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A noninvasive method for studying quantitatively heat-evoked nocifensive hindlimb withdrawal reflexes in lightly
M M Hämäläinen1, T Kauppila, T Taira
1Department of Physiology, University of Helsinki, Finland.
Abstract:
We have developed a noninvasive method for studying quantitatively the magnitude of hindlimb withdrawal reflexes induced by noxious heat in lightly anesthetized rats. The amplitude, latency, and duration of the hindlimb withdrawal was determined by a very small piezoceramic device placed on the hamstring muscle while the glabrous skin of the hindpaw was stimulated using a feedback-controlled contact thermostimulator. An increase in the amplitude and duration of the withdrawal response, concomitant with a decrease in the response latency, was found with increasing stimulus temperature. The sensitivity of the method was verified using morphine, which produced a dose-related (3.5-7.0 mg/kg) attenuation of all these response components. The use of a piezoceramic device for measuring the withdrawal response provides a quantitative, noninvasive method for evaluating the magnitude of various components of the nocifensive withdrawal reflexes induced by noxious stimuli in lightly anesthetized rats.