Couch, Y. | bioRxiv Science

bioRxiv2022

The effects of fasting on ischemic infarcts in the rat

BackgroundInflammation has been found to be largely detrimental early in the acute phase of stroke but beneficial at more chronic stages. Fasting has been shown to reduce inflammation acutely. We aimed to determine whether post-ischemic fasting improves stroke outcomes through attenuated inflammation. MethodsAfter an endothelin-1 lesion was created in the striatum, animals were subjected to either normal feeding or water-only fasting for 24 hours. ResultsIt was found that at 24 hours, fasting reduced infarct volume and BBB breakdown and lowered both circulating and brain neutrophils. ConclusionsThese findings suggest that fasting is a potentially beneficial non-pharmacological additive therapeutic option for cerebral ischemia, which might act by reducing inflammation in the acute disease stage.

neuroscience↗

bioRxiv2022

Metabolic clearance rate modeling: A translational approach to quantifying cerebral metabolism using hyperpolarized pyruvate.

Hyperpolarized carbon-13 MRI is a promising technique for in vivo metabolic interrogation of alterations between health and disease. This study introduces a model-free formalism for quantifying the metabolic information in hyperpolarized imaging. This study investigated a novel model-free perfusion and metabolic clearance rate (MCR) model in pre-clinical stroke and in the healthy human brain. Simulations showed that the proposed model was robust to perturbations in T1, transmit B1, and kPL. A significant difference in ipsilateral vs contralateral pyruvate derived cerebral blood flow (CBF) was detected in rats (140 {+/-} 2 vs 89 {+/-} 6 mL/100g/min, p < 0.01, respectively) and pigs (139 {+/-} 12 vs 95 {+/-} 5 mL/100g/min, p = 0.04, respectively), along with an increase in fractional metabolism (26 {+/-} 5 vs 4 {+/-} 2 %, p < 0.01, respectively) in the rodent brain. In addition, a significant increase in ipsilateral vs contralateral MCR (0.034 {+/-} 0.007 vs 0.017 {+/-} 0.02 s-1, p = 0.03, respectively) and a decrease in mean transit time (MTT) (31 {+/-} 8 vs 60 {+/-} 2, p = 0.04, respectively) was observed in the porcine brain. In conclusion, MCR mapping is a simple and robust approach to the post-processing of hyperpolarized magnetic resonance imaging.

physiology↗