Serotonin Influences the Endogenous Opiate Peptides in the Rat Spinal Cord to Participates in Pain Modulation

Yan-Juan Pan, Zhi-Kui Yin, Jun Yang, Ying Zhao, Da-Xin Wang

College of Pharmacy, Xinxiang Medical University, Henan, China.
College of Pharmacy, Xinxiang Medical University, Henan, China; 2Subei People’s Hospital of Jiangsu Province, Yangzhou University, Jiangsu, China.
Subei People’s Hospital of Jiangsu Province, Yangzhou University, Jiangsu, China..

DOI: 10.4236/ojanes.2012.22008                

Abstract

Spinal cord is a necessary pathway that transfers the body nociceptive inputs to the brain. Endogenous opiate peptides have been proven to participate in the nociceptive process at spinal level. It has reported that serotonin (5-HT, 5-hydroxytryptamine) in spinal cord plays a role in pan modulation, which can be blocked by opiate receptor antagonists. The present study was designed to investigate the interaction between 5-HT and endogenous opiate peptides at rat spinal level effecting on pain modulation. The results showed that 1) pain stimulation increased not only leucine-enkephalin (L-Ek), β-endorphin (β-Ep) and dynorphin A_1-13 (DynA_1-13) concentrations but also 5-HT and 5-hydorxyindoleace acid (5-HIAA, the 5-HT main metabolic product) concentrations in spinal cord significantly; 2) 5-HT could increase L-Ek, β-Ep and DynA_1-13 concentrations in spinal cord in a dose-dependent manner, whereas cypotolamine (a 5-HT receptor antagonist) decreased L-Ek, β-Ep and DynA_1-13 concentrations in spinal cord. The data suggested that 5-HT antinociceptive role might be involved in the endogenous opiate peptide system through 5-HT receptors at spinal level.

Keywords

Serotonin; Endogenous Opiate Peptide; Spinal Cord; Antinociception

Conflicts of Interest

The authors declare no conflicts of interest.

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