Neuropeptide Y (NPY) is the most abundant peptide hormone of the central nervous system. It is involved in various processes including stress management, the development of anxiety behaviour and body weight regulation. A collaborative research group including scientists from the Max Planck Institute for Medical Research in Heidelberg has demonstrated using mice that intensive maternal care during infancy promotes the effect of NPY in the brain. As a result of receiving such care, the animals were also less anxious in adulthood and weighed more than their counterparts who had received less affection. The research group was able to show that the effect is explained by the maternal care which stimulated the persistent formation of certain NPY receptors in the forebrain.
Isn’t any effect of NPY dependent on olfactory/pheromonal input? I think the connection from olfaction to the mother-infant bond and associated physiological changes during behavioral development makes the NPY correlate more clear.
The affection is typically associated with lactation/ nutrition from the mammalian mother and with her pheromones. Nutrition is such an obvious epigenetic influence on brain development that it should be somewhat clear why social odors would also be a powerful influence on brain development and behavior.