The neurotransmitter serotonin is synthesized from the amino acid tryptophan through 5-HTP. In which tryptophan gets converted into 5-HTP via the enzyme tryptophan hydroxylase and 5-HTP gets converted into serotonin via the enzyme L-amino acid decarboxylase.[4] Serotonin is later degraded into 5-hydroxyindoleacetic acid (5-HIAA) by monoamine oxidase.
Chae, H. S., Kang, O. H., Choi, J. G., Oh, Y. C., Lee, Y. S., Jang, H. J., Kim, J. H., Park, H., Jung, K. Y., Sohn, D. H., and Kwon, D. Y. 5-hydroxytryptophan acts on the mitogen-activated protein kinase extracellular-signal regulated protein kinase pathway to modulate cyclooxygenase-2 and inducible nitric oxide synthase expression in RAW 264.7 cells. Biol Pharm Bull 2009;32(4):553-557. View abstract.
The combination of supplemental 5-HTP and a dopamine decarboxylase inhibitor is also thought to reduce the risk for cardiovascular complications, as excess serum (but not neural) serotonin is associated with heart valve disease in rats.[56] Due to the accumulation of 5-HTP in neural tissue following the combination[54] it is plausible to assume a reduction in systemic serotonin; this has not been demonstrated yet, however.

Oxytocin is a hormone that also acts as a neurotransmitter in the brain. Some popular media have incorrectly labeled it the “love hormone,” because it is associated with good feelings and emotions. But its role in the body is much more complex than that. It is not a bliss or hug hormone, but it does appear to be connected to human emotions and the regulation of childbirth and breast-feeding.

Despite these many roles, oxytocin is often reduced to a misleading label. While “hormone of love” may be great for catchy headlines and compelling marketing slogans, they are ultimately misleading. Jennifer Bartz from the Mount Sinai School of Medicine has found that oxytocin can have completely opposite effects on the way people behave, depending on how they view their relationships to other people.
In addition to angiogenesis and neurogenesis, cell- and pharmacologically based therapies substantially remodel white matter in the ischemic brain. Treatment of experimental stroke with MCSs, rhEPO, or sildenafil significantly increases axonal density encapsulating the ischemic lesion. Dynamic changes of white matter structure along the ischemic boundary have been imaged in living animals by diffusion tensor imaging (DTI) and fractional anisotropy (FA) measurements. Data from these MRI indices demonstrate that administration of rhEPO or sildenafil augments axonal remodeling and angiogenesis and that both of them are spatially and temporally correlated. Administration of MSCs, rhEPO, and thymosin beta 4 (Tβ4) dramatically increases the number of oligodendrocyte progenitor cells in the corpus callosum, the striatum, and the V/SVZ of the ischemic hemisphere and mature oligodendrocytes in the ischemic boundary adjacent to myelinated axons. These findings suggest that cell- and pharmacologically based therapies promote generation of oligodendrocyte progenitor cells in the ischemic brain that migrate to target axons, where they extend their processes myelinating the axons.
Osteoclast differentiation was assessed by tartrate-resistant acid phosphatase (TRAP) staining and activity. After 5 days of culture, cells were stained for TRAP kit using a leukocyte acid phosphatase kit (Sigma Aldrich, St Louis, MO, USA). Cells with three or more nuclei were counted as multinucleated mature osteoclasts. To measure TRAP activity, cells were fixed with 10% formalin for 10 min and 95% ethanol for 1 min, and then 100 μl of citrate buffer (50 mM, pH 4.6) containing 10 mM sodium tartrate and 5 mM p-nitrophenylphosphate (Sigma-Aldrich) was added to the wells containing fixed cells in the 48-well plates. After incubation for 1 h, enzyme reaction mixtures in the wells were transferred to new plates containing an equal volume of 0.1 N NaOH. Absorbance was measured at 410 nm using a microplate reader.
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Mouse BMMs were cultured with M-CSF (30 ng/mL) and RANKL (100 ng/mL) or CM collected from PDLCs for 5 days (A) and 60 minutes (B). The mRNAs expression was determined by PCR analysis (A). The phosphorylation of MAPKs (p38, JNK, and ERK), and activation of NF-κB were determined by Western blot analysis (B). Data were representative of three independent experiments. The bar graph shows the fold increase in protein or mRNA expression compared with control cells * Statistically significant differences compared with the control, p<0.05.
When combined with antidepressants of the MAOI or SSRI class, very high parenteral doses of 5-HTP can cause acute serotonin syndrome in rats.[23][24] It is unclear if such findings have clinical relevance, as most drugs will cause serious adverse events or death in rodents at very high doses. In humans 5-HTP has never been clinically associated with serotonin syndrome, although 5-HTP can precipitate mania when added to an MAOI.[25]
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