Desipramine modulation of α-, γ-synuclein, and the norepinephrine transporter in an animal model of depression

The mechanisms underlying depression remain elusive. We previously determined that α-synuclein (α-Syn) modulates the activity and trafficking of the norepinephrine transporter (NET) in a manner that is dependent on its interactions with microtubules (MTs). Here we sought to determine if α-Syn, or the other synuclein family members, β-synuclein (β-Syn) and γ-synuclein (γ-Syn), modulate NET activity in an animal model of depression, the Wistar-Kyoto (WKY) rat. The NET-selective antidepressant desipramine (DMI) was chronically administered for 14 days to WKY rats and the strain from which it was outbred that does not show depressive-like behavior, the Wistar rat. This drug regimen induced significant behavioral improvements in the WKY, but not the Wistar rat, in the forced swim test. In WKY rats there was an overexpression of γ-Syn which was reduced following DMI treatment. In parallel, DMI caused an increase in both α-Syn and NET in the frontal cortex. Frontal cortex synaptosomes from WKY rats were not sensitive to nocodazole, a compound that promotes MT destabilization. However, in WKYs treated with DMI, nocodazole induced an increase in [ ³H]-NE uptake. This trend was reversed in Wistars. Underlying these DMI-induced changes were alterations in the protein interactions between the synucleins and NET with the tubulins. These results are the first to implicate α-Syn or γ-Syn in the pathophysiology of depression and suggest that targeting synucleins may provide a new therapeutic option for depression.