title: beta-Adrenergic receptor agonists increase apoptosis of adipose tissue in mice.
abstract: beta-Adrenergic receptor (beta-AR) agonists increase muscle mass and decrease body fat in rodents and livestock. With oral administration, however, the effects of beta1-AR and beta2-AR can be different, depending on the species tested. We tested the effects of clenbuterol, a beta2-AR agonist, and ractopamine, a beta1/beta2-AR agonist, on growth, adiposity and adipose tissue apoptosis in male and female mice by feeding diets containing control, 200 ppm clenbuterol, or 200 or 800 ppm ractopamine. Food intake (FI) was measured daily; body weight (BW) and temperatures (BT) were measured on days 0, 3, 7, 10, 14, 17, and 20. On day 21 mice were sacrificed, body composition was determined using PIXImus densitometry, and muscle and adipose tissues were collected. There were no treatment effects on BT, FI, BW, feed efficiency or body composition. Retroperitoneal (Rp) and epididymal/parametrial (Epi/Par) fat pad masses were reduced in both 800 ppm ractopamine (40+/-3mg and 207+/-20mg, respectively) and clenbuterol (35+/-7 mg and 211+/-22 mg) treated mice compared to control (66+/-8 mg and 319+/-30 mg, P<0.05). Brown adipose tissue (BAT) mass was greater (P<0.05) in clenbuterol treated mice compared to other treatments. Adipose tissue apoptosis (% DNA fragmentation) was increased in Epi/Par fat pads in clenbuterol (5.2+/-1.1%) and 800 ppm ractopamine (4.1+/-0.8%) treated mice compared to control (1.7+/-0.4%, P<0.05). These findings show that WAT apoptosis can be induced by activation of beta-AR in mice, although the mechanism is unknown.
authors.affiliation: Department of Animal and Dairy Science, University of Georgia, Athens, GA 30602, USA.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Page
authors.forename: Diane L
authors.initials: DL
authors.lastname: Hartzell
authors.forename: Changlong
authors.initials: C
authors.lastname: Li
authors.forename: Alisha L
authors.initials: AL
authors.lastname: Westby
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Della-Fera
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Azain
authors.forename: T Dean
authors.initials: TD
authors.lastname: Pringle
authors.forename: Clifton A
authors.initials: CA
authors.lastname: Baile
mesh_terms: D000273:Adipose Tissue / Q000166:cytology / Q000187:drug effects*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001823:Body Composition / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002976:Clenbuterol / Q000494:pharmacology*; D053938:DNA Fragmentation / Q000187:drug effects; D004435:Eating / Q000187:drug effects; D005260:Female; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009929:Organ Size / Q000187:drug effects; D010627:Phenethylamines / Q000494:pharmacology*
chemical_list: D000318:Adrenergic beta-Agonists; D010627:Phenethylamines; C060897:ractopamine; D002976:Clenbuterol