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Distribution and effects of 5--HT_(1A) receptors in distal cerebral spinal fluid--contacting neurons in rat brain parenchyma in neuropathic pain

Jiang Wenxu, Zhang Licai

The Affiliated Nanjing Children's Hospital of Nanjing Medical University.Nanjing 210008,Jiangsu

Abstract

The present study aimed to explore the effects of 5-HT_(1A) receptors in the distal cerebral spinal fluid-contacting neurons(CSF-CNs) in rat brain parenchyma in neuropathic pain. The model of neuropathic pain with chronic constriction injury (CCI) of thesciatic nerve was made in Sprague-Dawley rats. The behavioral studies of animal were scored and the paw withdrawal latency (PWL)and paw withdrawal threshold (PWT) were measured. The distribution and expression of 5-HT_(1A) receptors were observed in the distalCSF-CNs in brain parenchyma with double labeling of cholera toxin subunit B with horseradish peroxidase (CB-HRP) and 5-HT_(1A) receptors with immunhistochemistry. The relationship between 5-HT_(1A) receptors in distal CSF-CNs and neuropathic pain wasanalyzed. The results were as follows. On days 1, 3, 7, 14 of neuropathic pain, the PWL was 19.37±2.74, 12.04±1.77, 8.74±1.15 and12.31±1.94, respectively; the PWT was 18.58±3.62, 13.05±1.81, 6.66±1.43 and 11.55±2.01, respectively. CB-HRP-labeled neuronsof two clusters were always found in definite region but not in other area in brain parenchyma. The number of neurons double-labeledwith CB-HRP/5-HT_(1A) receptors in each group was 276.14±36.00, 161.72±28.41,108.64±6.81, and 139.76±44.64, which was about95%, 60%, 40% and 55% of all CB-HRP-iabeled neurons in the four courses of neuropathic pain, respectively. It is suggested that thedistal CSF-CNs are always located in a special region in rat brain parenchyma and most of them have 5-HT_(1A) receptors. A negativecorrelation is found between the expression of 5-HT_(1A) receptors and neuropathic pain.

Key words: cerebral spinal fluid-contacting neuron;5-HT_(1A) receptor;neuropathic pain;Rat

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Citing This Article：

Jiang Wenxu, Zhang Licai. Distribution and effects of 5--HT_(1A) receptors in distal cerebral spinal fluid--contacting neurons in rat brain parenchyma in neuropathic pain. Acta Physiol Sin 2008; 60 (2): 243-248 (in Chinese with English abstract).