Related Experiment Video
Updated: Aug 17, 2026

Optogenetic Activation of Afferent Pathways in Brain Slices and Modulation of Responses by Volatile Anesthetics
Published on: July 23, 2020
Nociceptin system does not affect MAC of volatile anaesthetics
S Himukashi1, Y Miyazaki, H Takeshima
1Department of Anaesthesia, Kyoto University Hospital, Kyoto, Japan. himukash@kuhp.kyoto-u.ac.jp
Background:
Nociceptin is the endogenous agonist of the opioid receptor-like (ORL) 1 receptor (NOP), and both nociceptin and NOP are widely expressed in the brain and spinal cord, which are target organs of general anaesthetics. As nociceptin has been reported to be involved in modulating pain mechanisms and stress responses, it is possible that the activity of the nociceptin system affects the anaesthetic potency of general anaesthetics. To address this possibility, we investigated the minimum alveolar concentrations (MACs) of various volatile anaesthetics in nociceptin receptor knockout mice (NOP-/-) and wild-type mice (NOP+/+).
Methods:
We used male NOP-/- mice and NOP+/+ mice. MACs for halothane, isoflurane and sevoflurane were determined by the tail-clamp method.
Results:
MACs for halothane, isoflurane and sevoflurane in NOP-/- mice were 1.60 (SD 0.06), 1.68 (0.08) and 3.36 (0.07)%, respectively. In NOP+/+ mice, MACs for halothane, isoflurane and sevoflurane were 1.59 (SD 0.07), 1.72 (0.07) and 3.38 (0.09)%, respectively.
Conclusion:
MACs in NOP-/- mice did not significantly differ from those in NOP+/+ mice for halothane, isoflurane and sevoflurane. This result suggests that the nociceptin system does not affect the anaesthetic potency of volatile anaesthetics.
Related Concept Videos
Local Anesthetics: Differential Sensitivity of Nerve Fibers
Local Anesthetics: Mechanism of Action
Local anesthetics are amphiphilic molecules consisting of a hydrophobic aromatic part linked to a hydrophilic group by an ester or amide linkage. They are weak bases and are usually available as salts, which increases their solubility and stability. Once administered, LAs exist in the body either...
Local Anesthetics: Adverse Effects
Once absorbed into the systemic circulation, local anesthetics can affect the organs that depend on the functioning of sodium...
Parenteral Anesthetics: Overview
General Anesthesia: Overview
General anesthesia induces unconsciousness in the whole body, while the others target specific areas or sensations. It is administered to minimize adverse effects, maintain...
Inhalational Anesthetics: Overview

