Anxiety is an unpleasant physiological state in which an overreaction to a situation occurs. It has been suggested that different brain regions are involved in the modulation and expression of anxiety, including the amygdala, hippocampus, and frontal cortex. Dysfunction of neurotransmitters and their receptorscan lead to many mood disorders like anxiety. There are evidences that dopamine plays an important role in anxiety modulation in different parts of the brain. Some evidence has shown that the mesolimbic, mesocortical and nigrostriatal dopaminergic system are involved in anxiety. Both dopamine D1 and D2 receptor mechanisms are important in mediating anxiety.
The activity of dopaminergic system is modulated by several neurotransmitters, including glutamatergic neurons from the medial prefrontal cortex (mPFC), GABAergic fibers from the nucleus accumbens (NAc) as well as the ventral pallidum and cholinergic fibers from the pedunculopontine nucleus and the laterodorsal tegmental nucleus. Thus, changes in the glutamatergic, and GABAergic, as well as mediated transmission in the mesolimbic, mesocortical and nigrostriatal dopaminergic system may influence anxiety-like behavior.