An electronic pressure-meter nociception paw test for mice

Abstract

The aim of the present investigation was to describe and validate an electronic mechanical test for quantification of the intensity of inflammatory nociception in mice. The electronic pressure-meter test consists of inducing the animal hindpaw flexion reflex by poking the plantar region with a polypropylene pipette tip adapted to a hand-held force transducer. This method was compared to the classical von Frey filaments test in which pressure intensity is automatically recorded after the nociceptive hindpaw flexion reflex. The electronic pressure-meter and the von Frey filaments were used to detect time versus treatment interactions of carrageenininduced hypernociception. In two separate experiments, the electronic pressure-meter was more sensitive than the von Frey filaments for the detection of the increase in nociception (hypernociception) induced by small doses of carrageenin (30 µg). The electronic pressure-meter detected the antinociceptive effect of nonsteroidal drugs in a dose-dependent manner. Indomethacin administered intraperitoneally (1.8-15 mg/kg) or intraplantarly (30-300 µg/ paw) prevented the hypersensitive effect of carrageenin (100 µg/ paw). The electronic pressure-meter also detected the hypernociceptive effect of prostaglandin E 2 (PGE 2 ; 10-100 ng) in a dosedependent manner. The hypernociceptive effect of PGE 2 (100 ng) was blocked by dipyrone (160 and 320 µg/paw) but not by intraplantar administration of indomethacin (300 µg/paw). The present results validate the use of the electronic pressure-meter as more sensitive than the von Frey filaments in mice. Furthermore, it is an objective and quantitative nociceptive test for the evaluation of the peripheral antinociceptive effect of anti-inflammatory analgesic drugs, which inhibit prostaglandin synthesis (indomethacin) or directly block the ongoing hypernociception (dipyrone).

Morphine peripheral analgesia depends on activation of the PI3Kγ/AKT/nNOS/NO/K ATP signaling pathway

“…Electronic pressure-meter test. Mechanical hypernociception was tested in mice (20-30 g) and rats as previously reported (35,36). In a quiet room, mice or rats were placed in acrylic cages with wire-grid floors.…”

Measuring Changes in Tactile Sensitivity in the Hind Paw of Mice Using an Electronic von Frey Apparatus

“…Reduction in time and intensity of previously specified responses to noxious stimuli are used to measure pain states in these animals as rodent subjects are not otherwise able to report a sensation of pain 6 . Altered responses to temperature and pressure are commonly used as metrics of tissue sensitivity in rodent models of inflammatory nociception that can be caused by infection 7,8 , chemical exposure 6,9,10 , surgical incision 11 , as well as neuropathic pain caused by nerve ligation 12 …”

“…0.4-15 g 13 ) of weighted tips manually applied to test tissue in serial increments until pain behaviors are induced in controls vs. experimental subjects. There are various methods for using these tips or hairs to assess mechanical sensitivity 6,13 ; the most frequently used method is as follows. A tip with a certain pressure (within the series; e.g.…”

“…In addition to increased time spent by each subject confined in a von Frey chamber, this also increases the number of times that test tips of various weights are applied to inflamed tissue causing greater discomfort to the rodents in the study. Furthermore, 50% withdrawal thresholds are calculated and compared between groups of rodents; the individual responses of experimental subjects are typically not normalized to their individual untreated baseline responses with, to our knowledge, one exception 6 . As a consequence, rodent subjects are not usually reported as assigned to treatment groups on the basis of consistent baseline responses within a previously determined range and neither are individual subjects evaluated on the basis of a consistently applied set of exclusion criteria that allow for baseline responses to be standardized for any particular set of studies and assays.…”

An electronic pressure-meter nociception paw test for rats

“…In recent years, classical von Frey filaments have become popular among mechanical tests applied to rats (3)(4)(5), although this test presents some disadvantages such as the large number of attempts required to evaluate the nociceptive threshold and the problems with the standardization of the filaments (6). The electronic pressure-meter has been previously used in humans (7) and rats (8).…”