Serotonin Synthesis and Metabolism | Sigma-Aldrich

Serotonin is a neurotransmitter involved in the transmission of nerveimpulses. Neurotransmitters are chemical messengers within the brain thatallow the communication between nerve cells.

A flowchart showing the synthesis pathway of melatonin from dietary tryptophan

Furthermore, methamphetamine kills serotonergic neurons and thus a methamphetamine user�s brain may forever be lacking or have decreased levels of serotonin, which may certainly affect various aspects of normal functioning. A person needs a relatively high level of serotonin to maintain a manageable level of aggressiveness as well as an overall feeling happiness. Because of a decreased amount of serotonergic neurons, a methamphetamine user will always have an inadequate amount of serotonin levels. This will results in permanent changes in behavior and mood, such as feelings of depression and guilt.

Melatonin in the skin: synthesis, metabolism and functions

Circadian melatonin production in the pineal gland and retina is under the control of serotonin N-acetyltransferase (NAT) and hydroxyindole-O- methyltransferase. Because NAT activity varies diurnally, it has been considered both the melatonin rhythm-generating enzyme and the rate-limiting enzyme of melatonin synthesis. In rats with dramatically reduced NAT activity due to a H28Y mutation in NAT, melatonin levels remained the same as in wildtype controls, suggesting that NAT does not determine the rate of melatonin production at night. Using a combination of molecular approaches with a sensitive in vivo measurement of pineal diurnal melatonin production, we demonstrate that (i) N-acetylserotonin (NAS), the enzymatic product of NAT, is present in vast excess in the night pineals compared with melatonin; (ii) the continuous increase in NAT protein levels at late night does not produce a proportional increase in melatonin; and (iii) an increase in NAS in the same animal over several circadian cycles do not result in corresponding increase in melatonin output. These results strongly suggest that NAT is not the rate-limiting enzyme of melatonin formation at night.

Melatonin Effects on Serotonin Synthesis ..

As Roman said, your scheme and accompanying text is well-organized! However, since you make a point in the text to discuss the fact that serotonin is a branch point and can enter different pathways rather than continuing in melatonin synthesis, it would be helpful to indicate this in the scheme by labeling serotonin and including another set of arrows to show its other possible destinations.

pathway of serotonin synthesis from tryptophan ..

Using an in vitro flow-through system we demonstrated that (1) isolated retinal tissue could exhibit a rhythm of melatonin release, (2) the rhythm of melatonin synthesis is directly entrainable by 24-h light-dark cycles, and (3) supplementation of the culture medium with serotonin is necessary for robust, rhythmic production of melatonin in constant darkness. These results show definitively that the eyes are the loci of a biological clock and, in light of previous studies showing the disruptive effects of blinding on the circadian system, strengthen the hypothesis that the ocular clock is a circadian pacemaker that can affect the rest of the circadian system via the cyclic synthesis and release of melatonin.

Serotonin synthesis remains at its ..

I think this page wonderfully shows the synthesis of melatonin. My only comment would be to perhaps label the substrates in the pathways (melatonin, tryptophan etc.). That might make it slightly easier to follow along with the supplementing text.

Melatonin Supports CYP2D-Mediated Serotonin Synthesis …

The aim of our study was to demonstrate that melatonin supported (via its deacetylation to 5-methoxytryptamine) CYP2D-mediated synthesis of serotonin from 5-methoxytryptamine.