Oxytocin Factor Clinically Proven

Research investigating the causal effects of oxytocin on a number of conditions including depression, stress and anxiety dates back to 1998. Provided here is an overview of oxytocin research identified in the literature, numerous research studies, and corresponding implications. Much scientific evidence is first obtained through research with non-mammals. Such research is considered common and acceptable in the scientific community.

Objectives: Oxytocin (OT) has long been implicated in maternal bonding, sexual behavior and social affiliation behaviors. This paper reviews the wide effects of oxytocin and its key role in well-being.

Methods: Studies were identified through Medline, Pubmed, and PsychINFO search of the English-language literature from the past sixty years (1959 to 2009) using the key word “oxytocin” in human studies. Of the 287 articles identified, 102 were selected for review.

Results: OT induces a general sense of well-being including calm, improved social interactions, increased trust, and reduced fear as well as endocrine and physiological changes. Some central effects of OT are temporary and its release is associated with induction of secondary biochemical actions which mediate long-term benefits including blood pressure reduction, calm and affiliative behavior. As OT release is augmented by touch and physiological support so the hormone is involved in both the cause and benefits of social interactions. Just as OT has widespread effects in factors encompassing well-being, its dysfunction is associated with morbidity and decreased quality of life as observed neuropsychiatric conditions such as autism, schizophrenia and social phobias.

Oxytocin (OT) is a neuropeptide consisting of nine amino acids produced by the paraventricular and supraoptic nuclei of the hypothalamus. After OT synthesis the neuropeptide is transported and stored in the neurohypophysis (posterior pituitary) where it is released into the circulation and to peripheral effects. Another pathway is whereby paraventricular nuclei have specific projections, which deliver Oxytocin to other structures in the brain including amygdala, hypothalamus, and hippocampus and nucleus accumbens. OT induces labor through increasing uterine tone and promoting uterine contractions. OT is also involved in maternal bonding, sexual behavior and affiliation. This paper reviews the wide effects of oxytocin and its key role in well-being. In its broadest sense well-being encompasses fulfillment with how we feel within ourselves, the way we relate to our environment and the way in which we relate to others. Well-being is a state of absence of mental and physical disease and also of positive emotions and contentment. Feelings of trust, strong social networks and ability to relate to others are all favorable factors that promote well-being. Conversely, fear, anxiety, isolation, lack of social support as well as physiological risk factors such as high blood pressure and release of stress hormones are all detrimental to our sense of emotional and physical well-being. This review explores these factors and examines neuropsychiatric conditions where well-being is impaired and explores the key role OT plays within the symptom domains in these conditions.

Conclusions: Oxytocin (OT) is of potential use in enhancing interpersonal and individual well-being, and might have more applications in neuropsychiatric disorders especially those characterized by persistent fear, repetitive behavior, reduced trust and avoidance of social interactions.

Role of oxytocin in well-being at the individual level OT also acts at the individual level by promoting factors that facilitate close bonding. The ability to trust, have reduced levels of fear and to maintain have healthy interactions in the environment is fundamental to the overall sense of well being.

Source: IsHak, W.W., et al., Oxytocin role in enhancing well-being: A literature review. Journal of Affective Disorders (2010), doi: 10.1016/j.jad.2010.06.001

