VGF
mRNA and its precursor-derived products are selectively expressed in certain neurons and promptly respond to
neurotrophins and to neural/electrical activity. Proteomic studies have previously revealed a reduction in some VGF
peptides in the cerebrospinal fluid of patients affected by
Alzheimer's disease and other conditions, suggesting their potential diagnostic and clinical significance. As the presence of VGF
peptides within the human cortex has been somewhat elucidated, they were studied postmortem in the frontal, parietal, and temporal cortex areas of control subjects and patients affected by
Parkinson's disease, and in parietal cortex samples from patients with
Alzheimer's disease. We raised
antibodies to the C-/N-terminal portions of the proVGF precursor
protein, to the TPGH and TLQP sequences and to the neuroendocrine regulatory
peptide (NERP)-1, all used for
enzyme-linked
immunosorbent assay coupled with gel chromatography and for immunohistochemistry. In the control brain samples, the levels of TPGH and C-terminus
peptides were about 130-200 and 700-2000 pmol g⁻¹, respectively, the N-terminus and NERP-1
peptides were less represented (about 10-30 and 4-20 pmol g⁻¹, respectively), and the TLQP
peptides were below detection limits. Upon gel chromatography, the VGF
antisera mainly revealed small molecular weight forms (i.e. about 0.8-1.3 kDa), whereas VGF immunolocalisation was found within different types of neuron in rat and bovine brain cortices. In the
Parkinson's disease samples, a clear-cut decrease was revealed in the parietal cortex only, exclusively for TPGH and NERP-1
peptides, whereas in the
Alzheimer's disease samples, a reduction in all of the VGF
peptides was shown. The results suggest the involvement of VGF in the physiological or pathophysiological mechanisms occurring in the parietal cortex of patients with Parkinson's and
Alzheimer's diseases.