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Selective increase of dark phase water intake in neuropeptide-Y Y2 and Y4 receptor knockout mice
Thomas Wultsch1, Evelin Painsipp, Sabine Donner
1Department of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria.
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.
Insights
Neuropeptide-Y (NPY) receptors Y2 and Y4 regulate nocturnal water intake. Knockout mice lacking these receptors show increased dark-phase water consumption, suggesting NPY
Area of Science:
- Neuroendocrinology
- Behavioral Neuroscience
- Physiology
Background:
- Neuropeptide-Y (NPY) is a key regulator of ingestive behavior and energy homeostasis.
- NPY receptors, specifically Y2 and Y4, have been implicated in modulating food intake.
- The role of NPY receptors in water consumption, particularly during different light/dark cycles, remains less understood.
Purpose of the Study:
- To investigate the impact of NPY Y2 and Y4 receptor gene deletion on water intake in mice.
- To determine if water consumption patterns differ between light and dark phases in knockout mice.
- To explore the potential involvement of beta-adrenoceptors and angiotensin AT1 receptors in NPY-mediated water intake.
Main Methods:
- Utilized Y2 and Y4 receptor knockout mice and control littermates.
- Measured daily water consumption by weighing water bottles over four consecutive days.
- Administered beta-adrenoceptor antagonist propranolol and angiotensin AT1 receptor antagonist telmisartan to assess their effects on water intake.
Main Results:
- No significant difference in water intake was observed during the light phase between control and knockout mice.
- Y2 and Y4 receptor knockout mice exhibited significantly increased water intake (46-63%) during the dark phase compared to controls.
- Total daily water intake was also enhanced in knockout mice; this effect was not modulated by propranolol or telmisartan.
Conclusions:
- NPY, acting through Y2 and Y4 receptors, plays a critical role in regulating nocturnal water consumption.
- The enhanced dark-phase water intake in knockout mice suggests a disruption in normal inhibitory mechanisms.
- Beta-adrenoceptors and angiotensin AT1 receptors do not appear to mediate this specific NPY-dependent nocturnal water intake regulation.
