title: The effects of aging on leukocyte glucocorticoid receptor concentration and response to dexamethasone in dogs.
abstract: Glucocorticoid receptor concentration (GR) was determined in mononuclear (MNS) and polymorphonuclear (PMNS) cells isolated from 8 aged and 9 young male dogs. In addition, leukocyte responses to dexamethasone (0.1 mg kg(-1) i.v.) and plasma glucose concentration were also measured. The GR in MNS and PMNS was higher (p<0.05) in young dogs (6.64 +/- 0.57 and 7.04 +/- 0.29 fmolesx10(6) cells, respectively, versus 4.40 +/- 0.24 and 5.06 +/- 0.33 fmolesx10(6) cells, respectively, in aged dogs). The maximum increase in neutrophils (DeltaNEU) was lower (p<0.05) in aged dogs 6003.38 +/- 1398.5x10(6) versus 11168.67 +/- 1863.16x10(6) cells l(-1) in young dogs. The maximum decrease in lymphocytes (DeltaLYM) was lower (p<0.05) in aged dogs 550 +/- 56.75x10(6) cells l(-1) versus 1825.89 +/- 313.1x10(6) cells l(-1) in young dogs. In young dogs, significant (p<0.05) correlations between GR in PMNS and DeltaNEU (r=0.80) and between GR in MNS and DeltaLYM (r=0.76) were observed. In aged dogs, these correlations were not significant. The lower GR value and the lack of correlation between this parameter and its respective Delta in aged dogs suggest that changes in leukocytes responsiveness to glucocorticoids is occurring during the aging process.
authors.affiliation: Laboratório de Zoofisiologia, Departamento de Ciências Fisiológicas, Fundação Universidade Federal de Rio Grande, Rua Eng Alfredo Huch, 475, Rio Grande 96201-900, RS, Brazil.
authors.forename: Maria B C
authors.initials: MB
authors.lastname: Pereira
authors.forename: Maria C F
authors.initials: MC
authors.lastname: Traverse
authors.forename: Daniela M
authors.initials: DM
authors.lastname: Barros
authors.forename: Adalto
authors.initials: A
authors.lastname: Bianchini
authors.forename: Pablo E
authors.initials: PE
authors.lastname: Martínez
mesh_terms: D000375:Aging / Q000097:blood*; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D004285:Dogs / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D005938:Glucocorticoids / Q000494:pharmacology*; D007958:Leukocyte Count; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009504:Neutrophils / Q000187:drug effects / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000097:blood*
chemical_list: D001786:Blood Glucose; D005938:Glucocorticoids; D011965:Receptors, Glucocorticoid; D003907:Dexamethasone