Electroconvulsive seizure thresholds and kindling acquisition rates are altered in mouse models of human KCNQ2 and KCNQ3 mutations for benign familial neonatal convulsions.
OBJECTIVE
Benign familial neonatal convulsions (BFNC) is caused by mutations in the KCNQ2 and KCNQ3 genes, which encode subunits of the M-type potassium channel. The purpose of this study was to examine the effects of orthologous BFNC-causing mutations on seizure thresholds and the acquisition of corneal kindling in mice with heterozygous expression of the mutations.


METHODS
The effects of the Kcnq2 gene A306T mutation and the Kcnq3 gene G311V mutation were determined for minimal clonic, minimal tonic hindlimb extension, and partial psychomotor seizures. The rate of corneal kindling acquisition was also determined for Kcnq2 A306T and Kcnq3 G311V mice.


RESULTS
Seizure thresholds were significantly altered relative to wild-type animals in the minimal clonic, minimal tonic hindlimb extension, and partial psychomotor seizure models. Differences in seizure threshold were found to be dependent on the mutation expressed, the seizure testing paradigm, the genetic background strain, and the gender of the animal. Mutations in Kcnq2 and Kcnq3 were associated with an increased rate of corneal kindling. In the Kcnq2 A306T mice, an increased incidence of death occurred during and immediately following the conclusion of the kindling acquisition period.


CONCLUSIONS
These results suggest that genetic alterations in the subunits that underlie the M-current and cause BFNC alter seizure susceptibility in a sex-, mouse strain-, and seizure-test dependent manner. Although the heterozygous mice do not appear to have spontaneous seizures, the increased seizure susceptibility and incidence of death during and after kindling suggests that these mutations lead to altered excitability in these animals.
Otto
James F
JF
Department of Pharmacology and Toxicology, University of Utah, Salt Lake City, Utah, USA.
Singh
Nanda A
NA
Dahle
E Jill
EJ
Leppert
Mark F
MF
Pappas
Chris M
CM
Pruess
Timothy H
TH
Wilcox
Karen S
KS
White
H Steve
HS
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D004195:Disease Models, Animal; D004558:Electric Stimulation; D004562:Electrocardiography; D020936:Epilepsy, Benign Neonatal / Q000235:genetics* / Q000503:physiopathology; D005260:Female; D055879:Gene Knock-In Techniques / Q000379:methods; D020022:Genetic Predisposition to Disease; D006579:Heterozygote; D006801:Humans; D051658:KCNQ2 Potassium Channel / Q000235:genetics* / Q000502:physiology; D051659:KCNQ3 Potassium Channel / Q000235:genetics* / Q000502:physiology; D007696:Kindling, Neurologic / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D009154:Mutation / Q000235:genetics*; D020125:Mutation, Missense / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics; D012640:Seizures / Q000235:genetics* / Q000503:physiopathology; D012737:Sex Factors
D051658:KCNQ2 Potassium Channel; D051659:KCNQ3 Potassium Channel; D009419:Nerve Tissue Proteins