The neurotransmitters serotonin and noreprinephrine apparently are needed for proper neural responses. Most researchers believe that deficient levels result in depressive syndromes. This soon leads to fatigue pessimism, withdrawal and inadequate functioning.

MAO is believed to metabolise these neurotransmitters so they will not become too prominent. If they were, it might result in excess neural firing and "manic" behaviour. Conversely, if MAO builds up to a higher level, there may be a deficit of neurotransmitters as the MAO does its job too well. G.H.3`s reported capacity to balance MAO action may reduce the problem.

In contrast to many MAO inhibitors (where a tyramine-restricted diet is needed) G.H3 acts as a reversible inhibitor of MAO. It isolates the MAO from the neurotransmitters and thus prevents there over metabolisation. Under stress or in the presence of tyramine, the procaine reverses this action so the MAO can perform its other necessary functions.