Comparison of analgesic effect following different thalamotomy in rats / 中国神经精神疾病杂志

ABSTRACT

Background To provide clinical evidence for ablative application by comparison of the analgesic effect following different thalamotomy in rats.Methods Thirty rats were randomly assigned into sham and 4 thalamotomies groups central medial thalamic nucleus ( CM), parafascicular thalamic nucleus ( PF), ventral posterolateral thalamic nucleus (VPL), and CM +Cigulum (cg). Two μL 10% phenol dissolved in glycerin were used for stereotactic thalamotomy. The thermal pain thresholds before and after procedures were evaluated with the tail stimulate test. The formalin test was carried out in an open field apparatus where the animal formalin-induced responses (licking duration, flexing duration, and flinching frequency of the injected paw) were recorded for 60 min.Results Changes of pain thresholds in all ablative groups were significantly higher than that in the sham group, especially it was higher in VPL group. Differences of the factor thalamotomy were found to be due to the shorter licking in the ablative groups than that in the sham group (P ＜0.01 ), whereas flexing duration and flinching frequency were only slightly affected by thalamotomy. Moreover, licking duration was lower in VPL group than in CM and CM + cg groups ( P ＜0.05), whereas nociceptive responses did not differ between the CM and CM+cg groups (P ＞0.05).Conclusions In acute period, CM, PF, VPL, CM + cg neurolysis all showed to elevate the thermal pain threshold and to reduce the pain-induced behavioral responses related to supraspinal neural circuits (licking of the injected paw). Among them, the damage of VPL might be the most active one. CM + cg damage did not get better antinociceptive effect than single CM ablation.