using cross-linking with paraformaldehyde perfusion and subsequent precipitation from soluble hippocampal samples using specific antibodies. Protein binding, defined by the specificity of the antibody, to specific DNA sequences is then quantified following polymerase chain reaction (PCR) amplification with targeted primers and Southern blotting. PCR allows for identification of precise DNA sequences and Southern blotting permits quantification of those same sequences. The experiment provides information on the amount of a specific DNA sequence bound to a specific protein. The charm of this approach is the ability to directly examine the interaction of specific proteins with specific DNA sequences at the time the biological sample is obtained. ChIP analysis of hippocampal samples from postnatal day-6 pups reveals dramatically increased NGFIA binding to the exon 17 promoter in the offspring of high-LG compared with low-LG mothers.67 These findings confirm that maternal care regulates the binding of NGFIA to the exon 17 promoter sequence in pups.
