Related Experiment Video
Updated: Aug 9, 2026
Optogenetic Activation of Afferent Pathways in Brain Slices and Modulation of Responses by Volatile Anesthetics
Published on: July 23, 2020
Orexins increase cortical acetylcholine release and electroencephalographic activation through orexin-1 receptor in
Hai-long Dong1, Satoru Fukuda, Eri Murata
1Department of Anesthesiology & Reanimatology, Faculty of Medical Science, University of Fukui, Fukui, Japan..
Background:
Cholinergic arousal system plays an important role in the maintenance of consciousness. The authors investigated whether the intrabasalis injection of orexin-A or orexin-B and the electrically stimulated pedunculopontine tegmentum nuclei (PPTg: the origin of cholinergic ascending pathways) may alter acetylcholine efflux and electroencephalographic activity in the somatosensory cortex in relation to the orexinergic system in isoflurane-anesthetized rats.
Methods:
Either orexin-A (10, 30, or 100 pmol) or orexin-B (10, 30, or 100 pmol) (n = 6 each) was injected into the basal forebrain while the electroencephalogram was measured during 1.0 minimum alveolar concentration (1.2%) isoflurane anesthesia. Injection of Ringer's solution was used as a control. The PPTg was electrically stimulated twice with the following conditions: 1-s stimulus train (0.2 ms, 100 Hz, 400 microA) per min for 20 min. Twenty minutes before the second PPTg stimulation, Ringer's solution or 20 microg SB334867, an orexin-1 receptor antagonist (n = 5 each) was injected into the basal forebrain.
Results:
Injection of orexin-A (30 and 100 pmol) and orexin-B (100 pmol) significantly increased the acetylcholine efflux in the somatosensory cortex (P < 0.05). Injection of orexin-A (10, 30, 100 pmol) and orexin-B (30, 100 pmol) changed the burst and suppression patterns to arousal electroencephalogram. Compared with orexin-B, injection of a lower dose of orexin-A induced increase in the acetylcholine efflux and arousal electroencephalogram. SB334867 significantly attenuated the increases in the acetylcholine efflux and electroencephalographic activation evoked by PPTg stimulation.
Conclusion:
The authors demonstrated that orexin-A was more potent than orexin-B in producing alteration of cholinergic basal forebrain neuronal activity and that the cortical activation induced by the PPTg stimulation against isoflurane anesthesia may be mediated through the orexin-1 receptors in the basal forebrain.
