@misc{oai:repo.qst.go.jp:00070547,
 author = {Yukiko, Hori and Nagai, Yuji and Oh-Nishi, Arata and Suhara, Tetsuya and Minamimoto, Takafumi and 堀 由紀子 and 永井 裕司 and 大西 新 and 須原 哲也 and 南本 敬史},
 month = {Sep},
 note = {Motivation toward action is affected by predicted outcome (e.g., reward size), desire for the outcome (e.g., hunger or thirst), as well as mood of the subject. Our previous study indicated that low motivational state is characterized by instrumental task performance in a monkey model of hypothyroidism, which is associated with symptoms of fatigue or depression (Minamimoto et al., 2010, Soc. Neurosci. Abstr). It has been shown that performance of goal-directed action is affected by dopaminergic manipulations (e.g., lesion or drug). We hypothesized that hypothyroidism induces dysfunctions of the dopaminergic system, which in turn lead to low motivation. Here, we studied dopamine receptor density in hypothyroidism model monkeys using positron emission tomography (PET). PET scan data were obtained with [11C]FLB457 (high affinity for extrastriatal D2 receptors) for both pre-hypothyroid control and hypothyroid state. Hypothyroid state was defined as when the monkey's thyroxin level reached less than 2 micro g/dl continuously after administration of antithyroid agent (methimazole, 100 mg/day) for 2 months. The subtraction image of [11C]FLB457 of control from hypothyroidism revealed the binding potential of D2 receptors as being increased specifically in the ventromedial prefrontal cortex (VMPFC). This result suggests that the upregulation of D2 receptors occurred by the decrease of dopamine release in VMPFC in hypothyroidism, resulting in low motivation for task performance., 第34回日本神経科学大会（Neuro2011）},
 title = {Alteration of dopaminergic function in a primate model of hypothyroidism revealed by PET},
 year = {2011}
}