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(Model: LE7306)
Determination of the animal threshold response to pain induced in the paw by the application of a uniformly increasing pressure

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! NEW RESEARCH WORK ! A recent publication by R. Weibel, D. Reiss, L. Karchewski, O. Gardon, A. Matifas et al. in "PLOS One" highlights the merits of using Bioseb's Rat Paw Pressure: Mu Opioid Receptors on Primary Afferent Nav1.8 Neurons Contribute to Opiate-Induced Analgesia: Insight from Conditional Knockout Mice

Mu Opioid Receptors on Primary Afferent Nav1.8 Neurons Contribute to Opiate-Induced Analgesia: Insight from Conditional Knockout Mice
R. Weibel, D. Reiss, L. Karchewski, O. Gardon, A. Matifas et al.
IGBMC Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Illkirch, France
Published in "PLOS One" (2013-09-12)

Opiates are powerful drugs to treat severe pain, and act via mu opioid receptors distributed throughout the nervous system. Their clinical use is hampered by centrally-mediated adverse effects, including nausea or respiratory depression. Here we used a genetic approach to investigate the potential of peripheral mu opioid receptors as targets for pain treatment. We generated conditional knockout (cKO) mice in which mu opioid receptors are deleted specifically in primary afferent Nav1.8-positive neurons. Mutant animals were compared to controls for acute nociception, inflammatory pain, opiate-induced analgesia and constipation. There was a 76% decrease of mu receptor-positive neurons and a 60% reduction of mu-receptor mRNA in dorsal root ganglia of cKO mice. Mutant mice showed normal responses to heat, mechanical, visceral and chemical stimuli, as well as unchanged morphine antinociception and tolerance to antinociception in models of acute pain. Inflammatory pain developed similarly in cKO and controls mice after Complete Freund’s Adjuvant. In the inflammation model, however, opiate-induced (morphine, fentanyl and loperamide) analgesia was reduced in mutant mice as compared to controls, and abolished at low doses. Morphine-induced constipation remained intact in cKO mice. We therefore genetically demonstrate for the first time that mu opioid receptors partly mediate opiate analgesia at the level of Nav1.8-positive sensory neurons. In our study, this mechanism operates under conditions of inflammatory pain, but not nociception. Previous pharmacology suggests that peripheral opiates may be clinically useful, and our data further demonstrate that Nav1.8 neuron-associated mu opioid receptors are feasible targets to alleviate some forms of persistent pain.


The Randall & Selitto test is based on determination of the animal threshold response to pain induced in the paw by the application of a uniformly increasing pressure.

Operating principle In the BIOSEB rat paw-pressure, a stimulation unit allows the gradual increase (at selectable rates) of the pressure applied on the animal paw. The pressure increase is achieved by a step-motor inducing the progressive advancement of a sliding support with a distal conic tip (1 mm diameter).

The conic tip is mounted on an extensiometric load cell, making possible the visualization on the digital display of the current force applied at each moment of the test (grams). The motor and tip units are mounted on a pivoting stand preventing any excess pressure on the animal paw.

The Control Unit makes possible the adjustment of the force transducer, balance and reset, as well as the selection of the step-motor current speed.

A remote foot-switch controls the motor turn on / off allowing rapid hands-free experiments. An automatic system is activated once the distal extreme of the sliding support track is reached or when the pedal is released at the test ending point. Then, the motor reverse its rotation at its higher speed, sliding up the conic tip again.

The optional SEDACOM software (new version 2.0 available) can be used and represents an easy and convenient way to visualize and export the data on a computer for further analysis.

Parameters Measured

• Pressure applied on the paw until the withdrawal or animal squeak (rats)
• Pressure applied on the tail until the withdrawal (mice)
• Pressure applied on the paw until a flexor response of the toes (mice)

Key features

• Digital display
• Pressure increasing rate adjustment
• Foot-switch control
• New optional Data Transfer software SEDACOM 2.0

Flat and pointed tip
Flat and pointed tip

Publications (Click on an article to show details and read the abstract)


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Power Supply 110V/220V, 50/60Hz
Stimuli Resolution 1 gram
Maximum Stimuli 999 gram
Material Composition Methacrylate
Computer Requirements PC (Windows 7 or higher)
Maximum number of stations 1 per computer (multiple set-ups also available under request)
Certifications CE Compliant
Control Unit Dimensions 350 (W) x 350 (D) x 130 (H) mm
Stimulation Unit Dimensions 150 (W) x 210 (D) x 166 (H) mm

Rat Paw Pressure
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