Netzeband Jeffrey G, Schneeloch Jaimes R, Trotter Carol, Caguioa-Aquino Jodilyn N, Gruol Donna L
Department of Neuropharmacology, Alcohol Research Center, The Scripps Research Institute, 10550 North Torrey Pines Rd., La Jolla, CA 92037, USA.
Alcohol Clin Exp Res. 2002 Mar;26(3):386-93.
Alcohol exposure during human fetal development can result in fetal alcohol syndrome, a condition characterized by central nervous system dysfunction. Detailed studies in animal models of fetal alcohol syndrome show that the cerebellar region is particularly sensitive to alcohol exposure during early development; however, the cellular mechanisms underlying the alcohol sensitivity of the immature cerebellum are poorly understood.
Primary neuronal cultures of cerebellar cells were prepared from embryonic day 20 rat pups. Cultures were exposed to ethanol (33 mM; 150 mg/100 ml) during the main period of morphological development of the Purkinje neurons, from 6 to 17 days in vitro. After the ethanol treatment, the response of Purkinje neurons to the selective metabotropic glutamate receptor (mGluR) agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD; 300 microM) was examined in parallel fura-2 Ca2+ imaging and current-clamp experiments. In an additional set of experiments, ethanol-treated cultures were allowed to withdraw from ethanol overnight before recordings were performed.
In Ca2+ imaging studies, the mean peak amplitude of ACPD-evoked Ca2+ signals was depressed in the dendritic region of chronic ethanol-treated Purkinje neurons compared with control neurons (p < 0.05, unpaired t test), whereas there was no apparent difference in the somatic region. In contrast, peak ACPD-evoked Ca2+ signals were enhanced in both the somatic and dendritic regions of withdrawn Purkinje neurons compared with control neurons. Parallel current-clamp studies showed no consistent effect of chronic ethanol treatment or ethanol withdrawal on the membrane response to ACPD.
These results show that prolonged ethanol exposure and early withdrawal lead to alterations in mGluR-evoked Ca2+ signaling in cerebellar Purkinje neurons. Metabotropic GluRs in the Purkinje neuron play important roles in cerebellar development and function, suggesting that alterations of mGluR signaling pathways by ethanol may play a key role in the actions of ethanol on the developing cerebellum.
人类胎儿发育期间暴露于酒精可导致胎儿酒精综合征，这是一种以中枢神经系统功能障碍为特征的病症。对胎儿酒精综合征动物模型的详细研究表明，小脑区域在早期发育过程中对酒精暴露特别敏感；然而，未成熟小脑对酒精敏感性的细胞机制却知之甚少。
从小鼠胚胎第20天的幼崽制备小脑细胞的原代神经元培养物。在体外培养的第6至17天，即浦肯野神经元形态发育的主要时期，将培养物暴露于乙醇（33 mM；150 mg/100 ml）。乙醇处理后，在同步的fura-2 Ca2+成像和电流钳实验中检测浦肯野神经元对选择性代谢型谷氨酸受体（mGluR）激动剂（1S,3R）-1-氨基环戊烷-1,3-二羧酸（ACPD；300 microM）的反应。在另一组实验中，乙醇处理的培养物在进行记录前先撤离乙醇过夜。
在Ca2+成像研究中，与对照神经元相比，慢性乙醇处理的浦肯野神经元树突区域中ACPD诱发的Ca2+信号的平均峰值幅度降低（p < 0.05，未配对t检验），而胞体区域没有明显差异。相比之下，与对照神经元相比，撤离乙醇的浦肯野神经元的胞体和树突区域中ACPD诱发的Ca2+信号峰值均增强。并行的电流钳研究表明，慢性乙醇处理或撤离乙醇对ACPD膜反应没有一致的影响。
这些结果表明，长时间乙醇暴露和早期撤离会导致小脑浦肯野神经元中mGluR诱发的Ca2+信号发生改变。浦肯野神经元中的代谢型谷氨酸受体在小脑发育和功能中起重要作用，这表明乙醇对代谢型谷氨酸受体信号通路的改变可能在乙醇对发育中小脑的作用中起关键作用。
