Distinct expression patterns of aging effects on the UPRER signaling pathway in rat colon and regulatory role of saponins from Panax japonicus

Int J Clin Exp Pathol. 2019 Sep 1;12(9):3279-3289. eCollection 2019.

Abstract

Background: Studies have reported that the unfolded protein response of ER (UPRER) declines in the several organs of aging mice. However, changes of UPRER during the aging process in the intestine are rarely reported. Our previous studies have demonstrated that Saponins from Panax japonicus (SPJ) have anti-aging effects in different murine models and can modulate ER stress. In the present study, we focused on age-dependent expressions of UPRER in the intestine of 6- to 24-month-old rats by an immunohistochemical (IHC) method and determined whether SPJ could regulate the three different UPRER branches of the colon in aging rats.

Methods: Aging rats had been treated with different doses (10 and 30 mg/kg) of SPJ for 6 months, which were mixed with feed, since they were 18 months old. Then the expressions of GRP78 and three different UPRER branches were determined by immunohistochemistry (IHC). Results: Total expressions of GRP78 and p-JNK increased, and other UPRER proteins decreased in the colon of aging rats, while SPJ treatment relieved the corresponding changes in aging rats. Here we also found different patterns of GRP78 and the three UPRER branches in the different layers of colon in rats.

Conclusion: The study demonstrated that UPRER declined and GRP78 increased in the colon of aging rats. SPJ could reverse most URPER changes in the colon of aging rats. This study also showed different expression patterns of the three branches of UPRER in different layers of the colon in rats.

Keywords: Aging; endoplasmic reticulum; intestine; saponins from Panax japonicus; unfolded protein response.