Hello, I’m Dr. Carlo Carandang, and I’m a psychiatrist. Today, I will talk about how SNRIs work. SNRIs are also known as serotonin norepinephrine reuptake inhibitors, and are antidepressants used to treat anxiety disorders and depression. So here is a diagram of two neurons connecting with one another. They connect to one another via the space called the synapse. So when neurons communicate with one another, one neuron releases a neurotransmitter and then it travels across the synapse and binds to postsynaptic receptors. So the neuron that is located before the synapse is called the presynaptic neuron, and the neuron that is located after the synapse is called the postsynaptic neuron.
So SNRIs increase both serotonin and norepinephrine in the synapse. In this article, we will focus on how SNRIs increase norepinephrine in the synapse. So in the presynaptic neuron, there’s a signal that comes down and it signals for the release of norepinephrine from these vesicles here in the presynaptic neuron. So norepinephrine is released into the synapse, and then it travels across the synapse and binds to the post-synaptic receptors. And once the neurotransmitter is done binding with the receptor, it is recycled back into the presynaptic neuron via these reuptake pumps, which pump the norepinephrine back into the presynaptic neuron. So it recycles it, and it doesn’t go to waste. So what an SNRI does is that it blocks the reuptake pump, so that the norepinephrine is not recycled back into the presynaptic neuron. What this does is that it effectively increases the norepinephrine concentration in the synapse.
So this is an example of how an SNRI increases norepinephrine in the synapse, and it also does the same thing to the serotonin neuron. The SNRI works on the serotonin neuron by blocking the serotonin reuptake pumps on the presynaptic neuron, and thereby increases serotonin by this same mechanism. So SNRIs are considered dual action antidepressants, as they increase both serotonin and norepinephrine in the synapse, whereas SSRIs, otherwise known as selective serotonin reuptake inhibitors, only increase serotonin in the synapse (and have no effect on norepinephrine neurons).
For more information and help on SNRIs and anxiety, please visit the rest of AnxietyBoss.com. Thank you for listening, I’m Dr. Carlo Carandang.