Regional Differences in Chronic Stress-induced Alterations in Mast Cell and Protease-activated Receptor-2-positive Cell Numbers in the Colon of Ws/Ws Rats.
OBJECTIVE
There have been no reports on the effect of chronic psychological stress on colonic immune cells or the regional differences. We aimed to investigate the effect of chronic psychological stress on the number of mast cells and protease-activated receptor (PAR)-2-positive cells in the rat colonic mucosa.


METHODS
Six-week-old and 14-week-old Ws/Ws rats, which lack mast cells after 10 weeks, were used as control and mast cell-deficient groups, respectively. The rats were divided into stress and sham-treated groups. Rats in the stressed group were exposed to water avoidance stress (WAS, 1 hour/day) for 13 days. Fecal pellet output and the number of mast cells and PAR-2-positive cells in colonic mucosa were compared between the WAS and sham groups.


RESULTS
In 6-week-old rats, the WAS group showed a significantly higher number of mast cells compared to the sham group. In 14-week-old rats, mast cells were nearly absent in the colonic mucosa. WAS significantly increased PAR-2-positive cells in 14-week-old rats, but not in 6-week-old rats. Indirect estimation of PAR-2-positive mast cells in 6-week-old rats suggested that the majority of increased mast cells following WAS did not express PAR-2. WAS increased mast cells and PAR-2-positive cells mainly in the proximal colon. Fecal pellet output was continuously higher in the WAS group than in the sham group, and the difference was significant for both 6-week-old and 14-week-old rats.


CONCLUSIONS
Chronic psychological stress increased the number of mast cells and PAR-2-positive cells in rat colonic mucosa, and these increases were more prominent in the proximal colon.
Digestive Disease Research Institute, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea. ; Department of Gastroenterology, Wonkwang University Sanbon Hospital, Gunpo, Gyeonggi-do, Korea.
Yong Sung
YS
Kim
Digestive Disease Research Institute, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea. ; Department of Physiology and Institute of Wonkwang Medical Science, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea.
Moon Young
MY
Lee
Digestive Disease Research Institute, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea. ; Department of Gastroenterology, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea.
Han Seung
HS
Ryu
Digestive Disease Research Institute, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea. ; Department of Physiology and Institute of Wonkwang Medical Science, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea.
Eul-Sig
ES
Choi
Digestive Disease Research Institute, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea. ; Department of Surgery, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea.
Jung Taek
JT
Oh
Digestive Disease Research Institute, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea. ; Department of Pathology, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea.
Ki Jung
KJ
Yun
Digestive Disease Research Institute, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea. ; Department of Gastroenterology, Wonkwang University School of Medicine, Iksan, Jeollabuk-do, Korea.
Suck Chei
SC
Choi
Colon; Mast cells; Rats; Receptor, PAR-2; Stress, psychological