Changes in expression of BDNF and its receptors TrkB and p75NTR in the hippocampus of a dog model of chronic alcoholism and abstinence

Chronic ethanol consumption can produce learning and memory deficits. Brain-derived neurotrophic factor (BDNF) and its receptors affect the pathogenesis of alcoholism. In this study, we examined the expression of BDNF, tropomyosin receptor kinase B (TrkB) and p75 neurotrophin receptor (p75NTR) in the hippocampus of a dog model of chronic alcoholism and abstinence. Twenty domestic dogs (9-10 months old, 15-20 kg; 10 males and 10 females) were obtained from Harbin Medical University. A stable alcoholism model was established through ad libitum feeding, and anti-alcohol drug treatment (Zhong Yao Jie Jiu Ling, the main ingredient was the stems of watermelon; developed in our laboratory), at low- and high-doses, was carried out. The Zhong Yao Jie Jiu Ling was effective for the alcoholism in dogs. The morphology of hippocampal neurons was evaluated using hematoxylin-eosin staining. The number and morphological features of BDNF, TrkB and p75NTR-positive neurons in the dentate gyrus (DG), and the CA1, CA3 and CA4 regions of the hippocampus were observed using immunohistochemistry. One-way ANOVA was used to determine differences in BDNF, TrkB and p75NTR expression. BDNF, TrkB and p75NTR-positive cells were mainly localized in the granular cell layer of the DG and in the pyramidal cell layer of the CA1, CA3 and CA4 regions (DG>CA1>CA3>CA4). Expression levels of both BDNF and TrkB were decreased in chronic alcoholism, and increased after abstinence. The CA4 region appeared to show the greatest differences. Changes in p75NTR expression were the opposite of those of BDNF and TrkB, with the greatest differences observed in the DG and CA4 regions.

慢性乙醇摄入可诱发学习与记忆功能障碍。脑源性神经营养因子（Brain-derived neurotrophic factor, BDNF）及其受体与酒精成瘾的发病机制紧密相关。本研究以慢性酒精成瘾及戒断状态下的家犬为模型，检测其海马组织中BDNF、原肌球蛋白受体激酶B（Tropomyosin receptor kinase B, TrkB）及p75神经营养因子受体（p75 neurotrophin receptor, p75NTR）的表达水平。本研究共纳入20只家犬，月龄为9~10个月，体质量15~20 kg，雌雄各10只，购自哈尔滨医科大学。通过自由摄食方式构建稳定的酒精成瘾模型，并辅以低、高剂量的解酒药物中药解酒灵（Zhong Yao Jie Jiu Ling）进行干预，该药物主要成分为西瓜茎，由本实验室自主研发，且对犬酒精成瘾具有明确的干预效果。采用苏木精-伊红染色法评估海马神经元的形态学特征，通过免疫组织化学染色观察海马齿状回（dentate gyrus, DG）及CA1、CA3、CA4脑区中BDNF、TrkB及p75NTR阳性神经元的数量与形态特点。采用单因素方差分析（one-way ANOVA）检验各组间BDNF、TrkB及p75NTR的表达差异。结果显示，BDNF、TrkB及p75NTR阳性细胞主要定位于齿状回的颗粒细胞层以及海马CA1、CA3、CA4区的锥体细胞层，且表达丰度依次为DG>CA1>CA3>CA4。慢性酒精成瘾模型组中，BDNF与TrkB的表达水平均显著下调，戒断后其表达水平则显著升高，其中CA4区的表达差异最为显著；p75NTR的表达变化趋势与BDNF、TrkB恰好相反，且在齿状回与CA4区的表达差异最为显著。