title: Selective increase of dark phase water intake in neuropeptide-Y Y2 and Y4 receptor knockout mice.
abstract: Neuropeptide-Y (NPY) is involved in the regulation of ingestive behaviour and energy homeostasis. Since deletion of the NPY Y2 and Y4 receptor gene increases and decreases food intake, respectively, we examined whether water intake during the light and dark phases is altered in Y2 and Y4 receptor knockout mice. The water consumption of mice staying in their home cages was measured by weighing the water bottles at the beginning and end of the light phase during 4 consecutive days. Control, Y2 and Y4 receptor knockout mice did not differ in their water intake during the light phase. However, during the dark phase Y2 and Y4 receptor knockout mice drank significantly more (46-63%, P<0.05) water than the control mice. The total daily water intake over 24 h was also enhanced. The enhanced water intake during the dark phase was not altered by the beta-adrenoceptor antagonist propranolol or the angiotensin AT1 receptor antagonist telmisartan (each injected intraperitoneally at 10 mg/kg). These data indicate that NPY acting via Y2 and Y4 receptors plays a distinctive role in the regulation of nocturnal water consumption. While beta-adrenoceptors and angiotensin AT1 receptors do not seem to be involved, water intake in Y2 and Y4 receptor knockout mice may be enhanced because presynaptic autoinhibition of NPY release and inhibition of orexin neurons in the central nervous system are prevented.
authors.affiliation: Department of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wultsch
authors.forename: Evelin
authors.initials: E
authors.lastname: Painsipp
authors.forename: Sabine
authors.initials: S
authors.lastname: Donner
authors.forename: Günther
authors.initials: G
authors.lastname: Sperk
authors.forename: Herbert
authors.initials: H
authors.lastname: Herzog
authors.forename: Bernhard A
authors.initials: BA
authors.lastname: Peskar
authors.forename: Peter
authors.initials: P
authors.lastname: Holzer
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal; D001562:Benzimidazoles / Q000494:pharmacology; D001565:Benzoates / Q000494:pharmacology; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D004326:Drinking / Q000187:drug effects / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D011433:Propranolol / Q000494:pharmacology; D017476:Receptors, Neuropeptide Y / Q000172:deficiency*; D000077333:Telmisartan; D013997:Time Factors
chemical_list: D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D001562:Benzimidazoles; D001565:Benzoates; D017476:Receptors, Neuropeptide Y; C095889:neuropeptide Y2 receptor; C109491:neuropeptide Y4 receptor; D011433:Propranolol; D000077333:Telmisartan