Hypothalamo-preoptic Histaminergic Projections in Sleep-Wake Control in the Cat

Eur J Neurosci. 1994 Apr 1;6(4):618-25. doi: 10.1111/j.1460-9568.1994.tb00306.x.

Abstract

Cats were chronically implanted with electrodes for polygraphic recordings and cannulae for intracerebral microinjections in order to study the functional role of histaminergic innervation of the preoptic-anterior hypothalamus in sleep-wake control. alpha-Fluoromethylhistidine (alpha FMH, 50 micrograms in 1 microliter), a specific inhibitor of the histamine-synthesizing enzyme, when injected bilaterally into the preoptic area, where numerous histaminergic fibres and terminal-like structures are present, caused a significant increase in deep slow wave sleep (S2) and paradoxical sleep (PS) and a decrease in wakefulness. In contrast, microinjections of histamine (5 or 30 micrograms in 1 microliter) in the same area dose-relatedly increased wakefulness and decreased both slow wave sleep and paradoxical sleep. The effects of histamine were reduced by pretreatment with mepyramine (1 mg/kg i.p.), a well known histamine H1 receptor antagonist, and were mimicked by a local injection of impromidine (1 microgram in 1 microliter), a potent histamine H2 receptor agonist. Microinjections of mepyramine alone (120 micrograms in 1 microliter) caused an increase in slow wave sleep. These results suggest that preoptic histaminergic innervation is involved in sleep-wake control and that the action might be mediated via both H1 and H2 receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / physiology*
  • Cats / physiology*
  • Dose-Response Relationship, Drug
  • Electroencephalography / drug effects
  • Female
  • Histamine / administration & dosage
  • Histamine / pharmacology
  • Histamine / physiology*
  • Histidine Decarboxylase / antagonists & inhibitors
  • Hypothalamus, Anterior / cytology
  • Hypothalamus, Anterior / drug effects
  • Hypothalamus, Anterior / physiology*
  • Impromidine / administration & dosage
  • Impromidine / pharmacology
  • Male
  • Methylhistidines / administration & dosage
  • Methylhistidines / pharmacology
  • Microinjections
  • Preoptic Area / cytology
  • Preoptic Area / drug effects
  • Preoptic Area / physiology*
  • Pyrilamine / administration & dosage
  • Pyrilamine / pharmacology
  • Sleep / drug effects
  • Sleep / physiology*
  • Sleep, REM / drug effects
  • Sleep, REM / physiology
  • Time Factors
  • Wakefulness / drug effects
  • Wakefulness / physiology*

Substances

  • Methylhistidines
  • alpha-fluoromethylhistidine
  • Histamine
  • Impromidine
  • Histidine Decarboxylase
  • Pyrilamine