Objective

Warm water immersion therapy (WWIT) has been widely used in the treatment of various clinical conditions, with analgesic and anti-inflammatory effects. However, its mechanism of action has not been fully investigated. The present study analyzed the role of spinal inhibitory neuroreceptors in the antihyperalgesic effect of WWIT in an experimental model of inflammatory pain.

Methods

Mice were injected with complete Freund’s adjuvant (CFA; intraplantar [i.pl.]). Paw withdrawal frequency to mechanical stimuli (von Frey test) was used to determine: (1) the effect of intrathecal (i.t.) preadministration of naloxone (a non-selective opioid receptor antagonist; 5 µg/5 µl), (2); AM281 (a selective cannabinoid receptor type 1 [CB₁] antagonist; 2 µg/5 µl), (3); and 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; a selective adenosine A₁ receptor antagonist; 10 nmol/5 µl), on the antihyperalgesic (pain-relieving) effect of WWIT against CFA-induced hyperalgesia.

Results

Intrathecal naloxone, AM281, and DPCPX significantly prevented the antihyperalgesic effect of WWIT. This study suggests the involvement of spinal (central) receptors in the antihyperalgesic effect of WWIT in a model of inflammatory pain.

Conclusions

Taken together, these results suggest that opioid, CB_1, and A₁ spinal receptors might contribute to the pain-relieving effect of WWIT.

中文翻译：

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脊髓抑制性神经受体在温水浸泡疗法的抗痛觉过敏作用中的作用。

目的

温水浸泡疗法（WWIT）已被广泛用于各种临床疾病的镇痛和抗炎作用。但是，其作用机理尚未得到充分研究。本研究分析了炎症性疼痛实验模型中脊髓抑制神经受体在WWIT的抗痛觉过敏作用中的作用。

方法

给小鼠注射完全的弗氏佐剂（CFA； plant内[i.pl.]）。用爪子对机械刺激的撤药频率（von Frey检验）确定：（1）鞘内预施用纳洛酮（一种非选择性阿片受体拮抗剂； 5 µg / 5 µl）的效果，（2）；AM281（一种选择性的1型大麻素受体[CB ₁ ]拮抗剂； 2 µg / 5 µl），（3）；和1,3-二丙基-8-环戊基黄嘌呤（DPCPX；一种选择性的腺苷A ₁受体拮抗剂； 10 nmol / 5 µl）对WWIT对CFA诱导的痛觉过敏的抗痛觉过敏作用。

结果

鞘内纳洛酮，AM281和DPCPX可以显着预防WWIT的抗痛觉过敏作用。这项研究表明，在炎症性疼痛模型中，脊髓（中央）受体参与了WWIT的抗痛觉过敏作用。

结论

综上所述，这些结果表明阿片样物质，CB ₁和A ₁脊柱受体可能有助于WWIT的止痛作用。