Abstract: Objective To study the expression of gonadotropin releasing hormone receptor (GnRH receptor) in the stomach of Sprague-Dawley rat exposed to light stress. Methods We established illumination stressed models that the rats were exposed to continuous light(totally 64 rats, 32 rats for experiment and control group, respectively). Then,stomachs were taken from the rats when the rats exposed to continuous light for 1 day, 2 days, 3 days, 4 days, 1 week, 2 weeks, 3 weeks, 4 weeks and their control groups, respectively.The localization and the expression of GnRHR and GnRHR mRNA in stomachs mucous membrane were detected using immunohistochemistry, Western blotting and realtime PCR. Results Immunoreactivity was displayed mostly in the parietal cells in gastric gland. There were not differences of this distribution in all groups of constant illumination and their control. The immunoreactive materials were distributed on membrane and in cytoplasm of all positive cells, but not in nuclei. The level of GnRHR in rats exposed to continuous illumination were higher from one week to four weeks compared with that in control(EM>P/EM><0.05), and the level of GnRHR reached the peak when rats were exposed to constant illumination for two weeks (EM>P/EM><0.01). The quantity of GnRH mRNA in rats exposed to continuous illumination were higher from three weeks to four weeks compared with that in control（EM>P/EM><0.05）. Conclusion The expression of GnRHR in digestive tract was effected by illumination stress.GnRH might regulate digestive function by interaction with GnRHR, suggesting that GnRH may be acted as a hormone, not only responded to normal physiological function of digestive tract but also responded to stre

Key words: Illumination, Stress, Stomach, GnRHR, Immunohistochemistry, Western blotting, Rat