title: Expression of connexin 30 and connexin 32 in hippocampus of rat during epileptogenesis in a kindling model of epilepsy.
abstract: OBJECTIVE
  Understanding the molecular and cellular mechanisms underlying epileptogenesis yields new insights into potential therapies that may ultimately prevent epilepsy. Gap junctions (GJs) create direct intercellular conduits between adjacent cells and are formed by hexameric protein subunits called connexins (Cxs). Changes in the expression of Cxs affect GJ communication and thereby could modulate the dissemination of electrical discharges. The hippocampus is one of the main regions involved in epileptogenesis and has a wide network of GJs between different cell types where Cx30 is expressed in astrocytes and Cx32 exists in neurons and oligodendrocytes. In the present study, we evaluated the changes of Cx30 and Cx32 expression in rat hippocampus during kindling epileptogenesis.
  
  
  METHODS
  Rats were stereotaxically implanted with stimulating and recording electrodes in the basolateral amygdala, which was electrically stimulated once daily at afterdischarge threshold. Expression of Cx30 and Cx32, at both the mRNA and protein levels, was measured in the hippocampus at the beginning, in the middle (after acquisition of focal seizures), and at the end (after establishment of generalized seizures) of the kindling process, by real-time PCR and Western blot.
  
  
  RESULTS
  Cx30 mRNA expression was upregulated at the beginning of kindling and after acquisition of focal seizures. Then it was downregulated when the animals acquired generalized seizures. Overexpression of Cx30 mRNA at the start of kindling was consistent with the respective initial protein increase. Thereafter, no change was found in protein abundance during kindling. Regarding Cx32, mRNA expression decreased after acquisition of generalized seizures and no other significant change was detected in mRNA and protein abundance during kindling.
  
  
  CONCLUSIONS
  We speculate that Cx32 GJ communication in the hippocampus does not contribute to kindling epileptogenesis. The Cx30 astrocytic network localized to perivascular regions in the hippocampus is, however, overexpressed at the initiation of kindling to clear excitotoxic molecules from the milieu.
authors.affiliation: Department of Physiology, Pasteur Institute of Iran, Tehran 131694-3551, Islamic Republic of Iran.
authors.forename: Bijan
authors.initials: B
authors.lastname: Akbarpour
authors.forename: Mohammad
authors.initials: M
authors.lastname: Sayyah
authors.forename: Vahab
authors.initials: V
authors.lastname: Babapour
authors.forename: Reza
authors.initials: R
authors.lastname: Mahdian
authors.forename: Siamak
authors.initials: S
authors.lastname: Beheshti
authors.forename: Ahmad Reza
authors.initials: AR
authors.lastname: Kamyab
mesh_terms: D000818:Animals; D015153:Blotting, Western; D000075302:Connexin 30; D017630:Connexins / Q000096:biosynthesis* / Q000235:genetics; D018076:DNA, Complementary / Q000096:biosynthesis / Q000302:isolation & purification; D004558:Electric Stimulation; D004827:Epilepsy / Q000378:metabolism*; D017629:Gap Junctions / Q000378:metabolism; D005786:Gene Expression Regulation; D006624:Hippocampus / Q000378:metabolism*; D007696:Kindling, Neurologic / Q000502:physiology*; D008297:Male; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D012640:Seizures / Q000378:metabolism; D013238:Stereotaxic Techniques; D000097002:Gap Junction beta-1 Protein
chemical_list: D000075302:Connexin 30; D017630:Connexins; D018076:DNA, Complementary; D012313:RNA; D000097002:Gap Junction beta-1 Protein; C508770:Gjb6 protein, rat