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Intrathecal injection of [Sar~(9), Met (O_(2))~(11)]-substance P, neurokinin-1 receptor agonist, increases nitric oxide synthase expression and nitric oxide production in the rat spinal cord

Sun Xiaocai, Li Wenbin, Li Shuqin, Li Qingjun, Chen Xiaoling, Ai Jie

Department of Pathophysiology,Institute of Basic Medicine,Hebei Medical University.Shijiazhuang 050017,Hebei

Abstract

In the spinal cord, nitric oxide (NO) pathway is involved in pain and hyperalgesia, and nitric oxide synthase (NOS) expression and NO production are upregulated following several noxious and lesion stimuli. However, the mechanism of the increases is yet not well understood. The present study was designed to address the question of whether substance P (SP) released in the spinal cord enhances NOS expression and NO production of the spinal cord in rats. [Sar~(9), Met (O_(2))~(11)]-substance P (Sar-SP), a neurokinin-1 (NK-1) receptor agonist, was administered by intrathecal injection via L_(5)-L_(6) intervertebral space to induce nociception. The pain threshold was determined by hot water induced tail flick test. NOS expression of the L_(5) segment of the spinal cord was determined using NADPH-d histochemical staining. NO production of the lumbar enlargement of the spinal cord was determined by assaying NO~(-)_(3) and NO~(-)_(2), the end product of NO metabolism, using the method of aqua fortis reduction.

Key words: Substance P;nitric oxide synthase;Nitric oxide;Sar-SP;Spantide nociception;Spinal cord;

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Citing This Article：

Sun Xiaocai, Li Wenbin, Li Shuqin, Li Qingjun, Chen Xiaoling, Ai Jie. Intrathecal injection of [Sar~(9), Met (O_(2))~(11)]-substance P, neurokinin-1 receptor agonist, increases nitric oxide synthase expression and nitric oxide production in the rat spinal cord. Acta Physiol Sin 2003; 55 (6): (in Chinese with English abstract).