title: Increased metabolic rate and insulin sensitivity in male mice lacking the carcino-embryonic antigen-related cell adhesion molecule 2.
abstract: OBJECTIVE
  The carcino-embryonic antigen-related cell adhesion molecule (CEACAM)2 is produced in many feeding control centres in the brain, but not in peripheral insulin-targeted tissues. Global Ceacam2 null mutation causes insulin resistance and obesity resulting from hyperphagia and hypometabolism in female Ceacam2 homozygous null mutant mice (Cc2 [also known as Ceacam2](-/-)) mice. Because male mice are not obese, the current study examined their metabolic phenotype.
  
  
  METHODS
  The phenotype of male Cc2(-/-) mice was characterised by body fat composition, indirect calorimetry, hyperinsulinaemic-euglycaemic clamp analysis and direct recording of sympathetic nerve activity.
  
  
  RESULTS
  Despite hyperphagia, total fat mass was reduced, owing to the hypermetabolic state in male Cc2(-/-) mice. In contrast to females, male mice also exhibited insulin sensitivity with elevated β-oxidation in skeletal muscle, which is likely to offset the effects of increased food intake. Males and females had increased brown adipogenesis. However, only males had increased activation of sympathetic tone regulation of adipose tissue and increased spontaneous activity. The mechanisms underlying sexual dimorphism in energy balance with the loss of Ceacam2 remain unknown.
  
  
  CONCLUSIONS
  These studies identified a novel role for CEACAM2 in the regulation of metabolic rate and insulin sensitivity via effects on brown adipogenesis, sympathetic nervous outflow to brown adipose tissue, spontaneous activity and energy expenditure in skeletal muscle.
authors.affiliation: Center for Diabetes and Endocrine Research, College of Medicine and Life Sciences, University of Toledo, Health Science Campus, 3000 Arlington Avenue, Mail Stop 1009, Toledo, OH 43614, USA.
authors.forename: P R
authors.initials: PR
authors.lastname: Patel
authors.forename: S K
authors.initials: SK
authors.lastname: Ramakrishnan
authors.forename: M K
authors.initials: MK
authors.lastname: Kaw
authors.forename: C K
authors.initials: CK
authors.lastname: Raphael
authors.forename: S
authors.initials: S
authors.lastname: Ghosh
authors.forename: J S
authors.initials: JS
authors.lastname: Marino
authors.forename: G
authors.initials: G
authors.lastname: Heinrich
authors.forename: S J
authors.initials: SJ
authors.lastname: Lee
authors.forename: R E
authors.initials: RE
authors.lastname: Bourey
authors.forename: J W
authors.initials: JW
authors.lastname: Hill
authors.forename: D Y
authors.initials: DY
authors.lastname: Jung
authors.forename: D A
authors.initials: DA
authors.lastname: Morgan
authors.forename: J K
authors.initials: JK
authors.lastname: Kim
authors.forename: K
authors.initials: K
authors.lastname: Rahmouni
authors.forename: S K
authors.initials: SK
authors.lastname: Rahmouni
authors.forename: S M
authors.initials: SM
authors.lastname: Najjar
mesh_terms: D050156:Adipogenesis; D002001:Adipose Tissue, Brown / Q000294:innervation / Q000378:metabolism* / Q000473:pathology; D050154:Adiposity; D000818:Animals; D015815:Cell Adhesion Molecules; D004734:Energy Metabolism; D005260:Female; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006963:Hyperphagia / Q000235:genetics / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D007031:Hypothalamus / Q000378:metabolism; D007333:Insulin Resistance; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D018482:Muscle, Skeletal / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012727:Sex Characteristics; D013564:Sympathetic Nervous System / Q000503:physiopathology; D009435:Synaptic Transmission
chemical_list: C087701:Ceacam2 protein, mouse; D015815:Cell Adhesion Molecules; D006023:Glycoproteins; D012333:RNA, Messenger