Abstract
Adrenomedullin (AM) was originally identified in pheochromocytoma
tissue and was characterized as a hypotensive peptide. The tissue
distribution and cellular localization of AM messenger RNA (mRNA) were
determined in mouse and rat tissues by in situ
hybridization. Three probes were used: two nonoverlapping probes to the
pro-AM N-terminal 20 peptide (PAMP) and AM peptide regions of mouse
pro-AM, and a larger complementary DNA (cDNA) probe spanning both the
PAMP- and AM peptide-coding regions. The most intense expression of AM
mRNA was in endometrium and epithelial cells lining the uterus and
mouse adrenal medulla. Moderate levels of expression were detected in
kidney glomerulus and cortical distal tubules, ovarian corpus luteum
and follicles, epithelial cells lining the bronchioles, cardiac atrium
and ventricle, posterior pituitary (particularly in female rats),
stomach, small intestine (microvilli, mucosa and submucosa), spleen,
and pancreas. Lower levels were observed in pulmonary alveoli, anterior
pituitary, and submandibular gland. No expression was detected in the
testis, thymus, skeletal muscle, or liver. The localization of AM mRNA
in epithelial cells lining the uterus, bronchioles, and
gastrointestinal tract indicates novel roles for AM, possibly as an
antimicrobial agent. The strong expression of AM in uterus, ovary, and
posterior pituitary suggests that AM plays a role in female
reproduction.