Abstract

Termination of antidepressant therapy often has negative consequences. While symptoms of antidepressant withdrawal are widely recognized, the molecular processes that underlie them are not well characterized. We show that certain aspects of Gα_s signaling remain suppressed following antidepressant withdrawal, even after others have reverted to baseline. Antidepressant treatment causes translocation of Gα_s protein from lipid rafts, to non-raft membrane regions. This results in augmented Gα_s signaling, including facilitated activation of adenylyl cyclase (AC) and increased cAMP accumulation. Using c6 or SK-N-SH cells and a lipid raft localized cAMP sensor, we show that Gα_s signaling is reduced in lipid rafts, even while signaling is enhanced elsewhere in the cell. These signaling changes mirror the changes in Gα_s localization observed following antidepressant treatment. Furthermore, we show that suppression of Gα_s signaling in lipid rafts persists at least 24 hr after cessation of antidepressant treatment. Gα_s localization was quantified following membrane isolation and sequential detergent extraction. We show that suppression of lipid raft Gα_s signaling persists for an extended time period after antidepressant withdrawal, while increased non-raft membrane Gα_s signaling reverts partially or fully upon cessation of antidepressant treatment. Translocation of Gα_s out of lipid rafts is also persistent. These events may reflect cellular adaptations to antidepressant treatment which contribute to antidepressant withdrawal syndromes, and may aid in the discovery of new treatments and strategies to mitigate these side effects.

Significance Statement This work explores, for the first time, the effects of antidepressants on Gα_s signaling following drug withdrawal. This provides novel insight into the cellular and molecular processes affected by antidepressant drugs, and their persistence after discontinuation of treatment.