Tricyclic antidepressant amitriptyline potentiates brain-derived neurotrophic factor expression mediated by PKC delta-NF-kappa B signaling in primary cultured astrocytes with connexin43-knockdown.
📄 Abstract
Depression is a major mental illness, and its underlying mechanisms remain unclear. Emerging evidence suggests that astrocytes, which play a crucial role in brain function, may be involved in the pathophysiology of depression. We previously showed that downregulation of astrocytic connexin43 (Cx43) enhances the antidepressant effect of amitriptyline. However, the precise molecular mechanisms underlying this phenomenon remain unknown. In the present study, we investigated the signaling pathways involved in the antidepressant action of amitriptyline using an in vitro model involving Cx43-knockdown astrocytes. We found that amitriptyline potentiated the expression of brain-derived neurotrophic factor (BDNF), a key neurotrophic factor, in Cx43-knockdown astrocytes. This potentiation was mediated by the activation of Gq protein-coupled lysophosphatidic acid (LPA) receptors, a pathway that was sensitized by Cx43 downregulation. We further demonstrated that this signaling cascade involved the activation of Protein Kinase C (PKC) δ and transcription factor NF-κB, but not the conventional BDNF transcription factor CREB. We propose that Cx43 downregulation enhances the antidepressant effect of amitriptyline by specifically engaging the Gq-PKCδ-NF-κB pathway. These findings suggest that Cx43 downregulation in astrocytes, which has been considered a pathological feature of depression, may paradoxically contribute to the therapeutic efficacy of antidepressants by sensitizing a specific signaling pathway. Our study provides new insights into the molecular mechanism of antidepressant action and highlights the potential role of astrocytic Cx43 in modulating therapeutic responses.