title: Changes in beta 1- and beta 2-adrenergic receptor mRNA levels in brown adipose tissue and heart of hypothyroid rats.
abstract: The aim of the present work was to study the effect of hypothyroidism on the expression of the beta-adrenergic receptor (beta-AR) in interscapular brown adipose tissue and heart. The total density of plasma membrane beta-AR per tissue is decreased by 44% in hypothyroid rat interscapular brown adipose tissue and by 55% in hypothyroid rat heart compared with euthyroid controls. The effects of hypothyroidism on the density of both beta 1- and beta 2-AR subtypes were also determined in competition displacement experiments. The densities of beta 1- and beta 2-AR per tissue are decreased by 50% and 48% respectively in interscapular brown adipose tissue and by 52% and 54% in the heart. Northern blot analysis of poly(A)+ RNA from hypothyroid rat interscapular brown adipose tissue demonstrated that the levels of beta 1- and beta 2-AR mRNA per tissue are decreased by 73% and 58% respectively, whereas in hypothyroid heart, only the beta 1-AR mRNA is decreased, by 43%. The effect of hypothyroidism on the beta 1-AR mRNA is significantly more marked in the interscapular brown adipose tissue than in the heart. These results indicate that beta-AR mRNA levels are differentially regulated in rat interscapular brown adipose tissue and heart, and suggest that the decrease in beta-AR number in interscapular brown adipose tissue and heart of hypothyroid animals may in part be explained by a decreased steady-state level of beta-AR mRNA.
authors.affiliation: Département de Biochimie Médicale, Centre Médical Universitaire, Genève, Switzerland.
authors.forename: J P
authors.initials: JP
authors.lastname: Revelli
authors.forename: R
authors.initials: R
authors.lastname: Pescini
authors.forename: P
authors.initials: P
authors.lastname: Muzzin
authors.forename: J
authors.initials: J
authors.lastname: Seydoux
authors.forename: M G
authors.initials: MG
authors.lastname: Fitzgerald
authors.forename: C M
authors.initials: CM
authors.lastname: Fraser
authors.forename: J P
authors.initials: JP
authors.lastname: Giacobino
mesh_terms: D002001:Adipose Tissue, Brown / Q000502:physiology*; D000818:Animals; D015152:Blotting, Northern; D015870:Gene Expression; D006321:Heart / Q000502:physiology*; D007037:Hypothyroidism / Q000503:physiopathology*; D008297:Male; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D013963:Thyroid Hormones / Q000502:physiology*
chemical_list: D012333:RNA, Messenger; D011943:Receptors, Adrenergic, beta; D013963:Thyroid Hormones