The ability to remember in adult mice can be affected by immune system factors that were present in their mother’s milk, reports a study published online in Nature Neuroscience. The findings show that these immune factors, or chemokines, transmitted to offspring through mother’s milk not only affect development of the immune system, but also of the brain and future cognitive abilities.
Miklos Toth and colleagues found that whether or not a mouse’s mother carried a particular immune system gene, TNF--alpha, affected memory skills in adulthood, regardless of whether the mouse itself carried the gene. Through a series of experiments ruling out effects of maternal behavior or in utero environment, they determined that this effect was due to chemokines transmitted to pups from the mother’s milk. Milk chemokines also caused changes in the brains of offspring, including increasing the number of new neurons born in the hippocampus, a region of the brain known to be involved in spatial and contextual memory, which in turn affected adulthood memory.