GJA1 and Parkinson disease: The upregulation of astrocytic Cx43 and phospho-Cx43 has been reported in rotenone models of PD in rat models in vivo and in vitro26,27; an increase in GJA1 mRNA and Cx43 immunoreactivity has been shown in a mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model28, and increased Cx43 expression has been observed in a lipopolysaccharide (LPS)-induced rat model of PD29.