Conjugated linoleic acid and betaine affect lipolysis in pig adipose tissue explants

Abstract

Consumers’ demand of leaner meat products is a challenge. Although betaine and conjugated linoleic acid (CLA) have the potential to decrease porcine adipose tissue, their mode of action is poorly understood. The aim of the study was to determine the lipolytic effect of betaine and CLA in the adipose tissue of Iberian pigs. Adipose tissue explants from five pigs (38 kg BW) were prepared from dorsal subcutaneous adipose tissue samples and cultivated for 2 h (acute experiments) or 72 h (chronic experiments). Treatments included 100 µM linoleic acid (control), 100 µM trans-10, cis-12 CLA, 100 µM linoleic acid + 1 mM betaine and 100 µM trans-10, cis-12 CLA + 1 mM betaine (CLABET). To examine the ability of betaine or CLA to inhibit insulin’s suppression of isoproterenol-stimulated lipolysis, test medium was amended with 1 µM isoproterenol ±10 nM insulin. Media glycerol was measured at the end of the incubations. Acute lipolysis (2 h) was increased by CLA and CLABET (85% to 121%; P < 0.05) under basal conditions. When lipolysis was stimulated with isoproterenol (1090%), acute exposure to betaine tended to increase (13%; P = 0.071), while CLA and CLABET increased (14% to 18%; P < 0.05) isoproterenol-stimulated lipolysis compared with control. When insulin was added to isoproterenol-stimulated explants, lipolytic rate was decreased by 50% (P < 0.001). However, supplementation of betaine to the insulin + isoproterenol-containing medium tended to increase (P = 0.07), while CLABET increased (45%; P < 0.05) lipolysis, partly counteracting insulin inhibition. When culture was extended for 72 h, CLA decreased lipolysis under basal conditions (18%; P < 0.05) with no effect of betaine and CLABET (P > 0.10). When lipolysis was stimulated by isoproterenol (125% increase in rate compared with basal), CLA and CLABET decreased glycerol release (27%; P < 0.001) compared with control (isoproterenol alone). When insulin was added to isoproterenol-stimulated explants, isoproterenol stimulation of lipolysis was completely blunted and neither betaine nor CLA altered the inhibitory effect of insulin on lipolysis. Isoproterenol, and especially isoproterenol + insulin, stimulated leptin secretion compared with basal conditions (68% and 464%, respectively; P < 0.001), with no effect of CLA or betaine (P > 0.10). CLA decreased leptin release (25%; P < 0.001) when insulin was present in the media, partially inhibiting insulin stimulation of leptin release. In conclusion, betaine and CLA produced a biphasic response regarding lipolysis so that glycerol release was increased in acute conditions, while CLA decreased glycerol release and betaine had no effect in chronic conditions. Furthermore, CLA and CLABET indirectly increased lipolysis by reducing insulin-mediated inhibition of lipolysis during acute conditions.

Betaine and L-Carnitine Synergistically Influence the Metabolome and Immune Response in Dogs

“…Increased dietary betaine was reported to reduce the adipose size of specific storage depots in geese [11]. Betaine also influences energy use by changing the effects of insulin on porcine adipose cells in explants [12]. In swine, betaine also influenced both the gene expression of uptake proteins and the concentration of fatty acids in muscle, which is associated with increased fatty acid oxidation [13].…”

Betaine Promotes Fat Accumulation and Reduces Injury in Landes Goose Hepatocytes by Regulating Multiple Lipid Metabolism Pathways

“…Betaine regulates fat metabolism, but the regulatory effect varies among species [ 28 , 29 , 30 , 31 ]. In humans, betaine prevents alcohol-induced steatosis by reducing liver fat deposition [ 32 ]; meanwhile, increased NAFLD severity is associated with betaine insufficiency, and elevated betaine levels improve liver injury and reduce fat deposition [ 33 ].In livestock and poultry, betaine increases carcass quality by increasing intramuscular fat and improves the egg-laying rate by inducing hepatic lipogenesis.…”

Recent Advances in the Knowledge of the Mechanisms of Leptin Physiology and Actions in Neurological and Metabolic Pathologies

“…Activation of the sympathetic nervous system inhibits the synthesis of this adipokine; β-adrenergic agonists decrease the rate of synthesis and secretion, without modifying the content of mRNA. In addition, these compounds are reported to block the stimulatory effect of insulin “in vitro”, although some synergistic effects of insulin and isoproterenol in tissue explants has been described [ 76 ]. Food intake and insulin are two of the main factors involved in the post-transcriptional regulation of leptin.…”