Changes in brain glucose retention produced by the stimulation of an insulin-sensitive reflexogenic zone in rats

Although it has been reported that insulin decreases glucose efflux from the brain causing an increase in brain glucose retention, its mechanism of action is still unknown. The present results indicate that peripheral insulin may act through the stimulation of insulin-sensitive receptors localized in the region irrigated by the coeliac trunk and innervated by the vagus nerve. Stimulation of this zone in anaesthetized, artificially ventilated rats with a bolus millidose of insulin (50 mU) caused a significant increase in brain glucose retention as a result of decreased glucose efflux from the brain. The same dose of insulin injected 1-2 cm caudally in the abdominal aorta below the coeliac trunk failed to increase brain glucose retention. The effects of insulin above the coeliac trunk disappear when the vagus nerve is sectioned, suggesting that the vagus participates as the afferent pathway of this reflex.