Expression and function of KCNQ channels in larval zebrafish

Dev Neurobiol. 2012 Feb;72(2):186-98. doi: 10.1002/dneu.20937.

Abstract

Members of the K(v)7 family generate a subthreshold potassium current, termed M-current, that regulates the excitability of principal central neurons. Mutations in two members of this family, K(v)7.2 (KCNQ2) and K(v)7.3 (KCNQ3) are associated with a neurological disorder known as benign familial neonatal convulsion (BFNC). Despite their importance in normal and pathological brain function, developmental expression and function of these channels remains relatively unexplored. Here, we examined the temporal expression of K(v)7 channel subunits in zebrafish larvae using a real-time quantitative PCR approach. Spatial expression in the larval zebrafish brain was assessed using whole-mount in situ hybridization. The mRNA for three members of the K(v)7 family (KCNQ2, 3 and 5) is reported in zebrafish between two and seven days post-fertilization (dpf). Using electrophysiological techniques, we show that inhibitors of K(v)7 channels (linopirdine and XE991) induce burst discharge activity in immature zebrafish between 3 and 7 dpf. This abnormal electrical activity is blocked by a K(v)7 channel opener (retigabine) and was also shown to evoke convulsive behaviors in freely swimming zebrafish. Using morpholino oligonucleotides directed against KCNQ3, we confirmed a role for KCNQ channels in generation of electrical burst discharges. These results indicate that functional K(v)7 channels are expressed in the larval zebrafish nervous system and could play a direct role in generation of seizure activity.

MeSH terms

  • Action Potentials / drug effects
  • Analysis of Variance
  • Animals
  • Anthracenes / pharmacology
  • Anticonvulsants / pharmacology
  • Brain / growth & development
  • Brain / metabolism*
  • Carbamates / pharmacology
  • Dose-Response Relationship, Drug
  • Electrophysiology
  • Gene Expression Regulation, Developmental / drug effects
  • Gene Expression Regulation, Developmental / physiology*
  • Indoles / pharmacology
  • KCNQ Potassium Channels / genetics
  • KCNQ Potassium Channels / metabolism*
  • Larva / anatomy & histology*
  • Locomotion / drug effects
  • Morpholinos / pharmacology
  • Phenylenediamines / pharmacology
  • Potassium Channel Blockers / pharmacology
  • Pyridines / pharmacology
  • RNA, Messenger / metabolism
  • Swimming
  • Zebrafish

Substances

  • 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone
  • Anthracenes
  • Anticonvulsants
  • Carbamates
  • Indoles
  • KCNQ Potassium Channels
  • Morpholinos
  • Phenylenediamines
  • Potassium Channel Blockers
  • Pyridines
  • RNA, Messenger
  • ezogabine
  • linopirdine