Effect of homocysteine and protective role of trimethylglycine on the structure of tibia in growing albino rats: histological and biochemical study

ABSTRACT

Homocysteine [HCY] is an amino acid that is formed as an intermediate during the metabolism of methionine. Epidemiological studies have shown that too much homocysteine in blood plasma leads to a higher risk of coronary heart disease and strokes. It is also characteristic for homocystinuria. Trimethylglycine TMG [known as betaine] is a methyl donor that helps the quick conversion of homocysteine into methionine. Is to investigate the structural and the biochemical changes that occur in the articular cartilage, the growth plate and the bone structure of tibia in growing albino rats after being treated with oral supplement of HCY and possible protective role of TMG. Thirty two young male albino rats were used in this experiment. They were equally divided into four group. The control group received a balanced standard diet, HCY treated group received 0.6mg HCY/kg b.w/ day, TMG treated group [0.6gm TMG/kg b.w/day] and an interacting group received both HCY and TMG. Rats were sacrificed every 2 weeks up till the 8[th] week specimens from the tibias were obtained and processed for histological and biochemical study. Indicated that examination of rat bones of HCY group showed apparently abnormal radial and longitudinal bone growth. H and E stained sections of proximal ends of tibias showed changes in chondrocytes of proximal tibia. The growth plate of the proximal tibia showed a lack of the orderly chondrocytes columns arrangement. Examination of shafts of tibial bone of the same group showed many degenerative changes in periostum.The matrix contained many resorption cavities that were filled with granulation tissue. In addition there was evidence of abnormal biochemical patterns represented by low bone mineral density and bone mineral content. Statistically significant decrease in bone width compared to an increase in length and cross section area was detected. On the other hand TMG showed improved bone formation and inhibition of bone resorption. Was concluded that HCY produced profound histological changes in the articular cartilage, growth plate and bone structure of tibia of growing male albino rats. Mean while treatment with TMG markedly decreased the induced damage by HCY