title: Expression of prolactin mRNA in rat mammary gland during pregnancy and lactation.
abstract: We studied the expression of prolactin (PRL) mRNA in the mammary gland of resting, pregnant, lactating, and weanling rats using in situ and solution reverse transcriptase-polymerase chain reaction (RT-PCR). In mid- to late pregnancy and throughout lactation, PRL mRNA was detected in both in situ and solution RT-PCR. These PRL mRNA signals were clearly identified in the cytoplasm of alveolar and ductal mammary epithelial cells by the in situ RT-PCR method. In mid- to late pregnancy, such as at the initiating point of PRL mRNA expression, we confirmed in some cases a lack of PRL mRNA by solution RT-PCR. In addition, in the early weaning phase, no signals were detected by solution RT-PCR. However, slight focal signals were detected in some poorly vacuolated cytoplasm of regressing acinar cells by in situ RT-PCR. These findings suggest that PRL mRNA in rat mammary gland begins in mid- to late pregnancy in parallel with the development of the mammary gland, continues throughout lactation, and declines in the early phase of weaning, with regression of mammary epithelial cells.
authors.affiliation: Department of Pathology, Tokai University School of Medicine, Kanagawa, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Iwasaka
authors.forename: S
authors.initials: S
authors.lastname: Umemura
authors.forename: K
authors.initials: K
authors.lastname: Kakimoto
authors.forename: H
authors.initials: H
authors.lastname: Koizumi
authors.forename: Y R
authors.initials: YR
authors.lastname: Osamura
mesh_terms: D000818:Animals; D005260:Female; D007774:Lactation / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000378:metabolism*; D008894:Milk Proteins / Q000378:metabolism; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D008894:Milk Proteins; D012333:RNA, Messenger; D011388:Prolactin