New insights into growth factor's role in brain d...( NEW YORK (Feb. 2 2009) -- New resear...),Health

NEW YORK (Feb. 2, 2009) -- New research sheds light on a neural growth factor called proBDNF, finding that it is present and potentially active during the perinatal period when the brain's circuitry and memory-encoding regions are being refined. Led by Weill Cornell Medical College investigators with those at the National Institutes of Health (NIH) and Memorial Sloan-Kettering Cancer Center (MSKCC), and reported in the Jan. 11 issue of the journal Nature Neuroscience, the study could lead to a better understanding of brain development and the formation of memories.

ProBDNF is the precursor form of mature brain-derived neurotrophic growth factor (BDNF), and both are active in the hippocampus and cortex -- areas key to learning, memory and higher thinking. Intriguingly, proBDNF and BDNF encourage different actions; BDNF promotes the differentiation of new neurons and their constituent parts (axons, dendrites and synapses), and proBDNF the pruning of synapses -- a process that occurs particularly in the early stages of life.

"Our results suggest that the nervous system plays an active role in both potentiating and dampening its own activity as necessary," says senior author Dr. Barbara Hempstead, the O. Wayne Isom Professor of Medicine at Weill Cornell Medical College and a leader in the field of neurotrophin research.

Dr. Hempstead and her research team, including lead authors Dr. Jianmin Yang and Dr. Chia-Jen Siao of Weill Cornell Medical College, developed new techniques that enabled them to observe when and where proBDNF and mature BDNF were being made in a mouse model. They found that proBDNF is most highly expressed in the hippocampus during the postnatal period of the mouse at about days 3 to 21, when large numbers of axons and synapses are being formed. They also found that p75 receptors, a class of receptors that encode a "death domain" in which neurons are killed or pruned, are also active during this period. These r
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