Effects of Nandrolone and TGF-β1 in growing rabbits with osteopenia induced by over-supplementation of calcium and vitamin D3

Abstract

The study was undertaken to find out the effects of over supplementation of dietary calcium and vitamin D3 on the mineralization of growing skeleton, taking rabbit as an animal model; further to study the effects of Nandrolone deconoate and TGF-β1 on the mineralization of osteopenic bones. Twenty four New Zealand White rabbits of either sex, 60 day old, were randomly divided in 4 equal groups, A, B, C and D. The animals of groups B, C and D were administered with oral supplementation of calcium (2000 mg/kg of standard rabbit feed) and vit-D3 (1000 IU/kg of standard feed) for 60 days. The animals of group A were given standard ration without any supplementation. After 60 days, the Ca-vit.D3 supplementation was discontinued; and the animals of group C were administered with TGF-β1 (10 ng, i.m.) once in every three days and animals of group D were given Nandrolone deconoate (10 mg, i.m.) once every week for 30 days, whereas in animals of group B, no treatment was given. All the animals were evaluated based on different observations like body weight, radiographic observations, circulating biochemical and hormone profile (plasma Ca, IP, AP, OC and iPTH) every 15 days up to 60 days after initiation of treatment. The results indicated that the body weight of rabbits in different groups increased gradually and steadily at different intervals till the end of observation period, however, the increase was non-significantly more in group D. The CI in group A increased gradually at different intervals; whereas in groups B, C and D, there was no appreciable increase in the CI during the period of Ca-vit.D3 supplementation, suggesting development of osteopenia. Treatment with TGF-β1 did not increase the CI significantly, whereas Nandrolone treatment resulted in significant increase in the CI on days 45 and 60. The plasma Ca levels showed slight but gradual increase from day 0 to 60 in almost all groups. Subsequently also, there was no marked change at different intervals in groups A and B; however, significant reduction in plasma Ca was noticed in group C on 15^th day and in group D on 60^th day after initiation of treatment. Plasma IP levels in groups B and C showed a decreasing trend up to day 60. After discontinuation of Ca-vit.D3 supplementation, in group B, it further decreased to remain significantly lower on 15^th day, and in groups C and D, it increased significantly on 60^th post-treatment day. There was no significant change in the AP activity during the entire period of study in group A; whereas significant reduction in AP activity was measured on 30^th and 60^th days of treatment in groups B and C, and on 15^th day of treatment in group D. Plasma iPTH values did not show any significant change at any interval during the first 60 days in all groups. On 30^th and 60^th days of treatment, the mean iPTH level remained significantly lesser in group B. In all groups treated with over supplementation of Ca and vit.D3, there was a non-significant increase in the plasma OC levels up to day 60; however, there was no significant difference between the groups. It can be concluded that additional supplementation of Ca and vit.D3 results in osteopenia in growing rabbits. Administration of Nandrolone helps to increase the mineral density in osteopenic bones, whereas TGF-β1 does not seem to have positive effect on the skeletal mineralization.