Dopamine D2-receptor messenger RNA is differentially regulated by dopaminergic agents in rat anterior and neurointermediate pituitary.
Hypothalamic dopamine (DA), acting at DA D2-receptors (D2-R) on pituitary target cells, mediates peptide release and biosynthesis of rat pituitary anterior lobe (AL) prolactin, and neurointermediate lobe (NIL) pro-opiomelanocortin (POMC). We were interested in determining if dopamine agonists and antagonists were capable of modifying D2-R gene expression in these pituitary cells. Utilizing the recently published sequence of the rat D2-R, we isolated a rat D2-R cDNA clone by polymerase chain reaction, and have synthesized RNA probes to quantitate levels of D2-R mRNA by solution hybridization/nuclease protection assay. We report here that 5-day administration of the DA antagonist haloperidol led to significant increases in both D2-R mRNA and POMC mRNA in the NIL; the DA agonist bromocriptine caused a significant decrease in NIL POMC mRNA with no parallel change in D2-R mRNA. In contrast, no significant changes in D2-R mRNA in AL were observed following treatment with either the DA agonist or antagonist. These data provide evidence for tissue-specific regulation of D2-R mRNA in response to dopaminergic manipulation.
Autelitano
D J
DJ
Fishberg Research Center for Neurobiology, Mount Sinai School of Medicine, New York, NY 10029.
Snyder
L
L
Sealfon
S C
SC
Roberts
J L
JL
D000818:Animals; D015342:DNA Probes; D015259:Dopamine Agents / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D010903:Pituitary Gland, Anterior / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011333:Pro-Opiomelanocortin / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000096:biosynthesis / Q000235:genetics*
D015342:DNA Probes; D015259:Dopamine Agents; D012333:RNA, Messenger; D011954:Receptors, Dopamine; D011333:Pro-Opiomelanocortin