Serotonin 1A receptor inhibits the status epilepticus induced by lithium-pilocarpine in rats

Neurosci Bull. 2014 Jun;30(3):401-8. doi: 10.1007/s12264-013-1396-x. Epub 2014 Jan 15.

Abstract

Status epilepticus (SE) is a life-threatening neurological emergency associated with a high mortality rate. The serotonin 1A (5-HT1A) receptor is a possible target for the treatment of SE, but its role in animal models and the precise area of brain involved remain controversial. The hippocampus is a candidate site due to its key role in the development of SE and the existence of a high density of 5-HT1A receptors. Therefore, we investigated the effects of subcutaneous and intrahippocampal activation of 5-HT1A receptors in lithium-pilocarpine-induced SE, and tested whether the hippocampus is a true effector site. We developed SE in male Sprague-Dawley rats by giving lithium chloride (LiCl; 3 meq/kg, i.p.) 22-24 h prior to pilocarpine (25 mg/kg, i.p.), and found that 8-OH-DPAT, a 5-HT1A receptor agonist administered subcutaneously (s.c.) at 0.5 or 1.0 mg/kg 1 h before pilocarpine injection increased the latency to the first epileptiform spikes, the electrographic SE, and the behavioral generalized seizures (GS), while reducing the total EEG seizure time (P <0.01). The duration of GS was shortened only by 1.0 mg/kg 8-OH-DPAT s.c. (P <0.05). All these effects were inhibited by combined administration of WAY-100635 (1.0 mg/kg, s.c.) (P <0.05), an antagonist of the 5-HT1A receptor, but WAY-100635 alone and low doses of 8-OHDPAT (0.01 and 0.1 mg/kg) did not alter seizure activity. Furthermore, intrahippocampal 8-OH-DPAT only shortened the GS duration (P <0.05). These findings imply that the 5-HT1A receptor is a promising therapeutic target against the generation and propagation of SE, and hippocampal receptors are involved in reducing the seizure severity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 8-Hydroxy-2-(di-n-propylamino)tetralin / toxicity
  • Action Potentials / drug effects
  • Analysis of Variance
  • Animals
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Electroencephalography
  • Hippocampus / cytology
  • Hippocampus / drug effects
  • Hippocampus / physiology
  • Lithium Chloride / toxicity*
  • Male
  • Muscarinic Agonists / toxicity*
  • Pilocarpine / toxicity*
  • Piperazines / therapeutic use
  • Pyridines / therapeutic use
  • Rats
  • Rats, Sprague-Dawley
  • Reaction Time / drug effects
  • Receptor, Serotonin, 5-HT1A / metabolism*
  • Serotonin Antagonists / therapeutic use
  • Status Epilepticus / chemically induced*
  • Status Epilepticus / drug therapy
  • Status Epilepticus / metabolism*
  • Time Factors

Substances

  • Muscarinic Agonists
  • Piperazines
  • Pyridines
  • Serotonin Antagonists
  • Pilocarpine
  • Receptor, Serotonin, 5-HT1A
  • N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide
  • 8-Hydroxy-2-(di-n-propylamino)tetralin
  • Lithium Chloride