Dehydration anorexia is attenuated in oxytocin-deficient mice.
Evidence in rats suggests that central oxytocin (OT) signaling pathways contribute to suppression of food intake during dehydration (i.e., dehydration anorexia). The present study examined water deprivation-induced dehydration anorexia in wild-type and OT -/- mice. Mice were deprived of food alone (fasted, euhydrated) or were deprived of both food and water (fasted, dehydrated) for 18 h overnight. Fasted wild-type mice consumed significantly less chow during a 60-min refeeding period when dehydrated compared with their intake when euhydrated. Conversely, fasting-induced food intake was slightly but not significantly suppressed by dehydration in OT -/- mice, evidence for attenuated dehydration anorexia. In a separate experiment, mice were deprived of water (but not food) overnight for 18 h; then they were anesthetized and perfused with fixative for immunocytochemical analysis of central Fos expression. Fos was elevated similarly in osmo- and volume-sensitive regions of the basal forebrain and hypothalamus in wild-type and OT -/- mice after water deprivation. OT-positive neurons expressed Fos in dehydrated wild-type mice, and vasopressin-positive neurons were activated to a similar extent in wild-type and OT -/- mice. Conversely, significantly fewer neurons within the hindbrain dorsal vagal complex were activated in OT -/- mice after water deprivation compared with activation in wild-type mice. These findings support the view that OT-containing projections from the hypothalamus to the hindbrain are necessary for the full expression of compensatory behavioral and physiological responses to dehydration.
Rinaman
Linda
L
University of Pittsburgh, Department of Neuroscience, 446 Crawford Hall, Pittsburgh, PA 15260, USA. Rinaman@pitt.edu
Vollmer
Regis R
RR
Karam
Joseph
J
Phillips
Donnesha
D
Li
Xia
X
Amico
Janet A
JA
D000818:Animals; D000855:Anorexia / Q000209:etiology* / Q000235:genetics / Q000523:psychology; D001810:Blood Volume / Q000502:physiology; D004247:DNA / Q000096:biosynthesis / Q000235:genetics; D003681:Dehydration / Q000150:complications* / Q000523:psychology; D004435:Eating; D005508:Food Deprivation / Q000502:physiology; D005838:Genotype; D006614:Hindlimb / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010121:Oxytocin / Q000172:deficiency*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis / Q000235:genetics; D012249:Rhombencephalon / Q000502:physiology; D014667:Vasopressins / Q000494:pharmacology
D016760:Proto-Oncogene Proteins c-fos; D014667:Vasopressins; D010121:Oxytocin; D004247:DNA