RESUMEN
Gap junctions are conductive channels formed by membrane proteins termed connexins, which permit the intercellular exchange of metabolites, ions and small molecules. Previous data demonstrated that traumatic brain injury (TBI) activates autophagy and increases microtubuleassociated protein 1 light chain 3 (LC3) immunostaining predominantly in neurons. Although previous studies have identified several extracellular factors that modulate LC3 expression, knowledge of the regulatory network controlling LC3 in health and disease remains incomplete. The aim of the present study was to assess whether gap junctions control the in vivo expression of LC3 in TBI. Using a modified weightdrop device, adult male SpragueDawley rats (weight, 350375 g) were subjected to TBI. Phosphorylated gap junction protein levels and LC3â ¡ levels were quantified using western blot analysis. The spatial distribution of immunoreactivity for phosphorylated connexin 43 (pCX43) and LC3â ¡ was analyzed by immunofluorescence. The results showed that pCX43 expression in the hippocampus reached a maximum level 6 h following injury. In addition, the immunoreactivity of pCX43 was localized in the astrocytes surrounding pyramidal neurons. The LC3â ¡ protein content remained at high levels 24 h following injury. Double immunolabeling demonstrated that LC3II dots colocalized with the hippocampus pyramidal neurons. Furthermore, inhibition of pCX43 reduced TBIinduced autophagy, according to western blot analysis. As astrocytic gap junction coupling is affected in various forms of brain injury, the results suggest that point gap junctions/connexins are important regulators of autophagy in the hippocampal neurons following TBI.