Caprylic Acid (MCTs) - reduce expression of lipogenic genes
Thank you for posting that up BT. MCTs, specifically caprylic acid (octonate) does much more than that. Permit me to introduce you to one of my secrets. Very few people know and understand what follows. Best explained by the study
Modulation of adipocyte lipogenesis by octanoate: involvement of reactive oxygen species, Wen Guo, Weisheng Xie and Jianrong Han, Nutrition & Metabolism 2006, 3:30
Background:
Medium-chain fatty acids (MCFA) belong to a unique type of fatty acids that is metabolized differently from either long-chain fatty acids or carbohydrates. Dietary Medium-chain triglycerides (MCT) inhibit body fat mass growth in both animals and human. Early studies suggest that this effect might be caused by rapid absorption of MCT-derived MCFA and their ß-oxidation in the liver, which reduces the circulating fatty acids available to the adipocytes [11]. This model is supported by the evidence that MCFA enters the ß-oxidation pathway in liver mitochondria independent of carnitine palmitoyl transferase I (CPT-I) [12].
[The afore-mentioned was presented by you BT & your wonderful illustrations]
However, it does not explain the findings that dietary MCT inhibits lipogenesis in adipocytes [13,14].
Furthermore, MCFA are recovered in the adipose tissue fatty acids up to 30 mole % in both animals and humans adapted to MCT diets [6,15-17]. These findings imply that a substantial influx of MCFA into the adipocytes occurs in vivo, which might affect adipose tissue function more than previously appreciated.
[MCTs in significant quantity do make there way into fat cells and do what?]
Indeed, we found that a reduction in fat mass was associated with reduced expression of lipogenic genes and adipocyte transcription factors in MCT-fed animals [6]. This effect was reproduced in cultured adipocytes treated with octanoate [18]. When added to differentiating rodent preadipocytes, MCFA also inhibits fat accumulation and reduces expression of adipocyte specific proteins [19,20]. In this study, we provide new evidence that octanoate suppresses lipogenesis, at least in part, by inactivating the key adipocyte transcription factor, peroxisome proliferator-activated receptor y (PPARy). Furthermore, our data revealed, for the first time, an involvement of reactive oxygen species (ROS) as a possible intermediate component that might regulate the anti-lipogenic effects.
[Wow!]
[What is so Wow?]
Discussion:
Fatty acid oxidation is normally activated only under fasting conditions when circulating levels of insulin and glucose are low. Conversely, lipogenesis is down-regulated by fasting. The mechanistic link between these two events, however, has not been established.
In this work, we provided the first evidence that medium-chain octanoate can be ß-oxidized in adipocytes independent of CPT-I regulation.
Hence, supplement of octanoate maintains active ß- oxidation in the presence of insulin and glucose. This is correlated with inhibition of lipogenesis and reduction of lipogenic gene expression. In other words, octanoate induces a metabolic state in adipocytes mimicking a fasting condition without actual hormone/nutrient deprivation. Our results also demonstrated that
ROS might be involved as a mediator for octanoate in lowering PPARy activity, the master control of lipogenic gene expression.
As extensively reviewed previously, PPARy is a prototypical member of the nuclear receptor superfamily which integrates the control of energy, lipid and glucose, homerostasis [50-54]. PPARy binds a variety of small lipophilic compounds derived from metabolism and nutrition. These ligands, in turn, determine cofactor recruitment and regulate the transcription of a variety of metabolic genes. Recent literature highlights the development of partial agonists of PPARy to block adipogenesis and reduce fat mass development [54-59]. In one of our previous studies, we proposed that octanoate might act as a partial agonist for PPARy because it can potentially bind to PPARy as does the long-chain fatty acids [29,60], hence competitively blocking the binding of the latter or other endogenous ligands. This model was supported, but not proved, by the findings that the anti-adipogenic [19] and antilipogenic (this work) effects of octanoate was efficiently blocked by selected synthetic PPARy agonists.
The current findings that octanoate induced ROS generation in adipocytes suggest that octanoate might also modulate PPARy activity indirectly via the ROS signaling pathways. It has been well established that ROS activates the stress-responsive protein kinases [61,62], which either directly or indirectly inhibit PPARy activity [47-49,62-67]. In our preliminary studies, we found that octanoate also induced sustained activation of Erk1/2 and JNK/SAPK (data not shown). How these kinase pathways are involved in the regulation of PPARy activity and lipogenesis in our cell system and, more importantly, in primary adipocytes, are currently under investigation.
Inhibition of adipocyte lipogenesis can be a useful tool for the prevention of obesity. In this regard, our studies contribute to the scientific basis for the application of MCT in dietary weight management. On the other hand, a complete inhibition of fat mass growth is disastrous since adipocytes play important roles in physiological functions of mammals.
Compared to the pharmaceutical inhibitors of lipogenesis [68,69], the effects of octanoate can be considered as moderate and yet might be more desirable for physiological regulation of body fat mass without adversely affecting normal fat tissue functions. According to recent surveys, a majority of the middle age population is moderately over-weighed (BMI 23–27), and a slight increase in BMI in this range is associated with a greater risk for metabolic syndrome [70,71]. It will be of important social and economical values if MCT can be used for body weight regulation in this sub-population, as demonstrated by a recent clinical trial [5].
Conclusion:
This study demonstrated that octanoate had a direct inhibitory effect on fat storage in adipocytes under conditions that normally favor lipogenesis. This was related to its unique ß-oxidation mechanism which links to elevated cellular ROS levels and subsequent inactivation of PPARy. The exact mechanism by which PPARy is inactivated, in particular, how ROS is involved in this process, still remains to be elucidated. Furthermore, ROS is known to have diverse and complex molecular targets, which might directly or indirectly influence the activities of additional adipocyte transcription factors or modify selected lipogenic proteins [44,71]. Elucidation of these mechanisms will be helpful for the application of MCT for dietary intervention to prevent obesity and may reveal possible pharmaceutical targets to modulate fat metabolism.
From the
RESULTS an important practical tip
[L-Carnitine & MCTs (Caprylic Acid) should not be used together & MCTs (Caprylic Acid) are more effective then L-Carnitine in the presence of insulin]
As shown in Figure 3A, ß-oxidation of octanoate was slightly inhibited (~18%) by insulin, a hormone that promotes the generation of the natural inhibitor of CPT-I [37], and Etomoxir, a pharmaceutical inhibitor of CPT-I. On the other hand, L-carnitine, an activator of CPT-I, caused a ~60% inhibition of octanoate oxidation. A combination of L-carnitine and exogenous oleate further enhanced the inhibition (> 85%). In contrast, ß-oxidation of oleate was increased by L-carnitine more than 2 fold but inhibited by insulin by about 60% (Fig. 3B), consistent with the literature [37]. These results indicate that in adipocytes, octanoate was mainly oxidized independent of CPT-I (> 80%). A small fraction (< 20%), that was sensitive to insulin and etomoxir, might be activated in the cytosol and hence depend on CPT-I to enter the mitochondria. The observation that L-carnitine inhibited, rather than promoted, ß-oxidation of octanoate suggests that activation of CPT-I largely increased the transport of endogenous fatty acids into the ß-oxidation pathway which compete with octanoate for the enzymes downstream from CPT-1. This competition was further enhanced in the presence of added oleate.
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