Establishment of a rat model of comorbid chronic inflammatory pain and depression using different doses of complete Freund's adjuvant
10.3969/j.issn.1005-4847.2025.05.002
- VernacularTitle:不同剂量完全弗氏佐剂建立慢性炎性疼痛抑郁共病大鼠模型的实验研究
- Author:
Tian WANG
1
;
Pu YANG
;
Xi ZHANG
;
Xin LI
;
Wenjing HUANG
;
Guangmei ZHENG
;
Xinyu HUANG
;
Zhiyi XU
;
Ying HUANG
;
Lili YIN
;
Shengyong SU
Author Information
1. 广西中医药大学第一临床医学院,南宁 530023
- Publication Type:Journal Article
- Keywords:
complete Freund's adjuvant;
different doses;
comorbid chronic pain and depression;
glutamate;
γ-aminobutyric acid;
brain-derived neurotrophic factor;
model study
- From:
Acta Laboratorium Animalis Scientia Sinica
2025;33(5):633-643
- CountryChina
- Language:Chinese
-
Abstract:
Objective To compare the success rate and stability of rat models of comorbid chronic pain and depression induced by different doses of complete Freund's adjuvant(CFA).Methods Sixty SD rats were divided randomly into a control group,low-dose CFA group(CFA-L),and high-dose CFA group(CFA-H)(n=20 rats per group).Rats in the CFA-L and CFA-H groups were injected with 50 and 100 μL CFA,respectively,and rats in the control group were injected with 0.9％sodium chloride solution.The general state,body weight,mechanical withdrawal threshold(MWT),and thermal withdrawal latency(TWL)were observed at 0,7,14,21,and 28 days after modeling.Depressive behavior was evaluated using the open field test(OFT),forced swim test(FST),and tail suspension test(TST).Glutamate(Glu)and γ-aminobutyric acid(GABA)levels in the anterior cingulate cortex were detected by enzyme-linked immunosorbent assay.Brain-derived neurotrophic factor(BDNF)expression in the anterior cingulate cortex was detected by immunohistochemistry,and pathological changes in the anterior cingulate cortex were observed by HE staining.Results(1)Regarding the general condition of the rats,the left ankle joint and toes were obviously red and swollen in the CFA-L and CFA-H groups on the 7th day after modeling,and the swelling was more severe in the CFA-H group.The redness and swelling of the left hind foot and ankle joint and toes gradually recovered in the CFA-L group on days 14,21,and 28 after modeling,but were still obvious in the CFA-H group,and the water and food intake decreased.(2)The body mass was significantly lower in rats in the CFA-H group compared with those in the blank and CFA-L groups on days 14,21,and 28 after modeling(P＜0.05,P＜0.05).(3)Regarding pain-related behavior,the MWT and TWL were significantly decreased in the CFA-L and CFA-H groups on the 7th and 14th days after modeling,compared with the control group(P＜0.05,P＜0.05).On day 21 after modeling,MWT was significantly lower in the CFA-H group than in the blank and CFA-L groups(P＜0.05,P＜0.05),and TWL was significantly lower in the CFA-L and CFA-H groups than in the blank group(P＜0.05,P＜0.05).On day 28 after modeling,MWT and TWL were significantly lower in the CFA-H group than in the blank and CFA-L groups(P＜0.05,P＜0.05).(4)In terms of depression-related behaviors,the total OFT movement distance was significantly lower in the CFA-H group than in the blank and CFA-L groups on day 7 after modeling(P＜0.05,P＜0.05).The total OFT distance and central dwell time were significantly lower in the CFA-H group than in the blank and CFA-L groups on days 14,21,and 28 after modeling(P＜0.05,P＜0.05),and the result in the FST and TST were significantly higher than in the blank and CFA-L groups(P＜0.05,P＜0.05).(5)Glu,GABA,and BDNF expression levels were significantly higher in the CFA-H group than in the blank and CFA-L groups(P＜0.05,P＜0.05),while GABA,Glu/GABA,and BDNF levels were significantly lower in the CFA-H group than in the blank and CFA-L groups(P＜0.05,P＜0.05,P＜0.05).(6)The CFA-L group showed less damage in the anterior cingulate cortex,more pyramidal cells,more arranged cells,clear nucleoli,and a small number of cells with karyokynesis and deep staining.Compared with the CFA-L group,rats in the CFA-H group showed a disordered cell arrangement in the injured area of the anterior cingulate cortex,a large number of pyknotic and hyperchromatic neurons,significantly fewer or absent pyramidal cells,and vacuoles,red blood cells,and neurofibrillary tangles in the interstitial space.Conclusions Injection of CFA 100 μL can be used to establish a rat model of chronic inflammatory pain and depression,showing hyperalgesia,depression-like behavioral changes,changes in levels of Glu,GABA,and BDNF in the anterior cingulate cortex,and pathological changes in the anterior cingulate cortex,consistent with the pathophysiological characteristics of chronic pain and depression.
