Figure 7. CR promotes beta-cell longevity by slowing-down beta-cell turnover rates.

(A) Study design. After 2 months of age, ¹⁵N-labelled mice were kept on AL, 20% CR or HFD for 12 months. (B) Multi-isotope imaging mass spectroscopy (MIMS) representation technique. (C) MIMS imaging and data quantification of layer 2 cortical neurons from ¹⁵N labelled mouse after chase with ¹⁴N diet. Each dot represents a single neuronal nucleus. (D) MIMS of pancreatic islets from AL, CR or HFD mice. (E) Scatter plot with 15N/14N ratios for beta cells at day 0 (no chase) and after 12 months (mo) on AL, HFD, or CR diet. Each dot represents individual beta cells. The dotted horizontal pink and black lines represent the mean and the lowest ¹⁵N/14N levels found in cortical neurons shown in (C). (F) Estimation of beta cells that are estimated to be LLC or young after 12 months on AL, CR or HFD.