4 Recovery of Bone Component in RPC Rats Treated with GH. A Discriminant Analysis Study

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Aims: To identify which dimensions of the skeleton are associated with growth recovery in intrauterine growth retarded rats treated with GH.Material and Methods. Wistar rats were divided into Control (C), Sham-operated (Sh), IUGR and IUGR+GH. IUGR was induced by partial ligature of uterine vessels on day 14th of pregnancy. GH was administrated from 21 to 60 days of age (Genotropin® 3.0 mg/kg/día). Sh animals were injected with diluent only. All the animals received stock diet ad libitum. At 84 days of age frontal and lateral radiographs were taken from each animal. Length, width and height of neurocranium (LN, AN, HN) and splanchnocranium (LE, AE, HE), and length and width of the femur (LF, AF); humerus (LH, AH) and tibiae (LT, AT), column length (LC) and upper, middle and lower pelvic width (API, APM, Aps) were measured on the radiographs. Data were processed by the Kolmogorov Smirnov tests and discriminant analysis. The latter builds functions which are linear combinations of the original variables, maximizing the between-groups variance and minimizing the within-groups variance.Results: Data were normally distributed. The discriminant analysis showed significant values for the Wilks coefficients and F values. The first function (66%of variation) was defined by APS, APM and LT, which were negatively correlated. The second function explained about 18% of the total variation and was defined by APS (negative correlation) and LT (positive correlation). In the bi-dimensional space created by both functions, LT discriminated between sexes and APS among treatments. This analysis separated IUGR from those treated with GH, who became closer to Sham.Conclusions: The growth hormone treatment in IUGR rats seems effective for body growth recovery. Tibial length is the most important variable for discriminating between sexes, while the upper pelvic width is the best variable for discriminating between the groups treated with GH.