Cell discharge correlates of posterior hypothalamic theta rhythm. Recipe for success in recording stable field potential

Brain Res. 2016 Sep 1:1646:551-559. doi: 10.1016/j.brainres.2016.06.038. Epub 2016 Jun 25.

Abstract

The theta rhythm discovered in the posterior hypothalamus area (PHa) differs from theta observed in the hippocampal formation. In comparison to hippocampal spontaneous theta, the theta recorded in the PHa is rarely registered, has lower amplitude, often disappears, and sometimes returns after a few minutes. These features indicate that spontaneous theta recorded in the PHa is not an appropriate experimental model to search for the correlation between PHa cell discharges and local field potential. In this paper we present standard experimental conditions necessary to record theta-related cells in the PHa in anesthetized rats. Three pharmacological agents were used in the experiments to induce PHa theta rhythm in urethanized rats: carbachol (CCH), carbenoxolone and kainic acid, which are potent enough to induce well-synchronized PHa theta. However, CCH was found to be the best pharmacological tool to induce PHa theta oscillations, due to its longest duration of action and lack of preliminary epileptogenic effects. It seems that CCH-induced theta can be the most suitable pharmacological model for experiments with the use of protocol of long-lasting recordings of PHa theta-related cell discharges.

Keywords: Anesthetized rats; Extracellular recordings; Posterior hypothalamus; Theta-related cell.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials* / drug effects
  • Animals
  • Carbachol / administration & dosage
  • Carbenoxolone / administration & dosage
  • Cholinergic Agonists / administration & dosage
  • Electroencephalography
  • Excitatory Amino Acid Agonists / administration & dosage
  • Hypothalamus, Posterior / drug effects
  • Hypothalamus, Posterior / physiology*
  • Kainic Acid / administration & dosage
  • Male
  • Neurons / drug effects
  • Neurons / physiology*
  • Rats
  • Rats, Wistar
  • Theta Rhythm* / drug effects

Substances

  • Cholinergic Agonists
  • Excitatory Amino Acid Agonists
  • Carbachol
  • Carbenoxolone
  • Kainic Acid