早期听觉剥夺对幼鼠听皮层NMDA受体亚单位的影响

Influence of Early Auditory Deprivation on Expression of N-Methyl-D-Aspartate Receptor Subunit Protein Levels in Auditory Cortex of Rat

目的观察听觉剥夺对幼鼠听皮层N-甲基-D-天冬氨酸(NMDA)受体亚单位NR1、NR2A及NR2B蛋白表达的影响。方法将36只新生幼鼠随机分为听觉剥夺组和对照组各18只,每组分别按出生周龄不同分3、5、7周龄组,每周龄组6只。听觉剥夺组在出生第7天开始用阿米卡星(Amikacin)500 mg/(kg.d)皮下注射,直到生后第16天。对照组皮下注射相同次数、同等容量的生理盐水。造模成功后,以10%水合氯醛腹腔注射麻醉后,分离出双侧听皮层组织,提取总蛋白。以Western blot法检测听皮层NR1、NR2A、NR2B蛋白表达水平。结果与同龄对照组比较,听觉剥夺组各周龄组听皮层NR1蛋白表达均显著降低(P<0.05);3周龄及5周龄组听皮层NR2A蛋白表达水平显著降低(P<0.05);3周龄组听皮层NR2B蛋白表达水平显著降低(P<0.05)。结论生后早期听觉剥夺降低了听皮层NMDA受体蛋白的表达,提示NMDA受体可能参与了听觉剥夺后认知功能障碍的发病机制。

Objective To observe the changes of n-methyl-d-aspartate （NMDA） receptor subunit NR1, NR2A, and NR2B protein levels in rat＇s auditory cortex after early auditory deprivation. Methods Little sprague dawley rats were divided into auditory deprivation group （n = 18 ） and control group （n = 18） randomly. Each group was divided into 3-week-old group, 5-week-old group and 7-week-old group （ n = 6 ）. Amikacin was administered subcutaneously at a dosage of 500 mg/（ kg · d） , from the seventh （p7） up to the 16th （p16） postnatal day. Control group were injected saline intraperitoneally （ i. p） at the same dosage and for the same course. Rats in each group were anesthetized by 10% Chloral hydrate after models successfully made and the protein of auditory cortex was gathered, the protein expressions of NR1, NR2A and NR2B were tested by western blot methods respectively. Results Compared with control group, the protein levels of NRI in auditory cortex of auditory deprivation group in all ages decreased significantly （P 〈 0. 05 ） , the protein levels of NR2A in auditory cortex in auditory deprivation group at p3w and p5w decreased significantly （ P 〈 0. 05 ） , and the protein levels of NR2B in auditory cortex in auditory deprivation group at p3w decreased significantly （ P 〈 0. 05 ）. Conclusion The expression level of NMDA receptor subunit protein level reduces in rat＇s auditory cortex by early auditory deprivation,which might participate in the mechanism of damaged cognition after early auditory deprivation.