Kumar Jaya, Hapidin Hermizi, Get Bee Yvonne-Tee, Ismail Zalina
Department of Physiology, Faculty of Medicine, Pre-Clinical Building, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56000 Cheras, Kuala Lumpur, Malaysia.
School of Health Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia.
Alcohol. 2016 Feb;50:9-17. doi: 10.1016/j.alcohol.2015.10.001. Epub 2015 Nov 14.
Withdrawal from long-term ethanol consumption results in overexcitation of glutamatergic neurotransmission in the amygdala, which induces an anxiety-like syndrome. Most alcoholics that suffer from such symptoms frequently depend on habitual drinking as self-medication to alleviate their symptoms. Metabotropic glutamate receptor subtype 5 (mGlu5) and protein kinase C (PKC) epsilon have been reported to mediate acute and chronic effects of ethanol. This study explores the changes in mGlu5 and PKC epsilon in the amygdala following acute administration of ethanol during ethanol withdrawal (EW) induced anxiety. Male Wistar rats were fed a modified liquid diet containing low-fat cow milk, sucrose, and maltodextrin, with a gradual introduction of 2.4%, 4.8% and 7.2% ethanol for 20 days. Six hours into EW, the rats were intraperitoneally injected with normal saline and ethanol (2.5 g/kg, 20% v/v), and exposed to open-field and elevated plus maze tests. Then, amygdala tissue was dissected from the rat brain for Western blot and gene expression studies. EW-induced anxiety was accompanied by a significant increase in mGlu5, total PKC epsilon, and phosphorylated PKC epsilon protein levels, and also of mRNA of mGlu5 (GRM5) in the amygdala. Acute administration of ethanol significantly attenuated EW-induced anxiety as well as an EW-induced increase in GRM5. The acute challenge of ethanol to EW rats had little effect on the phosphorylated and total protein levels of PKC epsilon in the amygdala. Our results demonstrate that amygdala PKC epsilon may not be directly involved in the development of anxiety following EW.
长期乙醇摄入戒断会导致杏仁核中谷氨酸能神经传递过度兴奋，进而诱发类似焦虑的综合征。大多数出现此类症状的酗酒者常常依赖习惯性饮酒进行自我治疗以缓解症状。据报道，代谢型谷氨酸受体5（mGlu5）和蛋白激酶C（PKC）ε介导乙醇的急性和慢性效应。本研究探讨了在乙醇戒断（EW）诱导的焦虑期间急性给予乙醇后杏仁核中mGlu5和PKCε的变化。雄性Wistar大鼠喂食含低脂牛奶、蔗糖和麦芽糊精的改良液体饮食，并逐步引入2.4%、4.8%和7.2%的乙醇，持续20天。在EW开始6小时后，给大鼠腹腔注射生理盐水和乙醇（2.5 g/kg，20% v/v），并进行旷场试验和高架十字迷宫试验。然后，从大鼠脑中分离出杏仁核组织用于蛋白质免疫印迹和基因表达研究。EW诱导的焦虑伴随着杏仁核中mGlu5、总PKCε和磷酸化PKCε蛋白水平以及mGlu5（GRM5）mRNA的显著增加。急性给予乙醇可显著减轻EW诱导的焦虑以及EW诱导的GRM5增加。对EW大鼠急性给予乙醇对杏仁核中PKCε的磷酸化和总蛋白水平影响不大。我们的结果表明，杏仁核PKCε可能不直接参与EW后焦虑的发生。
