Problem To determine if epidermal cell proliferation in colony-raised Fischer 344 rats changes with age and diet. Methods Fischer 344 rats fed ad libitum and calorie-restricted (CR) diets were obtained from the NIA colonies, and young, young adult, and old animals from both groups were used for this study (six in each group). Tissue sections from the dorsal skin (DS) and foot plate (FP) were used for immunohistochemical staining of proliferating cell nuclear antigen (PCNA). The proliferation index (PCNA-I) was computed from counts of stained and total number of keratinocytes. Simultaneous measurements of epidermal thickness were obtained from same sections. Data were analyzed with Excel and SPSS 14.0 software for statistics. Results Two-way analysis of variance (ANOVA) was applied to the data to probe the effect of age, diet, and age-diet interaction. A significant effect of age was noticed in the two parameters i.e., DS PCNA (F 3.96, P .011), FP epidermal width (F 3.37, P .021) and FP PCNA-I (F 9.0, P .000). A significant correlation between DS width and PCNA values was also noted (r 0.5, P .01). Conclusion There is a trend of reduction of PCNA positive cells with increasing age irrespective of thickness of epidermis, and this trend is more apparent in CR rats. Significance This cell proliferation study has implications in relation to CR effect on age-related disease conditions, and biogerontology. Support The study was partially funded by the 2007 Leslie Bernstein grant from AAFPRS foundation.
Identification of differentially expressed genes in aflatoxin B1- treated cultured primary rat hepatocytes and Fischer 344 rats
