Two Methods of Modeling of Spinal Superreflexia in Rats
We studied the relations between conditions of induction and quantitative characteristics of abnormally amplified monosynaptic reflex discharges (MSD) in ventral roots (VR) observed in two experimental situations: (i) 5 days after simultaneously performed denervation (transection of the sciatic nerve) and spinalization at the L1 level, and (ii) 5 days after preliminary denervation and with systemic injection of 4-aminopyridine (4-AP) in the course of the acute experiment. In both situations, the amplitude of the MSD conducted via the VR was close to the threshold of excitation of fibers in this root or even exceeded this value (a superreflexia phenomenon). Under both (i) and (ii) conditions, we observed generation of the second component of MSD in the VR, which was probably related to transition of excitation from excited to “silent” fibers in the VR. The latter of the above variants of induction superreflexia (5 days after denervation and with the effect of 4-AP in the acute experiment) is preferred because there is practically no death of the experimental animals in the course of the chronic experiment, there are no negative post-spinalization changes in the spinal cord, and the possibility of supraspinal activation of motoneurons is preserved.
Keywordsmonosynaptic reflex discharges spinal cord denervation 4-aminopyridine chronic spinalization superreflexia
Unable to display preview. Download preview PDF.
- 2.E. A. Makii and I. A. Krayushkina, “On the possibility of ephaptic excitation of the ventral root fibers under conditions of extremely expressed spinal hyperreflexia,” Byull. Eksp. Biol. Med., No. 6, 581–583 (1995).Google Scholar
- 3.E. A. Makii, P. F. Nerush, and A. G. Rodinskii, “Segmental reflex activity under conditions of superreflexia evoked by the action of substances increasing the activity of the spinal cord,” Neurophysiology, 32, No.2, 92–98 (2000).Google Scholar
- 4.H. Asada, W. Yasumo, and Y. Yamaguchi, “Evaluation of supraspinal involvement in spinal hyperactivity in rats with peripheral nerve section,” Neurosci. Res., Suppl., No. 9, 159 (1989).Google Scholar
- 6.R. Navarette, “Early changes in motoneurons synaptic activation recorded in vitro following neonatal nerve injury in the rat,” J. Physiol., 438, 220 (1991).Google Scholar
- 7.I. Ya. Serdyuchenko, P. M. Mantulo, and I. M. Karneta, “Effect of 4-aminopyridine on the recovery of segmental reflexes after transection of the sciatic nerve in rats,” Neirofiziologiya, 18, No.5, 702–705 (1986).Google Scholar
- 13.S. Jasser and A. Smith, “Effects of axotomy on sodium currents in bull frog sympathetic neuron,” Can. J. Physiol. Pharmacol., 70, No.5, A355–XXI (1992).Google Scholar
- 15.E. A. Makii and A. G. Rodinskii, “Structural/functional basis of a superreflexia phenomenon and abnormally increased responses in the rat spinal cord,” Arkh. Klin. Eksp. Med., 11, No.1, 81–85 (2002).Google Scholar
- 16.D. S. Vorontsov, General Electrophysiology [in Russian], Medgiz, Moscow (1961).Google Scholar