Figure 1. Schematic illustration of the tanycytic lactate shuttle fueling POMC neuronal activity.

Tanycytes lining the 3V wall sense peripheral glucose levels and extend projections to the ARH parenchyma. The study by Lhomme et al. (3) shows that glucose sensing in tanycytes (brown cells) is translated into a lactate signaling pool that travels throughout a tanycytic network via Cx43 gap junctions to magnify metabolic signaling efficiency. Lactate is transmitted via MCTs to POMC neurons, where it is converted to energy (ATP) to induce and sustain POMC neuronal firing. How communication between tanycytes and hypothalamic neurons occurs in the presence of other metabolites (e.g., amino acids and fatty acids) and how the pathway responds under pathophysiological conditions (e.g., obesity and T2D) remain to be elucidated. FFAs, free fatty acids.