Effect of metergoline on human anxiety

In order to assess the role played by serotonin (5-HT) in subjective anxiety, three groups of 12 healthy volunteers were given 12 mg metergoline (MET), 10 mg diazepam (DZ) or placebo (PB), under double-blind conditions, and submitted to a simulated public speaking (SPS) test. MET increased state-anxiety scores, measured by Spielberg's State-Trait Anxiety Inventory. The effect of MET was significantly different from both the PB and DZ groups immediately before the SPS test (prestress) as well as 24 h after medication, and from the DZ group only, 2.5 h after the test (poststress). In contrast, DZ did not significantly affect subjective anxiety. The SPS test significantly increased anxiety in DZ- or PB-treated subjects as compared to prestress scores, whereas the increases in the MET group were not significant, probably because pretest levels were already high. No drug effect on heart rate, skin electrical conductance and quality of sleep during the night following medication was found. In addition, the drugs did not cause bodily symptoms that could secondarily affect mood. Since MET is a 5-HT receptor antagonist, active on the central nervous system, an inhibitory role of 5-HT on subjective anxiety might be suggested.