This 2020 review attempted to consolidate thousands of research papers on oxytocin:
“Chemical properties of oxytocin make this molecule difficult to work with and to measure. Effects of oxytocin are context-dependent, sexually dimorphic, and altered by experience. Its relationship to a related hormone, vasopressin, have created challenges for its use as a therapeutic drug.
Widely used medical interventions i.e.:
- Exogenous oxytocin, such as Pitocin given to facilitate labor;
- Opioid medications that block the oxytocin system; or
- Cesarean sections that alter exposure to endogenous oxytocin
have lasting consequences for the offspring and/or mother.
Such exposures hold the potential to have epigenetic effects on the oxytocin systems, including changes in DNA methylation. These changes in turn would have lasting effects on the expression of receptors for oxytocin, leaving individuals differentially able to respond to oxytocin and also possibly to the effects of vasopressin.
Regions with especially high levels of OXTR [oxytocin receptor gene] are:
- Various parts of the amygdala;
- Bed nucleus of the stria terminalis;
- Nucleus accumbens;
- Brainstem source nuclei for the autonomic nervous system;
- Systems that regulate the HPA axis; as well as
- Brainstem tissues involved in pain and social attention.
Oxytocin protects neural cells against hypoxic-ischemic conditions by:
- Preserving mitochondrial function;
- Reducing oxidative stress; and
- Decreasing a chromatin protein that is released during inflammation
which can activate microglia through the receptor for advanced glycation end products (RAGE). RAGE acts as an oxytocin-binding protein facilitating the transport of oxytocin across the blood-brain barrier and through other tissues.
Directionality of this transport is 5–10 times higher from the blood to the brain, in comparison with brain to blood transport. Individual differences in RAGE could help to predict cellular access to oxytocin and might also facilitate access to oxytocin under conditions of stress or illness.
Oxytocin and vasopressin and their receptors are genetically variable, epigenetically regulated, and sensitive to stressors and diet across the lifespan. As one example, salt releases vasopressin and also oxytocin.
Nicotine is a potent regulator of vasopressin. Smoking, including prenatal exposure of a fetus, holds the potential to adjust this system with effects that likely differ between males and females and that may be transgenerational.
Relative concentrations of endogenous oxytocin and vasopressin in plasma were associated with:
These studies support the usefulness of measurements of both oxytocin and vasopressin but leave many empirical questions unresolved.
The vast majority of oxytocin in biosamples evades detection using conventional approaches to measurement.”
https://pharmrev.aspetjournals.org/content/pharmrev/72/4/829.full.pdf “Is Oxytocin Nature’s Medicine?”
I appreciated efforts to extract worthwhile oxytocin research from countless poorly performed studies, research that wasted resources, and research that actually detracted from science.
I was disappointed that at least one of the reviewers didn’t take this review as an opportunity to confess their previous wastes like three flimsy studies discussed in Using oxytocin receptor gene methylation to pursue an agenda.
Frank interpretations of one’s own study findings to acknowledge limitations is one way researchers can address items upfront that will be questioned anyway. Such analyses also indicate a goal to advance science.
Although these reviewers didn’t provide concrete answers to many questions, they highlighted promising research areas, such as:
- Improved approaches to oxytocin measurements;
- Prenatal epigenetic experience associations with oxytocin and OXTR; and
- Possible transgenerational transmission of these prenatal epigenetic experiences.