Are oestrogen receptors and protein tyrosine kinases involved in phytoestrogen-modulated steroid secretion by porcine adrenocortical cells?

The phytoestrogens genistein and daidzein had been found to affect the function of some tissues via oestrogen receptors (ER). In addition, genistein, but not daidzein, is considered to be a protein tyrosine kinase (PTK) inhibitor. Thus, the involvement of oestrogen receptors and PTK in phytoestrogen action on adrenocortical porcine steroidogenesis was examined in this study. The aims of the experiment were to test the effects of (i) ICI 182, 780 (ICI), an ER antagonist, on genistein- and daidzein-modulated cortisol and androstenedione (A4) secretion by adrenocortical cells isolated during the luteal and follicular phases of the porcine oestrous cycle; (ii) tyrphostin AG 957 (TAG), a nonsteroidal PTK inhibitor, on cortisol and A4 secretion by the cells and (iii) the phase of the porcine oestrous cycle on the mechanism of phytoestrogen action. Adrenals were harvested during the luteal (n = 5 animals) and follicular (n = 5 animals) phases of the oestrous cycle from locally slaughtered crossbred gilts. The isolated adrenocortical cells were incubated for 8 h (37 °C, 95% air, 5% CO2) with genistein (5 or 10 μM) or daidzein (5 or 10 μM) in the presence or absence of ICI (0.5 μM) or TAG (5 or 10 μM). Genistein and daidzein inhibited cortisol secretion and stimulated A4 secretion by porcine adrenocortical cells harvested during both the luteal and follicular phases of the oestrous cycle. The ER antagonist ICI did not eliminate phytoestrogen-induced changes in steroidogenesis. In contrast to genistein, TAG reduced the secretion of A4 and did not affect cortisol secretion. There was no observable effect due to the phase of the cycle. It is suggested that the mechanism of genistein and daidzein action in the adrenocortical cells of pigs is independent of ER and PTK. It is possible that PTK are involved in A4 secretion by porcine adrenocortical cells

Effects of dietary meals containing different levels of phytoestrogens on reproductive function in Bilgoraj ganders

The aim of this study was to investigate how long-term feeding of ganders with diets containing different levels of phytoestrogens affects the morphometry of testes, plasma steroid levels, sperm parameters and reproductive performance. Male Bilgoraj geese were fed diets containing grass meal (with low phytoestrogen levels) and those containing alfalfa meal and soybean meal (with higher levels of phytoestrogens). Testes were obtained from ganders at the peak of mating and the ongoing laying period as well as at the beginning of photorefractoriness. The morphometric parameters were measured in frozen testicular sections. Blood was collected monthly from December to June, and plasma testosterone, androstenedione and corticosterone concentrations were determined. During the mating season, semen was collected and its quantity and quality were investigated. In the flocks (ganders with geese) reproductive output was noted. Seasonal changes were observed in the morphology of testes and in plasma testosterone, androstenedione and corticosterone concentrations in ganders. The feeding of ganders with dietary meals containing higher levels of phytoestrogens did not affect the plasma steroid contents or the majority of the morphometric parameters of testes, except for the height of the seminiferous epithelium, which was lowered. Moreover, diets with higher levels of phytoestrogens decreased the volume of ejaculates and the percentage of normal spermatozoa. However, these changes were not reflected in the fertilisation rates