LONG-TERM POTENTIATION IN DORSAL HORN NEURONES INDUCED BY LOW FREQUENCY STIMULATION
Research field:Other
Authors:Fiskå A, Svendsen F, Rygh LJ, Gjerstad J, Tjølsen A, Hole K
Address of presenting
author:		Kjell Hole, Department of Physiology, University of Bergen, Årstadveien 19, 5009 Bergen, Norway.
E-mail:kjell.hole@pki.uib.no
Phone:+47-55586412
Fax:+47-55586410
Text of abstract Introduction
Understanding mechanisms of plasticity in spinal modulation of nociception may be important for the understanding of mechanisms of long-lasting pain. Previously we have shown that long-term potentiation (LTP) can be induced in single wide dynamic range (WDR) neurones in the dorsal horn after high-frequency stimulation of the sciatic nerve in intact urethane anaesthetized rats. Here we report the effect of a low-frequency conditioning stimulus on the same neurones.

Methods
Extracellular single unit recordings of firing responses of WDR cells to single test stimuli were made in intact urethane anaesthetized rats. High-frequency conditioning stimulation (20 trains each 2 s, 10 s intervals, 100 Hz, 0.5 ms pulses, 6 times the threshold for activating C-fibres) was used.

Results
The C-fibre-evoked responses were increased to 195 % of baseline values (P=0.018). Low-frequency conditioning stimulation (3 Hz) produced a similar increase of the C-fibre evoked responses (183% of baseline, P=0.029).

Conclusions
Thus, a spinal LTP can be induced with a stimulus submaximally activating C-fibres. This finding suggests that physiological stimuli may induce LTP of WDR neurones. The model presented here may be an important tool for further investigations of mechanisms of plasticity in spinal modulation of nociception.

Supported by the European Commission, the Norwegian Research Council and the Norwegian Cancer Society.

References
Svendsen,F., Rygh,L.J., Gjerstad,J., Fiskå,A., Hole,K.& Tjølsen, A. 1999. Brain Res. Protocols 4, 165-172.

Keywords:LTP, nociception, dorsal horn

Created 2000-04-23