Role of the cerebrospinal fluid-contacting nucleus in the descending inhibition of spinal pain transmission.

Abstract

The brainstem is well recognized as a critical site for integrating descending modulatory systems that both inhibit and facilitate pain at the level of the spinal cord. The cerebrospinal fluid-contacting nucleus (CSF-contacting nucleus) distributes and localizes in the ventral periaqueductal central gray of the brainstem. Although emerging lines of evidence suggest that the CSF-contacting nucleus may be closely linked to transduction and regulation of pain signals, the definitive role of the CSF-contacting nucleus in pain modulation remains poorly understood. In the present study, we determined the role of the CSF-contacting nucleus in rat nocifensive behaviors after persistent pain by targeted ablation of the CSF-contacting nucleus in the brainstem using the cholera toxin subunit B-saporin (CB-SAP), a cytotoxin coupled to cholera toxin subunit B. Compared with CB/SAP, CB-SAP induced complete ablation of the CSF-contacting nucleus, and the CB-SAP-treated rats showed hypersensitivity in responses to acute nociceptive stimulation, and exacerbated spontaneous nocifensive responses induced by formalin, thermal hyperalgesia and mechanical allodynia induced by plantar incision. Furthermore, immunohistochemical experiments showed that the CSF-contacting nucleus was a cluster of 5-HT-containing neurons in the brainstem, and the spinal projection of serotonergic axons originating from the CSF-contacting nucleus constituted the descending 5-HT pathway to the spinal cord. CB-SAP induced significant downregulation of 5-HT in the spinal dorsal horn, and intrathecal injection of 5-HT significantly reversed hypersensitivity in responses to acute nociceptive stimulation in the CB-SAP-treated rats. These results indicate that the CSF-contacting nucleus 5-HT pathway is an important component of the endogenous descending inhibitory system in the control of spinal nociceptive transmission.

• Authors: He Liu, Wei-Wei Yan, Xiao-Xing Lu, Xiu-Li Zhang, Jing-Qiu Wei, Xiao-Yu Wang, Tiao Wang, Tong Wu, Jing Cao, Cui-Jie Shao, Fang Zhou, Hong-Xing Zhang, Peng Zhang, Ting Zang, Xian-Fu Lu, Jun-Li Cao, Hai-Lei Ding, Li-Cai Zhang
• Journal: Experimental neurology (Exp Neurol) Vol. 261 Pg. 475-85 (Nov 2014) ISSN: 1090-2430 [Electronic] United States
• PMID: 25108066 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2014 Elsevier Inc. All rights reserved.

Chemical References

• Ribosome Inactivating Proteins, Type 1
• Formaldehyde
• Serotonin
• Cholera Toxin
• Saporins

Topics

• Animals
• Brain Stem (pathology)
• Cerebrospinal Fluid
• Cholera Toxin
• Disease Models, Animal
• Formaldehyde (toxicity)
• Heart Rate (drug effects)
• Male
• Nerve Net (pathology, physiopathology)
• Neural Pathways (metabolism, physiopathology)
• Pain (etiology, pathology)
• Pain Threshold (drug effects, physiology)
• Rats
• Rats, Sprague-Dawley
• Respiration (drug effects)
• Ribosome Inactivating Proteins, Type 1
• Saporins
• Serotonin (pharmacology)
• Signal Transduction
• Spinal Cord (pathology)