MAO medication inhibits MAOs, which normally inhibit serotonin, dopamine, and norepinephrine, so that these neurotransmitters can increase in concentration.

SSRIs (selective serotonin reuptake inhibitors) are used to treat depression because they block the reuptake of 5-HT serotonin, allowing it to remain in the locus coeruleus (LC) to block anxiety there.

While the other conditions—MDD, bedwetting, OCD, and PDD—are all FDA-approved for various first-generation and second-generation tricyclic medications, panic disorder is still an off-label use for TCAs. Currently, FDA approval favors selective serotonin reuptake inhibitors (SSRIs) for treatment of panic disorders.

MAOIs have long held a stigma of being associated with fatal dietary and adverse drug reactions—including phenylamines and anesthetic medications. Despite this stigma, recent studies have indicated that some of this longstanding research was based on outmoded or misinterpreted methodology.

Barbiturates and benzodiazepines are the two main types of anti-anxiety medication-- one you might have heard of is Valium. SSRIs (serotonin reuptake inhibitors) block the reuptake of serotonin into the neuron, therefore increasing the amount of serotonin in the synapatic cleft and making people feel happier since serotonin is a "feel good hormone." MAO inhibitors block monoamine oxidase from transporting "feel good hormones" from the brain, thereby increasing their availability and making people feel happier. SSRIs and MAO inhibitors are used to treat major depressive disorder and lithium is used to treat bipolar disorder. 

SSRI's, or Selective Serotonin Reuptake Inhibitors, inhibit reuptake of serotonin, and therefore increases the availability of serotonin in the brain. SSRIs are the most common treatment for clinical depression.

Benzos enhance the effect of the neurotransmitter GABA. The GABA neurotransmitter suppresses the activity of nerves. By enhancing it's function, overactive nerve signals that are believed to increase anxiety are calmed down.

Serotonin is most effective in treating disorders associated with mood, sleep, and motivation. When serotonin levels are too low, patients are at risk of developing depression and OCD tendencies. When serotonin levels are too high, patients lack motivation.

The other choices are incorrect. Glutamate's function is to register pain and store new information in memory. Norepinephrine is a major part of the autonomic nervous system and is important for attention and regulation of the flight-or-fright response. Last, dopamine is the neurotransmitter involved in rewards, motivation, executive functioning, and motor control. 

Dopamine works with the brain's reward system, motivation, and executive functioning in the frontal lobes. A lack of dopamine can lead to attention-deficit hyperactivity disorder, while too much can lead to aggression. Hyperactive, damaged, or a lack of dopamine receptors can lead to addictions, which attempt to increase dopamine levels in the brain.

Serotonin is the major neurotransmitter that regulates mood, sleep, and motivation. A lack of serotonin can lead to depression, OCD, and eating disorders. Too much serotonin can decrease motivation. Serotonin levels can be regulated through selective serotonin reuptake inhibitors, serotonin and norepinephrine reuptake inhibitors, tricyclic antidepressants, and other drugs.