Related Experiment Video

Updated: Sep 9, 2025

Cheek Injection Model for Simultaneous Measurement of Pain and Itch-related Behaviors
04:59

Cheek Injection Model for Simultaneous Measurement of Pain and Itch-related Behaviors

Published on: September 27, 2019

12.4K

Role of orexin receptors in histamine- and chloroquine-induced pruriceptive processing

Anna Kanemaru-Kawazoe1, Hideki Funahashi1, Yoichiro Kogoh1

  • 1Department of Psychiatry, Division of Clinical Neuroscience, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki city, Miyazaki 889-1692, Japan.

Neuroscience Research
|August 29, 2025
PubMed

Insights

Orexin A (OX-A) effectively reduces itch responses to histamine and chloroquine (CQ) by acting on orexin receptors. This suggests orexin peptides play a key role in modulating itch signaling pathways.

Area of Science:

  • Neuroscience
  • Pruritus Research
  • Itch Signaling Pathways

Background:

  • Orexin peptides are known to influence pain (nociception).
  • Their specific role in itch (pruriception) processing remains largely unexplored.
  • Understanding orexin's function in itch could reveal novel therapeutic targets.

Purpose of the Study:

  • To investigate the role of orexin A (OX-A) and orexin B (OX-B) in itch processing.
  • To determine the involvement of orexin receptors (OX1 and OX2) in mediating these effects.
  • To elucidate how orexin peptides modulate itch signals induced by histamine and chloroquine (CQ).

Main Methods:

  • Administration of OX-A and OX-B prior to histamine or CQ injections in a model system.
  • Assessment of scratching behavior and neuronal activation (c-Fos expression).
  • Use of orexin receptor 1 (OX1) and orexin receptor 2 (OX2) antagonists (SB334867, JNJ10397049) and an OX2 agonist (YNT185) to probe receptor involvement.

Main Results:

  • OX-A, but not OX-B, significantly reduced scratching events and c-Fos expression induced by histamine and CQ.
  • The anti-pruritic effects of OX-A were reversed by OX1 and OX2 antagonists, indicating receptor mediation.
  • An OX2 receptor agonist (YNT185) attenuated histamine-induced, but not CQ-induced, itch and neuronal activation.

Conclusions:

  • Orexin A demonstrates significant anti-pruritic effects, modulating itch processing.
  • Histamine and CQ-induced itch signals are differentially regulated by OX1 and OX2 receptors.
  • Orexin signaling represents a potential pathway for controlling specific types of itch.
Keywords:
C-FosMouseOX1 receptorsOX2 receptorsOrexin AOrexin BScratching behavior

More Related Videos

Intracerebroventricular Treatment with Resiniferatoxin and Pain Tests in Mice06:04

Intracerebroventricular Treatment with Resiniferatoxin and Pain Tests in Mice

Published on: September 2, 2020

8.3K
Chronic Post-Ischemia Pain Model for Complex Regional Pain Syndrome Type-I in Rats07:12

Chronic Post-Ischemia Pain Model for Complex Regional Pain Syndrome Type-I in Rats

Published on: January 21, 2020

7.8K

Related Concept Videos

Opioid Receptors: Overview01:22

Opioid Receptors: Overview

Opioid receptors, including the mu (μ, MOR), delta (δ, DOR), and kappa (κ, KOR) types, belong to the rhodopsin family of G protein-coupled receptors. These receptors are located throughout the central and peripheral nervous systems and in non-neuronal tissues such as macrophages and astrocytes. Opioid receptor ligands can be categorized into agonists or antagonists. Highly selective agonists include [d-Ala2, MePhe4, Gly(ol)5]-enkephalin or DAMGO for MOR, [D-Pen2,...
1.8K
Analgesia and Pain Management01:25

Analgesia and Pain Management

Pain is critical to various clinical pathologies, provoking an urgent need for effective management. Pain, whether acute or chronic, is a complex neurochemical process. Its alleviation depends on the type, with nonopioid analgesics effective for mild to moderate pain, such as musculoskeletal or inflammatory pain, while neuropathic pain responds best to anticonvulsants, tricyclic antidepressants, or serotonin/norepinephrine reuptake inhibitors. For severe acute or chronic pain, opioids may be...
788
Nociception01:44

Nociception

Nociception—the ability to feel pain—is essential for an organism’s survival and overall well-being. Noxious stimuli such as piercing pain from a sharp object, heat from an open flame, or contact with corrosive chemicals are first detected by sensory receptors, called nociceptors, located on nerve endings. Nociceptors express ion channels that convert noxious stimuli into electrical signals. When these signals reach the brain via sensory neurons, they are perceived as pain.
29.4K
Physiology of Smell and Olfactory Pathway01:20

Physiology of Smell and Olfactory Pathway

Humans detect odors with the help of specialized cells located in the upper part of the nasal cavity, called olfactory receptor neurons (ORNs). ORNs possess hair-like structures called cilia, which are receptive to sensations from the inhaled air. When an odorant molecule binds to a specific receptor on the cell of the cilia, it leads to a series of events that ultimately cause the ORN to send electrical signals to the olfactory bulb in the brain through the olfactory nerves.
The olfactory...
9.5K
Thermosensation01:43

Thermosensation

Peripheral thermosensation is the perception of external temperature. A change in temperature (on the surface of the skin and other tissues) is detected by a family of temperature-sensitive ion channels called Transient Receptor Potential, or TRP, receptors. These receptors are located on free nerve endings. Those detecting cold temperatures are closer to the surface of the skin than the nerve endings detecting warmth. These thermoTRP channels, while temperature selective, have relatively...
31.8K
G-Protein Gated Ion Channels01:21

G-Protein Gated Ion Channels

GPCRs are primarily responsible for our sense of smell, taste, and vision.  The binding of a sensory stimulus activates GPCR to stimulate effector proteins, many of which are ion channels in the sensory organs. GPCRs modulate the opening and closing of the target ion channels either directly by binding them, or by releasing second messengers that activate these channels. As ions move across the membrane, the membrane potential is altered, which induces an appropriate response.
Sensory...
4.8K