Adenosine A1 receptors modulate the Na+-Hypertonicity induced glutamate release in hypothalamic glial cells.

Glutamate release in response to a hypertonic stimulus is a well described phenomenon in the hypothalamus. Evidence suggests that hypothalamic glial cells release glutamate into the extracellular environment in hypertonic conditions. In the current study, we described autocrine regulation of adenosine on glutamate release induced by Na+hypertonicity in hypothalamic glial cell cultures. We showed that glial cells cultured from the cerebral cortex did not release glutamate or adenosine under hypertonic conditions. The findings suggest that the hypothalamus has specialized glial cells, which are responsive to osmotic variations. Stimulation or inhibition of adenosine A1 receptors modulates extracellular glutamate levels in hypothalamic glial cell cultures under hypertonic stimulation. Our results extend previous observations regarding the role of glial cells in the control of hypothalamic physiology. They further demonstrate for the first time that hypothalamic glial cells regulate Na+-hypertonicity-induced glutamate release by activation of adenosine A1 receptors via adenosine release.