Age-dependent changes of the perineuronal net in the mouse basal ganglia nuclei.

Aging promotes mild but progressive decline of motor behaviors and cognitive functions, related to loss of plasticity. Recovery of neural plasticity may become a possible clinical treatment against aging. Perineuronal net (PNN) is the extracellular matrix surrounding cell bodies of neurons, and is known to affect plasticity and survival of neurons. The basal ganglia are motor-related regions of the brain, and earlier reports revealed that neurons in the output nuclei of the basal ganglia form PNN. However, the detailed characteristics are not fully clarified yet. We found intensive PNN expression in the entopeduncular nucleus (EP) and substantia nigra pars reticulata (SNr). PNN surrounded parvalbumin-expressing large axon terminals in the EP and SNr. The proportion of PNN-forming neurons was lower in young mice, and gradually increased with age. The fluorescent intensity of PNN showed similar changes in the EP and SNr. We also showed that the motor ability examined by the rotarod test correlated with PNN expression in the SNr. It may provide the possibility of PNN modulation to improve plasticity and quality of behaviors in aged animals.