FIG. 8.

The RIP-N transgene does not affect glucose homeostasis in old mice. In the experiments presented in this figure, a cohort of 8 and 12 wild-type (+/+) and transgenic (+/RIP-N) female mice, respectively, and 11 and 10 wild-type and transgenic male mice, respectively, was used. A: Nonfasting glycemia was measured at the indicated times. The average values for the indicated groups are shown. Males had significantly higher glycemia values than females (P < 0.0001). There was also a significant decrease in glycemia as the mice aged (P < 0.0001). However, the glycemia between wild-type and RIP-N mice for a given sex was not statistically different (the P values are indicated on the figure). The statistical test used was ANOVA (repeated measures with a first-order autoregressive covariance structure). B: Four and three 106- to 109-week-old female wild-type and transgenic mice, respectively, were subjected to an IPGTT. Statistic analysis (t tests) was performed for each time point between wild-type and RIP-N mice (eight comparisons). No significant differences were recorded. This experiment was repeated once on 111- to 114-week-old females with similar results. C: The survival rate of the mice is presented. The statistical test used was a test of equality over strata (life-test procedure of the SAS/STAT software, including a log-rank test and a Wilcoxon test). Males survived significantly less than females (P = 0.0007 for the log-rank test and P = 0.0013 for the Wilcoxon test). However, the transgene did not affect survival within a given sex (P = 0.21 and 0.24 for the log-rank test and P = 0.20 and 0.33 for the Wilcoxon test, for females and males, respectively). D: Hematoxylin-eosin–stained paraffin-embedded pancreas sections from 130-week-old female control and RIP-N mice were produced. Representative images are shown. No histological differences were detected between wild-type and RIP-N islets. (A high-quality color digital representation of this figure is available in the online issue.)