brl-37344 and Weight-Gain

beta3-Adrenoreceptor agonists can stimulate lipolysis in the white adipose tissue and thermogenesis in the brown adipose tissue. These activities could be useful in the treatment of obesity and the associated metabolic syndrome. The effects of six-week oral administration of the newly synthesized substance B496 (methyl-4-[2-[2-hydroxy-3-(4-ethylcarbamoyl)phenoxyprophyl]amino]etyl)-phenoxyacetate hydrochloride) on serum glucose, triglycerides, total cholesterol, and leptin levels were studied in male Wistar rats fed with a high-fat diet. The animals were divided into a group treated with B496 (5 mg dissolved in 1 litre of water) and a control group. The results indicated a significant reduction in serum glucose levels (-26 %, p<0,01), triacylglyceride levels (-21 %, p<0,05) and leptin levels (-43 %, p<0,01). Further the effect of a single intraperitoneal dose (1 mg/kg) of B496 and BRL-37344 on serum leptin levels in the C57Bl/6J mouse was investigated. Administration of BRL-37344 resulted in a significant decrease in serum leptin levels (-55 %, p<0,001). This reduction was not demonstrated by newly synthesized substance B496.

Topics: Adrenergic beta-Agonists; Animals; Blood Glucose; Cholesterol; Ethanolamines; Leptin; Male; Mice; Mice, Inbred C57BL; Phenoxyacetates; Rats; Rats, Wistar; Receptors, Adrenergic, beta-3; Triglycerides; Weight Gain

Short day photoperiod promotes thermogenesis and extensive weight loss in Siberian hamsters (Phodopus sungorus sungorus). To determine whether a change in hormone-sensitive lipolysis occurs after short-photoperiod exposure, some lipolytic responses were measured on white adipocytes isolated from animals exposed in warm conditions to short or Long daylight photoperiod. The body mass of male Siberian hamsters exposed during 11 weeks to short days (SD; light: dark, 6:18 hr) reached only 50% of those kept in long days (LD; 16: 8 hr). In SD-hamsters, adipose depot mass also represented approximately 50% of the LD group. A lower DNA content was observed in intra-abdominal fat pads of SD-hamsters. Lipolytic responses to noradrenaline, adrenaline, isoproterenol and ACTH were unchanged. However, sensitivity to the beta-3 adrenergic agonist, BRL 37344, was moderately increased. The major component of the adrenergic control of lipolysis was mediated by beta-3 adrenoceptors in both LD- and SD-Siberian hamsters. The limited antilipolytic effect of alpha-2 adrenergic agonists, PYY or insulin was rather surprising in Siberian hamsters since these inhibitory systems are efficient in hibernants and other photoperiod-sensitive rodents. Our results show that, after short photoperiod exposure, white adipose tissue mass and DNA content are reduced, especially in the epididymal fat pad, with only minor changes in the adipocyte sensitivity to lipolytic hormones.

Topics: Adipocytes; Adipose Tissue; Adrenergic beta-Agonists; Adrenocorticotropic Hormone; Animals; Cricetinae; DNA; Epinephrine; Ethanolamines; Isoproterenol; Lipolysis; Male; Norepinephrine; Peptide YY; Phodopus; Photoperiod; Propanolamines; Sympathomimetics; Weight Gain; Weight Loss