Blockade of GABAA receptors disrupts isoperiodic neuronal oscillations in the intergeniculate leaflet of the rat

• Published in: Brain research 2004-05, Vol.1009 (1-2), p.82-87
• Main Authors: BLASIAK, T, LEWANDOWSKI, M. H
• Format: Article
• Language: English
• Subjects: Action Potentials - drug effects; Animals; Bicuculline - pharmacology; Biological and medical sciences; Biological Clocks - drug effects; Biological Clocks - physiology; Central nervous system; Circadian Rhythm - drug effects; Circadian Rhythm - physiology; Drug Administration Routes; Electrophysiology; Fundamental and applied biological sciences. Psychology; GABA Antagonists - pharmacology; Geniculate Bodies - cytology; Immunohistochemistry - methods; Male; Neurons - physiology; Neuropeptide Y - metabolism; Picrotoxin - pharmacology; Rats; Rats, Wistar; Receptors, GABA - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2004.02.045

The intergeniculate leaflet of the thalamus is, besides the suprachiasmatic nucleus of the hypothalamus, the other important neuronal element of the mammalian biological clock. The extracellularly recorded activity of neurons constituting the intergeniculate leaflet, recorded in vivo, is characterized by distinct, very regular ultradian oscillations. The majority of neurons in the circadian timing system are GABAergic. Many, if not all, neurons of the suprachiasmatic nucleus and intergeniculate leaflet contain GABA. In the present study we examined the effects of the GABA(A) receptor antagonist bicuculline and the chloride channel blocker picrotoxin on isoperiodic neuronal oscillations in the intergeniculate leaflet of rats. We recorded extracellular multiple-unit neuronal activity from the intergeniculate leaflet of anesthetized rats. During the recording of isoperiodic oscillations, bicuculline or picrotoxin were stereotaxically injected at different concentrations into the lateral ventricle of rat brain. In all the experiments, injection of GABA(A) receptor antagonists transiently disrupted the isoperiodic phasic discharge recorded from the intergeniculate leaflet. These data suggest that GABA(A) receptors are involved in the generation of ultradian rhythmical neuronal oscillations in rat intergeniculate leaflet.