Acute Hyperglycemia Decreases Neurovascular Coupling Magnitude in Healthy Females and Males

Abstract

Neurovascular coupling (NVC) is the link between neural activity and the corresponding changes to regional cerebral blood flow. Chronic hyperglycemia associated with diabetes has deleterious effects on vascular function. However, the potential effects of acute hyperglycemia on NVC in healthy humans is unknown. We aimed to characterize the effects of acute hyperglycemia on NVC response magnitude in females and males, and hypothesized that acute hyperglycemia would reduce NVC response magnitude. 40 healthy participants (21.6±1.7 yrs; BMI 24.1±4.1 kg/m2; 20 females) were instrumented with electrocardiogram (ECG) to measure heart rate (HR), Finometer to measure mean arterial pressure (MAP), transcranial Doppler ultrasound (TCD) for measurement of posterior cerebral artery velocity (PCAv). Blood glucose was tested using a glucometer and capillary draw via sterile lancet. NVC responses were elicited using  a standardized strobe light visual stimulus (VS; 6Hz, 360rpm; 5x30sec on/60sec off) before (fasted) and 30-min after an acute hyperglycemic load (75g glucose, 300ml; 4.8±0.4 vs. 7.5±1.2 mg/dl; P<0.0001). NVC magnitude was quantified as the difference (delta) and percent (%)-change between the mean baseline (2-min average) and the mean of five responses over the 30- sec VS. Acute hyperglycemia reduced delta NVC responses (4.8±3.9 vs. 3.3±3.4 cm/s; P=0.004) and %-change NVC responses (12.5±9.6 vs. 8.1±7.9%; P=0.002). Neither delta nor %-change NVC responses were different between women and men while fasted (P=0.98; P=0.74), nor when hyperglycemic (P=0.42; P=0.34). Our data suggest that acute hyperglycemia decreases NVC response magnitude in healthy adults equally in females and males. Funding Sources: NSERC Discovery, MRU Faculty of Science and Technology

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