Effects of selenium,iodine deficiency and their combination on bone and cartilage growth in parental and first filial generation rats / 中国地方病学杂志

ABSTRACT

Objective To study the effects of selenium deficiency,iodine deficiency and combined selenium and iodine deficiency on bone and cartilage growth in the parental and the first filial generation rats. Methods Forty-eight weanling healthy SD rats were randomly divided into selenium deficieney, iodine deficiency, combined selenium and iodine deficiency and control groups according to their body mass. These rats were fed with selenium deficiency, iodine deficiency, combined selenium and iodine deficiency, and normal fodder, respectively. The parental rats (about 3 months old) were mated in each group 8 weeks after the beginning of the experiment. Right tibias and left knee joints were collected when the parental generation rats were about 6 months and the first filial generation rats were about 3 months old. Tibial length, mid-shaft tibial diameter, and articular cartilage diameters of the right tibias were measured by vernier caliper. Left knee joints were embedded and cut into sections and the thickness of the growth plate cartilage, layers of proliferative and hypertrophic chondrocytes in growth plate cartilage were observed under the light microscope. Results The selenium deficiency had significant effect on serum selenium level of the parental and the first filial generation rats(F value were 239.56,232.68, P< 0.01), and also on serum T4 level of the first filial generation rats(F value were 6.95, P < 0.05). The iodine deficiency had significant effect on serum T3 and T4 level in the two generations rats(F value were 14.11,14.05,30.29,34.53, P < 0.01 ). There were interactions between selenium deficiency and iodine deficiency on serum T4 level in the first filial generation rats (F= 5.99, P< 0.05). The serum selenium of selenium deficiency group[ (30.28 ± 6.34), (43.95 ± 9.75)μg/L],combined selenium and iodine deficiency group[ (30.33 ± 5.18), (35.40 ± 3.16)μg/L] were significantly lower than iodine deficiency group[(345.83 ± 29.55), (245.24 ± 9.95)μg/L] and the controls[ (358.64 ± 30.50), (236.50 ±9.75) μg/L] in the two generations. The serum T3 of combined selenium and iodine deficiency group [(0.55 ± 0.05 ),(0.88 ± 0.14)nmol/L] were significantly lower than the controls[(0.75 ± 0.08), (1.26 ± 0.26)nmol/L] in the two generations. The serum T4 of iodine deficiency [ (24.11 ± 2.29), (42.10 ± 8.92) nmol/L ] and combined selenium and iodine deficiency group[ (20.66 ± 1.93), (26.55 ± 5.98)nmol/L] were significantly lower than the controls[ (36.15 ±2.74), (52.79 ± 8.84)nmol/L] and selenium deficiency group[ (28.12 ± 3.33), (52.02 ± ll.99)nmol/L] in the two generations. The selenium deficiency and iodine deficiency had significant effect on tibial length, thickness of the growth plate cartilage, layers of proliferative and hypertrophic chondrocytes in first filial generation rats(F values were 24.31,6.98,40.76,56.15,25.24,82.82, 10.07,5.57, P <0.05 or <0.01). There were interactions between selenium deficiency and iodine deficiency on tibial length, thickness of the growth plate cartilage, layers of proliferative and hypertrophic chondrocytes (F values were 5.68,24.86,41.82,9.12, P <0.05 or <0.01 ). The tibial length of the selenium deficiency group[ (33.17 ± 0.34)mm] and combined selenium and iodine deficiency group[ (31.30 ± 0.87)mm] were significantly lower than the controls[ (34.12 ± 0.32)mm, P< 0.05]. Thickness of the growth plate cartilage [ (1.60 ± 0.18)mm ], layers of proliferative chondrocyte (8.54 ± 0.81), and hypertrophic chondrocyte (4.95 ± 0.37)of the combined selenium and iodine deficiency group were significantly decreased when compared to the selenium deficiency group[ (3.03 ± 0.10)mm, 14.68 ± 0.84,6.60 ± 0.31], iodine deficiency group[ (2.90 ± 0.09)mm, 13.75 ±0.33,6.61 ± 0.84 ] and the controls [ (3.19 ± 0.09) mm, 14.94 ± 0.36, 6.64 ± 0.26, P <0.05]. Thickness of the growth plate cartilage, layers of proliferative chondrocyte of the iodine deficiency group were lower than the controls(P<0.05). Conclusions Selenium deficiency impair tibial growth in first filial generation rats, iodine deficiency retarded the chondroncyte proliferation and decreases the thickness of growth plate cartilage in first filial generation rats, and combined selenium and iodine deficiency significantly impair the growth of bone and cartilage in first filial generation rats.