Effect of illumination stress on the expression of gonadotropin-releasing hormone in stomach of SD rats

Abstract

AIM: To observe the expression changes of gonadotropin-releasing hormone (GnRH) in the stomach of Sprague-Dawley (SD) rats exposed to light stress. METHODS: SD rats were exposed to continuous light to establish illumination-stressed models. Then, gastric tissues were taken from the rats exposed to continuous light for 1 d, 2 d, 3 d, 4 d, 1 wk, 2 wk, 3 wk, 4 wk and their corresponding controls, respectively. The localization and expression of GnRH protein and GnRH mRNA were detected by immunohistochemistry and real-time polymerase chain reaction (PCR), re-spectively. RESULTS: Immunoreactivity was displayed mostly in the parietal cells of rat stomachs, and there were no differences in this locolization be- tween the illumination stress groups and their corresponding control groups. Compared with that in the control group, the mean gray scale of GnRH in the rats exposed to continuous illumina- tion was increased from 2 wk to 4 wk (2 wk: 105.7 ± 7.9 vs 77.4 ± 7.2, P 0.05; 3 wk: 97.4 ± 7.7 vs 77.6 ± 6.6, P 0.05; 4 wk: 93.2 ± 2.1 vs 77.9 ± 4.0, P 0.05). The quantity of GnRH mRNA in the rats exposed to continuous illumination was also higher than that in the controls (2 wk: 1.01 ± 0.10 vs 0.80 ± 0.01, P 0.05; 3 wk: 0.95 ± 0.07 vs 0.81 ± 0.01, P 0.05; 4 wk: 0.94 ± 0.05 vs 0.82 ± 0.01, P 0.05). CONCLUSION: The expression of GnRH in digestive tract can be effected by illumination stress. GnRH may regulate digestive function by autocrine and paracrine, suggesting that GnRH may be a kind of hormone not only responded to normal physiological function of digestive tract but also responded to stress activity.