Fig. 7

Effect of intrathecal pre-administration of RU38486 on exacerbated post-surgical pain induced by short-term immobilization stress. a, b Mechanical stimuli. c, d Heat stimuli. e Cold stimuli. a, c, e Responses of ipsilateral paws. b, d Responses of contralateral paws. The incision plus immobilization plus intrathecal vehicle (In + Im + V) group had significantly lower paw withdrawal threshold to mechanical stimulation (a) and shorter paw withdrawal latencies to heat (c) and cold (e) stimuli on the ipsilateral side on day 9 post-incision than the incision plus control plus vehicle group. In contrast, RU38486 (2 μg/10 μl) 1 h before each 6 h of immobilization for 3 days completely abolished these reductions (a, c, e). RU38486 did not alter basal paw withdrawal responses to mechanical, heat, and cold stimuli on the contralateral side of the incision plus immobilization group (b, d) and on either ipsilateral (a, c, e) or contralateral (b, d) side of the sham plus immobilization group. Intrathecal vehicle (V) did not affect basal paw withdrawal responses on either side of any group. Mean ± SEM. **P < 0.01 vs the corresponding sham plus control group with intrathecal vehicle. N = 5/group. In incision, Im 3d immobilization, V vehicle