Cells were pretreated with indicated concentrations of Tβ4 peptide for 2 hours and then incubated with 200 μM H2O2 for 48 hours (A-C). Protein expressions were assessed by Western blot analysis (A). The production of NO (B) and PGE2 (C) were measured by Griess reaction and ELISA, respectively. Data replicated the quantifications of NO and PGE2 with the standard deviation of at least three experiments (n = 4). The bar graph shows the fold increase in protein expression compared with control cells. * Statistically significant differences compared with the control, p<0.05. # Statistically significant difference compared with the H2O2—treated group.
High and low oxytocin levels are possible, but research has not yet found any implications of these conditions. Men with high levels of oxytocin sometimes develop benign prostatic hyperplasia, or the enlarging of the prostate gland. This condition can cause urinary complaints. A lack of oxytocin can prevent the milk letdown reflex and make breastfeeding difficult. Low oxytocin levels have also been linked to depression, but using oxytocin to treat mental health conditions has not yet been studied sufficiently.
Addiction vulnerability: Concentrations of endogenous oxytocin can impact the effects of various drugs and one's susceptibility to substance use disorders. Additionally, bilateral interactions with numerous systems, including the dopamine system, Hypothalamic–pituitary–adrenal axis and immune system, can impact development of dependence. The status of the endogenous oxytocin system might enhance or reduce susceptibility to addiction through its interaction with these systems. Individual differences in the endogenous oxytocin system based on genetic predisposition, gender and environmental influences, may therefore affect addiction vulnerability.[72] Oxytocin may be related to the place conditioning behaviors observed in habitual drug abusers.
In the male mammal, the small peptide hormone oxytocin is produced in similar quantities within the hypothalamo-pituitary magnocellular system as in the female, yet for the male little is known about the physiology associated with this hormone. The present review summarizes what is known about the function of oxytocin in the male mammal and tries to take account of both central and systemic effects, and those linked with a local production of oxytocin within the male reproductive organs. In several species a pulse of systemic oxytocin, presumably of hypothalamic origin, appears to be associated with ejaculation. The systemic hormone could act peripherally stimulating smooth muscle cells of the male reproductive tract, but could also reflect central effects in the brain modulating sexual behaviour. In addition to systemic oxytocin, the peptide is also made locally within the testis, and possibly also the epididymis and prostate. In the former tissue it appears to have an autocrine/paracrine role modulating steroid metabolism, but may in addition be involved in contractility of the seminiferous tubules. However, the latter function may involve the mediacy of Sertoli cells which under some circumstances can also exhibit the components of a local oxytocin system. In the prostate of the rat and the dog oxytocin is linked again to steroid metabolism and may also act as a growth regulator. Finally, oxytocin in seminal fluid is discussed and its possible role in respect to the fate of the semen following ejaculation.
But returning hunters also need to share meat with their families and friends; this is where oxytocin comes into play. It can help overcome the potentially negative social effects of testosterone. Men who were absent for longer seem to need more oxytocin to reconnect with their families; it seems that absence does indeed make the heart grow fonder, via an oxytocin blast.

To determine the direct effect of Tβ4 peptide on osteoclastogenesis, mouse BMMs were directly exposed to Tβ4 peptide. Direct treatment with Tβ4 peptide also reduced the number of multinucleated TRAP-positive cells and TRAP activity in a dose-dependent manner (Fig 7A and 7B). Since Tβ4 downregulated H2O2-induced various cytokines expression, the indirect effect of Tβ4 on osteoclast formation through PDLC cells using co-culture system were investigated. After addition of Tβ4 peptide to the BMMs-PDLCs co-culture, the number of osteoclast and TRAP activity were also significantly decreased (Fig 7C and 7D).
