Regional distribution of immunoreactive prolactin-releasing peptide in thehuman brain

Regional distribution of prolactin-releasing peptide (PrRP) in the human br ain was studied by radioimmunoassay. The antiserum raised against human PI RP-SI in a rabbit was: used in the assay, which showed 100% cross reaction with PrRP-20 and no significant cross reaction with other peptides. The hig hest concentrations of immunoreactive-PrRP were found in hypothalamus (912 +/- 519 fmol/g wet weight, n = 6, mean +/- SEM), followed by medulla oblong ata (496 +/- 136 fmol/g wet weight) and thalamus (307 +/- 117 fmol/g a et w eight). On the other hand, immunoreactive-PrRP was not detected in frontal lobe or temporal lobe (<50 fmol/g wet weight). Sephadex G50 column chromato graphy of the immunoreactive-PrRP in the hypothalamus and medulla oblongata showed three immunoreactive peaks; one peak eluting in the position of PrR P-30, one eluting in the position of PrRP-31 and one eluting earlier. Rever se phase high-performance liquid chromatography (HPLC) of these brain tissu e extracts showed a peak eluting in the position of PrRP-20 and PrRP-31. Th e present study has shown fur the first time the presence of immunoreactive -PrRP in the human brain. The immunoreactive-PrRP levels in the human hypot halamus were, however, lower than the levels of other neuropeptides with pr olactin-releasing activity, such as thyrotropin-releasing hormone and vasoa ctive intestinal polypeptide. (C) 2000 Elsevier Science Inc. All rights res erved.