Norepinephrine monamine oxidase

Here then is the logic behind the first version of the chemical-imbalance theory. Iproniazid is a monamine oxidase inhibitor - it inhibits the oxidation of norepinephrine and serotonin in the synapses, thereby leaving more of these neurotransmitters available in the brain. When depressed people take iproniazid, they get better. Therefore insufficient norepinephrine and/or serotonin causes depression.12... 

FIGURE 27.6 The synthesis and actions of norepinephrine. MAO = monamine oxidase NE = norepinephrine DBH = dopamine a-hydroxylase. 

Monamine oxidase— An enzyme found in the brain and liver which breaks down catecholamines such as norepinephrine, serotonin and dopamine. 

Figure 2-2 illustrates the irreversible inhibition of the flavine-enzyme monamine oxidase (MAO) by the antihypertensive agent pargyline. This enzyme is important in the catabolism of catechol- and other biogenic amines, including epinephrine and norepinephrine to their corresponding aldehydes. Equation 2.8 illustrates the oxidation of monamines by way of an imino intermediate while the oxidized flavine prosthetic group FAD is simultaneously reduced. 

Monamine Oxidase Inhibitors (MAOI). The enzyme monoamine oxidase inactivates norepinephrine, dopamine, epinephrine, and serotonin. By inhibiting monoamine oxidase, the levels of these neurotransmitters rise. Examples of these drugs includes isocarboxazid (Marplan), phenelzine sulfate (Nardil), and tranycypromine sulfate (Parnate). 

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