Related Experiment Video
Updated: Jul 16, 2026
04:11
A Conditioned Place Preference Protocol for Measuring Incubation of Craving in Rats
Published on: November 6, 2018
Nucleus accumbens NMDA receptor subunit expression and function is enhanced in morphine-dependent rats
Fraser Murray1, Neil J Harrison, Sarah Grimwood
1AstraZeneca, Alderley Park, Macclesfiled, Cheshire, SK10 4TG, UK.
European Journal of Pharmacology
|February 27, 2007
Summary
Morphine dependence alters N-methyl-d-aspartate (NMDA) receptor expression, decreasing it in some brain areas but increasing it in the nucleus accumbens. This NMDA receptor change enhances function, potentially contributing to opiate dependence.
Area of Science:
- Neuroscience
- Pharmacology
- Molecular Biology
Background:
- Previous studies indicated reduced N-methyl-d-aspartate (NMDA) receptor subunits in the forebrain of morphine-dependent rats.
- Morphine dependence is associated with alterations in neurotransmitter systems, including dopamine and glutamate.
Purpose of the Study:
- To investigate regional differences in NMDA receptor expression in morphine-dependent rats.
- To determine the functional relevance of these NMDA receptor changes in the context of opiate dependence.
Main Methods:
- Western blotting was used to quantify NR1, NR2A, and NR2B NMDA receptor subunit protein expression in specific brain regions (frontal cortex, hippocampus, nucleus accumbens).
- MK-801-induced hyperactivity and dopamine metabolism were assessed in morphine-dependent and control rats to evaluate NMDA receptor function.
Main Results:
- NR1 and NR2A NMDA receptor subunits decreased in the frontal cortex and hippocampus but increased significantly in the nucleus accumbens of morphine-dependent rats.
- NR2B subunit expression remained unchanged across all examined brain regions.
- MK-801-induced hyperactivity and dopamine metabolism increases were significantly enhanced in the nucleus accumbens of morphine-dependent rats.
Conclusions:
- NMDA receptor function, particularly involving the NR2A subunit in the nucleus accumbens, is enhanced in morphine-dependent rats.
- This enhanced NMDA receptor function in the nucleus accumbens may play a crucial role in the neurobiological mechanisms underlying opiate dependence.
More Related Videos
Related Concept Videos
01:22Opioid 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...
01:25Analgesia 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...
01:15Drug Abuse and Addiction: Pharmacological Phenomena
Drug dependence, abuse, and addiction are complex phenomena that can precipitate various abnormal states. Physical dependence refers to a state of pharmacological adaptation to a drug. This adaptation often results in tolerance—a reduced response to the drug after repeated administrations. When the drug use is abruptly stopped, withdrawal symptoms occur due to the body's need to readjust from the pharmacologically induced imbalance. However, tolerance and withdrawal symptoms do not necessarily...
01:15Opioid Analgesics: Synthetic and Semisynthetic Opioids
Synthetic and semisynthetic opioids are pivotal in pain management and tackling opioid addiction. Semisynthetic opioids, including morphinans (morphine derivatives), oxycodone, oxymorphone, hydrocodone, and hydromorphone, have improved pharmacokinetic profiles compared to morphine. Additionally, heroin and 6-MAM (6-Monoacetylmorphine) show better CNS penetration than morphine due to heightened lipid solubility. Hydromorphone, a potent opioid, undergoes hepatic metabolism to form the active...
01:20Opioid Analgesics: Morphine and Other Natural Cogeners
Opioids are a class of drugs that mimic endogenous opioid peptides and act on opioid receptors, and help in pain relief. These compounds are classified as natural, synthetic, or semi-synthetic. Natural opioids, like morphine, codeine, and thebaine, are derived from the opium poppy plant (Papaver somniferum or Papaver album) and are termed opiates. Synthetic opioids are artificial, while semi-synthetic opioids combine natural and synthetic compounds. Morphine, a prototypical opioid, possesses a...