Investigation of Gender Difference of Physiological Response in Gonadectomy in Sprague-Dawley (SD) Rats

Aim: Sex hormones, including testosterone and estrogen, result in various pathophysiological changes in the body. To evaluate the pathophysiological changes following gonadectomy in male and female rats, we performed gonadectomy at the same age in male and female Sprague-Dawley (SD) rats.

Methods: Male and female Sprague-Dawley rats castrated by bilaternal orchidectomy and ovariectomy at 6 weeks of age (six animals of each sex per group). Food intake, body weight, and clinical chemical parameters such as glucose, insulin, triglyceride and total cholesterol levels, were examined every 4 weeks from 8 to 40 weeks of age. Statistical analysis of differences between control and gonadectomized rats was performed using the F-test, followed by the Student’s t-test or Aspin-Welch’s t-test.

Results: In orchidectomized (ORX) rats, food intakes and body weights were decreased, whereas in ovariectomized (OVX) rats, the body weights were significantly elevated without an obvious change in food intake. In clinical chemical analysis, hypercholesterolemia was observed in both ORX and OVX rats, but the triglyceride level was obviously decreased only in ORX rats during the observational period. In OVX rats, decrease of insulin sensitivity and significant increase of adipose tissue weights were observed. In bone metabolic analysis, bone mineral content in ORX rats and bone mineral density in OVX rats were decreased, respectively.

Conclusion: Both orchidectomy and ovariectomy in rats affect glucose/lipid and bone metabolism, and especially, the glucose metabolism was deteriorated in OVX rats. Both male and female sex hormones play a key role in metabolic disease, such as diabetes, hyperlipidemia and osteoporosis.