Modulating Role of Dietary Fat, Energy Restriction, and the Effect of Age on the Expression of Proliferating Cell Nuclear Antigen and Protein Kinase C Activity in Prostate Glands of Rats

Abstract

The present study investigated the role of dietary fat and energy restriction (ER) on the proliferative status and the protein kinase c (PKC) activity in the prostate glands in young (3-week-old, n = 40) and adult rats (10-week-old, n = 40). F344 male rats, young and adult, were allocated to four dietary groups (n = 10/group): high fat (23% wt/wt) or low fat (5% w/w) ad libitum (HFAL or LFAL) and high- or low-fat energy restriction (HFER or LFER). Energy-restricted rats were fed 80% of the energy intake of the ad libitum fed rats. After 12 weeks of feeding, the proliferating cell nuclear antigen (PCNA) labeling index in prostate glands was higher in young rats than in adult rats. Both the HFAL and LFAL groups had higher PCNA labeling index than both the HFER and LFER groups in each age group. In addition, the HFAL group had higher PCNA labeling index than the LFAL group. Dietary fat and ER markedly affected the PKC activity, which decreased in the order HFAL > HFER = LFAL > LFER for both young and adult animals. The effect of high-fat diet and ER were more evident in the younger animals than in the adult animals. Among the young animals, the absolute total PKC activity was higher (P ≤ 0.05) in the high-fat groups than in the low-fat groups and a higher proportion of the total PKC was associated with the membrane fraction. In both young and adult rats, ER decreased the total PKC activity and the ratio of PKC activity in the cytosol to the membrane fractions compared with the ad lib counterparts. We conclude that age, a high-fat diet, and energy restriction modulate PCNA expression and the PKC activity of prostatic tissue.