摘除双侧眼球对大鼠视交叉上核节律性的影响

EFFECT OF EYE BALL ENUCLEATION ON CIRCADIAN RHYTHM OF THE RAT SUPRACHIASMATIC NUCLEUS

成年Ｗｉｓｔａｒ雌鼠５７只，随机分为实验组３０只，行双眼摘除术。对照组２７只。术后４周将各组动物体重相近的每３只列为一个配伍组，分别在０９：００～１０：００、１７：００～１８：００、２３：００～２４：００三个时间处死。将含有视交叉上核的脑组织经固定、恒冷箱切片后，用免疫组化ＡＢＣ法染色显示视交叉上核内含ＶＩＰ或ＡＶＰ的神经元，微机图像分析仪上测量光镜下这两种神经元的相对切面面积及平均免疫反应强度。结果：（１）对照组不同时间处死的动物ＶＩＰ能神经元切面面积以２３：００～２４：００最大，０９：００～１０：００次之，１７：００～１８：００最小，呈昼夜节律变化，ＡＶＰ能神经元也以２３：００～２４：００最大，但在０９：００～１０：００和１７：００～１８：００间差异无显著性；（２）摘除双眼后各时间组间ＶＩＰ能神经元和ＡＶＰ能神经元切面面积均不再显示显著性差异。提示实验组动物视交叉上核的这两种神经元功能活动的昼夜节律已发生改变；（３）实验组和对照组动物的ＶＩＰ能神经元和ＡＶＰ能神经元平均免疫反应强度在所测的三个时间中，均未见明显差异。

Suprachiatsmatic nucleus(SMN),as an important circadian rhythm oscillator in mammal, receives the information of environmental light-dark cycle and keeps the circadian rhythm synchronized with environment by retinohypothalamic projection to SCN.In this study, we explored the effects of interrupting the light path by eye ball enucleation on circadian rhythm of SCN to approach the mechanism of circadian rhythm. 57 adult female Wistar rats were used. Bilateral eye ball enucleation of 30 rats among them were perforrned. Keeping 4 weeks under normal light-dark cycle (06: 30～19: 30 light on), blocks of both the operated animals and control group (27rats) were divided according to body weight and rats were killed at three different periods of time:09: 00～10:00, 17:00～18:00, 23:00～24:00. Coronal sections (40μm) were cut on cryostat microtome. VIP-immunoreactive (IR) neurons and AVP-IR neurons were shown by immunohistochemical ABC process.The general sectional areas of both kinds of neurons in SCN were measured with microcomputer image analysis system under light microscope. Results: (1)In each randomized block of control animals the sectional areas of VIP-IP neurons in SCN had similar changes in circadian rhythm,the largest area being at 23:00～24:00, the next at 09:00～10:00 and the smallest at 17:00～18:00 (P<0.001). The sectional areas of AVP-IR neurons in SCN of the control rats were also similar to VIP-IP neurons, the largest areas were at 23:00～24:00, but no significant difference was found between 09:00～10:00 and 17:00～18:00 groups. (2) After eye ball enucleation, in general, there was no significant changes of both VIP-IR and AVP-IR neurons in rats killed in different time.This indicated that the circadian rhythm of SCN was changed in the experimental group. (3)After eye ball enucleation, the sectional area of VIP-IR neurons in SCN were smaller than control rats, especially at 17:00～18:00 and 23:00～24:00. But no significant difference was found in that of AVP-IR neurons between the two groups. The results suggest that eye ball enucleation may inhibit relatively the function of VIP-IR neurons which receive the light information directly in normal, but has no significant effect on AVP-IR neurons.