Changes of Colon in Rats with Different Ages in Response to Lipopolysaccharide

Abstract

Background: Lipopolysaccharide (LPS) is an endotoxin that causes inflammation, and the content of LPS increases gradually during the process of aging. Whether the response of the colon to LPS stimulation will increase with age is yet unknown.

Objective: The study investigated the effects of LPS stimulation on the colon of adult and aging rats.

Method: 43 healthy male SD rats were divided into 4 different groups: adult group and LPS-stimulated adult group at the age of 4 months, and aging group and LPS-stimulated aging group at the age of 22 months. Rats were stimulated by intraperitoneal injection of LPS (1mg/kg) for 24 h. The morphological changes of the colon were observed, and intestinal inflammatory response, tight junction proteins, apoptosis, and proliferation in intestinal epithelial cells were detected.

Results: A series of morphology changes occurred in the colon of adult rats after LPS stimulation, the higher inflammatory response (TLR4, NF-κB, and IL-1β), changes in the protein levels of tight junctions (ZO-1, Claudin1, and Claudin2), and increased apoptosis (Bax, Bcl2) and proliferation (PCNA) of intestinal epithelial cells. The above changes were also found in aging rats. LPS stimulation further promotes the above changes to some extent in the colon of aging rats.

Conclusion: A series of colon changes in rats was significantly damaged during LPS stimulation and aging, and these changes were further aggravated to some extent in LPS-stimulated aging rats.

Keywords: LPS; aging; apoptosis; inflammation; intestinal epithelial cells; tight junction.