5-HTP appears to reduce food intake secondary to increasing satiety, although most studies are currently conducted in women (in regards to 5-HTP being related to serotonin, this may be relevant; see our creatine page and the Depression section for more information). At least one study that was mixed gender supports the notion it benefits both genders, however
Outside the brain, oxytocin-containing cells have been identified in several diverse tissues, including in females in the corpus luteum[34][35] and the placenta;[36] in males in the testicles' interstitial cells of Leydig;[37] and in both sexes in the retina,[38] the adrenal medulla,[39] the thymus[40] and the pancreas.[41] The finding of significant amounts of this classically "neurohypophysial" hormone outside the central nervous system raises many questions regarding its possible importance in these different tissues.
So far, few studies have definitively linked autism to problems in oxytocin signalling. Some of the clearest evidence emerged in February, from a team led by neurogeneticist Daniel Geschwind of the University of California, Los Angeles. The group showed that mice that lacked a working copy of the Cntnap2 gene — which has been implicated in a small subset of human autism cases — had fewer oxytocin-containing neurons in the hypothalamus and socialized less with other mice than did control mice15. After receiving doses of oxytocin every day for two weeks, the mice behaved normally again. “Until this, there was no evidence that there was a subtype of autism that had to do with oxytocin deficits,” Geschwind says.
Double immunofluorescent staining for BrdU (red, A) and NeuN (green, B) to identify newborn neurons (yellow after merge, C) in the dentate gyrus of hippocampus from rats examined 35 days after TBI. Micrographs (D) show location of DiI injection in the CA3 region (indicated by white asterisk). In the CA3 region, axons projected from granule neurons in the dentate gyrus will take up injected DiI to their cell bodies. Co-localization (merge, H) of BrdU-positive nuclei (green, F) within retrogradely DiI labeled (red, E) granule cells were examined at 35 days after TBI. Scale bar = 25 μm (C, H). Scale bar = 50 μm (D).
Thymosin Beta 4 is a peptide that was first found within the thymus gland. Since its discovery, other types of thymosin have been found in different tissues throughout test subjects. Thymosin Beta 4 is typically found in both types of muscles – skeletal (the muscles that are required to move) and smooth muscles (such as the heart). When damage occurs in a tissue, Thymosin Beta 4 is upregulated. Then when traumas take place, Thymosin Beta 4 is released in order to help the subject heal from the trauma. This peptide also helps to prevent adhesions from forming, which means there will be less scar tissue and potentially more flexibility. It has potent anti-inflammatory characteristics.
The soluble form of Ac-SDKP peptide, derived from thymosin beta-4, has been described as a natural inhibitor of pluripotent hematopoietic stem cell proliferation and as a stimulator of angiogenesis, both in vitro and in vivo (Koutrafouri et al., 2001; Wang et al., 2004). This peptide has been selectively bound to acrylated hyaluronic acid hydrogels via thiol groups from cysteine residues (Song et al., 2014). Unfortunately, the immobilization process was poorly characterized and the effect of hydrogels on EC function was not tested in vitro. In a mouse model of chronic myocardial infarction, hydrogels with immobilized Ac-SDKP did not show improved regeneration potential. Yet, Ac-SDKP-HA hydrogels with entrapped stem cell homing factor SDF-1 showed a significant increase of myocardial regeneration and recovery of heart function, as compared to groups with only one or none of these factors, suggesting a potentially interesting synergistic effect.
Humans are social animals. Our individual prospects depend to a significant degree on the prospects of the group(s) to which we belong, and how well we get along with the group(s). Survival means being acutely sensitive to who is on our side and who is not. So it isn’t surprising that trust matters so much to how we go about protecting ourselves. And it isn’t surprising to find the instinct for trust rooted deep in the brain.

A 2002 review concluded that although the data evaluated suggests that 5-HTP is more effective than placebo in the treatment of depression, the evidence was insufficient to be conclusive due to a lack of clinical data meeting the rigorous standards of today.[2] More and larger studies using current methodologies are needed to determine if 5-HTP is truly effective in treating depression.[3][4] In small controlled trials 5-HTP has also been reported to augment the antidepressant efficacy of the antidepressant clomipramine.[5][6][7]