Leptin immunoexpression and innervation in rat interscapular brown adipose tissue of cold-acclimated rats: the effects of L-arginine and L-NAME.

Abstract

Abstract:The aim of the present study was to explore the effect of nitric oxide on leptin immunoexpression and innervation in interscapular brown adipose tissue (IBAT) of room-and cold-acclimated rats. Animals acclimated both to roomtemperature (22 ± 1°C) and cold (4 ± 1°C) were treated with L-arginine, a substrate for nitric oxide synthases (NOSs), or N?-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NOSs, for 45 days. Leptin expression and localization in brown adipocytes was studied by immunohistochemistry, and innervation stained by the Bodian method. Strong leptin immunopositivity was observed in brown adipocytes cytoplasm of all room-acclimated groups, but nuclear leptin positivity was found only in L-NAME treated rats. In cold-acclimated control and L-NAME treated rats leptin immunopositivity was absent, while L-arginine treatment reversed the cold-induced suppression of leptin expression. Comparing to control, L-arginine, and even more L-NAME, at 22 ± 1°C induced greater innervation. In conclusion, L-arginine treatment changes leptin expression pattern on cold in rat IBAT.

Effects of long-term sucrose overfeeding on rat brown adipose tissue: a structural and immunohistochemical study

“…Because brown adipocytes receive direct sympathetic innervation (Bachman et al, 2002;Bamshad et al, 1999;Korac et al, 2008a), the demonstration of noradrenergic nerves within BAT is very important with respect to thermogenesis. A stimulatory effect of sucrose feeding on the activity of the SNS was recognised a long time ago (Young and Landsberg, 1977).…”

“…Depending on the intensity and duration of stimulus, the response of BAT primarily implies induction of UCP1 synthesis (Klingenspor, 2003;Puigserver et al, 1996;Ricquier et al, 1984;Ricquier and Bouillaud, 1986;Suter, 1969), mitochondriogenesisdominantly regulated through the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α)-related pathway network (Jornayvaz and Shulman, 2010;Puigserver et al, 1998)and increased multilocularity and lipid turnover in brown adipocytes (Petrovićet al, 2008;Rabi et al, 1977;Suter, 1969), followed by recruitment of new brown adipocytes from interstitial cells and preadipocytes (Cannon and Nedergaard, 2004;Klingenspor, 2003;Ricquier et al, 1984). Enhanced innervation, blood flow and angiogenesis go in line with these changes (Gélöen et al, 1992;Klingenspor, 2003;Korac et al, 2008a).…”

L-Arginine in Nutrition: Multiple Beneficial Effects in the Etiopathology of Diabetes

“…Our extensive research on BAT physiology has shown that the L-arginine/NO action on BAT involves structural, metabolic and molecular remodeling of this tissue, in terms of its functional activation. In that context, L-arginine supplementation to cold-acclimated rats induced BAT hyperplasia, proliferation and differentiation of brown adipocytes, increased tissue vascularization and innervation as well as mitochondriogenesis [142][143][144][145]. Such structural changes in BAT are accompanied by L-arginineinduced recruitment of the molecular program including key thermogenesis-related regulatory and effectors molecules: PGC-1 , peroxisome proliferator-activated receptor (PPAR ), vascular endothelial growth factor (VEGF), and UCP1 [146].…”