[Insulin protects the loss of colonic interstitial cells of Cajal and acetylcholine in patients with type 2 diabetes mellitus].
OBJECTIVE
A deficiency of interstitial cells of Cajal (ICC) and neuronal nitric oxide synthase (nNOS) in the gastrointestinal muscle layer have been shown in both diabetic animal models and patients with diabetes mellitus (DM), but little is known about the alteration of colonic acetylcholine (Ach) expression in patients with DM, and it is remain unclear whether those changes are related to different treatments. This study examined whether the ICC density, or the expression of Ach containing nerves in the colon, was altered in patients with type 2 DM, and whether those changes were protected by insulin treatment.


METHODS
Paraffin embedded colonic specimens that have been fixed in 10% formalin were collected from 81 patients with colon cancer who underwent colectomy (non-DM as controls, M/F = 17/12; DM with insulin treatment, M/F = 12/12; DM with oral medication treatment, M/F = 19/9). Serial sections were stained with antibodies to c-kit and Ach using immunohistochemical method.Meanwhile, mast cells were stained with toluidine blue. The ICC number was calculated by subtraction of the number of mast cells from the number of c-kit positive cells. The number of ICC and the expression of Ach were compared among the controls and DM patients with different treatment.


RESULTS
C-kit positive cells, which located within the inner muscle layer and muscular plexus mainly, were expressed in control group and they were much more regular and less vacuolization than that of controls. The density of both intramuscular-ICC (ICC-IM) and myenteric ICC (ICC-MY) were much lower in patients with DM than that in the controls. Furthermore, ICC density in DM patients who underwent insulin treatment was higher than that in patients with oral medical therapy (control vs insulin vs oral medication group: ICC-MY, 60.12 vs 23.95 vs 16.49, P = 0.000; ICC-IM, 41.79 vs 33.18 vs 25.88, P = 0.000). In addition, the alteration of Ach expression in colonic enteric nerves was similar as the pattern of ICC (control vs insulin vs oral medication group: 147.50 vs 103.82 vs 86.38, P = 0.000). There was no influence of gender and age to the alteration of ICC and Ach.


CONCLUSIONS
The colonic ICC and Ach in DM patients is irregular, and the distribution is loose, with lots of vacuolization. The density of clonic ICC-IM and ICC-MY were lower in DM patients than that in controls accompanied with downregulation of enteric nerves Ach expression. These alterations could be protected by insulin treatment.
Tang
Xiao
X
Department of Gastroenterology, Third Hospital, Peking University, Beijing 100191, China.
Duan
Li-ping
LP
Wei
Yan-yu
YY
Yang
Xue-song
XS
Zhong
Yan-feng
YF
D000109:Acetylcholine / Q000378:metabolism*; D000368:Aged; D003106:Colon / Q000166:cytology / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D007328:Insulin / Q000627:therapeutic use*; D056885:Interstitial Cells of Cajal / Q000166:cytology*; D008297:Male; D008875:Middle Aged
D007004:Hypoglycemic Agents; D007328:Insulin; D000109:Acetylcholine