[The role of HO/CO in the spinal nociception transmission and hyperalgesia of rats induced by formalin].

Objective: To investigate the role of heme oxygenase and carbon monoxide (HO/CO) in the development of spontaneous pain and hyperalgesia of rats induced by formalin injection.

Methods: Zinc protoporphyrin Znpp (the inhibitor of HO) was intrathecally injected to the rats with formalin inflammatory pain. Hemin (the agonist of HO) was intrathecally injected to the normal rats.

[Effect of formalin inflammatory pain on expression of HO-1 in spinal cord of rats].

Objective: To investigate whether formalin inflammatory pain can induce the change in heme oxygenase-1 (HO-1) expression in the spinal cord of rats or not and the time course character.

Methods: 42 SD rats were divided into 7 groups (n = 6): control formalin 6 h, formalin 12 h, formalin 1 d, formalin 2 d, formalin 3 d and formalin 7 d groups. Rats were subcutaneously injected with 0.

[Effects of nitric oxide on spontaneous pain reaction and neuronal apoptosis in the spinal cord of rats induced by formalin inflammatory pain].

Objective: To observe whether formalin inflammatory pain can induce neuron apoptosis in rats spinal cord or not and the effects of nitric oxide on the spontaneous pain reaction and neuron apoptosis in the spinal cord of rats with formalin inflammatory pain.

Methods: Formalin-induced paw licking time was used to reflect the degree of spontaneous pain of rats, and the flow cytometry was used to detecte neuron apoptosis rate of spinal cord.

Results: Compared with control group, the apoptosis ratio of spinal neuron was increased in the rats with formalin inflammatory pain, and peaked at 3d after formalin injection.