Quantification of the hindlimb extensor thrust response in rats

This report describes a procedure for measuring the extensor thrust response (ETR) and summarizes the results of initial validation experiments using adult Long-Evans rats. The ETR can be quickly elicited and the force measured by pressing against the hindlimb footpads with a small rectangular plate...

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Bibliographic Details
Published in:Neurotoxicology and teratology 1997-09, Vol.19 (5), p.405-411
Main Authors: Ross, J.F, Handley, D.E, Fix, A.S, Lawhorn, G.T, Carr, G.J
Format: Article
Language:English
Subjects:
Acrylamide
Amphetamine
Animals
Biological and medical sciences
Central Nervous System Agents - pharmacology
Central Nervous System Agents - toxicity
Central Nervous System Depressants - pharmacology
Central Nervous System Stimulants - pharmacology
Chlorpromazine
Chlorpromazine - pharmacology
Depression, Chemical
Dextroamphetamine - pharmacology
Extensor thrust response
Female
Forelimb - drug effects
Forelimb - physiology
Forelimb/hindlimb grip strength
General aspects. Methods
Hindlimb - drug effects
Hindlimb - physiology
Male
Medical sciences
Neural Conduction - drug effects
Peripheral Nerves - drug effects
Rat
Rats
Reflex - drug effects
Reflex - physiology
Time Factors
Toxicology
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Summary:This report describes a procedure for measuring the extensor thrust response (ETR) and summarizes the results of initial validation experiments using adult Long-Evans rats. The ETR can be quickly elicited and the force measured by pressing against the hindlimb footpads with a small rectangular plate or bar attached to a digital force gauge. Output of the force gauge is analyzed and displayed with commercially available hardware and software. The first experiment compared the acute effects of IP injection of chlorpromazine (CPZ; 1, 4, or 7 mg/kg) or amphetamine (AMP; 0.3, 1, or 3 mg/kg) on the ETR and forelimb/hindlimb grip strength (FL/HL-GS) in male and female rats. CPZ decreased both ETR and FL/HL-GS values. Both 1 and 3 mg/kg AMP increased grip strength values but decreased ETR values. A second experiment compared the evolution of changes in ETR, FL/HL-GS, and peripheral neurophysiological measures during 8 weeks of daily oral dosing of 10 mg/kg acrylamide (ACR) monomer. ACR-treated rats exhibited a progressive decrease in ETR beginning after 3 weeks of dosing, whereas a reduction of HL-GS was observed beginning much later, after 7 weeks of dosing. The deficit in ETR progressed in the absence of any changes in spontaneous or evoked electrophysiological abnormalities in neuromuscular function, but was accompanied by a decrease in peripheral nerve conduction velocity. Taken together, the results indicate that the ETR can be used to characterize functional effects in both single dose and repeated dose experiments. The data also indicate that the ETR does not merely duplicate the information provided by FL/HL-GS, and suggest a hypothesis that the ETR may be sensitive to neurotoxicant-induced changes in somatosensory function.
ISSN:0892-0362
1872-9738
DOI:10.1016/S0892-0362(97)00044-5