title: The major histocompatibility complex genes impact pain response in DA and DA.1U rats.
abstract: Our recent studies have shown that the difference in basal pain sensitivity to mechanical and thermal stimulation between Dark-Agouti (DA) rats and a novel congenic DA.1U rats is major histocompatibility complex (MHC) genes dependent. In the present study, we further used DA and DA.1U rats to investigate the role of MHC genes in formalin-induced pain model by behavioral, electrophysiological and immunohistochemical methods. Behavioral results showed biphasic nociceptive behaviors increased significantly following the intraplantar injection of formalin in the hindpaw of DA and DA.1U rats. The main nociceptive behaviors were lifting and licking, especially in DA rats (P<0.001 and P<0.01). The composite pain scores (CPS) in DA rats were significantly higher than those in DA.1U rats in both phases of the formalin test (P<0.01). Electrophysiological results also showed the biphasic increase in discharge rates of C and Aδ fibers of L5 dorsal root in the two strains, and the net change of the discharge rate of DA rats was significantly higher than that of DA.1U rats (P<0.05). The mechanical thresholds decreased after formalin injection in both strains (P<0.01), and the net change in the mechanical threshold in DA was greater than that in DA.1U rats (P<0.05). The expression of RT1-B, representation of MHC class II molecule, in laminae I-II of L4/5 spinal cord in DA rats was significantly higher than that in DA.1U rats in the respective experimental group (P<0.05). These results suggested that both DA and DA.1U rats exhibited nociceptive responses in formalin-induced pain model and DA rats were more sensitive to noxious chemical stimulus than DA.1U rats, indicating that MHC genes might contribute to the difference in pain sensitivity.
authors: Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China.
authors: Yuan
authors: Y
authors: Guo
authors: Department of Pharmacology and Toxicology in the Brody School of Medicine at East Carolina University, Greenville, NC, USA.
authors: Fan-Rong
authors: FR
authors: Yao
authors: Research Center, Stomatological Hospital, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710004, PR China; Department of Neural and Pain Sciences, University of Maryland Dental School, 650 West, Baltimore Street, Baltimore, MD 21201, USA.
authors: Dong-Yuan
authors: DY
authors: Cao
authors: Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China.
authors: Li
authors: L
authors: Li
authors: Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China.
authors: Hui-Sheng
authors: HS
authors: Wang
authors: Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China.
authors: Wen
authors: W
authors: Xie
authors: Department of Physiology and Pathophysiology, School of Basal Medical Science, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China. Electronic address: zhaoy502@mail.xjtu.edu.cn.
authors: Yan
authors: Y
authors: Zhao
mesh_terms: D000818:Animals; D020296:Animals, Congenic; D004195:Disease Models, Animal; D004202:Disinfectants / Q000633:toxicity; D005260:Female; D005557:Formaldehyde / Q000633:toxicity; D005786:Gene Expression Regulation / Q000235:genetics; D006649:Histocompatibility Antigens / Q000378:metabolism; D006930:Hyperalgesia / Q000503:physiopathology; D008285:Major Histocompatibility Complex / Q000235:genetics*; D008297:Male; D009412:Nerve Fibers / Q000502:physiology; D010146:Pain / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology; D010812:Physical Stimulation / Q000009:adverse effects; D051381:Rats; D013116:Spinal Cord / Q000503:physiopathology; D013997:Time Factors
chemical_list: D004202:Disinfectants; D006649:Histocompatibility Antigens; C038353:histocompatibility antigens RT, rat; D005557:Formaldehyde
keywords: DA rats; DA.1U rats; Formalin; Major histocompatibility complex; Pain; RT1-B