The levels of neurotrophin-3 protein in the rat brain determined by enzyme immunoassay show a pattern distinct from nerve growth factor.

Using the monoclonal antibody 3W3 a two-site enzyme immunoassay (EIA) for neurotrophin-3 (NT-3) was established. The assay was sensitive to levels of NT-3 below 10 pg/ml and does not recognize nerve growth factor (NGF) or brain-derived neurotrophic factor (BDNF). In the adult rat brain, highest levels of NT-3 (1-1.5 ng/g tissue) were found in hippocampus and piriform cortex. Also the cerebellum contained detectable NT-3 protein. In the postnatal (P1 and P5) rat brain very high levels of NT-3 (7-9 ng/g) were found in the cingulate cortex consistent with previous observations of a local, transient NT-3 mRNA expression. NT-3 was also found prenatally in hippocampus, telencephalon and cerebellum. The EIA shows that the pattern of NT-3 protein in brain tissues is distinct from that of NGF.