W1548 Role of Lysophosphatidylcholine in Intestinal Alkaline Phosphatase Release and Restoration

Background and aims: Although prevalence of peptic ulcers is higher in men compared with that in women, the mechanism underlying this gender difference is not fully understood. Many recent studies have indicated that heat shock proteins (HSPs), which function as molecular chaperones, play an important role in cellular responses to stress-related events. However, gender difference in expression of HSPs remains unclear. In order to understand the mechanism of gender difference in prevalence or severity of gastric mucosal lesion, expression levels of HSPs and contribution of estrogen to HSPs expression in the gastric mucosa were evaluated in this study. Materials and methods: In order to evaluate the basal expression level and induction ability of HSPs, the gastric mucosa was removed from male and female Wistar rats before (0 h) and after exposure to Water-Immersion stress (WIstress) for 3, 6 or 12 hrs (n=4 at each time point). Also gastric ulcer index after WI-stress and the expression levels of HSP60, HSP72, and HSP90 in the rat gastric mucosa were analyzed by Western blot. Effect of estrogen (estradiol) (10mg/kg, i.p.) on gastric mucosal HSPs expression was also studied. Results: Most significant gender difference in gastric ulcer index was observed at 12 hrs-WI-stress exposure (p=0.047). The expression of HSP60 and HSP90 in gastric mucosa was significantly higher in female than those in male at this time point (p=0.0027, p=0.0017 respectively), whereas expression of HSP72 did not show gender difference. Intraperitoneal injection of estrogen induced significantly higher level of HSP60 (1 hr; p=0.032), HSP72 (6 hrs; p=0.017), and HSP90 (1 hr; p=0.0016) compared with male control rats in the gastric mucosa. Conclusions: Our results suggested that estrogen might play important roles in gastric mucosal protection inducing gastric mucosal HSPs. Our findings might at least partly explain one of the mechanisms of gender difference in gastric mucosal protection.