Upregulation of connexins 30 and 32 gap junctions in rat hippocampus at transcription level by chronic central injection of lipopolysaccharide

Background: Gap junctions composed of connexins (Cx) are functional in cell defense by propagation of toxic/death molecules to neighboring cells. Hippocampus, one of the brain regions with particular vulnerability to damage, has a wide network of gap junctions. Functional response of astrocytic Cx30 and neuronal Cx32 to hippocampal damage is unknown. Methods: We infused lipopolysaccharide (LPS) intracerebroventricularly (2.5 µg/rat) once daily for two weeks to create neuroinflammation. The mRNA and protein levels of the Cx were measured in the hippocampus after 1^st, 7^th and 14^th injection by real-time PCR and Western-blot techniques. Results: A significant increase in Cx32 and Cx30 gene expression was observed after 7^th and 14^th injection of LPS with no significant change in their protein abundance. Conclusion: Transcriptional overexpression of hippocampal Cx30 and Cx32 could be an adaptive response to production of intracellular toxic molecules but it is not accompanied with post- transcriptional overexpression and might have no functional impact.