Antidepressants Produce Persistent G -Associated Signaling Changes in Lipid Rafts after Drug Withdrawal.

Termination of antidepressant therapy often has negative consequences. Although symptoms of antidepressant withdrawal are widely recognized, the molecular processes that underlie them are not well characterized. We show that certain aspects of G signaling remain suppressed after antidepressant withdrawal, even after others have reverted to baseline. Antidepressant treatment causes translocation of G protein from lipid rafts to nonraft membrane regions. This results in augmented G signaling, including facilitated activation of adenylyl cyclase and increased cAMP accumulation. Using CC6 or SK-N-SH cells and a lipid raft-localized cAMP sensor, we show that G signaling is reduced in lipid rafts, even while signaling is enhanced elsewhere in the cell. These signaling changes mirror the changes in G localization observed after antidepressant treatment. Furthermore, we show that suppression of G signaling in lipid rafts persists at least 24 hours after cessation of antidepressant treatment. G localization was quantified after membrane isolation and sequential detergent extraction. We show that suppression of lipid raft G signaling persists for an extended time period after antidepressant withdrawal, whereas increased nonraft membrane G signaling reverts partially or fully upon cessation of antidepressant treatment. Translocation of G out of lipid rafts is also persistent. These events may reflect cellular adaptations to antidepressant treatment that contribute to antidepressant discontinuation syndromes and may aid in the discovery of new treatments and strategies to mitigate the symptoms of depression and antidepressant withdrawal. SIGNIFICANCE STATEMENT: This work explores, for the first time, the effects of antidepressants on G signaling after drug withdrawal. This provides novel insight into the cellular and molecular processes affected by antidepressant drugs and their persistence after discontinuation of treatment.