Analysis of the serum concentrations of kisspeptin and neurokinin B in the geese during reproductive cycle and their localisation in the ovary

Kisspeptin and neurokinin B (NKB) have various functions. Their expression has been demonstrated in rat and human ovary, and estrogen affects their activity, suggesting a role for these molecules in the control of ovary function. However, whether these signaling systems are present in geese ovary, and the associated with serum estrogen remains largely unexplored. In this study we investigated the expression of kisspeptin and NKB in the ovary, and analysed their changes in the serum during the reproductive cycle and their association with serum estradiol in the geese. The results showed both kisspeptin and NKB immunoreactivity was found in the ovary, with marked expression in the granular layer and theca of the follicle, where intense coexpression of kisspeptin and NKB was also detected. The serum concentrations of kisspeptin and NKB in geese were significantly higher (P < 0.05) in broody period than in laying period and laying cessation stage. However, the level of estradiol was markedly higher (P < 0.05) in laying period than in broody and laying cessation stage. Serum kisspeptin was positively correlated with NKB (r = 0.866, P < 0.001), serum estradiol was negatively correlated with kisspeptin (r = −0.977, P < 0.05) and NKB (r = −0.887, P < 0.05). Overall, the existence of kisspeptin and NKB in geese ovary, and the difference of their serum concentrations during reproductive cycle and the inverse correlation with serum estradiol are highly suggestive of a role for kisspeptin and NKB in the regulation of geese reproductive function.