Figure 8

Hypothetical mechanisms of therapeutic effects against PD by mirtazapine. DA, dopamine, 5-HT, 5-hydroxytryptamine (serotonin); NA, noradrenaline; GABA, γ-aminobutylic acid; MSN, medial spiny neuron; D₁R, dopamine D₁ receptor; D₂R, dopamine D₂ receptor; α₁-NAR, α₁ noradrenaline receptor; α₂-NAR, α₂ noradrenaline receptor; 5-HT_1AR, 5-HT_1A receptor: 5-HT₂R, 5-HT₂ receptor. Dashed lines indicate hypothetical innervation and receptors. The circle indicates a stimulatory effect by mirtazapine, while the crosses indicate an inhibitory effect by mirtazapine. See details in Discussion.