Inhibition of autophagy in the amygdala ameliorates anxiety-like behaviors induced by morphine-protracted withdrawal in male mice.

OBJECTIVE: Morphine withdrawal triggers a range of negative affective states, wherein anxiety is typically common, significantly contributing to the morphine relapse. To date, the exact mechanism underlying morphine withdrawal-induced anxiety has remained unclear. Previous studies have proposed that autophagy is involved in the pathogenesis of morphine addiction and anxiety; however, the possible relationship between autophagy and morphine withdrawal-induced anxiety has not been explored before. In this study, we aimed to reveal the potential role of autophagy in anxiety-like behaviors elicited by protracted morphine withdrawal, and which brain region is involved. METHODS: We established the model mice of anxiety by chronic intermittent escalating-dose morphine administration for 7 days and then withdrawing for 4 days. Anxious behaviors were detected using the Open field test and the Elevated plus maze test. Western blot was performed to measure the change of autophagy-associated proteins (ATG5, Beclin-1, LC3) in different brain regions. RESULTS: Our results showed that intraperitoneal injection of an autophagy inhibitor 3-Methyladenine attenuated protracted morphine withdrawal-induced anxiety-like behaviors in male mice. Moreover, protracted morphine withdrawal predominantly promoted autophagy in the amygdala, rather than other related brain regions, suggesting the crucial involvement of amygdala in autophagy-mediated anxiety after morphine withdrawal. We further validated that 3-Methyladenine can effectively reduce autophagy-associated protein levels in the relevant brain region. CONCLUSION: These findings indicated that protracted morphine withdrawal-elicited autophagy in the amygdala contributes to the anxiety-like behaviors and may have implications for the future treatment of this disorder.