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Related Concept Videos

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. Thus, pain helps the...
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Local Anesthetics: Mechanism of Action

Local anesthetics (LAs) block sensory and motor impulses by inhibiting the sodium channels on the nerve cell membranes. This induces temporary loss of sensation, relieving pain in a specific body area.
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: Differential Sensitivity of Nerve Fibers01:24

Local Anesthetics: Differential Sensitivity of Nerve Fibers

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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, D-Pen5]-enkephalin or DPDPE for...
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Neurochemical transmission, the conduction of electrical impulses between neurons mediated by neurotransmitters, plays a vital role in various physiological processes. Autonomic drugs exert their effects by modulating neurotransmission within the autonomic nervous system. For instance, drugs such as hemicholinium block the precursor uptake necessary for synthesizing acetylcholine, an essential autonomic neurotransmitter. Following synthesis, neurotransmitters are stored in vesicles. Metyrosine...

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Related Experiment Video

Updated: Jun 12, 2026

Intracranial Pharmacotherapy and Pain Assays in Rodents
02:26

Intracranial Pharmacotherapy and Pain Assays in Rodents

Published on: April 9, 2019

Neural basis for improgan antinociception.

M M Heinricher1, M E Martenson, J W Nalwalk

  • 1Department of Neurological Surgery, Oregon Health and Science University, Portland, OR 97239, USA. heinricm@ohsu.edu

Neuroscience
|June 24, 2010
PubMed
Summary
This summary is machine-generated.

Improgan, a novel non-opioid pain reliever, activates specific brainstem neurons to reduce pain. This drug, derived from histamine antagonists, offers a new pathway for analgesia without opioid receptor binding.

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Area of Science:

  • Neuroscience
  • Pharmacology
  • Pain Research

Background:

  • Improgan is a novel non-opioid analgesic derived from histamine antagonists.
  • It reduces nociception via central mechanisms in the periaqueductal gray and rostral ventromedial medulla (RVM).
  • Improgan's molecular target and receptor binding profile (non-opioid, non-histamine, non-cannabinoid) remain unidentified.

Purpose of the Study:

  • To investigate the cellular mechanisms by which improgan produces antinociception in the RVM.
  • To determine if improgan directly engages pain-modulating neurons in the RVM.
  • To compare improgan's effects on RVM neuronal activity with known analgesics like opioids and cannabinoids.

Main Methods:

  • In vivo single-cell extracellular recordings were performed in lightly anesthetized rats.
  • Neuronal activity (ON-cells, OFF-cells, NEUTRAL-cells) in the RVM was recorded before and after improgan administration.
  • The effects of improgan on neuronal firing patterns during noxious stimulation were analyzed.

Main Results:

  • Improgan administration led to continuous activity of OFF-cells, which normally inhibit nociception.
  • ON-cell discharge, associated with nociceptive facilitation, was depressed by improgan.
  • NEUTRAL-cell firing remained unaffected, indicating a specific modulation of pain pathways, not a general neuroexcitatory effect.

Conclusions:

  • Improgan engages RVM pain-modulating neurons to produce antinociception.
  • Its effects on RVM neuronal activity (activating OFF-cells, inhibiting ON-cells) are comparable to mu-opioids and cannabinoids.
  • This suggests a common downstream mechanism for analgesia involving the RVM for improgan, opioids, and cannabinoids, supporting improgan's role as a specific analgesic agent.