October - December 2015, Volume 11, Issue 4

Ciortea R, Mihu D, Georgescu CE, Borda MI, Ungur RA, Irsay L, Ciortea V

Influence of the Association of Melatonin and Estrogens on Bone Turnover Markers in Ovariectomised Rats

Acta Endo (Buc) 2015, 11 (4): 425-430
doi: 10.4183/aeb.2015.425

Introduction. Bone formation takes place through a continuous remodeling process, which involves the resorption of old bone by osteoclasts and the formation of new bone tissue by osteoblasts, melatonin contributing to the hormonal modulation of the action of osteoblasts and osteoclasts. Aim. The aim of this study is to evidence the influence of melatonin administered in combination with estrogen on bone turnover markers in female Wistar rats with bilateral surgical ovariectomy. Material and method. The study was performed on 40 female Wistar rats with a weight of 160-200 g, which underwent bilateral surgical ovariectomy. At 14 days postovariectomy, hormone replacement therapy (estradiol benzoate – E2b – 10 μg/day) and combined estrogen (estradiol benzoate – E2b – 10 μg/day) and melatonin (added to the drinking water in a concentration of 25 μg/mL or 50 μg/mL – ethanol concentration 0.01%) – treatment were initiated over a period of 12 consecutive weeks. Subsequently, venous blood was collected for the determination of serum osteocalcin and C-terminal telopeptide of collagen type I levels. Results. Melatonin administered in combination with estrogen to ovariectomized female rats induces an increase in serum osteoalcin levels (statistically significant differences between all four groups p=0.001) and a decrease in serum C-terminal telopeptide of collagen type I levels (statistically significant differences between group I and the other three groups p=0.005; p=0.001; p=0.001 and between group II and group IV p=0.007). The influence on bone formation and resorption markers depends on the administered melatonin dose and on the post-ovariectomy estradiol level. Conclusions. Melatonin potentiates the effects of estradiol on bone in ovariectomized rats.

Keywords: melatonin, bone turnover, osteocalcin, C-terminal telopeptide of collagen type I.

Correspondence: Viorela Mihaela Ciortea MD, “Iuliu Hatieganu” University of Medicine and Pharmacy, Medical Rehabilitation Department, 8 Victor Babes, Cluj-Napoca, 400012, Cluj, Romania, E-mail: viorela.ciortea@yahoo.com