This anti-social effect of a social hormone brings some nuance to the story of oxytocin. In one study, researchers found that Dutch students given a snort of the hormone became more positive about fictional Dutch characters, but were more negative about characters with Arab or German names. The finding suggests that oxytocin's social bonding effects are targeted at whomever a person perceives as part of their in-group, the researchers reported in January 2011 in the journal PNAS.
Expanding upon the possible anti-panic effects of 5-HTP, one study using 2mg/kg 5-HTP to children (3.2-10.6 years of age) at bedtime for 20 days noted that 5-HTP was asssociated with beneficial response (more than 50% reduction in night terror frequency) of 93.5% of children relative to 28.6% in placebo. Oddly, 6 months after the initial supplementation period the 5-HTP group still reported less sleep terrors (83.9% reporting improvement).
It has been noted that isolated supplementation of 5-HTP may deplete or reduce the bioactivity of catecholamines such as dopamine (which extends to L-Tryptphan) and that this relationship also acts in reverse, with supplemental L-Tyrosine possibly able to deplete 5-HTP and Serotonin itself, which extends to supplemental L-DOPA which may reduce all intermediate of serotonin synthesis although L-DOPA may also deplete L-Tyrosine (as it is merely later in the same metabolic chain). Due to excessive levels of either one depleting the other, some authors have suggested that combination therapy of 5-HTP and L-Tyrosine (the furthest back in the metabolic chain while still passing rate limiting enzymes) is a potentially useful avenue for anti-depressive effects.
In some studies that record appetite suppression with 5-HTP supplementation, nausea appears to also be reported at higher freqencies than placebo, although some interventions note this as the only relevant side effect. Short term studies tend to note that nausea persists throughout the study period while those expanding beyond three weeks note that reports of nausea tend to decline at this time point.
Skin damage and aging are induced to a large extent by free radicals from the sun and environmental pollutants and from oxidants produced during infection and inflammation. Lipid peroxidation of membranes and increased inflammatory substances, such as thromboxanes and leukotriens, add insult to injury. While skin damage accumulates with age, repair processes slow down. Thus, any boost by a molecule that would reduce free radicals and accelerate molecular events in healing has the potential to hasten skin repair. Tb4 has such healing qualities.
Although maternal bonding may not always be hardwired — after all, human females can adopt babies and take care of them — oxytocin released during pregnancy "does seem to have a role in motivation and feelings of connectedness to a baby," Young said. Studies also show that interacting with a baby causes the infant's own oxytocin levels to increase, he added.
The oxytocin peptide is synthesized as an inactive precursor protein from the OXT gene. This precursor protein also includes the oxytocin carrier protein neurophysin I. The inactive precursor protein is progressively hydrolyzed into smaller fragments (one of which is neurophysin I) via a series of enzymes. The last hydrolysis that releases the active oxytocin nonapeptide is catalyzed by peptidylglycine alpha-amidating monooxygenase (PAM).
5-HTP is decarboxylated to serotonin (5-hydroxytryptamine or 5-HT) by the enzyme aromatic-L-amino-acid decarboxylase with the help of vitamin B6. This reaction occurs both in nervous tissue and in the liver. 5-HTP crosses the blood–brain barrier, while 5-HT does not. Excess 5-HTP, especially when administered with vitamin B6, is thought to be metabolized and excreted.