Trust and Fear

3.2.1. Oxytocin increases trust and reduces fear

OT plays a key role in modulating anxiety, increasing trust and reducing fear. OT exerts these effects through specific OT receptors found within the Amygdala central to neurological pathways that mediate fear, trust and social recognition (Heinrichs et al., 2004; Huber et al., 2005; Richard et al., 1991; Veenema and Neumann, 2008). OT excites the GABAergic neurons in the amygdala and also inhibits neurons excited by vasopressin in response to fear (Viviani and Stoop, 2008). Amygdala hyper activation leads to impairment in emotional and mental state and is a key symptom domain in many neuropsychiatric disorders. It has been shown that DSM-IV depression is associated with amygdale hyper activation in response to standardized emotion face recognition task using fMRI (Peluso et al., 2009). OT may exert its effects through reduction in fear and attenuating the functional connectivity between amygdala and brainstem connectivity (Ferguson et al., 2002). Kirsch and colleagues reported that in healthy males (n=15) OT infusion reduced amygdala activation and coupling of amygdale to brainstem regions after exposure to stress as seen on functional MRI. These results were also accompanied by a reduction in sympathetic behavioral manifestations of fear in response to angry and fearful facial expressions (Kirsch et al., 2005). OT also modulated amygdala activation in response to happy facial expressions in a facial affect recognition test (Domes et al., 2007b). OT administration is associated with increased trust. Kosfield et al. found that in a test experiment which required financial investment, male volunteers (n=58) who received intranasal OT 50 min prior to test showed increased levels of trust as shown by significantly higher MU (money transfer amount units) per investor compared to placebo. OT test subjects when participated in a similar experiment but one that assessed level of risk taking exhibited identical money transfer rates to the placebo group, suggesting the increased trust is unrelated to increased risk taking (Kosfield et al., 2005). In a study of healthy test subjects (n=49) OT administration lead to continued trusting behavior both on subjective reporting of trust as well as on detailed questionnaire, despite several breaches of trust in a simulated trust game while the placebo group lost their trusting behavior. The OT group also showed reduced activation of amygdala, midbrain and striatum regions on fMRI during simulated breaches of trust (Baumgartner et al., 2008). There are also gender differences with regards to some of the affects of OT and estrogen induces OT receptors in the amygdala (Patisaul et al., 2003; Somponpun and Sladek, 2002).

3.2.2. OT increases pro-social behavior and social recognition

Humans are social creatures and pro-social behavior is critical for the individual to interact with environment, which encompasses well-being. Impairment in social behavior is associated with decreased quality of life and psychopathological states (Heinrichs et al., 2008; 38, 43]. In animal models administration of exogenous synthetic OT enables animals to overcome avoidance and to inhibit defensive behavior that aids approach behavior and OT might actually be essential for initiating social interactions (Heinrichs et al., 2008; Insel,1992). OT administration in mice selectively decreased the separation response and increased social contact (Insel, 1992; Kavaleirs et al., 2003). Rats injected with OT spent more time in the center of the arena as compared to controls and conversely OT antagonists reverse this behavior. Decrease in prairie vole OT function achieved by administration of OT antagonists was also associated with attenuation of social interactions and marked social isolation (Carter et al., 2008). These animal studies have led to human studies to investigate mechanisms of this effect. Guastella and colleagues suggest that mechanism by which OT promotes prosocial behavior is through increased gaze to the eye region of the human face. In a double blind RCT (randomized control study), healthy males (n=52) who received OT showed increased number of fixations and total gaze time specifically towards the eye region of the human face in comparison to those who received placebo (Guastella et al., 2008). Another study found that OT administration to healthy males (n=30) improves performance on the ability to infer affective mental state of others as seen on the RMET (reading the mind in the eyes test) as compared to placebo (Domes et al., 2007a). OT infusion in healthy women (n=36) improved memory recognition of faces shown to subjects in a portrait recognition test, suggesting another possible mechanism for how OT might specifically aid social behavior is through human memory for facial identity (Savaskan et al., 2008). OT not has also been implicated in social learning including recognition of fellow members of in animal models. OT action specifically in the medial amygdala and its activation is both necessary and sufficient for social recognition and retention in mice (Ferguson et al., 2001). For example OT knockout mice fail to express memory of con specifics after repeated exposure despite normal learning abilities and conversely OT infusion in amygdala restores social learning (Ferguson et al., 2000). OT also plays a role in risk aversion and personal protection along with recognition of con-specifics (members of the same species). For example OT knockout mice displayed significant social amnesia and were also unable to recognize and avoid infected con specifics and subsequently became infected. With OT administration the female mice were able to recognize odor in infected male mice and avoided them (Kavaliers et al., 2003). The most efficient benefit of OT administration has been shown when OT is directly injected into the amygdala as suggested in studies done with null OT mutant mice where direct interamygdala injection restored social recognition (Winslow et al., 2001).

Source: IsHak, W.W., et al., Oxytocin role in enhancing well-being: A literature review. Journal of Affective Disorders (2010), doi: 10.1016/j.jad.2010.06.001

 

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