Decline in motor functions in aging is related to the loss of NMDA receptors

The aim of the study was to assess the contribution of central dopaminergic and glutamatergic systems to the age-dependent loss of motor functions in rats. Rats of three age groups were compared: young (3-5-month-old), middle -aged (20-21-month-old) and old (29-31-month-old). The obtained results sho wed an age-dependent decline in the electromyographic (EMG) resting and ref lex activities in the gastrocnemius and tibialis anterior muscles, as well as in the T-maze performance. Although these disturbances were accompanied with significant age-dependent decreases in the binding to NMDA, AMPA and d opamine D2 receptors, and a decline in the number of nigral dopamine neuron s, they were significantly correlated with the loss of the binding to NMDA receptors only. The reduction in T-maze performance with aging was addition ally correlated with a decrease in motor functions (EMG activity). The stud y suggests a crucial role of the loss of NMDA receptors in age-dependent mo tor disabilities, as well as in disturbances measured in the T-maze. (C) 20 01 Published by Elsevier Science B.V.