Prolactin-releasing peptide (PrRP) is a novel bioactive peptide, originally
isolated from bovine hypothalamus by utilizing an orphan seven-transmembra
ne-domain receptor expressed in the human pituitary gland. In this paper, w
e analyzed the tissue distribution of rat and human PrRP and their receptor
mRNAs by quantitative reverse transcription-polymerase chain reaction (RT-
PCR) and Northern blotting. In RT-PCR analysis, rat PrRP receptor mRNA was
detected in the central nervous system, and the highest expression was dete
cted in the pituitary gland. In addition, in situ hybridization revealed th
at rat PrRP receptor mRNA was highly expressed in the anterior lobe of the
pituitary. On the other hand, rat PrRP mRNA was most abundantly expressed i
n the medulla oblongata, while significant levels of expression were widely
detected in other tissues. In Northern blot analyses, human PrRP receptor
mRNA was detected only in the pituitary gland among tissues examined. Human
PrRP mRNA was detected in the medulla oblongata and in the pancreas. In co
ntrast to the pattern of mRNA expression, the highest content of bioactive
PrRP was found in the hypothalamus rather than the medulla oblongata in the
rat brain, indicating that PrRP mRNA does not always parallel with mature
PrRP in tissue distribution. The wide distribution of PrRP and its receptor
suggests that they have various functions not only in the pituitary gland
but also in the other tissues. (C) 1999 Elsevier Science B.V. All rights re
served.