title: Suckling stimulus suppresses messenger RNA for tyrosine hydroxylase in arcuate neurons during lactation.
abstract: Tyrosine hydroxylase (TH) mRNA in tuberoinfundibular dopamine (TIDA) neurons is suppressed during lactation but rebounds upon pup removal. A time course of TH mRNA changes after pup removal revealed three phases: (1) a nuclear phase (evident 1.5 hours after pup removal, maximal at 3 hours) with TH mRNA appearing in 1 or 2 nuclear loci with little or no change in cytoplasmic mRNA; (2) a cytoplasmic phase (noted 6 hours after pup removal, peaked 12-24 hours) with a significant increase in total TH mRNA levels mainly in the cytoplasm; and (3) a stabilization phase (24-48 hours after pup removal) when nuclear signals were low and cytoplasmic RNA showed a slight decline with extension of RNA clusters into the cell dendrites. In rats whose pups could suckle only on one side, TH was up-regulated only on the side contralateral to nipple blockade. These data indicate that after suckling terminates, TH up-regulation is evident at 1.5 hours, but 6 hours is needed before the cells transport sufficient mRNA into the cytoplasm. The rapid signaling of TH up-regulation stems from the fact that the TIDA neurons respond to neural signals from termination of suckling.
authors.affiliation: Laboratory for Pregnancy and Newborn Research, Department of Physiology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Berghorn
authors.forename: W W
authors.initials: WW
authors.lastname: Le
authors.forename: T G
authors.initials: TG
authors.lastname: Sherman
authors.forename: G E
authors.initials: GE
authors.lastname: Hoffman
mesh_terms: D000818:Animals; D000833:Animals, Suckling / Q000502:physiology; D001111:Arcuate Nucleus of Hypothalamus / Q000166:cytology / Q000201:enzymology*; D002395:Catecholamines / Q000096:biosynthesis; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D007030:Hypothalamo-Hypophyseal System / Q000166:cytology / Q000201:enzymology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007774:Lactation / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013391:Sucking Behavior / Q000502:physiology*; D013997:Time Factors; D014158:Transcription, Genetic / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics*; D015854:Up-Regulation / Q000235:genetics
chemical_list: D002395:Catecholamines; D012333:RNA, Messenger; D014446:Tyrosine 3-Monooxygenase