Neuroplasticity

by Moheb Costandi

Pups that are repeatedly licked and groomed during the first week of life are better able to cope with stress and fearful situations in adulthood, compared to those that had little or no contact with their mothers. These differences are associated with alterations in activity of the glucocorticoid receptor gene in the hippocampus. The glucocorticoid receptor plays a critical role in the stress response, and the pups that received high levels of care from their mothers expressed it at higher levels than those who received less attention. These effects were attributable to epigenetic modifications to the DNA, which alter gene expression by changing the physical structure of the chromosomal region containing the genes. Frequent licking and grooming led to epigenetic changes that opened up the chromosomal region containing the glucocorticoid receptor gene and made it more accessible to the cell’s protein synthesis machinery, whereas lack of maternal care caused different epigenetic modifications that closed off the chromosome and reduced gene activity.