Prevention of post-menopausal osteoporosis in rats by sesame oil

By Dr. Priyom Bose, Ph.D.Reviewed by Benedette Cuffari, M.Sc.Jan 4 2024

A recent Scientific Reports study uses a rat model to assess the beneficial effects of sesame oil supplement extracted from Sesamumindicum L. on post-menopausal osteoporosis.

Study: Daily supplement of sesame oil prevents post-menopausal osteoporosis via maintaining serum estrogen and aromatase levels in rats. Image Credit: Pixel-Shot / Shutterstock.com

Background

A fundamental cause of post-menopausal osteoporosis (PO) in older women is estrogen deficiency. PO is characterized by low bone mineral density (BMD), which significantly affects the quality of life in older women.

A common treatment for PO is hormone replacement therapy (HRT); however, HRT increases the risks associated with breast cancer and irregular vaginal hemorrhage. Thus, there remains an urgent need to develop safer therapeutic agents for osteoporosis patients.

After menopause, estrogen deficiency accelerates bone turnover, during which bone formation is unable to keep pace with bone resorption. Alkaline phosphatase (ALP) is a clinical biomarker for diagnosing osteoporosis, whereas procollagen I C-terminal propeptide (PICP) is associated with bone formation. With regard to bone resorption rates, crosslinked N-telopeptide (NTx) is a valuable marker.

Sesame oil influences the sex hormone status and is rich in lignans, antioxidants, and fatty acids. Although recent research has reported the beneficial effects of sesame oil in osteoporosis patients, the exact mechanism of action is not well understood.

About this study

The present study assessed the potential mechanisms through which sesame oil affects ovariectomy (OVX)-treated rats with PO. To this end, 24 twelve-week-old female rats were kept under a half-half light/dark cycle. PO was induced by removing both ovaries. 

Rats were divided into four groups, including the OVX group, the SOL group, where OVX rats were administered with 0.25 mL/kg/day sesame oil; the SOH group, in which OVX rats were administered with 0.5 mL/kg/day sesame oil, and a sham group, in which rats underwent a sham operation.

At the end of the experiment, ALP, osteocalcin, PICP, NTx, aromatase, and plasma estrogen l levels were measured. BMD was also determined, and bone histopathology was performed.  

Key findings

Daily supplementation with sesame oil effectively prevented the development of osteoporosis, improved bone formation, and reduced markers of bone resorption in OVX rats. Serum estradiol and aromatase levels were also much higher with daily sesame oil supplementation, which could be one of the mechanisms that drive the maintenance of estradiol levels in rats. 

ALP levels are often much higher in post-menopausal women as compared to pre-menopausal women, which was similarly observed in osteoporosis rats. In the present study, sesame oil supplementation reduced serum ALP and NTx levels and increased serum osteocalcin levels, PICP levels, and BMD in OVX-rats.

Sesame oil also raised serum estradiol levels in OVX-rats, which could be driven by lignans present in sesame oil, which have other phytoestrogenic compounds. An alternative to estrogen replacement therapy could be phytoestrogens due to their lower side effects.

Serum estrogen levels may be maintained by the activation of the aromatase-related pathway. In the present study, sesame oil helped maintain serum estradiol and aromatase levels.

The imbalance in the gut microbiota (GM) is another key topic concerning osteoporosis patients. A strong correlation between bone mass and gut GM was noted in OVX-mice. The bone loss induced by OVX can be prevented by probiotics, such as Bifidobacterium and Lactobacillus.

Conclusions

The present study reported the beneficial effects that daily supplementation with sesame oil can provide with regard to osteoprotection by raising serum estradiol and aromatase levels. 

Some notable limitations of the current study include the lack of evaluation of the RANKL/RANK/OPG pathway, which is essential for bone remodeling and is considered a therapeutic target in OVX-rats. Thus, future research is needed to determine the role of sesame oil in increasing BMD through this signaling pathway. 

The researchers also failed to analyze the baseline BMD of each rat prior to the index procedure, which could have affected the analysis of BMD changes within each group. However, measurements of only post-therapy BMD are commonly reported in the literature.