Eucommia ulmoides Oliver as a Prophylactic against Restraint Stress in Water-induced Gastric Erosion in Rats

Abstract

The aim of this study is to investigate the pharmacological effect of Eucommia ulmoides Oliv. and its components as prophylactics against restraint stress in water (RSW)-induced gastric erosion. In the test, an extract of E. ulmoides bark prepared using hot water was dissolved in water and used to assay its protective effect against gastric erosion in rats exposed to RSW for 7 h. Oral administration of the E. ulmoides extract (500 mg/kg per day) dissolved in 1 ml distilled water demonstrated a 44.9% protective effect against RSW-induced gastric erosion. The protective effect observed following the oral administration of the extract (50 and 500 mg/kg per day) for 2 weeks was dose-dependent. Oral administration of a 500 mg/kg dose of E. ulmoides extract increased the circulating prolactin (PRL) level and the expression level of the hypothalamic PRL receptor long form (PRLR(L)) mRNA in rats. Chlorogenic acid (CHA, 30 mg/kg per day) and geniposidic acid (GEA, 30 mg/kg per day), the major components of the E. ulmoides extract, showed a significant inhibitory effect on gastric erosion (20.9% and 21.8%, respectively) and an increase in the circulating PRL level and the expression level of the receptor mRNA in the hypothalamus. We showed that the protective effect of the E. ulmoides extract against gastric erosion may be partially due to the effects of CHA and GEA. E. ulmoides extract and its components enhance the circulating PRL level and stimulate hypothalamic PRLR(L) to produce an anti-stress effect. These results suggest that the PRLR(L)-driven actions in the hypothalamus that are induced by E. ulmoides extract and its components are important for coping with acute stress.