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Sypniewska M. 
“The Effect of Baclofen on the Hind Limb Flexor Reflex of the Spinal Rat”. 
Pol. J. Pharmacol. Pharm.. 1979;31(5):493-501.
The effect of baclofen on the hind limb flexor reflex of the spinal rat was studied. Male spinal Wistar rats (170-200 g) were used. The effect of i.v. drugs on the neuromuscular transmission was assessed as twitches of the tibial anterior muscle in response to electric stimulation of the peripheral part of the severed sciatic nerve. The effect on picrotoxin-induced convulsions was tested in rats pretreated with 5 mg/kg i.p. baclofen (Lioresal, ClBA-Geigy) and 1 hr later with 6 mg/kg s.c. picrotoxin (Fluke). Baclofen (0.05-0.5 mg/kg) either had no effect on the flexor reflex or reduced it insignificantly. Higher doses produced a depression of the flexor reflex, and a dose of 5 mg/kg completely abolished this reflex. The action of baclofen appeared shortly after administration and was long-lasting. Picrotoxin and bicuculline (Sigma) produced stimulation of the flexor reflex. Picrotoxin (2 mg/kg) stimulated this reflex which occasionally was accompanied by convulsions. The action of picrotoxin commenced a few minutes after the injection and lasted for 0.5-1 hr. The animals did not survive higher doses of picrotoxin. Baclofen (0.5-1 mg/kg) diminished the stimulatory action of picrotoxin. The high dose of baclofen (5 mg/kg) completely antagonized the stimulatory action of picrotoxin abolishing the flexor reflex and prevented the stimulation induced by this compound. Increasing doses of picrotoxin (2, 3 and 4 mg/kg), given in succession to the rat with the reflex abolished by baclofen resulted in occurrence of single twitches preceding the death of animals. Bicuculline (0.5-1 mg/kg) stimulated the flexor reflex; it was violent but short lasting and always accompanied with convulsions. Baclofen inhibited the stimulatory action of bicuculline. Administration of increasing doses of the latter drug (0.5, 0.75 and 1 mg/kg) did not cause stimulation of the flexor reflex already abolished by previous injection of baclofen. Baclofen, 5 mg/kg, did not change the stimulation induced by clonidine (Boehr.Ingelheim) (0.1 mg/kg); it antagonized the effect induced by amphetamine (0.5 mg/kg, SK+F). Baclofen (5 mg/kg) diminished also the stimulation induced by quipezine (MilesAmes, 0.1 mg/kg) and LSD (5 mcg/kg Delysid, Sandoz) and completely abolished the reaction induced by fenfluramine (1 mg/kg, Servier). Even at 5 mg/kg baclofen had no effect on the neuromuscular transmission. Baclofen did not protect either intact nor spinal rats against picrotoxin-induced convulsions.
Notes # : Only abstract on file
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