Evolution of Brain Morphology in Spontaneously Hypertensive and Wistar-Kyoto Rats From Early Adulthood to Aging: A Longitudinal Magnetic Resonance Imaging Study

Abstract

The influence of hypertension and aging alone on brain structure has been described extensively. Our understanding of the interaction of hypertension with aging to brain morphology is still limited. We aimed to detect the synergistic effects of hypertension and aging on brain morphology and to describe the evolution patterns of cerebral atrophy from spatial and temporal perspectives. In 8 spontaneously hypertensive rats (SHRs) and 5 Wistar-Kyoto rats, high-resolution magnetic resonance imaging scans were longitudinally acquired at 10, 24, 52, and 80 weeks. We analyzed the tissue volumes of gray matter, white matter, cerebral spinal fluid, and total intracranial volume (TIV), and then evaluated gray matter volume in detail using voxel-based morphometry (VBM) and region of interest-based methods. There were interactive effects on hypertension and aging in tissue volumes of gray matter, white matter, and TIV, of which gray matter atrophy was most pronounced, especially in elderly SHRs. We identified the vulnerable gray matter volume with combined effects of hypertension and aging in the septal region, bilateral caudate putamen, hippocampus, primary somatosensory cortex, cerebellum, periaqueductal gray, right accumbens nucleus, and thalamus. We automatically extracted the septal region, anterior cingulate cortex, primary somatosensory cortex, caudate putamen, hippocampus, and accumbens nucleus and revealed an inverted-U trajectory of volume change in SHRs, with volume increase at the early phase and decline at the late phase. Hypertension interacts with aging to affect brain volume changes such as severe atrophy in elderly SHRs.

Alterations in Human Hippocampus Subregions across the Lifespan: Reflections on White Matter Structure and Functional Connectivity

“…In terms of trajectory, we found that with the increase of age, the change of FA showed an inverted U-shaped trajectory, and the peak occurs around the age of 30. This was consistent with previous studies [ 73 , 74 ], where Coupé et al found that white matter trajectory based on absolute and normalized volumes followed an inverted U-shape with a maturation peak around midlife [ 73 ]. These results indicated that during the early phase of brain development, white matter expansion exceeded general growth, but there was a contraction of hippocampal white matter from maturity to aging, which may contribute to age-related memory decline [ 75 ].…”

Age-Dependent FOSB/ΔFOSB Response to Acute and Chronic Stress in the Extended Amygdala, Hypothalamic Paraventricular, Habenular, Centrally-Projecting Edinger-Westphal, and Dorsal Raphe Nuclei in Male Rats

“…Although in this study we saw some limited decline of the FOSB/ΔFOSB signal’s CVMS response with age, the magnitude of the decline and the high basal expression suggests that the sensory systems were not severely compromised in our rats. The decline might be attributable in part to the aging-related cortical atrophy ( Yang et al, 2021 ) also.…”

Angiotensin II differentially affects hippocampal glial inflammatory markers in young adult male and female mice

“…There is emerging evidence that hypertension is becoming more common in late adolescence and early adulthood (Azegami et al 2021;Hamrahian and Falkner 2022). In addition, there is increasing awareness that the duration of hypertension can impact the onset of neural degeneration (Schaare et al 2019;Yang et al 2021) and cognitive dysfunction (Yaffe et al 2014(Yaffe et al , 2021Mahinrad et al 2020;Zhou et al 2022). Although the age of onset of hypertension may influence the trajectory of degenerative disease in later life, the effect of hypertension on brain health in young adult subjects is relatively underinvestigated.…”