Figure 3.

Photoinhibition of VMN^NOS1 neurons selectively impairs glucagon responses during insulin-induced hypoglycemia. A: Schematic demonstrating bilateral microinjection of the Cre-dependent inhibitory SwiChR-YFP virus, and fiberoptic placement dorsal to the injection site, targeting the VMN of Nos1-Cre⁺ mice. B: Representative image of EYFP fluorescence showing bilateral infection and expression within the VMN of Nos1-Cre⁺ mice. C: Blood glucose levels in Nos1-Cre⁺ mice during bilateral laser off (Mock) or laser-induced inhibition (Inhib) of VMN^NOS1 neurons. Blue shading represents duration of laser-induced inhibition. D: Changes in glucagon levels during insulin-induced hypoglycemia during mock and photoinhibition of VMN^NOS1 neurons (n = 12 for all). Values are mean ± SEM. P values by two-way ANOVA. *P < 0.05. 3V, third ventricle; ARC, arcuate nucleus.