長期處理methimazole對縫核及邊緣系統中血清素受器之影響

Chronic Treatment of Methimazole Alters Expression of Serotonin Receptors in Raphe Nuclei and Limbic System

甲狀腺素為調節生理代謝作用的重要激素，先前動物研究也顯示，成年大鼠甲狀腺機能減退，可能會影響大腦中血清素系統的功能並誘發憂鬱行為的表現。本實驗利用長期在飲水中添加methimazole，來抑制甲狀腺素的功能，並以real-time PCR來觀察大鼠多個腦區（包括縫核、海馬迴、杏仁核及中側前額葉內，相關血清素受體表現量的變化。結果顯示經MMI處理之大鼠腦縫核及海馬迴內，5-HT_(1A)型受器的表現量均有增加的情況。此外，5-HT_(2A)型受器在中縫核中表現量增加，而5-HT_(2C)型受器及血清素轉運蛋白（SERT）在海馬迴中表現量增加。這些受器的表現量改變，推測可能與維持該腦區的活性有關，並可能因此導致憂鬱症的產生。

Thyroid hormones play an essential and critical role for metabolism, growth, and tissue differentiation in chordate. Thyroid dysfunction such as hypothyroidism is a frequent disease in adults, leading to neurological symptoms and emotional disease including depression. The interaction between thyroid hormones and serotonin of central nervous system may account for it. The present study was aimed to determine the expression level of serotonin receptors including 5HT_(1A), 5HT_(2A), 5HT_(2C), 5HT_(3A), and serotonin transporter (SERT) in hippocampus, amygdala, raphe nuclei, and medial prefrontal cortex in the rat after chronic treatment of methimazole (MMI) by using real time PCR. Results showed the mRNA level of 5-HT_(1A) was increased in raphe nuclei and hippocampus of the MMI-treated animals. The mRNA of 5-HT_(2A) receptor was elevated in raphe nuclei, and the mRNA of 5-HT_(2C) receptor and SERT were increased in hippocampus. In conclusion, we found that chronic administration of MMI changes expression of serotonin receptors in the raphe nuclei and limbic system, and could be the reason due to depression.