Age-Related Changes in the Indices of Cerebral Blood Flow Velocity in Rats

Aging is accompanied by changes in the structure and functional activity of cerebral vessels, which may lead to cerebral blood flow impairments. Here, age-related changes in the indices of cerebral blood flow velocity (BFV) were studied using Doppler ultrasonography. The state of blood flow in the cortex and subcortical structures of the cerebral hemispheres was comparatively analyzed by the value of linear velocities and blood flow indices in Sprague–Dawley rats aged 4 vs. 18 months. It was found that by the age of 18 months, the level of cerebrovascular resistance decreased, as indicated by an increase in end-diastolic BFV and a decrease in the Gosling pulsatility index. At the same time, the perfusion of the frontal and parietal lobes of the cerebral hemispheres increased due to an increase in the peak systolic, end-diastolic, and mean velocities per cardiac cycle; collateral blood supply to the brain was activated, as evidenced by a decrease in the mean systolic BFV in the frontal lobe. All these changes may represent primary adaptive manifestations of the impaired cerebral hemodynamics aimed at maintaining adequate perfusion of the aging brain.