The 5-HT1B/1D Agonist CGS-12066B Attenuates Clasp Knife Reflex in the Cat. Miller, J.F., K.D. Paul, W.Z. Rymer, and C.J. Heckman. Veterans Administration, Lakeside Hospital and Department of Physiology, Northwestern University School of Medicine, Chicago, IL 60611.
APStracts 2:0127N, 1995.
SUMMARY AND CONCLUSIONS
1. The effect of intrathecal injection of the selective serotonin (5-HT)1B/1D receptor agonist CGS-12066B maleate (825 nmoles) was assessed on stretch- evoked clasp knife inhibition of hindlimb ankle extensor muscle reflex force in precollicular decerebrate cats in which neural transmission in dorsolateral spinal pathways was blocked bilaterally by focal cooling. 2. During cold block, ramp and hold stretches of the medial gastrocnemius muscle (MG) evoked only a brief reflex excitation which was followed by powerful, long-lasting inhibition (the clasp knife reflex). Both the amplitudes of peak force evoked by the ramp and sustained force output during the last 500 ms of the hold phase of the stretch were depressed by more than 50%. 3. Reflex force output during the hold portion of stretch was significantly improved on postdrug cold block trials, although peak force remained depressed. CGS-12066B did not significantly alter stretch-evoked force output in decerebrate cats when spinal cord neural transmission was unimpaired. 4. These data suggest that selective 5-HT1B/1D agonists may be of therapeutic usefulness in the treatment of reflex disorders arising from partial spinal cord injury. 

Received 9 March 1994; accepted in final form 11 April 1995.
APS Manuscript Number J158-5.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on  2 May 1995.