Body composition and bone markers in obese (β) growing rats: Influence of the dietary calcium content

Abstract

Osteoporosis and obesity are interrelated. We compare the effect of feeding different dietary Ca levels on body weight (BW) and composition and its relation to bone markers levels, in genetically modified obese (βO) rats during growth. Rats were mated and fed diets varying Ca content (g/100 g): high, 0.9 (GβH); normal, 0.5 (GβN); low, 0.2 (GβL). A Wistar group was run simultaneously (GCW) (fed according to AIN93). At weaning, male pups continued feeding the same diet till 50 days of age. Food consumption and BW were recorded. At the end of the experience, body composition, BAP, BGP, and CTX were determined. Results (mean± SD): Food intake was similar in all groups. BW was lower in GβH vs. N and H groups (162± 18 vs. 217± 31 and 221± 37; p< 0.01). Ash content (g/100 g) increased in Gβ as dietary Ca content increases (1.26±0.42, 2.04± 0.25, 2.51± 0.17; p< 0.01), without reaching GCW values (2.90± 0.40). Lipid percentage was higher in GβL and GβN (14.7± 1.3 and 13.6± 2.7) vs. GCW (10.9±2.6) and in GβH (12.6± 2.2; p< 0.05). BAP (IU/L) did not show differences among Gβ groups (186± 27, 193±39 and 184± 30), being higher vs. GCW (67.8± 10.0). BGP showed an inverse correlation with dietary Ca level in Gβ (447± 45, 375±46, and 279± 73), being lower than GCW (825± 106; p< 0.01). CTX (mg/ml) did not show differences between GCW (88± 16) and GβH (87± 4) but they were higher than GβN and GβL (69± 12 and 70± 3, respectively; p< 0.01). Conclusions: In βO rats, the increase in dietary Ca content decreased BW changes and body lipids content and increased total BMC. Bone markers suggest an imbalance in bone metabolism related to the adipose tissue. UBACYT B 091.