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NADH augments blood flow in physiologically activated retina and visual cortex
Yasuo Ido1, Katherine Chang, Joseph R Williamson
1Diabetes and Metabolism Unit, Boston Medical Center, EBRC 820, and Department of Medicine, Boston University School of Medicine, 650 Albany Street, Boston, MA 02118, USA.
Summary
Increased cellular energy metabolism, specifically the reduction of NAD+ to NADH, drives blood flow in the brain's visual centers during stimulation. This process involves nitric oxide signaling.
Area of Science:
- Neuroscience
- Physiology
- Biochemistry
Background:
- Mechanisms increasing retinal and visual cortex blood flow during visual stimulation remain unclear.
- Energy metabolism and redox signaling are implicated in regulating cerebral blood flow.
Purpose of the Study:
- To test the hypothesis that increased cytosolic NADH fuels redox signaling pathways augmenting blood flow.
- To elucidate the role of NADH/NAD+ and lactate/pyruvate ratios in visual cortex blood flow regulation.
Main Methods:
- In vivo experiments in rats involving visual stimulation.
- Administration of lactate and pyruvate to modulate NADH/NAD+ ratios.
- Inhibition of nitric oxide synthase to assess its role.
Main Results:
- Injected lactate augmented, while pyruvate attenuated, stimulation-induced blood flow increases.
- Inhibition of nitric oxide synthase prevented the flow augmentation.
- Cytosolic NADH levels correlated with increased blood flow.
Conclusions:
- Cytosolic NADH plays a crucial role in signaling pathways that increase blood flow during visual stimulation.
- Nitric oxide production is a key downstream mediator in this cascade.
- Metabolic redox state directly influences neurovascular coupling in the visual system.