The biologically active form of oxytocin, commonly measured by RIA and/or HPLC techniques, is also known as the octapeptide "oxytocin disulfide" (oxidized form), but oxytocin also exists as a reduced straight-chain (non-cyclic) dithiol nonapeptide called oxytoceine. It has been theorized that oxytoceine may act as a free radical scavenger, as donating an electron to a free radical allows oxytoceine to be re-oxidized to oxytocin via the dehydroascorbate / ascorbate redox couple.
These proteins, which typically contain 2-4 repeats of the β-thymosin sequence, are found in all phyla of the animal kingdom, with the probable exception of sponges The sole mammalian example, a dimer in mice, is synthesised by transcriptional read-through between two copies of the mouse β15 gene, each of which is also transcribed separately. A uniquely multiple example is the protein thypedin of Hydra which has 27 repeats of a β-thymosin sequence.
Horvath, G. A., Stockler-Ipsiroglu, S. G., Salvarinova-Zivkovic, R., Lillquist, Y. P., Connolly, M., Hyland, K., Blau, N., Rupar, T., and Waters, P. J. Autosomal recessive GTP cyclohydrolase I deficiency without hyperphenylalaninemia: evidence of a phenotypic continuum between dominant and recessive forms. Mol.Genet.Metab 2008;94:127-131. View abstract.
Johansson, A., Westberg, L., Sandnabba, K., Jern, P., Salo, B., & Santtila, P. (2012). Associations between oxytocin receptor gene (OXTR) polymorphisms and self-reported aggressive behavior and anger: Interactions with alcohol consumption [Abstract]. Psychoneuroendocrinology 37(9), 1546-56. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/22421562
Traumatic brain injury (TBI) remains a leading cause of mortality and morbidity worldwide. No effective pharmacological treatments are available for TBI because all Phase II/III TBI clinical trials have failed. This highlights a compelling need to develop effective treatments for TBI. Endogenous neurorestoration occurs in the brain after TBI, including angiogenesis, neurogenesis, synaptogenesis, oligodendrogenesis and axonal remodeling, which may be associated with spontaneous functional recovery after TBI. However, the endogenous neurorestoration following TBI is limited. Treatments amplifying these neurorestorative processes may promote functional recovery after TBI. Thymosin beta4 (Tβ4) is the major G-actin-sequestering molecule in eukaryotic cells. In addition, Tβ4 has other properties including anti-apoptosis and anti-inflammation, promotion of angiogenesis, wound healing, stem/progenitor cell differentiation, and cell migration and survival, which provide the scientific foundation for the corneal, dermal, and cardiac wound repair multicenter clinical trials. Here, we describe Tβ4 as a neuroprotective and neurorestorative candidate for treatment of TBI.
Much of human behavior is influenced by hormones. There’s cortisol, involved in our stress response and energy balance. Testosterone, a male sex hormone, tends to make men more competitive. Oxytocin has various social and physiological functions in the brain and the body, but is sometimes referred to as the “love hormone” due to its role in social bonding. These are all simplifications, but hormones do underlie many aspects of what we do and what we feel.
The relationship between oxytocin and human sexual response is unclear. At least two non-controlled studies have found increases in plasma oxytocin at orgasm – in both men and women.1718 The authors of one of these studies speculated that oxytocin’s effects on muscle contractibility may facilitate sperm and egg transport.19 Murphy et al. (1987), studying men, found that oxytocin levels were raised throughout sexual arousal and there was no acute increase at orgasm.20 A more recent study of men found an increase in plasma oxytocin immediately after orgasm, but only in a portion of their sample that did not reach statistical significance. The authors noted that these changes “may simply reflect contractile properties on reproductive tissue.”21
The hormone does not act alone. In 2013, neuroscientist Robert Malenka at Stanford University in California and his colleagues showed that oxytocin works together with the neurotransmitter serotonin to reduce the excitability of neurons in the nucleus accumbens9, a brain region involved in reward. This process seems to support the preference of mice to return to environments where they had rewarding social interactions with other animals. “Oxytocin is part of a system,” Carter says, “and it's not the only molecule that matters, but it's one that in some way is regulatory over a large number of other systems.”
Oral 5-HTP results in an increase in urinary 5-HIAA, a serotonin metabolite, indicating that 5-HTP is peripherally metabolized to serotonin, which is then metabolized. This might cause a false positive test in tests looking for carcinoid syndrome. Due to the conversion of 5-HTP into serotonin by the liver, there could be a risk of heart valve disease from serotonin's effect on the heart, as based on preclinical findings. However, 5-HTP has not been associated with cardiac toxicity in humans.