Endocrine Abstracts

Glucocorticoid-induced osteoporosis is the most common form of secondary osteoporosis. The primary effects are on osteoblasts and osteocytes. Glucocorticoids impair the replication, differentiation and function of osteoblasts. These effects lead to a suppression of bone formation, characteristically in the pathogenesis of this form of osteoporosis. On the other hand, available software for image analysis are expensive, inflexible or methodologically dense. ImageJ, an open source, has proven easy to operate, and retrieve reliable results.

We used a commercial dexamethasone, a widely used and potent synthetic member of the glucocorticoid class that has anti-inflammatory and immunosuppressant effects to induce bone loss in male rats Wistar.

Briefly, rats were splitted in three groups: the ‘low’ dose (5.25 mg/kg), the ‘high’ dose (8 mg/kg) and the control group (saline solution), which were administered for 5 weeks. The rodents were screened every week for the weight change. At the end of the experiment the animals were eutanized and we obtained blood from cardiac punction for bone alkaline phosphatase and tartrate resistant acid phosphatase (TRAP) determinations. Also we extracted the femurs and fixed for histological image examination using ImageJ software.

The results indicated that alkaline phosphatase was higher in the group with ‘high’ dose (P=0.048) compared with control, but no difference was found between the ‘low’ dose and control. Also, no significant difference was found in the TRAP circulating levels. The image analysis was focused on the relative quantitation of the cortical bone surface, delimiting the cortical area over the total histological bone section under scrutiny. These data showed significant decreases in both treatment groups (P<0.01) when compared with control.

Although it is known that ImageJ has a plugin for bone analysis (BoneJ), the results showed here compel for the use and development of cheaper and more flexible options in order to evaluate and validate osteoporosis animal models.