Harris S J, Wilce P, Bedi K S
Department of Anatomical Sciences, University of Queensland, St Lucia, Brisbane, Australia.
J Anat. 2000 Oct;197 Pt 3(Pt 3):477-85. doi: 10.1046/j.1469-7580.2000.19730477.x.
Visual system abnormalities are commonly encountered in the fetal alcohol syndrome although the level of exposure at which they become manifest is uncertain. In this study we have examined the effects of either low (ETLD) or high dose (ETHD) ethanol, given between postnatal days 4-9, on the axons of the rat optic nerve. Rats were exposed to ethanol vapour in a special chamber for a period of 3 h per day during the treatment period. The blood alcohol concentration in the ETLD animals averaged approximately 171 mg/dl and in the ETHD animals approximately 430 mg/dl at the end of the treatment on any given day. Groups of 10 and 30-d-old mother-reared control (MRC), separation control (SC), ETLD and ETHD rats were anaesthetised with an intraperitoneal injection of ketamine and xylazine, and killed by intracardiac perfusion with phosphate-buffered glutaraldehyde. In the 10-d-old rat optic nerves there was a total of approximately 145,000-165,000 axons in MRC, SC and ETLD animals. About 4% of these fibres were myelinated. The differences between these groups were not statistically significant. However, the 10-d-old ETHD animals had only about 75,000 optic nerve axons (P < 0.05) of which about 2.8 % were myelinated. By 30 d of age there was a total of between 75,000-90,000 optic nerve axons, irrespective of the group examined. The proportion of axons which were myelinated at this age was still significantly lower (P < 0.001) in the ETHD animals (approximately 77 %) than in the other groups (about 98 %). It is concluded that the normal stages of development and maturation of the rat optic nerve axons, as assessed in this study, can be severely compromised by exposure to a relatively high (but not low) dose of ethanol between postnatal d 4 and 9.
视觉系统异常在胎儿酒精综合征中很常见，尽管出现这些异常的酒精暴露水平尚不确定。在本研究中，我们研究了在出生后第4至9天给予低剂量（ETLD）或高剂量（ETHD）乙醇对大鼠视神经轴突的影响。在治疗期间，将大鼠置于特殊的腔室中，每天暴露于乙醇蒸气中3小时。在任何给定日期的治疗结束时，ETLD组动物的血液酒精浓度平均约为171mg/dl，ETHD组动物约为430mg/dl。将10日龄和30日龄由母亲抚养的对照（MRC）、分离对照（SC）、ETLD和ETHD大鼠组腹腔注射氯胺酮和赛拉嗪麻醉，然后通过心脏内灌注磷酸盐缓冲戊二醛处死。在10日龄大鼠的视神经中，MRC、SC和ETLD组动物的轴突总数约为145,000 - 165,000条。其中约4%的纤维有髓鞘。这些组之间的差异无统计学意义。然而，10日龄的ETHD组动物只有约75,000条视神经轴突（P < 0.05），其中约2.8%有髓鞘。到30日龄时，无论检查的是哪个组，视神经轴突总数在75,000 - 90,000条之间。此时，ETHD组动物有髓鞘轴突的比例（约77%）仍显著低于其他组（约98%）（P < 0.001）。结论是，本研究评估的大鼠视神经轴突的正常发育和成熟阶段，在出生后第4至9天暴露于相对高剂量（而非低剂量）乙醇时会受到严重损害。
