Thanos Panayotis K, Wang Gene-Jack, Volkow Nora D
National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD and the Behavioral Neuropharmacology & Neuroimaging Laboratory, Medical Department,Brookhaven National Laboratory, Upton, New York.
Alcohol Res Health. 2008;31(3):233-7.
Positron emission tomography (PET) is an imaging technology that measures the concentration, distribution, and pharmacokinetics of radiotracers-molecules that are labeled with short-lived positron-emitting variants of chemical elements naturally found in the body. These radioisotopes can be attached to compounds involved in normal brain function and then injected into the blood stream. The signals emitted by these radiotracers then are measured using specific detectors. PET is a highly sensitive method; it measures radioisotope concentrations in the nanomolar to picomolar range (10-9 to 10-12 M) . Therefore, the technique can be used to label compounds that are of pharmacological and physiological relevance. These radiotracers then can be used to probe neurochemical and metabolic processes at the relevant physiological concentrations without perturbing the system that is measured. To exert their effects on the brain, alcohol and other drugs (AODs) act on signaling molecules (i.e., neurotransmitters) in the brain as well as on the molecules on the surface of neurons (i.e., receptors) with which the neurotransmitters interact. Specific compounds that selectively bind to such receptors, to the molecules that transport neurotransmitters back into cells, and to the enzymes that are involved in the synthesis or metabolism of neurotransmitters can be labeled for use as PET radiotracers. As a result, PET can be used to assess the metabolic and neurochemical actions of AODs and to evaluate the consequences of chronic AOD use. Since its inception, PET has been used extensively to study the effects of AODs in human and nonhuman primates; however, the recent development of microPET technology has expanded its applications to research in rodents. In addition, increasing numbers of studies are using PET methodology to assess the involvement of genetic variations in individual genes (i.e., polymorphisms) in brain function and neurochemistry. The studies discussed are divided into those that assess the effects of alcohol on brain function (i.e., brain metabolism and cerebral blood flow) and those that assess the effects of alcohol on brain function (i.e., brain metabolism and cerebral blood flow) and those that assess its effects on neurochemistry.
正电子发射断层扫描（PET）是一种成像技术，它可测量放射性示踪剂的浓度、分布和药代动力学。放射性示踪剂是指那些用人体中天然存在的化学元素的短寿命正电子发射变体标记的分子。这些放射性同位素可以附着在参与正常脑功能的化合物上，然后注入血流中。然后使用特定的探测器测量这些放射性示踪剂发出的信号。PET是一种高度灵敏的方法；它可测量纳摩尔至皮摩尔范围内（10⁻⁹至10⁻¹² M）的放射性同位素浓度。因此，该技术可用于标记具有药理和生理相关性的化合物。然后，这些放射性示踪剂可用于在相关生理浓度下探测神经化学和代谢过程，而不会干扰被测量的系统。酒精和其他药物（AODs）要对大脑产生影响，需作用于大脑中的信号分子（即神经递质）以及神经递质与之相互作用的神经元表面分子（即受体）。能够选择性结合此类受体、将神经递质转运回细胞的分子以及参与神经递质合成或代谢的酶的特定化合物，可被标记用作PET放射性示踪剂。因此，PET可用于评估AODs的代谢和神经化学作用，并评估长期使用AODs的后果。自问世以来，PET已被广泛用于研究AODs在人类和非人类灵长类动物中的作用；然而，微型PET技术的最新发展已将其应用扩展到啮齿动物研究。此外，越来越多的研究正在使用PET方法来评估个体基因中的基因变异（即多态性）在脑功能和神经化学中的作用。所讨论的研究分为评估酒精对脑功能（即脑代谢和脑血流量）的影响以及评估酒精对神经化学影响的研究。
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