Receptor density in monocularly deneruated rats

目的：研究眼球摘除缝合大鼠生后10天单眼视觉结构中腺苷A1受体和苯二氮卓类受体及糖代谢的变化。方法：采用眼球摘除或眼睑缝合剥夺大鼠右眼，于术后不同时间进行脑放射自显影。分别用[1-甲基-1 1C]8-dicyclopropylmethyl-1-methyl-3-propylxanthine([11C]MPDX)和[11C]氟马西尼定位腺苷A1受体和苯二氮卓，用[14C]2-脱氧葡萄糖评价糖代谢。[11 C]MPDX与对侧SC腺苷A1受体的特异性结合在去核后即刻显著降低，在…后仍维持在较低水平5d后，对侧SC内[11C]氟马西尼与苯二氮卓类受体的特异性结合增加。SC对[14C]2-脱氧葡萄糖的摄取在摘除眼球后仅一天就被抑制，然后恢复到同侧水平。在对所有三种示踪剂进行调查的任何时间，对侧和同侧之间的任何其他视觉结构都没有发现显著差异。另一方面，眼睑缝合后，三种示踪剂均呈对称性图像，未见明显改变。结论：轴突变性与腺苷A1受体密度降低有关，导致单眼去核大鼠突触后苯二氮受体密度增加，而缝合眼睑PN10大鼠未见突触后苯二氮受体密度增加。视觉剥夺方法均未引起视觉结构中两种受体的改变，也未引起任何视觉结构中糖代谢的改变，但仅在摘除后1d的对侧SC糖代谢下降。这些结果表明，苯二氮卓类受体对突触前神经末梢的变性敏感，但不受视觉剥夺的影响，在PN10时，大鼠的视觉功能不受影响。

PURPOSE.To study the changes in adenosine A1 and benzodiazepine receptors and glucose metabolism in the visual structures of rats following monocular deprivation by enucleation and eyelid suture at postnatal day 10.METHODS.The right eye of rats were deprived by enucleation or eyelid suture and ex vivo autoradiography of the brain was performed at different times up to 45 days after the treatment. [1-methyl-1 1C]8-dicyclopropylmethyl-1-methyl-3-propylxanthine ([11C]MPDX) and [11C]flumazenil were used to map adenosine A1 receptors and benzodiazepine, respectively, and glucose metabolism was evaluated with [14C]2-deoxyglucose, and. The receptor-specific binding for 11C activity and the uptake of 14C activity in the superior colliculus (SC), visual cortex (VC) and dorsal lateral geniculate body (DLG) were determined.RESULTS.The specific binding of [11C]MPDX to the adenosine A1 receptors in the contralateral SC significantly decreased immediately after enucleation and remained low thereafte … More r, whereas the specific binding of [11C]flumazenil to benzodiazepine receptors in the contralateral SC increased after 5 days. The uptake of [14C]2-deoxyglucose in the SC was depressed only one day after enucleation and then returned to the ipsilateral level. No significant difference between contralateral and ipsilateral sides was found in any other visual structures at any time investigated for the all three tracers. On the other hand, after the eyelid suture all three tracers showed symmetrical images without any detectable changes.CONCLUSIONS.The axon degeneration related a decrease of the adenosine A1 receptor density resulted in an upregulation of postsynaptic benzodiazepine receptor density in monoculaely enucleated, not in eyelid sutured, rats at PN 10. Neither visual deprivation methods induced alteration in both receptors nor in glucose metabolism in any visual structures, except that the glucose metabolism was decreased only in the contralateral SC one day after the enucleation. These results suggest that the benzodiazepine receptors are susceptible to degeneration of presynaptic nerve terminals, but not to visual deprivation, and that the visual functions are not determined in rats at PN 10. Less