TY - JOUR
T1 - Plasma leptin determination in ruminants
T2 - Effect of nutritional status and body fatness on plasma leptin concentration assessed by a specific RIA in sheep
AU - Delavaud, C.
AU - Bocquier, F.
AU - Chilliard, Y.
AU - Keisler, D. H.
AU - Gertler, A.
AU - Kann, G.
PY - 2000
Y1 - 2000
N2 - A specific leptin RIA was developed to assess concentrations of leptin in ovine plasma, and was shown to be efficient with bovine and caprine plasma. A specific, high-affinity antibody was generated against recombinant ovine leptin which, when used in a competitive leptin RIA, provided valid estimates of linearity (r=+0.989-0.998), recovery (102%), repeatability (13%) and limit of sensitivity (0.83 ng/ml for 100 μl sample size). Serial dilutions of five ovine, bovine or caprine plasma samples showed good linearity and parallelism with the recombinant ovine leptin standard curve. A comparison of this RIA was made with a commercial 'multi-species' RIA kit using 56 ovine plasma samples. Major differences were found in assay sensitivity. Non-lactating, non-pregnant, ovariectomized ewes were fed a ration for 65 days which provided 90 ± 9% (control; n=12) or 39 ± 2% of maintenance energy requirements (underfed; n = 16) in order to analyse the respective effects of body fatness (estimated by either an in vivo dilution technique or body condition scoring) and of nutritional status on plasma leptin concentration. There was a significant positive correlation between body fatness or body condition score and plasma leptin levels (r=+0.68, P<0.001 or r=+0.72, P<0.001 respectively). When concentrations of leptin were assessed over time, underfed ewes exhibited a dramatic reduction in plasma leptin values (-56%, P<0.001). These data provide strong evidence that, in sheep, the variations in plasma concentrations of leptin are related to variations in body fatness (35%) and, to a lesser extent, in nutritional status (17%).
AB - A specific leptin RIA was developed to assess concentrations of leptin in ovine plasma, and was shown to be efficient with bovine and caprine plasma. A specific, high-affinity antibody was generated against recombinant ovine leptin which, when used in a competitive leptin RIA, provided valid estimates of linearity (r=+0.989-0.998), recovery (102%), repeatability (13%) and limit of sensitivity (0.83 ng/ml for 100 μl sample size). Serial dilutions of five ovine, bovine or caprine plasma samples showed good linearity and parallelism with the recombinant ovine leptin standard curve. A comparison of this RIA was made with a commercial 'multi-species' RIA kit using 56 ovine plasma samples. Major differences were found in assay sensitivity. Non-lactating, non-pregnant, ovariectomized ewes were fed a ration for 65 days which provided 90 ± 9% (control; n=12) or 39 ± 2% of maintenance energy requirements (underfed; n = 16) in order to analyse the respective effects of body fatness (estimated by either an in vivo dilution technique or body condition scoring) and of nutritional status on plasma leptin concentration. There was a significant positive correlation between body fatness or body condition score and plasma leptin levels (r=+0.68, P<0.001 or r=+0.72, P<0.001 respectively). When concentrations of leptin were assessed over time, underfed ewes exhibited a dramatic reduction in plasma leptin values (-56%, P<0.001). These data provide strong evidence that, in sheep, the variations in plasma concentrations of leptin are related to variations in body fatness (35%) and, to a lesser extent, in nutritional status (17%).
UR - http://www.scopus.com/inward/record.url?scp=0034038574&partnerID=8YFLogxK
U2 - 10.1677/joe.0.1650519
DO - 10.1677/joe.0.1650519
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C2 - 10810316
AN - SCOPUS:0034038574
SN - 0022-0795
VL - 165
SP - 519
EP - 526
JO - Journal of Endocrinology
JF - Journal of Endocrinology
IS - 2
ER -