In a study that hasn’t been published yet, Feldman found that oxytocin receptor genes are also linked to empathy in couples. She looked at variants in the gene that have been linked with an increased risk for autism, a disorder that is marked by major social communication deficits. She found that the more of these “risk variants” a person had, the less empathy they showed toward their partner when that partner shared a distressing experience.
Monomeric β-thymosins, i.e. those of molecular weight similar to the peptides originally isolated from thymus by Goldstein, are found almost exclusively in cells of multicellular animals.[4] Known exceptions are monomeric thymosins found in a few single-celled organisms, significantly those currently regarded as the closest relatives of multicellular animals:[5] choanoflagellates [6] and filastereans.[7] Although found in very early-diverged animals such as sponges, monomeric thymosins are absent from arthropods and nematodes, which do nevertheless possess "β-thymosin repeat proteins" which are constructed from several end-to-end repeats of β-thymosin sequences.[8] Genomics has shown that tetrapods (land vertebrates) each express three monomeric β-thymosins, which are the animal species' equivalents (orthologues) of human β4, β10 and β15 thymosins, respectively. The human thymosins are encoded by the genes TMSB4X, TMSB10 and TMSB15A and TMSB15B. (In humans, the proteins encoded by the two TMSB15 genes are identical.) Bony fish in general express orthologues of these same three, plus an additional copy of the β4 orthologue.[9]
To prevent adverse effects, always consult your physician and pharmacist before taking any drug or supplement. Inform your doctor and pharmacist about all drugs you take, whether they are prescription, non-prescription, vitamins, supplements, or herbs. Be sure to read and understand the Drug Facts section of the product label before taking any medication, and never take more than what is specified by your doctor. Dietary supplements are drugs, so be sure to keep them out of sight and reach of children and pets.
Oxytocin is relatively safe when used at recommended doses. Potential side effects include: Central nervous system: Subarachnoid hemorrhage, seizures; Cardiovascular: Increased heart rate, blood pressure, systemic venous return, cardiac output, and arrhythmias;Genitourinary: Impaired uterine blood flow, pelvic hematoma, tetanic uterine contractions, uterine rupture, postpartum hemorrhage.
In years past, oxytocin had the reputation of being an "uncomplicated" hormone, with only a few well-defined activities related to birth and lactation. As has been the case with so many hormones, further research has demonstrated many subtle but profound influences of this little peptide, particularly in regards to its effects in the brain. Oxytocin has been implicated in setting a number of social behaviors in species ranging from mice to humans. For example, secretion or administration of oxytocin in humans appears to enhance trust and cooperation within socially-close groups, while promoting defensive aggression toward unrelated, competing groups.
I’ve used powdered 5-HTP a couple times now, it doesn’t taste great and it’s resulted in an unpleasant stomach upset that lasted 45–60 minutes. For that reason I’ll likely not continue to use it. I did not find it’s effect on mood remarkable enough that I would want to put up with the stomach upset. My go to Nootropics for mood are Rhodiola and Phenibut and my go to Biohacks for mood are meditation and no fap, I don’t feel the need to use a whole lot more mood promoting strategies.

Milk ejection reflex/Letdown reflex: in lactating (breastfeeding) mothers, oxytocin acts at the mammary glands, causing milk to be 'let down' into subareolar sinuses, from where it can be excreted via the nipple.[47] Suckling by the infant at the nipple is relayed by spinal nerves to the hypothalamus. The stimulation causes neurons that make oxytocin to fire action potentials in intermittent bursts; these bursts result in the secretion of pulses of oxytocin from the neurosecretory nerve terminals of the pituitary gland.
The idea that oxytocin is central to social cognition made it an attractive candidate for treating psychiatric disorders, especially autism spectrum disorder. People with this condition, who often have problems with social interaction and communication, may not process social stimuli appropriately — and scientists theorized that oxytocin might reverse some of the symptoms. Beginning in 2010, results emerged that seemed to support this theory: researchers found that single puffs of oxytocin could temporarily improve measures of empathy and social cooperation in people with autism spectrum disorder.
5-HTP has been linked in very rare instances to a condition known as EMS, or eosinophilia-myalgia syndrome, which combines extreme muscle tenderness with abnormalities in the blood. A contaminant that was found in some tryptophan supplements in the late 1980s, and was linked to a small number of EMS cases, was also found in some 5-HTP supplements.  It’s important to talk with your doctor before you begin taking 5-HTP or any other supplement, and to make sure you’re getting your supplements from a reliable provider.  

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]