Oxytocin, produced by the hypothalamus – also known as the “love hormone”, as it is released in the presence of partners – can also be a strong ally in controlling and preventing osteoporosis. A study carried out on female rats at the end of the fertile period, Paulista State University (Unesp), showed that the hormone reversed factors that precede the condition, such as decreased bone density and resistance and also substances that favor bone formation.
“Our study focuses on the prevention of primary osteoporosis. Therefore, we investigate physiological mechanisms that occur in the pre-menopause period. At this stage of a woman’s life, preventive measures can prevent bones from becoming fragile and fractures from occurring, which could reduce quality and life expectancy, ”she says. Fapesp Agency Rita Menegati Dornelles, coordinator of the Laboratory of Endocrine Physiology and Aging of the Department of Basic Sciences at Unesp in Araçatuba.
The study, published in Scientific Reports, was supported by São Paulo State Research Support Foundation (Fapesp). Dornelles points out that there are two important hormonal milestones in a woman’s life: puberty and perimenopause (transition to menopause, which can last for several years). These events mark, respectively, the beginning and the end of the fertility period.
“Post-menopause is studied a lot, when the woman stops menstruating. However, the hormonal fluctuations that occur before, in perimenopause, are already quite strong and are related to the gradual decrease in bone density. There is a need for studies aimed at preventing osteoporosis at this stage, since the period after menopause represents about a third of life and must be lived with quality ”, he stresses.
In the study, the researchers applied only two doses of the hormone oxytocin – with a 12-hour difference between one injection and another – in a group of 10 Wistar rats. The animals were 18 months old, something unusual for laboratory studies, as research is usually carried out on young animals undergoing ovariectomy.
On average, laboratory mice live about three years. The females in the study were in the period of periestropause, equivalent to human perimenopause, and in a natural aging process.
After 35 days of treatment with oxytocin, blood samples and the femoral neck of the animals were analyzed. There was also a comparison of these data with those of 10 other rats, also 18 months old, who did not receive the hormone.
In the comparison, animals that received oxytocin doses showed bone structure without signs of osteopenia (loss of bone density). The picture was different in the control group. “Oxytocin helps to modulate the bone remodeling cycle of senescent rats. The animals that received the hormone had an increase in biochemical markers associated with bone renewal, such as the expression of proteins that favor bone formation and mineralization ”, says Dornelles.
In the analysis of blood samples, it was possible to observe a greater presence of important systemic bone biomarkers, such as alkaline phosphatase activity. “Produced by osteogenic cells, the substance is associated with the mineralization process. We also observed a reduction in another enzyme (TRAP) associated with bone resorption ”, he points out.
The rats that received oxytocin showed denser bones. “We found that the femoral neck region was more resistant, with less porosity, better biomechanical compression response, in addition to presenting physico-chemical properties that guaranteed greater density”, he says.
Oxytocin is a hormone produced in the cerebral hypothalamus and was characterized in the beginning of the last century and its release was associated, above all, with childbirth and breastfeeding.
More recent studies have shown that a large number of cells (in addition to hypothalamus) also secrete the hormone. “Oxytocin is secreted by bone cells and our studies are showing its association with bone metabolism in females during the aging process. Generally, women in the post-menopausal period, with a higher rate of osteoporosis, have lower concentrations of oxytocin in the blood plasma ”, emphasizes Dornelles.
The group of researchers from Unesp has been working for 10 years on studies on the involvement of oxytocin in bone metabolism. “In that time we were able to characterize animal models that simulate the period of perimenopause in women”, he points out.
According to projections made by the World Health Organization (WHO), there will be a 630% increase in hip fractures (associated with osteoporosis) in Brazil, while in developed countries the expected increase will be 50%.
“The increase is related to the aging of the population, which has increasing rates due to the quality of life, nutrition and physical activity, for example, important means of disease prevention”, highlights the researcher.
In the study, students specifically analyzed the region of the neck of the femur, as hip fractures occur three times more frequently in the female body. “The consequences of these fractures are very drastic, such as difficulty or impossibility of locomotion and comorbidities”, he says.
Dornelles points out that hip fractures are associated with high reported mortality rates. Up to 24% of patients die in the first year after a hip fracture and the increased risk of death may persist for at least five years.
“The loss of function and independence among the survivors is profound. Around 40% are unable to walk independently, of this total, 60% need assistance one year later. Less than half of those who survive hip fractures recover their previous level of function ”, he reveals.
The researchers intend to conduct, in the future, clinical studies on the effect of oxytocin on the prevention of osteoporosis in humans. “The hormone is produced naturally in our body and has already been synthesized in the laboratory. Even so, a long study will be necessary to evaluate the efficacy, safety and also to know the most suitable dosage of the hormone ”, says Dornelles.
The article can be consulted by email https://www.nature.com/articles/s41598-020-64683-0.