Abstract # 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
     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.