The potential implication of neurokinin B in the modulation of prolactin secretion at the pituitary level in cyclic gilts.

Based on the previous studies, neurokinin B (NKB) participation in the modulation of prolactin secretion at the pituitary level can be assumed, but information concerning this topic is largely insufficient. Therefore, in the present study, we aimed: 1) to evaluate changes in the expression of NKB precursor (Tac3) and its receptor (Tacr3) genes as well as the content of NKB and TACR3 proteins in the porcine anterior pituitary throughout the estrous cycle (days 2 - 3, 9 - 10, 12 - 13, 15 - 16, 19 - 20); 2) to determine in vitro the influence of NKB on the expression of Prl, D2r and Trhr genes in the anterior pituitary cells (incubated for 4 h) as well as on prolactin secretion by these cells (incubated for 4 and 24 h) during chosen days of the estrous cycle (9 - 10, 15 - 16, 19 - 20). The experiments have shown alterations in the expression of Tacr3 mRNA and TACR3 protein content, but not in Tac3 mRNA and NKB protein. The treatment with NKB stimulated the expression of Prl (days 15 - 16), D2r (days 9 - 10) and Trhr (days 19 - 20) genes, but its potential to modulate prolactin secretion was observed only following 24-h incubation, specifically inhibition by NKB alone and stimulation by NKB with dopamine on days 19 - 10 of the cycle. These results indicate some implications of NKB in the modulation of prolactin secretion at the pituitary level in cyclic pigs, however further experiments are required to better clarify its role in this process.