P2‐355: Folate deficiency impairs brain oxygen delivery in rat: Detection by non‐invasive near infrared spectroscopy
Year: 2010
Type: article
Abstract: Dietary vascular risk factors, including poor folate status are powerful and potentially modifiable predictors of cognitive impairment among older adults. The prevalence of folate deficiency has been estimated at 5-10% of middle aged and elderly adults exposed to food folate fortification, and as much as 30% in unfortified populations. In mouse, we have shown consuming a diet deficient in vitamins folate, B12 and B6 to cause a 30% decrease in brain capillary density in association with significantly impaired performance on the Morris water maze. Similarly, folate deficiency in rat impairs cognition and causes cerebral microvascular damage, without concomitant neurodegeneration. Based on these observations we hypothesized that folate deficiency should result in functional decrements in cerebral blood volume, oxygen delivery and vascular reactivity, all of which should be detectable non-invasively by near-infrared spectroscopy (NIRS). We developed a NIRS device for non-invasive evaluation of these parameters in rat. We used this device to measure absolute tissue concentrations of oxygen free and bound hemoglobin, and tissue oxygen saturation, and related hemodynamic parameters at rest and during transient mild hypoxia and hypercapnia, in Sprague Dawley rats folate deficient diets for up to 20 weeks. Total hemoglobin concentration [tHb] was 23% lower in folate deficient than in control rats at baseline, hypoxia and recovery (73 ± 10 vs. 95 ± 14 μM tHb (Mean ± SD); p < 0.02). Brain tissue oxygen saturation (StO2%) was significantly lower in folate deficient than in control rats with baseline and recovery values of 55% ± 7% vs. 66% ± 4% (p < 0.03), and 43% ± 8% vs. 55% ± 6% (p < 0.01) during hypoxia for folate deficient vs. control rats respectively. However the change in brain StO2 during hypoxia was similar in both groups with a -13% ± 2% for control rats and -12% ± 4% for folate deficient rats. In contrast, arterial oxygen saturation did not differ by diet with baseline values of 96% ± 2% for both groups, indicating that the decrements detected by NIRS in brain were independent of blood oxygen carrying capacity. Our results point to microvascular rarefaction and diminished oxygen delivery as a basis of folate-deficiency associated cognitive impairment.
Source: Alzheimer s & Dementia
Institution: Tufts University
Language: English
Subfield: Rheumatology
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2084476822