A study of the uterine protein variations during the estrus cycle in the cow: A comparison with the serum proteins

To investigate uterine protein changes during the estrus cycle in the bovine, 115 pluriparous genital tracts and blood samples were collected from the abattoir in Urmia. Genital tracts were considered healthy based on gross examination of the uterus and uterine histopathological findings. The phase of the estrus cycle was determined by the examination of the structures present on the ovaries and the uterine tonicity. Of the collected samples, 24 were pro-estrus, 21 estrus, 24 met-estrus and 46 diestrus. The uterus was incised and uterine fluid was collected by gentle scraping of the uterine mucosa with a curette. The total protein concentration, protein profiles (on agarose gel electrophoresis) in the uterine fluid were evaluated and compared with those of the serum. Total protein, α1, α2, β1 and β2 globulin values in the uterus were significantly higher than those of the serum (P < 0.05), while, the albumin, γ1 and γ2 globulin values in the serum were higher than those of the uterus throughout the cycle. During pro-estrus, uterine fluid β2 (1.96 g/dl) and serum γ1 (1.07 g/dl) and γ2 (1.27 g/dl) globulins were higher than those in the other phases of the cycle. During estrus, serum total protein was lower than the other phases (4.92 g/dl), which was considered to be due to a reduction in serum α1 (0.25 g/dl), γ1 (0.65 g/dl) and γ2 (0.64 g/dl) globulins in this phase. In met-estrus uterine fluid β1 globulin was in the lowest (1.19 g/dl) and serum γ2 globulin at a high level (1.24 g/dl). It was concluded that uterine proteins as well as serum proteins fluctuate during the estrus cycle and, except for the albumin and γ globulins, its protein content is higher than the serum. During the follicular phase of the cycle uterine α globulins are higher than those in other phases, with an elevation in β1 and a reduction in β2 and γ globulin values during estrus, which may reflect the preparation of the uterus for receiving spermatozoa for the conception in this phase.