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Psychology Antidepressants and Phototherapy
Psychology Antidepressants and Phototherapy
| Antidepressants and Phototherapy |
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Page 2 of 2 Mechanisms of Action Antidepressants are thought to exert their effects at particular subsets of neuronal synapses throughout the brain. Their major interaction is with the monoamine neurotransmitter systems (dopamine, norepinephrine, and serotonin). Dopamine, norepinephrine, and serotonin are released throughout the brain by neurons that originate in the ventral brainstem, locus ceruleus and the raphe nuclei, respectively. These neurotransmitters interact with numerous receptor subtypes in the brain that are associated with the regulation of global state functions including appetite, mood states, arousal, vigilance, attention, and sensory processing. SSRls act by binding to presynaptic serotonin reuptake proteins, thereby inhibiting reuptake and increasing the levels of serotonin in the synaptic cleft. TCAs act by blocking presynaptic reuptake of both serotonin and norepinephrine. MAOls act by inhibiting the presynaptic enzyme (monoamine oxidize) that catabolizes norepinephrine, dopamine, and serotonin, thereby increasing the levels of these neurotransmitters presynaptically. These immediate mechanisms of action are not sufficient to explain the delayed antidepressant effects (typically 2 to 4 weeks). Other unknown mechanisms must play a role in the successful psychopharmacologic treatment of depression.
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