尾壳核内注射脑啡肽和bestatin对大鼠操作式条件反射的影响  

EFFECT OF INJECTION OF ENKEPHALIN AND BESTATIN IN CAUDATE-PUTAMEN ON OPERANT CONDITIONING IN RATS

作　　者：张世仪[1] 张艳萍[1] 张敏磊[1] 齐慧新[1] 王玢[2] 

机构地区：[1]中国医学科学院基础医学研究所,北京100005 [2]北京师范大学生物系,北京100875

出　　处：《生理学报》1992年第5期448-454,共7页Acta Physiologica Sinica

基　　金：国家自然科学基金

摘　　要：在条件反射箱内训练雌性Wistar大鼠建立操作式防御性条件反射。训练时灯光先出现15s,然后结合给予脚掌电击8s。每天训练30次。如果动物能在灯光出现15s内按下反应键以避免电击,即谓建立了条件反应。在条件反应率(CR)连续5d达到80％以上后,即进行双侧尾壳核埋植套管手术。术后2—3d,向双侧尾壳核内注射甲硫氨酸脑啡肽(MEK)或bestatin(一种氨基肽酶抑制剂)。注射后30min,2h,24h,48h分别进行条件反射测验(每轮30次)。尾壳核内注射生理盐水作自身对照。实验结果表明:生理盐水注射后,CR仍保持在80％以上。MEK(60ng)或bestatin(10μg)注射后30min和2h,CR显著下降。2h测验时伴有条件反应潜伏期(L)延长。CR及L两项指标于注射后24h和48h恢复至对照水平。纳洛酮(2mg/kg)腹腔注射能阻断bestatin的效应。MEK或bestatin尾壳核内注射后对自发活动无明显影响。上述结果提示尾壳核的脑啡肽有可能参与条件反射再现的调节。bestatin可能通过增加内源性脑啡肽而产生类似MEK对条件反射的作用。Female Wistar rats were trained in a Skinner-box, 30 trials per day in adark room to establish operant defence conditioning. Training started with alight (15 s), then combined with footshock for further 8 s. When the rats learnedto press the key to avoid footshock within 15 s, conditioned response was consideredestablished. Aner the rats reached a conditioning rate (CR) above 80% for 5days, cannulae were implanted into caudate-putamen. Two to three days later,Met-enkephalin (MEK) or bestatin (an aminopeptidase inhibitor) was injectedbilaterally into caudate-putamen. 30 min, 2 h, 24 h and 48 h after injection,conditioning tests were conducted, with each session consisting of 30 trials. Con-trol experiments were done when 0.9% NaCl (NS) was injected. After injection of NS, CR maintained above 80% in all 4 test sessions. MEK(60 ng/rat) or bestatin (10 μg/rat) significantly lowered the CR during the 30 minand 2 h test session. In the latter case, the latency (L) was also prolonged. How-ever both CR and L returned to the control level in the 24 h and 48 h test ses-sions. Naloxone (2 mg/kg, i.p.) blocked the conditioning-depression effect ofbestatin. No significant alteration was seen in locomotor activity after MEK orbestatin injection. The results suggest that enkephalin in caudate-putamen maybe involved in the regulation of retrieval of conditioning. Bestatin mimics theeffect of MEK on conditioning reflex probably by increasing production of endog-enous enkephalin.

关 键 词：尾壳核 脑啡肽 BESTATIN 条件反射 

分 类 号：R338.61[医药卫生—人体生理学]