Neurotransmitters Mechanisms and Antidepressants

Antidepressants A note on layout: The neurotransmitters are listed from the most often targeted by antidepressant drugs (serotonin) to the least often targeted (dopamine). The mechanisms are listed in functional or “life cycle” order from the perspective of the neurotransmitter, which is first synthesized, then released, binds receptors, and ultimately is broken down. The drug classes are listed in order of historical discovery. Neurotransmitters Mechanisms (to boost NT) Serotonin Norepinephrine Dopamine SER, 5-HT NE DA Increase synthesis Cause release Receptor agonist Partial agonist Presynaptic antagonist Inhibit reuptake Inhibit breakdown Antipsychotics* Antidepressant classes Monoamine oxidase inhibitors Tricyclic antidepressants Selective serotonin reuptake inhibitors Satiety Fight or flight Salience Example: Levodopa, 5-HTP Amphetamine (Adderall®) Pramipexole Buspirone (BuSpar®) Mirtazapine (Remeron®) Fluoxetine (Prozac®) Phenelzine (Nardil®) 1952 MAOIs 1953 TCAs 1955 SSRIs High: Fullness, contentment Alert, concentration, memory Reward, desire, learning, alert 1977 First: Chlorpromazine (Thorazine®) Iproniazid and isoniazid Imipramine (Tofranil®) Zimelidine Low: Anxiety, OCD, aggression, hungry Inattentive Inactive, unmotivated, hungry Boosts: Used for: DA and SER, respectively PD and useless, respectively NE > DA >> SER DA SER SER, NE SER SER, NE, DA ADHD, narcolepsy Parkinson’s (PD) Anxiety > depression Depression > anxiety Depression, anxiety, OCD Depression > anxiety Notable: Mechanism: Haloperidol (Haldol®) Antagonist* Phenelzine, selegiline, moclobemide, harmaline Amitriptyline (Elavil®), chlomipramine (Anafranil®) Inhibit breakdown Inhibit reuptake Fluoxetine (Prozac®), sertraline (Zoloft®), paroxetine (Paxil®), citalopram (Celexa®), escitalopram (Lexapro®), fluvoxamine (Luvox®), dapoxetine Inhibit reuptake