1Conservation Ecology Center, Smithsonian Conservation Biology Institute, 2Research Department, American College of Obstetricians and Gynecologists, 3Department of Neuroscience, Georgetown University, 4Department of Anthropology, George Washington University, 5Department of Human Evolutionary Biology, Harvard University
Thursday Evening, Park Concourse
Milk is not just food, but also a means by which mammalian mothers signal biochemically to their offspring. Milk contains physiological levels of growth factors and other hormones; these signaling molecules have important effects on growth and development of neonates. We investigated whether commercially available assays designed to measure two growth factors (EGF and TGF-β2), their receptors, and the metabolic hormone adiponectin in human biological samples were effective for non-human primate milks. Milk samples for gorilla (N=1), orangutan (N=1), baboon (N=9), and common marmoset (N=5) came from the Smithsonian National Zoological Park’s Milk Repository; milk samples for rhesus macaque (N=59) came from individuals housed at the California National Primate Research Center. We performed parallelism and recovery tests to validate the assay kits (R&D Systems, Minneapolis). Longitudinal samples from the gorilla, orangutan and macaques allowed a comparison of the pattern of expression with previously published patterns in human breast milk. All analytes were successfully measured in gorilla; for other taxa one or more assays were not successful. Milk adiponectin declined across lactation in gorilla and orangutan, similar to humans, although adiponectin concentration was low compared to human breast milk (gorilla=4.8±.5 ng/ml, orangutan = 1.4±.1 ng/ml, human range = 5 – 80 ng/ml). Macaque milk adiponectin (6.9±.4 ng/ml) was higher than ape milk, and appeared to increase with infant age. Milk EGF concentrations were highest in gorilla milk (29.7±.9 ng/ml), followed by orangutan (7.8±.4 ng/ml) and macaque (2.9±.2 ng/ml); these values are all below those found in mature human milk (75±12 ng/ml).
Partially funded by GW-SI Opportunity Fund Research Grant, Endocrine Signaling via Milk in Primates, Bernstein & Power (Co-PIs) and by NSF grant BCS-0921978, Hinde (PI)