Facilitation of Hippocampal Kindling and Exacerbation of Kindled Seizures by Intra-CA1 Injection of Quinine: A Possible Role of Cx36 Gap Junctions.
BACKGROUND
GABAergic interneurons in the hippocampal CA1 area are mutually communicated by gap junctions (GJs) composed of connexin36 (Cx36). We examined the role of Cx36 in CA1 in manifestation of kindled seizures and hippocampal kindling in rats.


METHODS
Quinine, as the specific blocker of Cx36, was injected into CA1, and kindled seizures severity was examined 10 min afterward. Moreover, quinine was injected into CA1 once daily, and the rate of CA1 kindling was recorded.


RESULTS
Quinine 0.5 and 1 mM caused 2- and 3.5-fold increase in the duration of total seizure behavior and generalized the seizures. Primary and secondary afterdischarges (AD) were also significantly increased. Quinine 0.1 mM augmented the rate of kindling and the growth of secondary AD.


CONCLUSIONS
Cx36 GJs in CA1 are the main components of hippocampal inhibitory circuit. Any interruption in this path by pathologic or physical damages can trigger hippocampal hyperexcitability and facilitate epileptogenesis.
Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran.|Department of Physiology, Faculty of Veterinary Medicine, Tehran University, Tehran, Iran.
Fatemeh
F
Etemadi
Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran.
Mohammad
M
Sayyah
Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran.
Hamid
H
Gholami Pourbadie
Department of Physiology, Faculty of Veterinary Medicine, Tehran University, Tehran, Iran.
Vahab
V
Babapour
D000818:Animals; D017630:Connexins / Q000378:metabolism*; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000503:physiopathology*; D007696:Kindling, Neurologic / Q000187:drug effects*; D008297:Male; D011803:Quinine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012640:Seizures / Q000503:physiopathology; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology; D000097004:Gap Junction delta-2 Protein
D017630:Connexins; D011803:Quinine; D000097004:Gap Junction delta-2 Protein
CA1; Connexin36; Gap junctions; Kindling; Quinine