UNCONTROLLABLE NOCICEPTIVE STIMULATION UNDERMINES LOCOMOTOR RECOVERY IN SPINALLY CONTUSED RATS. M.A.Hook*; G.Garcia; E.D.Crown; A.R.Ferguson; R.C.Miranda; J.W.Grau / Dept Psychol, Medical Anatomy, Texas A&M Univ, College Station, TX, USA
Previous studies have shown that intermittent tailshock undermines the recovery of hindlimb function in rats with a contusion injury (Grau, 2001, Soc Neuro Abs, 27, 2039). To further investigate this effect, we compared the consequences of 1) intermittent and continuous shock, and 2) controllability of shock exposure, on the recovery of locomotor function. All rats were anesthetized with pentobarbital and given a mid-thoracic contusion injury (12.5 mm drop). For Experiment 1, subjects were given intermittent shocks (over 14.4 or 72sec; 2 sec ITI), one continuous shock (2.88 or 72 sec), or no shock. The impact of shock treatment was then assessed using the BBB scale. Seventy-two seconds of intermittent or continuous shock undermined recovery (p<.05). In Experiment 2, one group of rats (master) received shock to one leg when they extended the limb (contingent shock). A second group (yoked) received the same amount of shock independent of leg position (noncontingent shock). A third group received no shock. Subjects were trained 24 and 48 hrs (30 min/day) after being given a contusion injury. Master rats learned to maintain the shocked leg in a flexed position, thus minimizing net shock exposure. Yoked rats failed to learn. Recovery of function was then assessed with the BBB scale. Yoked rats displayed significantly less recovery of function than master and unshocked rats. Thus, the effects of nociceptive stimulation are modulated by both the duration and controllability of shock exposure.
Supported by: MH60157 & NS41548 to JWG & RCM.
Citation: M.A.Hook, G.Garcia, E.D.Crown, A.R.Ferguson, R.C.Miranda, J.W.Grau. UNCONTROLLABLE NOCICEPTIVE STIMULATION UNDERMINES LOCOMOTOR RECOVERY IN SPINALLY CONTUSED RATS. Program No. 204.11. 2002 Abstract Viewer/Itinerary Planner. Washington, DC: Society for Neuroscience, 2002. CD-ROM.