Chronic melatonin administration on bone tissue of ovariectomized rats

• Grant number: 21/10404-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2022
• End date: August 31, 2023
• Field of knowledge: Health Sciences - Physical Education
• Principal Investigator: Wladimir Rafael Beck
• Grantee: Milena Rossales Castro
• Host Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

The state of hypoestrogenism promotes metabolic imbalances, with bone tissue being heavily impacted. Hormonal deficit compromises bone remodeling by intensifying osteoclastic activity, which leads to a decrease in bone mineral density and intensifies the chances of fractures and degenerative bone diseases. In an attempt to reverse the scenario, estrogen hormone replacement therapy is used, but it has caused numerous side effects. As an alternative, melatonin seems to be a promising pharmacological method in reason of its almost inexpressive side effects in face of its great beneficial potential, becoming the subject of studies as a preventive or therapeutic agent for bone damage as a result of the hypoestrogenic condition. However, considering that bone is not a simple organ to be modulated, the literature presents some inconsistencies in studies that examine the roles of this indoleamine in bone properties. Therefore, the purpose of the study will be to investigate the effects of chronically administered melatonin on bone tissue parameters commonly compromised by estrogen deficit. Wistar rats will be divided into 4 groups (control, melatonin, and ovariectomized with or without melatonin). At 90 days of age, bilateral ovariectomy will be realized and, 8 days later, the protocol of administration of melatonin by orogastric gavage will be started during the night period for 12 weeks. After the interventions, the animals will be euthanized for the collection of biological material (right and left femurs) and analysis of their biometric, biophysical, biochemical, biomechanical, and microtomographic properties. There will be data testing for normality and the effects of ovariectomy and melatonin will be evaluated in an appropriate analysis of variance (ANOVA) with a significance level of 5% for all analyses. The hypothesis is that indoleamine will act in a protective way, maintaining the tissue homeostasis scenario and helping to prevent bone diseases, despite the adverse hypoestrogenic state.(AU)