Aging-associated inflammatory and oxidative changes in the rat urinary bladder and dorsal root ganglia - preventive effect of caloric restriction [L6 dorsal root ganglia]

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.研究目的：阐明大鼠膀胱衰老相关功能损伤的分子机制，并探讨长期热量限制（caloric restriction, CR）对该类机制是否具有预防作用。 材料与方法：将雄性Fischer 344大鼠分为三组：自由摄食的年轻组（6月龄，Y组，n=16）、自由摄食的老年组（25~28月龄，O+AL组，n=15），以及自6周龄起每周限制摄食3天的老年组（25~28月龄，O+CR组，n=16）。对大鼠膀胱及L6背根神经节（L6 dorsal root ganglia, L6DRG）开展cDNA微阵列分析与实时聚合酶链式反应（real-time polymerase chain reaction, RT-PCR）检测，并对膀胱组织进行氧化应激检测与免疫组织化学分析。 结果：相较于Y组与O+CR组，O+AL组大鼠膀胱内83个基因、L6DRG内48个基因出现上调（变化倍数>2）。上述基因主要与免疫应答及炎症反应相关。免疫组织化学结果显示，细胞毒性T淋巴细胞相关丝氨酸蛋白酶颗粒酶B（Granzyme B）以及间质胶原酶基质金属蛋白酶13（matrix metalloproteinase 13, Mmp13）在O+AL组大鼠膀胱中的表达强度显著高于Y组与O+CR组。氧化应激标志物丙二醛（Malondialdehyde, MDA）水平在O+AL组中高于Y组，而O+CR组与Y组之间无显著差异。 结论：在大鼠模型中，衰老可导致膀胱及背根神经节内免疫与炎症相关基因上调，同时伴随膀胱组织氧化应激与纤维化改变；长期热量限制可缓解上述衰老相关的病理变化。