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Microglia-neuron contacts have been shown to regulate neural network activity through the formation and elimination of synapses. The pathogenesis of major depressive disorder is accompanied by a decline in brain-derived neurotrophic factor (BDNF) signaling, associated with increased microglia activity that disrupts cognitive function. The actions of both typical and rapid-acting antidepressant drugs, which have been shown to increase BDNF signaling through the tropomyosin receptor kinase B (TrkB) receptor, decrease microglia activation and the levels of pro-inflammatory cytokines. The mechanisms that govern antidepressant drug action on neuron-microglia synapse interactions during stress exposure are poorly understood. Examining the link between BDNF signaling and the microglial pro-inflammatory response, we demonstrate that TrkB signaling elicits the neuronal secretion of CD22 (Siglec-2), a sialic acid-binding immunoglobulin-type lectin, to inhibit microglial activation and alleviate depression-like symptoms. In a chronic mild stress (CMS) mouse model of depression decreased expression of the postsynaptic scaffolding protein PSD-95 and Gαi1/3 were found to compromise TrkB signaling leading to reduced CD22 levels in hippocampal tissue. Restoration of TrkB-Gαi1/3-Akt signaling with dSyn3, a peptidomimetic compound targeting the PDZ3 domain of PSD-95, enhanced CD22 expression to inhibit microglial activation, promote dendritic spine formation and rapidly mitigate depression-like symptoms. Furthermore, hippocampal overexpression of CD22 in neurons was sufficient to reduce microglial activation and depressive-like behaviors in CMS mice. Ketamine, a rapid-acting antidepressant, increased CD22 expression to mitigate depression-like symptoms. While neuronal knockdown of CD22 in the hippocampus did not significantly impair the rapid (within 4 hours) antidepressant effects typically observed with S-ketamine administration, strikingly, knockdown of CD22 attenuated the long-acting (within 3 days) antidepressant effects of S-ketamine, as evidenced by sustained immobility in the TST and FST, and a lack of improvement in sucrose preference. In contrast, fluoxetine, a typical SSRI, failed to increase CD22 expression or inhibit microglia activity. These results suggest that rapidly-acting anti-depressant drugs enhance TrkB-induced neuronal expression and secretion of CD22 to promote the homeostatic state of microglia required for antidepressant actions.