The prevalence of depression in diabetes mellitus (DM) patients is very high, and it severely impacts the prognosis and quality of life of these patients. Sodium-glucose co-transporter 2 (SGLT2) inhibitors, a new type of oral hypoglycemic drugs, have been shown to alleviate depressive symptoms in DM patients; however, the mechanism underlying this effect is not well understood. The lateral habenula (LHb) plays an important role in the pathogenesis of depression expresses SGLT2, suggesting that the LHb may mediate antidepressant effects of SGLT2 inhibitors. The current study aimed to investigate the involvement of the LHb in the antidepressant effects of the SGLT2 inhibitor dapagliflozin. Chemogenetic methods were used to manipulate the activity of LHb neurons. Behavioral tests, Western blotting, immunohistochemistry, and neurotransmitter assays were used to determine the effects of dapagliflozin on the behavior of DM rats, AMP-activated protein kinase (AMPK) pathway and c-Fos expression in the LHb and 5-hydroxyindoleacetic acid (5-HIAA)/5-hydroxytryptamine (5-HT) ratio in the dorsal raphe nucleus (DRN). We found that DM rats demonstrated depressive-like behavior, increased c-Fos expression, and decreased AMPK pathway activity in the LHb. Inhibition of LHb neurons alleviated the depressive-like behavior of DM rats. Both systemic and local LHb administration of dapagliflozin alleviated the depressive-like behavior and reversed the changes of the AMPK pathway and c-Fos expression in the LHb of DM rats. Dapagliflozin, when microinjected into the LHb, also increased 5-HIAA /5-HT in the DRN. These results suggest that dapagliflozin directly acts on the LHb to alleviate DM-induced depressive-like behavior and that the underlying mechanism involves activating the AMPK signaling pathway, leading to the inhibition of LHb neuronal activity, which in turn increases serotonergic activity in the DRN. These results will help develop new strategies for the treatment of DM-induced depression.
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