title: Prolactin delays hair regrowth in mice.
abstract: Mammalian hair growth is cyclic, with hair-producing follicles alternating between active (anagen) and quiescent (telogen) phases. The timing of hair cycles is advanced in prolactin receptor (PRLR) knockout mice, suggesting that prolactin has a role in regulating follicle cycling. In this study, the relationship between profiles of circulating prolactin and the first post-natal hair growth cycle was examined in female Balb/c mice. Prolactin was found to increase at 3 weeks of age, prior to the onset of anagen 1 week later. Expression of PRLR mRNA in skin increased fourfold during early anagen. This was followed by upregulation of prolactin mRNA, also expressed in the skin. Pharmacological suppression of pituitary prolactin advanced dorsal hair growth by 3.5 days. Normal hair cycling was restored by replacement with exogenous prolactin for 3 days. Increasing the duration of prolactin treatment further retarded entry into anagen. However, prolactin treatments, which began after follicles had entered anagen at 26 days of age, did not alter the subsequent progression of the hair cycle. Skin from PRLR-deficient mice grafted onto endocrine-normal hosts underwent more rapid hair cycling than comparable wild-type grafts, with reduced duration of the telogen phase. These experiments demonstrate that prolactin regulates the timing of hair growth cycles in mice via a direct effect on the skin, rather than solely via the modulation of other endocrine factors.
authors.affiliation: AgResearch Ruakura, Hamilton 2020, New Zealand. tony.craven@agresearch.co.nz
authors.forename: A J
authors.initials: AJ
authors.lastname: Craven
authors.forename: A J
authors.initials: AJ
authors.lastname: Nixon
authors.forename: M G
authors.initials: MG
authors.lastname: Ashby
authors.forename: C J
authors.initials: CJ
authors.lastname: Ormandy
authors.forename: K
authors.initials: K
authors.lastname: Blazek
authors.forename: R J
authors.initials: RJ
authors.lastname: Wilkins
authors.forename: A J
authors.initials: AJ
authors.lastname: Pearson
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D003864:Depression, Chemical; D004294:Domperidone / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D005260:Female; D015870:Gene Expression; D005838:Genotype; D006197:Hair / Q000187:drug effects / Q000254:growth & development*; D006202:Hair Dyes; D006204:Hair Removal; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D016513:Mice, SCID; D011388:Prolactin / Q000097:blood / Q000235:genetics / Q000494:pharmacology*; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D011863:Radioimmunoassay / Q000379:methods; D011981:Receptors, Prolactin / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D012867:Skin / Q000737:chemistry / Q000378:metabolism; D016038:Skin Transplantation
chemical_list: D015415:Biomarkers; D018492:Dopamine Antagonists; D006202:Hair Dyes; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; D011981:Receptors, Prolactin; D004294:Domperidone; D011388:Prolactin