title: Rapid eye movement sleep is reduced in prolactin-deficient mice.
abstract: Prolactin (PRL) is implicated in the modulation of spontaneous rapid eye movement sleep (REMS). Previous models of hypoprolactinemic animals were characterized by changes in REMS, although associated deficits made it difficult to ascribe changes in REMS to reduced PRL. In the current studies, male PRL knock-out (KO) mice were used; these mice lack functional PRL but have no known additional deficits. Spontaneous REMS was reduced in the PRL KO mice compared with wild-type or heterozygous littermates. Infusion of PRL for 11-12 d into PRL KO mice restored their REMS to that occurring in wild-type or heterozygous controls. Six hours of sleep deprivation induced a non-REMS and a REMS rebound in both PRL KO mice and heterozygous littermates, although the REMS rebound in the KOs was substantially less. Vasoactive intestinal peptide (VIP) induced REMS responses in heterozygous mice but not in KO mice. Similarly, an ether stressor failed to enhance REMS in the PRL KOs but did in heterozygous littermates. Finally, hypothalamic mRNA levels for PRL, VIP, neural nitric oxide synthase (NOS), inducible NOS, and the interferon type I receptor were similar in KO and heterozygous mice. In contrast, tyrosine hydroxylase mRNA was lower in the PRL KO mice than in heterozygous controls and was restored to control values by infusion of PRL, suggesting a functioning short-loop negative feedback regulation in PRL KO mice. Data support the notion that PRL is involved in REMS regulation.
authors.affiliation: Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University, Pullman, Washington 99164-6520, USA.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Obál
authors.forename: Fabio
authors.initials: F
authors.lastname: Garcia-Garcia
authors.forename: Balint
authors.initials: B
authors.lastname: Kacsóh
authors.forename: Ping
authors.initials: P
authors.lastname: Taishi
authors.forename: Stewart
authors.initials: S
authors.lastname: Bohnet
authors.forename: Nelson D
authors.initials: ND
authors.lastname: Horseman
authors.forename: James M
authors.initials: JM
authors.lastname: Krueger
mesh_terms: D000818:Animals; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011388:Prolactin / Q000097:blood / Q000172:deficiency* / Q000235:genetics; D012895:Sleep, REM / Q000187:drug effects / Q000235:genetics*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
chemical_list: D014660:Vasoactive Intestinal Peptide; D011388:Prolactin