Catecholamines are viewed as major stimulants of diet-and cold-induced thermogenesis and of-adrenoceptor triple knockout (TKO) mice and compared them to wild type animals. TKO mice exhibited normophagic obesity and cold-intolerance. Their brown fat had impaired morphology and lacked responses to cold of uncoupling protein-1 expression. In contrast, TKO mice had higher circulating levels of free fatty acids and glycerol at basal and fasted states, suggesting enhanced lipolysis. Hence, L L-adrenergic signalling is essential for the resistance to obesity and cold, but not for the lipolytic response to fasting.
These results show that the grafted cells preferentially integrate into the GCL and IPL and express ganglion cell or glial markers, thus exhibiting migratory and differentiation preferences when injected subretinally. It also appears that the retina, whether partially degenerated or already degenerated, does not provide signals to induce massive differentiation of RSCs into photoreceptors. This observation suggests that a predifferentiation of RSCs into photoreceptors before transplantation may be necessary to obtain graft integration in the ONL.
The purpose of the present work was to generate, from retinal stem cells (RSCs), a large number of cells committed toward the photoreceptor fate in order to provide an unlimited cell source for neurogenesis and transplantation studies. We expanded RSCs (at least 34 passages) sharing characteristics of radial glial cells and primed the cells in vitro with fibroblast growth factor (FGF)-2 for 5 days, after which cells were treated with the B27 supplement to induce cell differentiation and maturation. Upon differentiation, cells expressed cell type-specific markers corresponding to neurons and glia. We show by immunocytochemistry analysis that a subpopulation of differentiated cells was committed to the photoreceptor lineage given that these cells expressed the photoreceptor proteins recoverin, peripherin, and rhodopsin in a same ratio.
The retro-inverso form of the TAT sequence is effective in transducing cells from various compartments of the eye. After 14 days, the D-TAT FITC was clearly visible in the retina whereas L-TAT FITC had almost disappeared. The D-TAT peptide represents an interesting molecular transporter that, when coupled to a specific effector, may have potential therapeutic future, especially when a long-lasting action is needed.
Background: Rodent brown adipose tissue (BAT) is considered the main effector of adaptative thermogenesis as it contains a unique mitochondrial uncoupling protein, termed as uncoupling protein-1 (UCP1). The emergence of ectopic brown adipocytes in the white adipose tissue (WAT), called recruitment, might play an important role in the prevention of obesity. The recruitment phenomenon has until now been investigated mostly in vivo. Objectives: This study is an attempt to mimic in vitro the recruitment phenomenon. It consisted in culturing the stroma vascular fractions of mouse BAT and WAT in a brown adipocyte differentiation medium. The multilocular cells obtained, referred to as BAT B and WAT B adipocytes, respectively, were compared. Results: The BAT B and WAT B adipocytes were morphologically different. The expressions of UCP1, peroxisome proliferatoractivated receptor-g coactivator-1a (PGC-1a), leptin and resistin mRNAs were low in WAT B adipocytes as compared with those in BAT B adipocytes. The expressions of UCP1 and PGC-1a proteins were, however, much higher in WAT B adipocytes, amounting 51% and 36% of those in BAT B adipocytes. The patterns of expression of UCP1, PGC-1a and leptin in the BAT B and in WAT B adipocytes were different with a higher relative expression of PGC-1a in the latter. Rosiglitazone increased UCP1 mRNA expression 4.5-fold in the BAT B and significantly more, 7.9-fold, in the WAT B adipocytes. Retinoic acid and triiodothyronine increased UCP1 mRNA expression in the BAT B adipocytes 1.6-and 2-fold, respectively but, surprisingly, slightly decreased UCP1 mRNA expression in the WAT B adipocytes. Conclusions: The study suggests that the nature and possibly the origin of WAT brown adipocytes is different from that of BAT brown adipocytes. It proposes an in vitro approach that could prove very useful to better characterize the WAT brown adipocyte-like cells.
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