Aging-associated inflammatory and oxidative changes in the rat urinary bladder and dorsal root ganglia - preventive effect of caloric restriction [bladder]. Rattus norvegicus

Purpose: To disclose the molecular mechanisms of aging-related functional impairments of the rat bladder, and to determine whether long-term caloric restriction (CR) may have preventive effects on these mechanisms. Materials and Methods: Male Fischer 344 rats were divided into three groups: young (6 months-old) fed ad libitum (Y, N = 16), old (25-28 months-old) fed ad libitum (O+AL, N = 15), and old (25-28 months-old) fed restrictedly three days a week since 6 weeks-old (O+CR, N = 16). cDNA microarray analysis and real-time polymerase chain reaction (RT-PCR) of the bladder and L6 dorsal root ganglia (L6DRG) were performed. The bladder was subjected to oxidative stress measurement and immunohistochemistry. Results: In the O+AL group, 83 genes in the bladder and 48 genes in the L6DRG were up-regulated than compared with those of the Y and O+CR groups (fold change > 2). These genes were mostly related to immune- and inflammatory-responses. Immunohistochemistry showed that Granzyme B, a cytotoxic T-lymphocyte-associated serine protease, and matrix metalloproteinase 13 (Mmp13), an interstitial collagenase, were more strongly expressed in the bladder of the O+AL than the Y and O+CR groups. The level of Malondialdehyde (MDA), an oxidative stress marker, was higher in the O+AL than the Y group, whereas there were no significant differences between the O+CR and Y groups. Conclusions: In the rat, aging is associated with up-regulation of immune and inflammatory genes in the bladder and DRG as well as with oxidative and fibrotic changes of the bladder. Long-time CR reduced these aging-related changes. Overall design: Male Fischer 344 rats (Charles River Laboratories International, Inc. Yokohama, Japan) were divided into three groups: young (6 months-old) ad libitum fed with normal food (Y, N = 4), old (25-28 months-old) ad libitum fed with normal food (O+AL, N = 4) and old (25-28 months-old) that had been fed three days (on Monday, Wednesday, and Friday) a week since 6 weeks-old (O+CR, N = 4). The O+CR groups showed approximately 40% caloric restriction compared with the O+AL groups. Rats were maintained under standard laboratory conditions with a 12:12 h light: dark cycle, and free access to food pellets and tap water. The protocol was approved by the Institutional Animal Care and Use Committee of the University of Tokyo and Tokyo Metropolitan Hospital and Institute of Gerontology, and conformed to NIH guidelines for the care and use of experimental animals.