5-HT and human anxiety. Evidence from studies using acute tryptophan depletion.
There is abundant evidence that serotonin (5-hydroxytryptamine, 5-HT) is involved in anxiety in both animals and humans but there is conflicting evidence for the precise role it plays. Acute tryptophan depletion provides a technique for investigating a global reduction in brain 5-HT function and we have investigated its effect on anxiety in drug-free panic disorder patients and normal volunteers. We found little effect on general levels of anxiety but it enhanced the effect of a panic challenge using 5% carbon dioxide (5%CO2) in panic disorder patients. The effect in normal volunteers was less clear with no overall effect following 5%CO2 challenge or the psychological challenge of a simulated public speaking task. These results are discussed in relation to the literature and are broadly supportive of the hypothesis that 5-HT acts to inhibit panic anxiety at the level of the periaqueductal grey but facilitates general and conditioned anxiety at the level of medial temporal lobe structures.
Anderson
I M
IM
Neuroscience and Psychiatry Unit, University of Manchester, UK. ian.anderson@man.ac.uk
Mortimore
C
C
D001007:Anxiety / Q000503:physiopathology*; D001921:Brain / Q000502:physiology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D016584:Panic Disorder / Q000503:physiopathology*; D012016:Reference Values; D012701:Serotonin / Q000378:metabolism*; D012727:Sex Characteristics; D014364:Tryptophan / Q000172:deficiency*
D012701:Serotonin; D014364:Tryptophan