title: Hypothalamic neurogenesis is not required for the improved insulin sensitivity following exercise training.
abstract: Neurons within the hypothalamic arcuate nucleus (ARC) are important regulators of energy balance. Recent studies suggest that neurogenesis in the ARC is an important regulator of body mass in response to pharmacological stressors. Regular exercise training improves insulin action, and is a primary treatment modality for obesity and type 2 diabetes. We examined whether exercise training causes hypothalamic neurogenesis and whether this contributes to exercise-induced improvements in insulin action. Short-term exercise in adult mice induced a proneurogenic transcriptional program involving growth factors, cell proliferation, and neurogenic regulators in the hypothalamus. Daily exercise training for 7 days increased hypothalamic cell proliferation 3.5-fold above that of sedentary mice, and exercise-induced cell proliferation was maintained in diet-induced obese mice. Colocalization studies indicated negligible neurogenesis in the ARC of sedentary or exercise-trained mice. Blocking cell proliferation via administration of the mitotic blocker arabinosylcytosine (AraC) did not affect food intake or body mass in obese mice. While 4 weeks of exercise training improved whole-body insulin sensitivity compared with sedentary mice, insulin action was not affected by AraC administration. These data suggest that regular exercise training induces significant non-neuronal cell proliferation in the hypothalamus of obese mice, but this proliferation is not required for enhanced insulin action.
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Borg
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Moyra
authors.initials: M
authors.lastname: Lemus
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Alex
authors.initials: A
authors.lastname: Reichenbach
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Ahrathy
authors.initials: A
authors.lastname: Selathurai
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Oldfield
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia.
authors.forename: Zane B
authors.initials: ZB
authors.lastname: Andrews
authors.affiliation: Department of Physiology, Monash University, Clayton, Victoria, Australia matthew.watt@monash.edu.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Watt
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D003561:Cytarabine / Q000494:pharmacology; D004435:Eating / Q000187:drug effects; D007031:Hypothalamus / Q000166:cytology*; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D055495:Neurogenesis / Q000502:physiology*; D010805:Physical Conditioning, Animal
chemical_list: D003561:Cytarabine