Selective serotonin reuptake inhibitors (SSRIs) are a widely prescribed class of antidepressants that play a key role in treating mood disorders. Understanding their mechanism of action is essential for MCAT success, particularly in the Psychological, Social, and Biological Foundations of Behavior section.

Our unique King of the Curve (KOTC) visual simplifies this complex neurochemical process, helping you grasp how SSRIs influence neurotransmission at the synaptic level.

How Do SSRIs Work?

The image above illustrates normal serotonin neurotransmission versus the effect of SSRIs. Let’s break it down step by step:

1. Normal Serotonin Transmission

• Tryptophan, an essential amino acid, is converted into serotonin (5-HT) in the presynaptic neuron.

• Serotonin is released into the synaptic cleft, where it binds to 5-HT receptors on the postsynaptic neuron, transmitting a signal.

• To regulate neurotransmission, serotonin is reabsorbed into the presynaptic neuron via serotonin transporters (SERTs) and recycled for future use.

2. The Effect of SSRIs

• SSRIs inhibit the serotonin transporter (SERT), preventing serotonin from being reabsorbed into the presynaptic neuron.

• This leads to an increased concentration of serotonin in the synaptic cleft.

• More serotonin remains available to stimulate postsynaptic 5-HT receptors, enhancing and prolonging neurotransmission.

3. Antidepressant Action

• The prolonged serotonin activity helps alleviate symptoms of depression and anxiety by improving mood regulation.

• Since serotonin plays a crucial role in emotions and cognition, SSRIs are effective in treating major depressive disorder (MDD), generalized anxiety disorder (GAD), and other psychiatric conditions.

MCAT Relevance: What You Need to Know

SSRIs are frequently referenced in MCAT behavioral science passages, particularly in topics related to:
✅ Neurotransmission and Synaptic Activity
✅ Biological Basis of Depression and Anxiety
✅ Drug Mechanisms and Pharmacology
✅ Effects of Neurotransmitters on Behavior

MCAT Passage Analysis Tips

• Identify the Neurotransmitter: If serotonin is mentioned, consider its role in mood regulation.

• Understand Drug Mechanisms: When presented with SSRIs or other psychotropic drugs, focus on how they alter neurotransmitter levels.

• Apply Scientific Reasoning: Expect questions on how SSRI treatment affects synaptic signaling, receptor activation, and long-term neural plasticity.

Expand Your MCAT Knowledge with KOTC

For more high-yield neuroscience concepts and 1000+ illustrations covering core MCAT topics, visit mcat.kingofthecurve.org.

Expand Your Knowledge with KOTC

For a more comprehensive understanding, visit mcat.kingofthecurve.org. Access over 1000+ illustrations summarizing core concepts essential for MCAT success.

Frequently Asked Questions (FAQs)