Effects of ovariectomy-induced estrogen deficit on rat behaviour, lipid metabolism, inflammation, bone mineral density, and turnover

Aim: The objective of the present study was to make a complex evaluation of behaviour, lipid metabolism, inflammation, and bone turnover in an ovariectomized rat model used to simulate postmenopausal clinical findings.Materials and methods: Female Wistar rats were divided into 2 groups of 16 animals each: sham operated (SO) animals and ovariectomized (OVX) animals. Three months after the operation, a battery of behavioural tests was performed including an open field test (OFT), elevated pus-maze test (EPM), the social interaction test (SIT), the forced swim test (FST), and a hot plate test (HPT). At termination of experiment, weight gain and fat deposits (total and retroperitoneal) were measured. Serum concentrations of blood lipids were determined. Tumor necrosis factor alpha (TNF-alpha) and alkaline phosphatase (ALP) serum concentrations were used for evaluation of the inflammation and bone turnover, respectively. Femur bone mineral density (BMD) was evaluated using dual energy X-ray absorptiometry.Results: OVX rats did not demonstrate any significant behavioural changes in OFT and EPM tests but showed a decreased interaction time in SIT and an increased immobility time in FST test which indicated anxiety and depression. The OVX rats had a significantly lower pain sensitivity threshold. They had greater weight gain, increased total and retroperitoneal fat deposits, as well as elevated total fat/body weight and retroperitoneal fat/body weight ratios. Blood cholesterol, ALP and TNF-alpha of the OVX group were also significantly higher. Femur BMD of OVX rats was slightly but not significantly reduced.Conclusions: Estrogen deficiency in OVX rats caused depression, anxiety, hyperalgesia, obesity, dyslipidemia, and inflammation before the reduction in bone mineral density was prominent