Senescence related changes in brain diazepam binding and motor performance.

Senescent mice showed attenuation of habituation in locomotor activity and marked deficit in the motor performance requiring limb coordination. Also, the binding of 3H-diazepam to the crude synaptosomal fraction prepared from cerebral cortex of the senescent mice was significantly altered. The binding maximum (Bmax) was significantly greater in the aged (23-26 months) mice, but no change was found in the apparent dissociation constant (Kd). Senescent related changes appear to include neurochemical alteration of the endogenous benzodiazepine system (increased receptor sites without any change in receptor affinity) and, perhaps, related physiological deficits in the limb coordination and/or strength.