Endocrine Abstracts

Objective: Human growth hormone (hGH) stimulates bone formation and have been proposed as therapeutic agents for osteoporosis. We have examined the effects of hGH on femoral and vertebral bone strength in osteoporotic rats.

Methods: Thirty-five Sprague-Dawley rats were assigned to study in three groups: (1) Normal rats (without ovariectomy and corticosteroid therapy) (2) Osteoporosis group: ovariectomized (OVX) or with glucocorticoid induced osteoporotic (GIO) rats (they were given 15 mg/kg/day metilprednisolon S.C. for 8 weeks) (It would be called as OSTEOPOROSIS GROUP) and (3) OVX or GIO rats under the growth hormon therapy (It would be called as TREATMENT GROUP). Sprague-Dawley rats were OVX at 120-140 days of age. Bone strength was assessed with compression test in vertebras and with three-point bending test in femurs by using Shimadzu Universal testing Machine AG-50kNG as newton (N). Vertebral and femoral bone mineral densities of these rats were assessed before and after treatment with Hologic QDR 4500 A, by small animal software. After the growth hormone treatment (Genotropin, 7.5 mg/kg/day for 4 weeks) rats were sacrificed.

Results: It was shown that growth hormone increases femoral and vertebral bone strength significantly in osteoporotic rats. While bone strength was found to be 108.25 ± 15.16 N in the femurs of the treatment group and 72.95 ± 17.83 in the femurs of osteoporosis group (p=0,000) whereas 177.49 ± 45.29 N in the vertebras of treatment group and 105.25 ± 27.79 N in vertebras of osteoporosis group (p= 0.000).

Conclusion: In this study, the use of growth hormone dosage 7.5 mg/kg/day was associated with the increase of femoral and vertebral bone strength significantly in Sprague-Dawley rats.