Shi Lei, Pang Hui, Linville Martha Constance, Bartley Angela Nicole, Argenta Anne Elizabeth, Brunso-Bechtold Judy Karen
Department of Neurobiology & Anatomy, Wake Forest University Health Sciences, Winston-Salem, NC 27157-1010, USA.
J Chem Neuroanat. 2006 Aug;32(1):46-53. doi: 10.1016/j.jchemneu.2006.04.001. Epub 2006 May 23.
Ultrastructurally identified inhibitory synapses in layer II of rat sensorimotor cortex decline between middle and old age [Poe, B.H., Linville, C., Brunso-Bechtold, J., 2001. Age-related decline of presumptive inhibitory synapses in the sensorimotor cortex as revealed by the physical disector. J. Comp. Neurol. 439, 65-72]. The current study investigated whether a loss or shrinkage of gamma-aminobutyric acid (GABA)ergic interneurons contribute to that decline. Coronal sections from middle-aged (15-17 months) and old (25-29 months) Fischer 344 X Brown Norway male rats were immunoreacted with antibodies to the GABA synthesizing enzyme glutamic acid decarboxylase (GAD); the calcium-binding protein parvalbumin (PV), or the neuronal marker NeuN. The number of GAD-immunoreactive (IR), PV-IR, and NeuN-IR cells were determined stereologically using the optical disector technique and the cross-sectional areas of GAD-IR cells were measured in layers II/III, IV, V and VI of sensorimotor cortex. Neither the number of GAD-IR or NeuN-IR cells, nor the size of GAD-IR cells, declined significantly between middle and old age. A modest decline in the PV-IR subset of inhibitory interneurons was observed, predominantly due to changes in layers V and VI. Stereological analysis of layer II/III GAD-IR boutons revealed a stability of immunocytochemically identified inhibitory terminals. Taken together, these results indicate a general maintenance of overall GABAergic neurons in sensorimotor cortex between middle and old age and the loss of ultrastructurally identified inhibitory synapses may be due to the decline of a subset of GABAergic terminals.
超微结构鉴定的大鼠感觉运动皮层II层抑制性突触在中年和老年之间减少[坡，B.H.，林维尔，C.，布伦索 - 贝乔尔德，J.，2001年。通过物理分割器揭示的感觉运动皮层中假定抑制性突触的年龄相关性下降。《比较神经学杂志》439，65 - 72页]。当前研究调查了γ-氨基丁酸（GABA）能中间神经元的丢失或萎缩是否导致了这种下降。对中年（15 - 17个月）和老年（25 - 29个月）的Fischer 344×Brown Norway雄性大鼠的冠状切片用GABA合成酶谷氨酸脱羧酶（GAD）、钙结合蛋白小白蛋白（PV）或神经元标志物NeuN的抗体进行免疫反应。使用光学分割器技术立体测定GAD免疫反应性（IR）、PV - IR和NeuN - IR细胞的数量，并在感觉运动皮层的II/III、IV、V和VI层测量GAD - IR细胞的横截面积。中年和老年之间，GAD - IR或NeuN - IR细胞的数量以及GAD - IR细胞的大小均未显著下降。观察到抑制性中间神经元的PV - IR亚群有适度下降，主要是由于V层和VI层的变化。对II/III层GAD - IR终扣的立体分析显示免疫细胞化学鉴定的抑制性终末具有稳定性。综上所述，这些结果表明感觉运动皮层中总体GABA能神经元在中年和老年之间总体保持稳定，超微结构鉴定的抑制性突触的减少可能是由于GABA能终末的一个亚群的下降。
