Chronic low vitamin intake potentiates cisplatin-induced intestinal epithelial cell apoptosis in WNIN rats

AIM： To investigate if cisplatin alters vitamin status and if VR modulates cisplatin induced intestinal apoptosis and oxidative stress in Wistar/NIN （WNIN） male rats.METHODS： Weanling, WNIN male rats （n = 12 per group） received adlibitum for 17 wk： control diet （20% protein） or the same with 50% vitamin restriction. They were then sub-divided into two groups of six rats each and administered cisplatin （2.61 mg/kg bodyweight） once a week for three wk or PBS （vehicle control）. Intestinal epithelial cell （IEC） apoptosis was monitored by morphometry, Annexin-V binding, M30 cytodeath assay and DNA fragmentation. Structural and functional integrity of the villus were assessed by villus height / crypt depth ratio and activities of alkaline phosphatase, lys, ala-dipeptidyl amino-peptidase, respectively. To assess the probable mechanism（s） of altered apoptosis, oxidative stress parameters, caspase-3 activity, and expression of Bcl-2 and Bax were determined.RESULTS： Cisplatin per se decreased plasma vitamin levels and they were the lowest in VR animals treated with cisplatin. As expected VR increased only villus apoptosis, whereas cisplatin increased stem cell apoptosis in the crypt. However, cisplatin treatment of VR rats increased apoptosis both in villus and crypt regions and was associated with higher levels of TBARS, protein carbonyls and caspase-3 activity, but lower GSH concentrations. VR induced decrease in Bcl-2 expression was further lowered by cisplatin. Bax expression, unaffected by VR was increased on cisplatin treatment. Mucosal functional integrity was severely compromised in cisplatin treated VR-rats.CONCLUSION： Low intake of vitamins increases the sensitivity of rats to cisplatin and promotes intestinal epithelial cell apoptosis.

Impaired glucose tolerance (IGT) to frank diabetes: Dietary manipulations in WNIN/GR-Ob rats

Background: Several rodent models are available to study obesity and obesity associated diabetic problems. We developed an obese mutant rat model viz., WNIN/GR-Ob from our existing WNIN (Inbred Wistar) stock of rats, which exhibit hyperglycemia on challenge with oral glucose. Since such impaired glucose tolerance (IGT) is a fore runner to frank diabetes status, we carried out a study to challenge the animals with different purified carbohydrate sources (glucose, sucrose, starch) and see the outcome. Methods: 48 obese rats of both genders and equal number of lean littermates of 35 days of age were taken for the study and were divided in to four groups, A, B, C, and D. A group received purified glucose based diet, B, received purified sucrose, C, received purified starch and the D, served as the control, receiving standard laboratory rat chow developed at our centre, containing roasted bengal gram as the source of carbohydrate. All diets were isocaloric in nature and contained 56 % carbohydrate in principle. Animals were fed for 8 weeks and parameters like food intake, body weights, and plasma glucose and insulin levels were measured in experimental and control rats at initial, 4 weeks and 8 weeks. Results: As expected, food intake, body weight and feed efficiency ratio were significantly higher in obese rats of all groups as compared to their lean littermate controls and also higher in stock diet, compared to purified diets. Both lean and obese animals showed higher values of glucose and insulin on purified diets compared to control diet. But amongst lean and obese animals, the latter showed sexual dimorphism in their response, the situation being worse in starch fed (C) group. Amongst the obese animals, the males seem to suffer more, compared to females, in starch fed group, followed by glucose and sucrose fed in that order. Conclusions: WNIN/ GR-Ob rats thus seem to be a useful animal model, vulnerable to diet manipulations, especially to carbohydrates. This has the potential to be used as a diabetic model, more akin to human systems, where diet is the major trigger for precipitating diabetes.