Differential expression of epidermal growth factor and transforming growth factor beta isoforms in dog endometrium during different periods of the estrus cycle.

Both epidermal growth factor (EGF) and transforming growth factor (TGF) play an important physiological role in the processes of proliferation and differentiation of several different cell types. However, the expression profiles of these factors in domestic bitches endometrium are still poorly recognized. The aim of the present study was to identify and analyze the differential expression of these factors in various stages of the estrus cycle. Endometrial tissue from proestrus (n = 17), estrus (n = 10), day 10 diestrus (n = 15), day 35 diestrus (n = 18) and anestrus (n = 25) was collected soon after ovariohysterectomy. Total RNA was isolated from the endometrium by means of Chomczyński and Sacchi method, treated by DNase I, and reverse-transcribed into cDNA. Quantitative analysis of EGF, TGFbeta1, TGFbeta2, and TGFbeta3 cDNA was performed by real-time quantitative polymerase chain reaction (RT-PCR). EGF expression in canine endometrium was increased in the estrus stage as compared to proestrus (P < 0.05), day 10 diestrus (P < 0.05), day 35 diestrus (P < 0.01) and anestrus (P < 0.001). We also found the differences in EGF expression between day 10 and day 35 of estrus as well as between day 35 of estrus with anestrus (P < 0.05, P < 0.01, respectively). The TGFf1 transcript contents were also higher in estrus as compared to other stages (P < 0.01). The TGFbeta2 and TGFbeta3 in the estrus stage was increased compared to proestrus, day 10 diestrus, day 35 diestrus and anestrus (P < 0.05). We proved that expression of EGF and TGFbeta transcript isoforms is related to the phase of estrus in bitches and therefore may be regulated by specific hormone concentrations during these periods. Our results confirm the hypothesis that these growth factors play a role in the regulation of biochemical changes in the endometrial tissues during the estrus cycle.