Study type: Medical/biological study (experimental study)

Comparative effect of thermal, mechanical, and electrical noxious stimuli on the electroencephalogram of the rat. med./bio.

Published in: Br J Anaesth 2007; 98 (3): 366-371

Aim of study (acc. to author)

There were two aims of this study:
1) to compare the EEG changes caused by cutaneous application of noxious thermal (52°C water bath), mechanical (forceps clamp 20 N), and electrical stimuli (50 V, 50 Hz for 2 s).
2) to identify the most promising modality of noxious stimulation that could be applied to future studies investigating EEG changes during the application of a cutaneous phasic acute pain stimulus.

Background/further details

The authors hypothesized that the stimuli investigated would cause quantitatively different EEG responses, because the perception of pain associated with each stimulus is qualitatively different. Thermal, mechanical, or electrical noxious stimuli are frequently applied in studies investigating EEG responses to noxious stimulation in animals, and these models have been used to investigate modulation of these responses by co-administration of different drugs.
48 (anesthetized) rats were divided into three groups (each group one stimulus).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 2 seconds

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 2 seconds
Exposure setup
Exposure source
Setup two stainless steel needle electrodes 1 cm apart at the right lateral tail
Additional info for measurement of reaction 6 silver-silver chloride electrodes 0.4 mm x 8 mm were placed in contact with the dura through holes in the skull
Parameters
Measurand Value Type Method Mass Remarks
cf. remarks - - - - voltage: 50 V

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • before exposure
  • after exposure

Main outcome of study (acc. to author)

Different noxious stimuli caused differing EEG alterations. Therefore, extrapolation of data between EEG studies using different modalities should be avoided. The variable EEG response to the mechanical and thermal stimuli suggests that these are unsuitable stimuli to investigate EEG responses to noxious stimulation in anaesthetized rats.

Study character:

Study funded by