HCN1 in the lateral habenula contributes to morphine abstinence-induced anxiety-like behaviors in male mice.

Anxiety disorders, common symptoms during morphine withdrawal, are important negative reinforcement factors leading to relapse. Lateral habenula serves as a negative reinforcement center, however its role in morphine withdrawal-induced anxiety remains uncovered. The hyperpolarization activated cyclic nucleotide-gated (HCN) channels have been reported to be important in emotion processing and addiction, but the role of HCN in anxiety from drug protracted abstinence remains elusive. In this study, by using behavioral test, Western blot, immunofluorescence, electrophysiology and virus-mediated regulation of HCN, we found that: (1) Intra-LHb injection of selective HCN blocker ZD7288 alleviated anxiety-like behaviors in morphine protracted abstinent male mice. (2) The LHb neuronal activity was increased by morphine protracted abstinence. (3) LHb neurons were inhibited by ZD7288 and activated by 8-Br-cAMP respectively, which were enhanced by morphine withdrawal. (4) HCN1 in the LHb was upregulated by morphine withdrawal. (5) Virus-mediated overexpression of HCN1 in the LHb was sufficient to produce anxiety-like behaviors in male mice and virus-mediated knockdown of HCN1 in the LHb prevented the anxiety-like behaviors in male mice. The findings reveal that selective blockade of HCN1 channels in the LHb may represent a therapeutic approach to morphine withdrawal-induced anxiety.