1. Maintenance of inhibitory interneurons and boutons in sensorimotor cortex between middle and old age in Fischer 344 X Brown Norway rats
- Author
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Lei Shi, Judy K. Brunso-Bechtold, Martha Constance Linville, Hui Pang, Anne Argenta, and Angela Nicole Bartley
- Subjects
Male ,Aging ,medicine.medical_specialty ,Glutamate decarboxylase ,Presynaptic Terminals ,Nerve Tissue Proteins ,Biology ,Inhibitory postsynaptic potential ,Cellular and Molecular Neuroscience ,Interneurons ,Rats, Inbred BN ,Internal medicine ,Male rats ,Image Processing, Computer-Assisted ,medicine ,Animals ,Sensorimotor cortex ,gamma-Aminobutyric Acid ,Cerebral Cortex ,Glutamate Decarboxylase ,BROWN NORWAY ,Nuclear Proteins ,Immunohistochemistry ,Rats, Inbred F344 ,Rats ,Parvalbumins ,Endocrinology ,nervous system ,biology.protein ,GABAergic ,NeuN ,Neuroscience ,Parvalbumin - Abstract
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.
- Published
- 2006
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