Roozendaal B, van Gool W A, Swaab D F, Hoogendijk J E, Mirmiran M
Brain Res. 1987 Apr 21;409(2):259-64. doi: 10.1016/0006-8993(87)90710-4.
The suprachiasmatic nucleus (SCN) of the hypothalamus is considered to be the endogenous clock of the mammalian brain, regulating circadian rhythmicity of a great number of physiological and behavioural parameters. Numerous studies have shown that the circadian organization in the rat is progressively disturbed in senescence. However, a recent study by Peng et al.17 using conventionally stained material, revealed no decrease in overall SCN cell number of senescent rats. Their results have now been confirmed in this study. In addition, an increase in SCN volume (P = 0.02) and nucleus diameter (P = 0.001) and an overall decrease in cell density (P = 0.006) was observed. All these parameters seem to confirm the absence of a general degeneration in the senescent SCN. However, the major aim of the present study was to determine whether a well-defined population of neurons, i.e. the vasopressinergic (AVP) cells of the SCN, shows changes with aging. Immunocytochemical staining with antivasopressin and morphometry revealed a decrease of 31% (P = 0.007) in the number of these SCN neurons, whereas the remaining vasopressin cells became larger (P = 0.001). There were no statistical significant differences between rats housed in standard cages and those housed in an enriched environment in either age group, but the groups were relative small. Changes in either the number or stainability of SCN vasopressin neurons may be a morphological correlate of changed circadian rhythms in senescence.
下丘脑的视交叉上核（SCN）被认为是哺乳动物大脑的内源性时钟，调节着大量生理和行为参数的昼夜节律。大量研究表明，大鼠的昼夜节律组织在衰老过程中会逐渐受到干扰。然而，Peng等人最近使用常规染色材料进行的一项研究显示，衰老大鼠的SCN细胞总数并未减少。他们的结果在本研究中得到了证实。此外，还观察到SCN体积增加（P = 0.02）、细胞核直径增加（P = 0.001）以及细胞密度总体下降（P = 0.006）。所有这些参数似乎都证实了衰老的SCN不存在普遍的退化。然而，本研究的主要目的是确定一群明确的神经元，即SCN的加压素能（AVP）细胞，是否会随着衰老而发生变化。用抗加压素进行免疫细胞化学染色和形态测量显示，这些SCN神经元的数量减少了31%（P = 0.007），而其余的加压素细胞则变大了（P = 0.001）。在两个年龄组中，饲养在标准笼子里的大鼠和饲养在丰富环境中的大鼠之间在这方面没有统计学上的显著差异，但样本量相对较小。SCN加压素神经元数量或可染性的变化可能是衰老过程中昼夜节律变化的形态学相关因素。
