Functions of glial cells in the retina of the honeybee drone.

In the retina of the honey bee drone, Apis mellifera male, physiological interactions between glial cells and neurons (the photoreceptors) are exceptionally clear-cut and amenable to investigation. The principal glia (outer pigment cells) contribute to the homeostasis of extracellular [K+] and [Na+] by 1) spatial buffering of K+ and 2) net uptake of K+ and Cl-. The glia supply carbohydrate metabolic substrate to the neurons; only the glia take up and phosphorylate glucose. Neuronal activity 1) modifies glycogen metabolism in the glia, and 2) can be signalled to the glia in the absence of elevated extracellular [K+].