Related Experiment Video
Updated: Jun 3, 2026
04:11
A Conditioned Place Preference Protocol for Measuring Incubation of Craving in Rats
Published on: November 6, 2018
Dorsal raphe nucleus enkephalin peptide modulates behavioral preference.
Kathryn Braden1, Andrew Trinagel2, Eric Acevedo2
1Biophotonics Research Center, Mallinckrodt Institute of Radiology, Washington University School of Medicine, Saint Louis, MO, USA. bradenk@wustl.edu.
Summary
Disrupting enkephalin in the dorsal raphe nucleus (DRN) alters pain and motivation. This study reveals novel opioid neuron populations in the DRN influencing motivated behaviors distinct from serotonin pathways.
Area of Science:
- Neuroscience
- Molecular Biology
- Behavioral Science
Background:
- The endogenous opioid system modulates motivation and affect.
- The dorsal raphe nucleus (DRN) is a key midbrain hub for behavioral control and opioid signaling.
Purpose of the Study:
- To investigate the role of DRN opioid signaling in motivated behaviors.
- To characterize the cellular distribution of enkephalin (Penk) neurons within the DRN.
Main Methods:
- CRISPR-Cas9 mediated knockdown of preproenkephalin (Penk) in the DRN of Penk-Cre mice.
- Assessment of behavioral responses to inflammatory pain, aversive stimuli, and appetitive rewards.
- Hiplex in situ hybridization to analyze gene expression and cell-type specific localization of DRN Penk.
Main Results:
- Knockdown of DRN Penk enhanced mechanical sensitivity and odor avoidance.
- Loss of DRN Penk reduced sucrose preference and social interaction.
- DRN Penk neurons are primarily glutamatergic and GABAergic, not serotonergic.
- Subtype-specific knockdown did not fully replicate behavioral deficits, suggesting a novel neuronal population.
Conclusions:
- DRN enkephalin signaling is critical for regulating pain, aversion, and reward-seeking behaviors.
- Enkephalin neurons in the DRN are distinct from serotonin cells and may represent a novel circuit for motivated behaviors.
Related Concept Videos
01:30Regulation of Food Intake
Short-term regulation of food intake primarily involves neural signals from the gastrointestinal (GI) tract, blood nutrient levels, and GI tract hormones. Communication between the gut and brain via vagal nerve fibers plays a significant role in evaluating the contents of the gut. Clinical studies have shown that protein ingestion produces a more prolonged response in these nerve fibers compared to an equivalent amount of glucose. Additionally, the activation of stretch receptors caused by GI...
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...