Dietary restriction as a modulator of age-related changes in rat kidney prostaglandin production.

Prostaglandin (PG) levels in kidney glomeruli isolated from rats under the dietary restriction (DR) regimen were investigated beginning at 6 weeks of age. The modulation of age and DR on PGs, thromboxane (TXA), and their precursor fatty acids were documented for PGE2, PGF2, 6 keto-PGF1, and TXA2 status in aged kidney. The results show that PGE2 and PGF2 production by the glomeruli of DR rats were consistently higher (10-17% and 11-25%, respectively) than in those of AL rats. Although levels of the potent vasodilator, PGI2 (as determined by 6 keto-PGF1,) were shown to decrease after 12 months of age in AL rats, steady levels were shown throughout life in DR rats. In contrast, levels of the typical vasoconstrictor, TXA2, were markedly elevated in AL rats compared to DR rats. As a consequence, PGI2/TXA2 ratios were shown to be decreased in AL rats, while remaining well-maintained in DR rats throughout lifespan. These results indicate that the life-prolonging action of DR attenuates age-related prostaglandin imbalances to preserve and maintain the autoregulation of the glomerular filtration rate (GFR) and other related kidney functions.