Harik S I, Sylvia A L
Gerontology. 1985;31(5):285-92. doi: 10.1159/000212711.
Cyclic AMP generation was measured in isolated minces of the ipsilateral and contralateral cortex of young (3-4 months) and aged (28-29 months) Fischer-344 rats, 2 weeks after unilateral lesion of the nucleus locus ceruleus (LC). Measurements were conducted under basal conditions and in the presence of 0.1 mM isoproterenol. Despite marked norepinephrine (NE) depletion of about 90% in the ipsilateral cerebral cortex in both age-groups, cyclic AMP generation under basal conditions was unaffected. However, whereas isoproterenol-stimulated cyclic AMP generation was significantly higher in the NE-depleted ipsilateral cerebral cortex of young rats, such 'denervation supersensitivity' was not apparent in aged rats. Also, endogenous levels of NE were 31% higher, and isoproterenol-stimulated cyclic AMP generation was 33% lower in the contralateral 'control' cortex of aged rats than in young rats. These results suggest an age-related defect in the postsynaptic expression of noradrenergic mechanisms in the rat cerebral cortex. Further research using intermediate ages is needed to establish whether these age-related findings are caused by 'senescence' or are 'developmental' phenomena.
在对年轻（3 - 4个月）和老年（28 - 29个月）的Fischer - 344大鼠进行单侧蓝斑核（LC）损伤2周后，测量其同侧和对侧皮质分离组织中的环磷酸腺苷（cAMP）生成。测量在基础条件下以及存在0.1 mM异丙肾上腺素的情况下进行。尽管两个年龄组的同侧大脑皮质中去甲肾上腺素（NE）均显著耗竭约90%，但基础条件下的cAMP生成未受影响。然而，虽然在年轻大鼠去甲肾上腺素耗竭的同侧大脑皮质中，异丙肾上腺素刺激的cAMP生成显著更高，但这种“去神经超敏反应”在老年大鼠中并不明显。此外，老年大鼠对侧“对照”皮质中的内源性NE水平高出31%，而异丙肾上腺素刺激的cAMP生成则比年轻大鼠低33%。这些结果表明大鼠大脑皮质中去甲肾上腺素能机制的突触后表达存在与年龄相关的缺陷。需要使用中间年龄段进行进一步研究，以确定这些与年龄相关的发现是由“衰老”引起还是“发育”现象。
