ABSTRACT
Objective To explore the nervous regulating mechanism in the effect of light intensity on reproductive performance. Methods Sixty healthy Jinghong-1 hens aged 100 days were randomly divided into four groups of 15 hens and applied a light of 30 lx, 20 lx, 10 lx, and 1 lx, respectively, for 7 days. The distribution and expression of gonadotropin-releasing hormone (GnKH) in mesencephalon and diencephalon were detected using immunohistochemical and image analysis methods. Results GnKH immunoreactive positive neurons were mainly observed in stratum griseum centrale (SCC) of tectum, nucleus isthmi pars magnocellularis (Imc) , nucleus isthmi pars parvocellularis (Ipc) , nucleus subpre-tectalis/interstito-pretectalis-subpretectalis (SP/IPS), nucleus of basal optic root (nbor), and nucleus semilunaris (Slu) of mesencephalon. The mean gray values of positive neurons in 30 lx and 20 lx groups were significantly higher than those of 10 lx and 1 lx groups (P0. 05) between 30 lx and 20 lx groups, but they were significant higher than those of 10 lx and 1 lx (P<0. 05) in PHN, PVN, and GLv. The percent cell area in Hot was the largest in 30 lx group, having no significant difference comparing 20 Ix, being significant higher than those of 10 lx and I Ix (P<0. 05). Those in 30 lx and 20 lx groups were significant higher than 10 lx and 1 lx (P<0.05) in PHN and PVN. Conclusion Light intensity affect the expression of GnRH in hen mesencephalon and diencephalon obviously in Jinghong-1 hens aged 100 days, regulating their reproductive function. The tectofugal pathway of the optical pathways, including collateral circulation of nucleus isthmi, plays an important role in the course of regulation.