Effect of membrane fluidity on brain receptors and transporters

本神经药理学研究项目的目的是研究脑膜组成/流动性对神经递质功能的影响。假设是膜组成和/或流动性的变化将对某些受体和转运体以及特定的大脑区域产生特异性影响。我们建议在体外研究使牛脑膜硬化的药物（半琥珀酸胆固醇和硬脂酸）与使膜流动的药物（亚油酸、l - α -磷脂酰胆碱和DHA、omega-3，一种广泛使用的营养补充剂）之间的剂量反应。我们将研究流动性变化对多巴胺（D2）、腺苷（A2A）、GABAA、5-羟色胺（5-HT1A、5-HT2A）谷氨酸（NMDA、mGluR5）受体与多巴胺转运体DAT的影响。额叶皮质、海马体和纹状体代表了从更多的液体到更坚硬的脑膜的范围，将被研究。流动性将用荧光探针测量。总膜受体和转运体将通过Western blot及其与特定放射配体结合的表面水平进行测量。功能变化将通过与第二信使和关键信号蛋白的偶联来测量。在大鼠体内，将对老年大鼠进行更硬膜的研究，而通过慢性他汀类药物治疗、DHA治疗或plasmalogen（以增加DHA水平）治疗来降低胆固醇，将对更多流体膜进行研究。对于体内实验，我们还将通过原位氢化这些受体的mRNA来评估它们的合成。我们期望小的膜变化将显著影响所研究的膜受体，这具有重要的生理后果。可以通过施用影响膜的化合物（或设计饮食）来增强针对这些受体和转运体的药物治疗的功效，从而成功地使其衰老。

The objective of this research program in neuropharmacology is to investigate the effect of membrane composition/fluidity on neurotransmitter function in the brain. The hypothesis is that changes of membrane composition and/or fluidity will have effects specific for certain receptors and transporters and specific for certain brain regions. We propose to investigate in vitro a dose-response of agents that rigidify membranes (cholesteryl hemisuccinate and stearic acid) compared to agents that fluidify membranes (linoleic acid, L-alpha-phosphatidylcholine and DHA, omega-3, a widely used nutritional supplement) in bovine brain membranes. We will investigate how fluidity changes affect dopamine (D2), adenosine (A2A), GABAA, serotonin (5-HT1A, 5-HT2A) glutamate (NMDA, mGluR5) receptors compared to the dopamine transporter DAT. The frontal cortex, the hippocampus and the striatum representing a range from more fluid to more rigid brain membranes will be studied. Fluidity will be measured with fluorescent probes. Total membrane receptors and transporters will be measured by Western blot and their surface levels with binding of specific radioligands. The functional changes will be measured with coupling to second messengers and key signaling proteins. In vivo in rats a condition presenting a more rigid membrane will be investigated with old rat whereas more fluid membranes will be investigated by reducing cholesterol with a chronic statin drug treatment, DHA treatment or plasmalogen (to increase DHA levels) treatment. For in vivo experiments we will also measure by in situ hydridization mRNA of these receptors to assess their synthesis. We expect that small membrane changes will significantly affect the membrane receptor investigated and that this has important physiological consequences. Compounds affecting membranes could be administered (or a diet designed) to enhance efficacy of drug treatments targeting these receptors and transporters for successful aging.