Hormones and sex steroid receptors in the female pig : effects of mating, artificial insemination, seminal plasma and genistein

Artificial insemination (AI) of sows and gilts is replacing mating in many countries. Another change over the last decades is that soya, rich in phytooestrogens, is routinely used in the diet to pigs. The aims of this thesis were to compare hormonal changes in blood plasma of the female pig during mating and insemination and to investigate if the phytooestrogen genistein influenced the hormonal responses and sex steroid receptor expression in the reproductive tract of inseminated gilts. Blood samples were taken via permanent catheters around mating or AI for analyses of hormones. Uterine and cervical cells were used in vitro to determine the role of seminal plasma. Three days after AI, gilts were euthanized and uterine and cervical tissues were prepared for morphological and immunohistochemical examination. Plasma cortisol concentration increased more during mating than AI in sows, in contrast prostaglandin F2α metabolite (PGFM) increased only after AI. By incubating cells from porcine cervix and uterus with seminal plasma prostaglandin synthesis was inhibited in a dose dependent manner, providing a possible explanation for the difference in PGFM after mating. When a feed relevant dose of genistein was added to gilts from 3 days before oestrus until 3 days after AI, prostaglandin F2α exhibited more frequent pulses with higher amplitudes after AI, the PGE2 level was elevated and plasma oxytocin was almost doubled. PGFM, however, had a similar pattern in both groups. Nevertheless gilts administered genistein showed no significant difference in cell proliferation or the expression of oestrogen receptors (ER) α and β or progesterone receptor in uterus and cervix. However, intra-treatment evaluation and correlations indicated that genistein may modulate receptor patterns and induce subtle morphological changes. In view of the results presented in this thesis it is surprising that the difference in reproductive performance is not greater between AI and mating, especially with the addition of soya to the diet.