4 research outputs found

    Ovariectomized rat model of osteoporosis

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    Osteoporosis affects about 200 million people worldwide and is a silent disease until a fracture occurs. Management of osteoporosis is still a challenge that warrants further studies for establishing new prevention strategies and more effective treatment modalities. For this purpose, animal models of osteoporosis are appropriate tools, of which the ovariectomized rat model is the most commonly used. The aim of this study is to provide a 4-step guideline for inducing a rat model of osteoporosis by ovariectomy (OVX): (1) selection of the rat strain, (2) choosing the appropriate age of rats at the time of OVX, (3) selection of an appropriate surgical method and verification of OVX, and (4) evaluation of OVX-induced osteoporosis. This review of literature shows that (i) Sprague-Dawley and Wistar rats are the most common strains used, both responding similarly to OVX; (ii) six months of age appears to be the best time for inducing OVX; (iii) dorsolateral skin incision is an appropriate choice for initiating OVX; and (iv) the success of OVX can be verified 1-3 weeks after surgery, following cessation of the regular estrus cycles, decreased estradiol, progesterone, and uterine weight as well as increased LH and FSH levels. Current data shows that the responses of trabecular bones of proximal tibia, lumbar vertebrae and femur to OVX are similar to those in humans; however, for short-term studies, proximal tibia is recommended. Osteoporosis in rats is verified by lower bone mineral density and lower trabecular number and thickness as well as higher trabecular separation, changes that are observed at 14, 30, and 60 days post-OVX in proximal tibia, lumbar vertebrae and femur, respectively

    Effect of Fetal Hypothyroidism on Cardiac Myosin Heavy Chain Expression in Male Rats

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    Abstract Background: Thyroid hormone deficiency during fetal life could affect the cardiac function in later life. The mechanism underlying this action in fetal hypothyroidism (FH) in rats has not been elucidated thus far. Objective: The aim of this study is to evaluation the effect of FH on cardiac function in male rats and to determine the contribution of ╬▒-myosin heavy chain (MHC) and ╬▓-MHC isoforms. Methods: Six pregnant female rats were randomly divided into two groups: The hypothyroid group received water containing 6-propyl-2-thiouracil during gestation and the controls consumed tap water. The offspring of the rats were tested in adulthood. Hearts from the FH and control rats were isolated and perfused with langendroff setup for measuring hemodynamic parameters; also, the heart mRNA expressions of ╬▒- MHC and ╬▓-MHC were measured by qPCR. Results: Baseline LVDP (74.0 ┬▒ 3.1 vs. 92.5 ┬▒ 3.2 mmHg, p < 0.05) and heart rate (217 ┬▒ 11 vs. 273 ┬▒ 6 beat/min, p < 0.05) were lower in the FH rats than controls. Also, these results showed the same significance in ┬▒dp/dt. In the FH rats, ╬▓-MHC expression was higher (201%) and ╬▒- MHC expression was lower (47%) than control. Conclusion: Thyroid hormone deficiency during fetal life could attenuate normal cardiac functions in adult rats, an effect at least in part due to the increased expression of ╬▓-MHC to ╬▒- MHC ratio in the heart