Figure 9.

Diagram describing the probable mechanism of action of I₂ receptor agonists. Under normal conditions, monoamines such as 5‐HT and noradrenaline undergo reuptake and are metabolized by MAO enzymes (solid arrow). Administration of I₂ receptor agonists, and I₂ receptor activation, inhibits MAO activity and allows monoamine neurotransmitters to be repackaged, increasing their synaptic concentration (dashed arrows). The corresponding increased activation of certain downstream monoaminergic receptors (i.e. 5‐HT_1A, 5‐HT_2A and α₁‐adrenoceptors) leads to the production of analgesia.