SSRIs "hijack" dopamine signaling as well launching serotonin signals

[HuckleB]

Not exactly new news, as this has been noted before. But this may be the most in-depth anyone has gone in search of understanding this function of the SSRIs.

SSRI antidepressants "hijack" dopamine signaling as well launching serotonin signals

http://www.news-medical.net/?id=9041

"Researchers have discovered that antidepressant drugs such as Prozac not only affect levels of the neurotransmitter serotonin in the brain, but also "hijack" dopamine signaling as well--causing it to launch serotonin signals. Their findings offer new insight into how Prozac and other "selective serotonin uptake inhibitors" (SSRIs) work and how they might cause problems in patients taking them.

SSRIs perform their antidepressant function by increasing the concentration of serotonin in the signaling junctions, called synapses, between neurons. This increase alleviates the deficiency of serotonin that causes depression.

As their name indicates, SSRIs prevent uptake of the serotonin after it has performed its task as a chemical messenger that enables one neuron to trigger a nerve impulse in a neighbor. SSRIs prevent this uptake by inhibiting the action of the molecular cargo carriers called transporters that recycle serotonin back to the neuronal storage sacs called vesicles.

Now, however, Fu-Ming Zhou (presently at the University of Tennessee) and colleagues at Baylor College of Medicine have revealed that SSRIs can have more complex effects on neurotransmitter traffic in the brain than just altering serotonin levels. They found that higher serotonin concentrations caused by SSRIs can "trick" transporters of another key neurotransmitter, dopamine, into retrieving serotonin into dopamine vesicles. Dopamine transporters have a low affinity for serotonin, but the higher serotonin levels result in its uptake by the dopamine transporters, found the scientists.

..."

[On the Road]

1. This is Very Interesting, But I Don't Understand

are they saying that SSRIs trick dopamine transporters into treating serotonin as dopamine, thus mimicking higher levels of dopamine?

What behavioral effects would high dopamine levels have, and have these been observed as a side effect of SSRIs?

I've taken SSRIs several times, but always stopped when it seemed unnecessary. The side effects were not worth it.

[kineneb]

2. Interesting, but what does it mean?

I am on a maintenance dose of Paxil-40mg. Without it I cannot function and slip into devastating depression. It also helps with the OCD and panic problems I have. I ignore the side effects, because life is much better with the meds.

[Conservativesux]

3. Basically, it means "No Sex". Dopamine is the key to sex-drive...

and is closely linked with the sex hormone, testosterone.

Its is no wonder so many people have sexual problems on the SSRI's if its hijacking the dopamine receptor sites.

[shrike]

4. I'm on an SSRI, but I find it fairly to get myself revved up

But I'm a woman. My sex drive is lower now, but sex is still extremely satisfying if not more so.

[HuckleB]

5. That's one possibility among many.

For one thing, the sexual side effects on any SSRI range from severe lack of interest and ability to enhanced interest and ability. Secondly, the theory that enhanced dopamine leads to increased sexual interest is based on one study, which makes this tie fairly tenuous. Researchers suspect that enhanced norepinephrine also plays a role, and there is a theory that lower levels of serotonin increase sexual interest. I don't buy this theory, myself. However, it might explain decreased sexual drive when taking SSRIs.

I guess the point is: the jury's out. We don't know for sure. Heck, we think Wellbutrin affects dopamine and norepinephrine, but the truth is that we don't actually know that for sure.

This is one more study on the way to enhanced understanding, and little more.