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

•Kisspeptin and NKB coexpressed in the granular layer and theca of the follicle in the geese.•The serum concentrations of kisspeptin and NKB were different during reproductive cycle.•Serum kisspeptin and NKB levels were both the inversely correlated with serum estradiol. 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