Control of Breathing by "Nerve Glue"

Long regarded as mere structural support for neurons, neuroglial cells are now considered pivotal for brain metabolism, the blood-brain barrier, cerebral hemodynamics, and neuronal function. Multitasking by glia involves numerous signaling and effector pathways that control various processes, including neurotransmitter uptake and release of gliotransmitters, such as glutamate or adenosine 5'-triphosphate (ATP). Acidosis of cerebrospinal fluid causes ATP release from astrocytic glia at the ventral brainstem surface, which excites neighboring brainstem neurons that stimulate neurons in the pre-Botzinger complex (pre-BotC), which controls inspiratory breathing movements. New insights into glial regulation of complex behavior, and particularly into respiratory circuit function, are evolving from application of genetically engineered optical stimulation and Ca2+ imaging tools, combined with other molecular and electrophysiological approaches. These advances in technology will enable direct analyses of respiratory-related neuron-glia interactions not only at the ventral brainstem surface but also within the preBotC, which generates a vital brain rhythm.