Head twitch response

We were talking the other day (or I was typing and you guys were reading) about serotonin. I found an article with a good description:

"Serotonin has tremendous influence over several brain functions, including the control of perception, cognition, sleep, appetite, pain, and mood and mediates these effects through interactions with receptors located throughout the central and peripheral nervous systems."

In this study they looked at the difference between serotonin in the brain and hallucinogens. Apparently they work differently, since serotonin works through different pathways in the brain.

Another great quote:

"Both serotonin and the N-methyltryptamines produce what is known as a head twitch response in animal models, which indicates that the serotonin 2A receptor has been activated."

Seriously? "Head twitch response?" Love the side effects.

Why SSRI?

So if dopamine has all this stuff to do with mental illness, why target serotonin in your medication? "Most antidepressant treatments do not directly enhance dopamine neurotransmission, which may contribute to residual symptoms, including impaired motivation, concentration, and pleasure." Why the hell not?

First, what is an SSRI (that's probably what you're taking if you're on meds). It is a selective serotonin reuptake inhibitor. What does that mean?

"SSRIs seem to relieve symptoms of depression by blocking the reabsorption (reuptake) of serotonin by certain nerve cells in the brain. This leaves more serotonin available in the brain. Increased serotonin enhances neurotransmission — the sending of nerve impulses — and improves mood. SSRIs are called selective because they seem to affect only serotonin, not other neurotransmitters."

So they give your brain more serotonin. When we have more dopamine, we respond with elated feelings, like when we have sex, take drugs, etc. What about serotonin? How does it work?

"A normal level of serotonin promotes feelings of happiness, but at times, the body becomes overly stressed and will begin to use higher levels of serotonin to compensate for being overwhelmed. Because of the increased stress level, the body will not be able to produce more serotonin to replace the amount that was taken from the reserve. The body will suffer a recession, so to speak, which can lead to a mild to moderate case of depression. The lower the level of serotonin in the brain, the deeper the depression."

So a lot like dopamine. They're both neurotransmitters that work to make you feel better. So which one is the cure for depression? Do we treat both? A new group of drugs does: SNDRI's.

"A serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI), or triple reuptake inhibitor (TRI), is a drug that acts simultaneously as a reuptake inhibitor for the monoamine neurotransmitters, serotonin, norepinephrine (noradrenaline) and dopamine, by blocking the action of the serotonin transporter (SERT), norepinephrine transporter (NET), and dopamine transporter (DAT), respectively. This, in turn, leads to increased extracellular concentrations of these neurotransmitters and, therefore, an increase in serotonergic, noradrenergic or adrenergic, and dopaminergic neurotransmission." A long explanation for "it works on both."

Some of the new ones like Effexor and Cymbalta work like this. I wonder if they'll get more popular? Of course, they're uppers, really, so bipolar folks would have to take a mood stabilizer as well.