title: Continuous stress-induced dopamine dysregulation augments PAP-I and PAP-II expression in melanotrophs of the pituitary gland.
abstract: Under continuous stress (CS) in rats, melanotrophs, the predominant cell-type in the intermediate lobe (IL) of the pituitary, are hyperactivated to secrete α-melanocyte-stimulating hormone and thereafter degenerate. Although these phenomena are drastic, the molecular mechanisms underlying the cellular changes are mostly unknown. In this study, we focused on the pancreatitis-associated protein (PAP) family members of the secretory lectins and characterized their expression in the IL of CS model rats because we had identified two members of this family as up-regulated genes in our previous microarray analysis. RT-PCR and histological studies demonstrated that prominent PAP-I and PAP-II expression was induced in melanotrophs in the early stages of CS, while another family member, PAP-III, was not expressed. We further examined the regulatory mechanisms of PAP-I and PAP-II expression and revealed that both were induced by the decreased dopamine levels in the IL under CS. Because the PAP family members are implicated in cell survival and proliferation, PAP-I and PAP-II secreted from melanotrophs may function to sustain homeostasis of the IL under CS conditions in an autocrine or a paracrine manner.
authors.affiliation: Department of Anatomy and Neurobiology, Osaka City University Graduate School of Medicine, Osaka, Japan. konishi@med.osaka-cu.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Konishi
authors.forename: Tokiko
authors.initials: T
authors.lastname: Ogawa
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kawahara
authors.forename: Sakiko
authors.initials: S
authors.lastname: Matsumoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kiyama
mesh_terms: D000626:Aminopeptidases / Q000096:biosynthesis*; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D008297:Male; D052717:Melanotrophs / Q000201:enzymology*; D000073718:Pancreatitis-Associated Proteins; D010902:Pituitary Gland / Q000166:cytology / Q000201:enzymology*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013312:Stress, Physiological; D013315:Stress, Psychological / Q000201:enzymology*
chemical_list: D000073718:Pancreatitis-Associated Proteins; C000612141:REG3A protein, human; D000626:Aminopeptidases; C497676:pyroglutamyl aminopeptidase I, rat; C023166:pyroglutamyl-peptidase II; D011761:Pyrrolidonecarboxylic Acid; D004298:Dopamine