Expression of adrenomedullin and proadrenomedullin N-terminal 20 peptide in human and rat prostate

Adrenomedullin (AM) and proadrenomedullin N-terminal 20 peptide (PAMP) are two recently discovered hypotensive peptides translated from the same messa ge transcript (preproAM mRNA). In this article we report the presence of AM , PAMP, and their mRNA in human and rat prostate and of AM receptor mRNA in rat prostate. PreproAM mRNA was found in the epithelium of normal human an d rat prostate glands by in situ hybridization. In humans, it was mainly ex pressed in the basal cells. In rat, its expression was higher in the ducts than in the acini of all the prostate lobes. Immunocytochemistry identified a similar distribution pattern for AM compared with its mRNA but showed di fferent locations for AM and PAMP immunoreactivity. The former was widespre ad in the epithelial whereas the latter was almost exclusively found in neu roendocrine cells. In rat, Western blot analysis confirmed the presence of high levels of AM peptide in the ventral robe and of its precursor in the v entral and dorsolateral robes. Immunoreactivity for serotonin, chromogranin A, PAMP, and AM defined four subpopulations of prostate neuroendocrine-lik e cells in rat, a cell type that has not been previously described.