Stimulation of glycogenolysis in astrocytes by fluoxetine, an antidepressant acting like 5-HT.

Fluoxetine is a recently introduced, widely used antidepressant. It is known as a specific inhibitor of serotonin uptake into synaptosomes but has not previously been recognized as having any direct effect on brain cell serotonin receptors. The present study describes direct effects of fluoxetine on free cytosolic calcium concentration and on breakdown of glycogen in astrocytes (a glial cell type), which are known to express serotonin receptors. Evidence is presented, suggesting that these effects are evoked by an agonist action on the 5-HT1C receptor.