FIG. 6.

Resistance of RIP-N mice to streptozotocin-induced diabetes. Wild-type (+/+) and RIP-N (+/RIP-N) females (nine each) were subjected to multiple low-dose injections of streptozotocin (Strepto.) (see research design and methods). Glucose blood levels were then determined at the indicated times. The results are expressed as the means ± SD (statistic analysis was performed for each time point between wild-type and RIP-N mice [eight comparisons]). This experiment has been repeated two more times with similar results (A). Alternatively, the mice were killed 8 days after the first streptozotocin injection, and apoptosis on islet sections was determined by the TUNEL assay (B). The results shown in the graph correspond to the means ± SD of the quantitation performed on three and four mice for the control and streptozotocin treatment, respectively (an average of 24 islets per mice were analyzed). Statistic analysis was performed on the indicated groups. As reported by others (47), we note that the percentage of basal apoptosis in islet cells in vivo is >10-fold lower than what is detected in in vitro cultured islets (compare with Fig. 4). * indicates a statistically significant difference as described in the research design and methods section. (A high-quality color digital representation of this figure is available in the online issue.)