Evidence for this role of oxytocin come from two types of experiments. First, infusion of oxytocin into the ventricles of the brain of virgin rats or non-pregnant sheep rapidly induces maternal behavior. Second, administration into the brain of antibodies that neutralize oxytocin or of oxytocin antagonists will prevent mother rats from accepting their pups. Other studies support the contention that this behavioral effect of oxytocin is broadly applicable among mammals.
Obesity. Early research suggests that taking 5-HTP might help reduce appetite, caloric intake, and weight in obese people. Other research suggests that using a specific mouth spray containing 5-HTP and other extracts (5-HTP-Nat Exts, Medestea Biotech S.p.a., Torino, Italy) for 4 weeks increases weight loss by about 41% in overweight postmenopausal women.
The cornea is the outer thin layer of epithelial cells protecting the eye. After wounding, timely resurfacing of the cornea with new cells is critical, to prevent loss of normal function and loss of vision. Corneal epithelial healing occurs in stages, with cells migrating, dividing and differentiating. Therapies for corneal injury are limited. Therefore, the recent finding that Tb4 promotes corneal wound repair in animal models offers hope for a therapeutic product that will improve the clinical outcome of patients with injured corneas.
Moreover, Tβ4 concentration revealed wide variability, and it decreased in the gingival crevicular fluid (GCF) as periodontal disease progressed . In contrast, Tβ4 mRNA expression was 3.76 fold higher in periodontitis-affected gingival tissue, compared with healthy individuals’ tissue obtained from public microarray data (GEO assession: GSE 23586) . However, the Tβ4 mRNA level did not change in the periodontal-diseased gingival tissue (arbitrary units; 6.249) when compared with healthy tissue (arbitrary units; 6.242) (GEO assession: GSE 10334) . Although Tβ4 exerts anti-inflammatory effects in vivo and in vitro, the precise role of Tβ4 in the inflammatory response remains unclear.
Many early studies of oxytocin for autism were limited because they assessed only a single dose and had relatively few participants, and later experiments with more doses failed to show the same promise. In 2010, clinical psychologist Adam Guastella at the University of Sydney in Australia studied 16 male adolescents with autism spectrum disorder, and found that one dose of oxytocin could improve their ability to gauge the emotions of others by looking at their eyes13. But when he tried giving twice-daily doses of the hormone for two months, he found no significant improvements in social interaction or social cognition14. “Studies to this point have really shown limited benefit of oxytocin in improving psychiatric illnesses over time,” he says. Guastella says that getting to the bottom of oxytocin's complex neurological effects will take time. “If we want a simple answer, we're not going to get it.”
Oxytocin production is controlled by a positive feedback mechanism. This mechanism allows the release of the oxytocin hormone when a trigger occurs. The hormone then causes an action in the body, such as the letdown of milk or the start of labor contractions, which signals more production of oxytocin. The feedback cycle continues until the action, such as childbirth or feeding the baby, is complete.
When combined with antidepressants of the MAOI or SSRI class, very high parenteral doses of 5-HTP can cause acute serotonin syndrome in rats. 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.