Cerebrovascular hemodynamic correlates of aging in the Lou/c rat: A model of healthy aging

The LOU/c rat is an inbred strain considered a model of healthy aging. It exhibits a longer free disease lifespan and a low adiposity throughout life. While this animal model has been shown to maintain eating behavior and neuroendocrine, metabolic and cognitive functions with age, no study has yet investigated vascular correlates in this model of healthy aging. In the present work, multispectral optical imaging was used to investigate the hemodynamic response in the somatosensory cortex of LOU/c rats following forepaw stimulation in three age groups, 4, 24 and 40 months. Results indicate reduced hemodynamic responses in the contralateral somatosensory cortex between young (4 months) and older groups following stimulation. This decrease was associated with an increase in the spatial extent of activation. The ipsilateral response did not change with aging leading to decreased laterality. Estimations of the relative change in the local cerebral metabolic rate of oxygen during stimulation based on multimodal data showed no significant change with age. The exponent describing the relation between blood volume and blood flow changes, Grubb's parameter, did display a significant change with age which may suggest vessel compliance modifications. This work finds its relevance in recent findings underlying the importance of vascular changes with aging and its impact on neurodegenerative disease.

Research highlights►The LOU/c rat was studied with optical imaging as a function of age. ►Evoked responses diminish with age in the contra but not the ipsilateral cortex. ►The spatial extent of activation increases with age. ►Grubb's parameter changes with age suggesting vessel compliance modifications.