GABAergic control of hypothalamic melanin-concentrating hormone-containing neurons across the sleep-waking cycle

Neuroreport. 2005 Jul 13;16(10):1069-73. doi: 10.1097/00001756-200507130-00008.


The perifornical-lateral hypothalamic area is implicated in regulating waking and paradoxical sleep. The blockade of GABAA receptors by iontophoretic applications of bicuculline (or gabazine) into the perifornical-lateral hypothalamic area induced a continuous quiet waking state associated to a robust muscle tone in head-restrained rats. During the effects, sleep was totally suppressed. In rats killed at the end of a 90 min ejection of bicuculline, Fos expression was induced in approximately 28% of the neurons immunoreactive for hypocretin and in approximately 3% of the neurons immunostained for melanin-concentrating hormone within the ejection site. These results suggest that neurons containing melanin-concentrating hormone are not active during waking and that the lack of a potent GABAergic influence during waking is consistent with their role in sleep regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Electroencephalography / methods
  • GABA Antagonists / pharmacology
  • GABA-A Receptor Antagonists
  • Hypothalamic Hormones / physiology*
  • Hypothalamus / drug effects
  • Hypothalamus / physiology*
  • Male
  • Melanins / physiology*
  • Neurons / drug effects
  • Neurons / physiology*
  • Pituitary Hormones / physiology*
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, GABA-A / physiology*
  • Sleep Stages / drug effects
  • Sleep Stages / physiology*
  • Wakefulness / drug effects
  • Wakefulness / physiology*


  • GABA Antagonists
  • GABA-A Receptor Antagonists
  • Hypothalamic Hormones
  • Melanins
  • Pituitary Hormones
  • Receptors, GABA-A
  • melanin-concentrating hormone