ESR2. Blood samples were taken at the time of surgery to measure E2 and P4 and the ratio between hormones was calculated. Differences between variables in the groups were calculated using the Kruskal-Wallis test followed by Student Newman between the groups (P <0.05). The correlation between steroid hormone plasma dosages and relative expression of target genes was conducted by Pearson's method. The relative gene expression of ESR2 was lower on days 40 and 50, compared to days 10, 20 and 30 (P <0.05), and showed a positive correlation with P4 (r: 0.5329; P: 0.0128 *). The relative gene expression of IGFBP3 increased throughout the diestrus (P <0.05) and that of IGFBP4 is higher at the end of the diestrus (days 50 and 60) and correlated negatively with P4 (r: -0.4622; P: 0.0174 *). ) and positively with the ratio E2 / P4 (r: 0.5663; P: 0.0025 *). It is concluded that estrogen receptor β gene expression (of the ESR2 gene) is regulated during diestrus in the womb of bitches, and that it is positively correlated with P4, although its decrease would be a mechanism involved in greater cell proliferation. endometrium after day 30 in response to E2. The results also suggest that the local modulators of the IGF1 system are IGFBP3 and IGFBP4 in the uterus of nonpregnant bitches.