Figure 1

Mechanical and thermal behavioral responses following perineural gp120/hCD4 treatment alone or in combination with a single 25 mg/kg i.p injection of 2'-3'-dideoxycytidine. A) Rats were assessed for low-threshold mechanical sensitivity (von Frey test) at 3, 7, 10, 14, 17, 28 days following perineural gp120/hCD4 treatment. Reduced behavioral thresholds for the hindpaw ipsilateral to the nerve lesion (black square) were significantly different from pre-operative baseline from post-operative day (POD) 3–28. The threshold force for the hindpaw contralateral to the nerve lesion (black diamond), did not meet the pre-determined criteria indicative of mechanical hypernociceptive behavior until POD17. The time course of sham injury did not differ from the uninjured animals (ipsilateral sham, black circle; contralateral sham, black triangle). (n = 10; * p < 0.01). POD: post-operative day after gp120/hCD4 treatment. B) Mean threshold force required for paw withdrawal to Von Frey stimulation following perineural gp120/hCD4 treatment and a single 25 mg/kg i.p injection of 2'-3'-dideoxycytidine (ddC; n = 10). The ddC injection was given on POD14 after gp120 treatment. Reduced behavioral thresholds for the hindpaw ipsilateral (black square) and contralateral (black diamond) to the nerve treatment were seen as early as POD17/post-injection day (PID) 3 and reached the lowest levels by POD21/PID7 (p < 0.01). The time course of sham injury did not differ from the uninjured animals (ipsilateral sham, black circle; contralateral sham, black triangle). C) gp120/hCD4 induced nerve injury did not produce changes in thermal responses as assessed by the Hargreaves test. Each bar is the mean withdrawal latency (± SE) of the hindpaw ipsilateral (white bar) or contralateral (black bar) to the nerve injury at POD 7 and 14 (n = 10). After a single i.p. injection of ddC at POD 14, thermal hyperalgesia was observed as early as PID 3 and reached the shortest latency by PID7 in the paws ipsilateral and contralateral to the gp120/hCD4 treatment. POD: post-operative day after gp120/hCD4 treatment; PID: post-injection day after ddc treatment. (n = 10; *p < .05).