Paul A K, Lobarinas E, Simmons R, Wack D, Luisi John C, Spernyak J, Mazurchuk R, Abdel-Nabi H, Salvi R
Department of Nuclear Medicine, State University of New York, University at Buffalo, Buffalo, NY 14214, USA.
Neuroimage. 2009 Jan 15;44(2):312-8. doi: 10.1016/j.neuroimage.2008.09.024. Epub 2008 Oct 2.
Although much is known about the perceptual characteristics of tinnitus, its neural origins remain poorly understood. We investigated the pattern of neural activation in central auditory structures using positron emission tomography (PET) imaging in a rat model of salicylate-induced tinnitus. Awake rats were injected with the metabolic tracer, fluorine-18 fluorodeoxyglucose (FDG), once in a quiet state (baseline) and once during salicylate-induced tinnitus. Tinnitus was verified using a behavioral technique. Brain imaging was performed using a high-resolution microPET scanner. Rats underwent magnetic resonance imaging (MRI) and reconstructed MRI and microPET images were fused to identify brain structures. FDG activity in brain regions of interest were quantified and compared. MicroPET imaging showed that FDG activity in the frontal pole was stable between baseline and tinnitus conditions, suggesting it was metabolically inert during tinnitus. Inferior colliculi (p=0.03) and temporal cortices (p=0.003) showed significantly increased FDG activity during tinnitus relative to baseline; activity in the colliculi and temporal cortices increased by 17%+/-21% and 29%+/-20%, respectively. FDG activity in the thalami also increased during tinnitus, but the increase did not reach statistical significance (p=0.07). Our results show increased metabolic activity consistent with neuronal activation in inferior colliculi and auditory cortices of rats during salicylate-induced tinnitus. These results are the first to show that microPET imaging can be used to identify central auditory structures involved in tinnitus and suggest that microPET imaging might be used to evaluate the therapeutic potential of drugs to treat tinnitus.
尽管人们对耳鸣的感知特征了解颇多，但其神经起源仍知之甚少。我们利用正电子发射断层扫描（PET）成像技术，在水杨酸盐诱导耳鸣的大鼠模型中，研究了中枢听觉结构的神经激活模式。清醒的大鼠在安静状态（基线）下和水杨酸盐诱导耳鸣期间分别注射一次代谢示踪剂氟-18氟脱氧葡萄糖（FDG）。通过行为学技术验证耳鸣情况。使用高分辨率微型PET扫描仪进行脑成像。大鼠接受磁共振成像（MRI），并将重建的MRI和微型PET图像融合以识别脑结构。对感兴趣脑区的FDG活性进行定量并比较。微型PET成像显示，额叶极区的FDG活性在基线和耳鸣状态之间保持稳定，表明其在耳鸣期间代谢不活跃。与基线相比，下丘（p = 0.03）和颞叶皮质（p = 0.003）在耳鸣期间FDG活性显著增加；下丘和颞叶皮质的活性分别增加了17%±21%和29%±20%。丘脑的FDG活性在耳鸣期间也有所增加，但增加未达到统计学意义（p = 0.07）。我们的结果表明，在水杨酸盐诱导的耳鸣期间，大鼠下丘和听觉皮质的代谢活性增加，与神经元激活一致。这些结果首次表明微型PET成像可用于识别参与耳鸣的中枢听觉结构，并提示微型PET成像可能用于评估治疗耳鸣药物的治疗潜力。
