Graph 15
   The  graph's vertical pathway  show spontaneous oxidation of dopamine induced by high extraneuronal oxygen pressure.
     Addition of oxygen occurs twice. First oxygen is added to dopamine to form 6-Hydroxydopamine.
   In the second  oxygen  addition,   6-hydroxydopamine already has all its sites for oxygen occupied. So hydrogen peroxide (H2O2) is generated.
   The generation of hydrogen peroxide within sensitive neurons produces detrimental effects on nerve terminals.
   The graph's horizontal pathway of dopamine is enzymaticaly regulated. The enzyme dopamine-beta-oxidase catalyzes the addition of oxygen to dopamine to synthesize noradrenaline, an essential molecule of life.