Targeted stabilization of astrocytic Cx43 gap junctions reverses depression-like behaviors via dual restoration of syncytial networks and glutamatergic homeostasis.

Depression, a debilitating global mental disorder affecting millions of people worldwide, is characterized by persistent low mood and anhedonia. Growing evidence identifies astrocyte dysfunction and glutamate metabolism imbalance as core pathological features of this condition. Notably, astrocytic connexin 43 (Cx43) downregulation and subsequent gap junction (GJ) impairment constitute recognized pathological features of depression. However, the development of direct therapeutic strategies targeting Cx43-GJ remains underexplored, representing a significant gap in current antidepressant drug discovery. Here, using integrated in vitro (corticosterone-induced dysfunctional astrocytes) and in vivo (chronic unpredictable stress [CUS]-induced mice) systems, we demonstrate that chronic stress depletes Cx43-GJs, driving astrocyte atrophy, disrupting syncytial network integrity, and dysregulating synaptic glutamate-glutamine cycling. Functional magnetic resonance imaging further revealed widespread impairment of whole-brain functional connectivity in CUS mice, while microRNA sequencing additionally confirmed glutamatergic synaptic dysfunction. Treatment with ZP1609, a selective Cx43-GJ stabilizer that preserves Cx43-GJ functionality without modulating connexin hemichannel activity, ameliorated depressive-like behaviors and specifically restored hippocampus-centered functional connectivity in CUS mice. Mechanistic investigation revealed ZP1609 exerts its effects through dual pathways: (ⅰ) stabilizing Cx43-GJs to maintain intercellular communication and reverse astrocyte structural atrophy, thereby restoring syncytial network integrity; and (ⅱ) normalizing astrocytic glutamate-glutamine cycling to mitigate synaptic excitotoxicity and protect glutamatergic synaptic function. Our findings suggest Cx43-GJ stabilization as a novel therapeutic strategy that simultaneously rectifies astrocyte network failure and glutamatergic synaptic impairment, providing preclinical evidence for Cx43-GJ-targeted antidepressants development.