In vitro activity: Mianserin (2 mg/kg s.c.) causes a modest increase of DOPAC levels up to about 30% above base-line, which is statistically significant when compared to saline. Mianserin increases extracellular norepinephnne, but a comparison with desipramine and idazoxan showed that both NE reuptake inhibition and alpha-2 autoreceptor blockade contributed to the mianserin-induced increase in extracellular norepinephnne. Mianserin and eltoprazine displays opposite effects in the elevated plus-maze: Mianserin induces anxiolytic-like effects, while eltoprazine shows anxiogenic-like ones. Mianserin treatment induces a decrease in the number of these sites, while eltoprazine treatment results in an increase.