Brain-derived neurotrophic factor (BDNF) expressed in the paraventricular hypothalamus (PVH) has been shown to play a key role in regulating energy intake and energy expenditure. BDNF is also expressed in other hypothalamic nuclei; however, the role in the control of energy balance for BDNF produced in these structures remains largely unknown. We found that deleting the Bdnf gene in the ventromedial hypothalamus (VMH) during embryogenesis using the Sf1-Cre transgene had no effect on body weight in mice. In contrast, deleting the Bdnf gene in the adult VMH using Cre-expressing virus led to significant hyperphagia and obesity. These observations indicate that the lack of a hyperphagia phenotype in the Sf1-Cre/Bdnf mutant mice is likely due to developmental compensation. To investigate the role of BDNF expressed in other hypothalamic areas, we employed the hypothalamus-specific Nkx2.1-Cre transgene to delete the Bdnf gene. We found that the Nkx2.1-Cre transgene could abolish BDNF expression in many hypothalamic nuclei, but not in the PVH, and that the resulting mutant mice developed modest obesity due to reduced energy expenditure. Thus, BDNF produced in the VMH plays a role in regulating energy intake. Furthermore, BDNF expressed in hypothalamic areas other than PVH and VMH is also involved in the control of energy expenditure.

Highlights d Deletion of the Bdnf gene in Emx1-expressing neurons of the brain leads to leanness d The Bdnf mutant displays elevated anxiety and impaired GABAergic transmission d The leanness of the mutant is due to increased basal metabolism and thermogenesis d Amygdalar BDNF re-expression reverses anxiety and metabolic phenotypes of the mutant

To explore the proliferation and differentiation characteristics of co-cultured porcine preadipocytes and muscle satellite cells, preadipocytes and muscle satellite cells were isolated from the healthy nascent landrace. Oil Red O stain and desmin immunohistochemistry were used to identify the two solo-cultured cells. Methyl thiazolyl tetrazolium (MTT) colorimetric assay was used to detect the proliferation characteristic of co-cultured cells, and the expression level of differentiation marker genes lipoprotein lipase (LPL), peroxisome proliferator-activated receptors (PPARγ), myogenic factor 5 (Myf5), myogenin (MyoG) were analyzed with reverse transcription PCR (RT-PCR) and western blot. The success of co-culture system was proved. In the co-cultured cells, slight lipid droplets were observed and appeared more slowly. The polykaryocytes fused into myotubes in co-cultured cells were less and relatively slow than that in solo myocytes. After fusion, the proliferation rate of co-cultured cells was higher than that in the solo-cultured muscle satellite cells (P < 0.01), and the duration were also longer. On day 5 and 10, the expression of the marker genes in earlier stage of cell differentiation (LPL and Myf5) were lower than those in the solo-cultured cells (P < 0.01) (except LPL gene at day 5). Moreover, the expression of intermediate and advanced stages' maker genes (PPARγ2 and MyoG) were hardly detectable at day 5, but increased significantly on day 10 (P < 0.01). These results confirm that the co-culture system could facilitate the cells' growth and proliferation, meanwhile, inhibited the cell differentiation.

Adiponectin plays a fundamental role in lipid and carbohydrate metabolism. However, its role in adipocyte differentiation remains controversial. To investigate the effect of gAd on lipid deposition in chicken adipocytes and its related signaling pathways, 200 μg/mL recombinant globular adiponectin, isoproterenol, SB253580, leucine, and rapamycin were used to treat chicken adipocytes. Results demonstrated that gAd increased the expression of endogenous adiponectin and AdipoR1 (P < 0.01); gAd inhibited triglyceride (TG) accumulation in chicken adipocyte and increased the release of free fatty acids (FFA) in medium; gAd decreased the expression of adipogenic marker genes CCAAT/enhancer binding protein alpha (C/EBPα) and fatty acid synthase (FAS), while activating the expression of lipolytic marker gene adipose triglyceride lipase (ATGL) (P < 0.01). Meanwhile, gAd activated the phosphorylation levels of p38 mitogen-activated protein kinase (p38 MAPK) and activating transcription factor 2 (ATF-2), and suppressed the phosphorylation levels of rapamycin (TOR) and p70 S6 Kinase (P < 0.01). In conclusion, the results demonstrate that gAd has an ability to inhibit lipids deposition in chicken adipocyte, which depends on the p38 MAPK/ATF-2 and TOR/p70 S6 Kinase pathways.