Smaller local brain volumes and cerebral atrophy in spontaneously hypertensive rats.

Abstract

Spontaneously hypertensive rats (SHR) have enlarged cerebral ventricles from 8 weeks of age onward and smaller brains than age-matched, normotensive Wistar-Kyoto (WKY) rats (controls). At 6-7 months of age local cerebral glucose utilization is apparently lower in many brain areas of SHR relative to WKY rats. These observations led to the hypothesis that there are morphological differences between these two strains of rats in many, if not all, brain areas. This hypothesis was tested in 6-7-month-old SHR and WKY rats by quantitating 1) the volumes of the ventricular system, whole brain, six gray matter structures, and two white matter areas; 2) the thickness of two regions of the cerebral cortex; and 3) the frequency of neuronal nuclei (neuronal frequency) in nine brain areas. Ventricular volume was twofold greater in SHR than in control rats. The volumes of the entire brain and all six gray matter structures plus the thickness of the two cortical regions were 11-25% less in SHR. Neuronal frequency was, however, similar in the two rat strains. The latter finding coupled with the smaller regional tissue volumes indicates appreciably fewer neurons per brain structure in young adult SHR than in controls. These results indicate significant cerebral structural differences between young adult SHR and WKY rats and suggest that structure as well as metabolism are abnormal in the SHR brain. is not only hypertensive but also hyperactive 2 " 4 and hydrocephalic. 5 -7 Relative to age-and sex-matched Wistar-Kyoto (WKY) rats, the normotensive control strain for SHR, total brain weight and volume are about 11% less in 12-week-old male SHR.8 For 8-month-old animals, Lehr et al 9 have reported that the midbrain and diencephalon are smaller and the pons is larger in SHR than WKY rats. Of relevance to these observations, magnetic resonance imaging has indicated that brain volume is reduced and ventricular volume is greater in humans with essential hypertension than in agematched control subjects. 10Local cerebral glucose utilization (LCGU) is highly dependent on local neural activity, is commonly used as an indicator of the functional state of cerebral tissue, and varies appreciably among brain areas and conditions.11 -13 For most brain structures, LCGU is virtually the same in 11-12-week-old SHR and WKY rats, but for the superior cervical, cardiac, and coeliac sympathetic ganglia, LCGU is significantly less in SHR than in WKY rats.13 At 6-7 months of age, however, LCGU

Regional Cerebral Blood Flow and Arterial Blood Volume and Their Reactivity to Hypercapnia in Hypertensive and Normotensive Rats

“…In T 2 -weighted images, ventricle areas indicating hyperintensity were enlarged in SHR, which is consistent with previous findings. [25][26][27] Interestingly, CBF maps were similar for both groups, but SHR had much smaller CBV a values as compared with WKY. To determine similarities and differences between WKY and SHR, we conservatively chose five ROIs (see Figure 1A), and calculated their CBF and CBV a values ( Figure 2).…”

Scaling of cerebral blood perfusion in primates and marsupials

“…Whether primates differ from mammals in general is not known, because we Values are obtained from the literature (L) and the present study (P). Mean of four studies (Bailey et al, 2004;Hasegawa et al, 2010;Karbowski, 2007;Tajima et al, 1993); 11 Mean of four studies (Nakao et al, 2001;Ohno et al, 1979;Sakurada et al, 1978;Takagi et al, 1987); 12 Sato et al, 1999; 13 Macgowan et al, 2015;14 Christopher Macgowan (personal communication); ICA lumen radius from three mice; Foramen radius calculated from ICA lumen radius×1.4 (see note 6). are unable to gauge brain perfusion in other groups with the technique of this study.…”

Quantitation and localization of blood‐to‐brain influx by magnetic resonance imaging and quantitative autoradiography in a model of transient focal ischemia

“…Of the various reasons for this selection, three are offered here. First, QAR is able to detect significant differences in radioactivity when they are separated by 200 m or more in the x-y plane of the tissue section (21,22) and within individual microvessels of diameters Ͼ 50 m (23). The tissue sections were 20 m thick, and a set of sections for QAR was obtained at 400-m intervals.…”