Okamoto K, Tashiro A, Hirata H, Bereiter D A
Department of Surgery, Rhode Island Hospital, Brown Medical School, Providence, RI 02903, USA.
Pain. 2005 Mar;114(1-2):203-11. doi: 10.1016/j.pain.2004.12.013. Epub 2005 Jan 26.
Sex differences in the cellular responses to morphine were examined in an animal model of temporomandibular joint (TMJ) pain. TMJ-responsive neurons were recorded in the superficial laminae at the trigeminal subnucleus caudalis/upper cervical cord (Vc/C(2)) junction region, the initial site of synaptic integration for TMJ afferents, in male and cycling female rats under barbiturate anesthesia. Unit activity was evoked by local injection of bradykinin into the TMJ capsule at 30 min intervals and the effects of morphine sulfate (0.03-3 mg/kg, i.v.) were assessed by a cumulative dose regimen. Morphine caused a dose-related inhibition of bradykinin-evoked unit activity in males and diestrous females in a naloxone-reversible manner, while evoked unit activity in proestrous females was not reduced. The apparent sex hormone-related aspect of morphine analgesia was selective for evoked unit activity, since the spontaneous activity of TMJ units was reduced similarly in all groups, while the convergent cutaneous receptive field area of TMJ units did not change in any group. These results were consistent with the hypothesis that sex hormone status interacts with pain control systems to modify neural activity at the level of the Vc/C(2) junction region relevant for TMD pain.
在颞下颌关节（TMJ）疼痛的动物模型中研究了细胞对吗啡反应的性别差异。在巴比妥类麻醉下，对雄性和处于发情周期的雌性大鼠，在三叉神经尾侧亚核/颈髓上段（Vc/C₂）交界处的浅层记录TMJ反应性神经元，此处是TMJ传入神经突触整合的起始部位。每隔30分钟向TMJ囊内局部注射缓激肽诱发单位活动，并通过累积剂量方案评估硫酸吗啡（0.03 - 3 mg/kg，静脉注射）的作用。吗啡以纳洛酮可逆的方式对雄性和动情间期雌性大鼠缓激肽诱发的单位活动产生剂量相关的抑制作用，而在动情前期雌性大鼠中诱发的单位活动并未降低。吗啡镇痛的明显性激素相关方面对诱发的单位活动具有选择性，因为TMJ单位的自发活动在所有组中均有类似降低，而TMJ单位的汇聚性皮肤感受野面积在任何组中均未改变。这些结果与以下假设一致，即性激素状态与疼痛控制系统相互作用，在与颞下颌关节紊乱病（TMD）疼痛相关的Vc/C₂交界区域水平改变神经活动。
