The Effects of Tachykinin1 Gene Products on Prepubertal Dabry's Sturgeon (Acipenser dabrynus) Pituitary Hormone Secretion and Gene Expression.

ABSTRACT

As an ancient and endangered species unique to the Yangtze River in China, the wild population of the Dabry's sturgeon has become scarce. Due to the long time till the first sexual maturity of Dabry's sturgeon, the population of artificially bred Dabry's sturgeon recovered slowly. As a member of the tachykinin family, TAC1 has been reported to have a variety of functions in mammals such as pain control, smooth muscle contraction and reproductive cycle regulation, but the function of Tac1 in fish has been rarely reported. In this study, we synthesized two tac1 gene products, Substance P (SP) and neurokinin A (NKA), and further verified the effect of two tac1 gene products on the secretion of related hormones in the pituitary of Dabry's Sturgeon by intraperitoneal injection and co-culture of primary cells. Expression studies revealed that the newly cloned tac1 were mainly distributed in the hypothalamus and pituitary tissue of the brain. In prepubertal Dabry's sturgeon, this study showed that the two gonadotropins' mRNA levels in pituitary tissue can be significantly increased by SP and NKA through intraperitoneal injection, and the LH protein level in serum was also increased. Further study showed that both NKA and SP could promote the two gonadotropins' mRNA expression in pituitary cells of Dabry's sturgeon. In addition, we explored the optimal dose and time of SP and NKA on pituitary cells is 24 h and over 10 nM. These results, as a whole, suggested that tac1 gene products play an important role in gonadotropin release and gonadal development in prepubertal Dabry's sturgeon.