Treatment effect with oxytocin in bone consolidation of rats during the periestropause and estropause

• Grant number: 21/09764-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2021
• End date: November 30, 2022
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Rita Cássia Menegati Dornelles
• Grantee: Ana Beatriz Doná Fiorotto
• Host Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

Changes in the plasma secretion of gonadal steroids that characterize stages of the female life cycle also interfere with the bone structure of these organisms, altering the process of bone remodeling and repair. The imbalance in bone microarchitecture results in osteopenia and osteoporosis, whose decrease in bone mass makes the bone structure fragile and susceptible to fracture. The failure in the repair process of these traumatic injuries determines high rates of functional impairment and mortality, with a great impact on public spending. Studies carried out in our laboratory showed important actions of oxytocin (OT) during the bone remodeling cycle in senescent rats. However, there are no studies that show its effect on bone healing and repair. Therefore, our aim is to investigate the quality of healing and bone consolidation after unilateral tibial fracture in rats in the peri-stratopause (18 months) and stratopause (24 months) period. This study will be carried out with 40 Wistar female rats with an initial age of 17 and 23 months, which after analysis of the estrous cycle will be randomly distributed into the following experimental groups, 10 animals each: VEH18 and VEH24 (animals aged 18 and 24 months, with osteotomy and treated with the vehicle - NaCl); OT18 and OT24 (animals with 18 and 24 months, with osteotomy and treated with OT). After 18 and 24 full months, the animals will do the walking test and will undergo osteotomy unilateral tibia. The animals in the VEH groups will receive two doses of vehicle/NaCl and the animals in the OT groups will receive two doses of OT 12 hours apart (7h - 19h/ip) on days 0 and 30. At the end of the experimental period, animals between 20 and 26 months will undergo the ambulation test and, later, be euthanized. Blood will be collected for analysis of plasma markers of bone metabolism, and the tibia for microtomography and bone densitometry analysis. The uterus will be removed, weighed, and body weight will be recorded before and after the experimental period. It is expected that OT enhances the bone healing process in tibial fractures in rats in the period of periestropause and stratopause, highlighting it as a promising intervention strategy for bone repair in these animals.(AU)