Abstract # 2413 Event # 19:

Scheduled for Thursday, June 19, 2008 11:30 AM-11:40 AM: Session 2 (Meeting Room 1GHI) Oral Presentation


Placental insulin-like growth factor II (IGF-II) and its relation to litter size and placental weight in captive common marmosets (Callithrix jacchus)

J. N. Rutherford
Northwestern University, Department of Anthropology, 1810 Hinman Avenue, Evanston, IL 60208, USA
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     Insulin-like growth factor-II (IGF-II) is a placental hormone that is critical to normal growth and development of the fetoplacental unit. We investigated the relations between placental IGF-II concentration and the variable conditions of placental weight, litter size and fetal weight in common marmosets (Callithrix jacchus). The null hypothesis tested was that IGF-II concentration (ng/g) is held in a “steady state” regardless of features of the placenta or litter. A sample of 22 marmoset placentas representing 10 twin and 12 triplet litters was analyzed by ELISA for tissue concentration of IGF-II. Recovery of hormone from tissue samples was high (>100%), and intra-assay coefficient of error was 2.6%. IGF-II was detected in all tissue samples. There were no correlations between IGF-II concentration and maternal weight or age. IGF-II concentration was not correlated with litter size, litter weight, or placental weight [Pearson correlation, a=0.05], However, within twin litters, IGF-II concentration drops significantly as litter weight increases [r(8)=-0.67, p=0.03]. In contrast, within triplets there was a non-significant relationship between concentration and litter weight [r(10)=0.45, p=0.15]. IGF-II concentration of large triplet placentas was only 49% of that measured in small triplet placentas. Although IGF-II concentration does not differ between twin and triplet litters, within-litter variation suggests that the dynamics of IGF-II regulation of fetal growth may be litter-size dependent.