Dissertation/Thesis Abstract

Roles of serotonin 2A receptor in a serotonin syndrome
by Zhang, Gongliang, Ph.D., Florida Atlantic University, 2010, 221; 3407173
Abstract (Summary)

Serotonin (5-HT) is a neurotransmitter in the central nervous system. Decrease in the brain 5-HT level could induce depression, showing a state of low mood, aversion to motion and feeling of worthlessness. About 12 million adults in the United States have depression. Antidepressants, such as monoamine oxidase inhibitors and selective serotonin reuptake inhibitors, can alleviate the depressive mood by increasing the brain's 5-HT activity, however they can also induce a potentially life-threatening side effect, namely 5-HT syndrome. This syndrome is manifested by neuromuscular hyperactivities, mental disorders and autonomic dysfunctions. Clinical studies have demonstrated that 5-HT2A receptor antagonists could effectively block severe symptoms of patients with the 5-HT syndrome. To understand the underlying mechanisms, in this study we examined the activity of the 5-HT2A receptor in rats with the 5-HT syndrome evoked by a combined injection of clorgyline, a monoamine oxidase inhibitor, and paroxetine, a selective 5-HT reuptake inhibitor. The major findings from my study were that: (1) Chronic clorgyline treatment significantly exacerbated 5-HT2A receptor-mediated symptoms of the 5-HT syndrome animals; (2) The 5-HT2A receptor-mediated symptoms were also aggravated when the 5-HT syndrome animals were housed in warm (32°C) ambient temperature; (3) Blocking 5-HT2A receptors in the medial prefrontal cortex alleviated the 5-HT syndrome through a circuit between raphe serotonergic neurons and medial prefrontal cortex glutamatergic neurons. Taken together, my data demonstrate that the activity of 5-HT 2A receptors may be enhanced by chronic antidepressant treatment and warm environmental temperature. The sensitized 5-HT2A receptor in the medial prefrontal cortex may exacerbate the syndrome through a positive-feedback circuit between medial prefrontal cortex and raphe nuclei, which would result in excessive 5-HT in the brain. This study casts a new light on the underlying mechanisms of the 5-HT syndrome.

Indexing (document details)
Advisor: Tao, Rui
School: Florida Atlantic University
School Location: United States -- Florida
Source: DAI-B 71/05, Dissertation Abstracts International
Subjects: Neurosciences, Toxicology
Keywords: Antidepressants, Clorgyline, Glutamate, Serotonin syndrome
Publication Number: 3407173
ISBN: 978-1-109-75065-2
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