Influence of fasting status on the effects of coconut oil on chick plasma and lipoprotein composition

Fasting/refeeding: an experimental model to study the impact of early thermal manipulation on hepatic metabolism in mule ducks

An increase in egg incubation temperature was previously shown to enhance the metabolism of mule ducks and increase liver fattening after overfeeding, through a metabolic programming mechanism. Here, we examined whether fasting (F) followed by refeeding (RF) in 11-wk-old mule ducks could become an accelerated model to study the mechanisms of metabolic programming following embryonic thermal manipulation. This study investigated the hepatic response of mule ducks subjected to 23 h of fasting and 1 h of refeeding, in control or thermally programmed animals (with an increase of 1°C, 16 h per day from days 13 to 27 of embryogenesis). Liver weight and energy composition, hepatocyte structure, plasma parameters, and gene expression levels were measured at 1, 2, and 4 h after RF. All these parameters were strongly affected by RF, whereas significant impacts of embryonic programming were measured in cell size (+1 µm on average), lipid composition (+4.2% of saturated fatty acids 4 h after the meal), and relative gene expressions (including HK1, SCD1, ELOVL6, and FASN). In addition to confirming previously identified molecular targets of thermal manipulation, this study revealed new ones, thanks to kinetic sampling after RF. Finally, the detailed description of the impact of the F/RF challenge on the liver structure, composition, and gene expression, but also on plasma parameters allowed us to draw a parallel with these same traits measured during overfeeding. This comparative analysis suggests that this protocol could become a pertinent model to study the mechanisms involved in embryonic liver thermal programming, without overfeeding.

Effects of coconut oil on testosterone-induced prostatic hyperplasia in Sprague-Dawley rats

Benign prostatic hyperplasia (BPH) is the benign uncontrolled growth of the prostate gland, leading to difficulty with urination. Saw palmetto lipid extracts (SPLE), used to treat BPH, have been shown to inhibit prostate 5α-reductase, and some major components, such as lauric, myristic and oleic acids also inhibit this enzyme. Coconut oil (CO) is also rich in fatty acids, mainly lauric and myristic acids. We investigated whether CO prevents testosterone-induced prostate hyperplasia (PH) in Sprague-Dawley rats. Animals were distributed into seven groups (10 rats each). A negative control group were injected with soya oil; six groups were injected with testosterone (3 mg kg−1) to induce PH: a positive control group, and five groups treated orally with SPLE (400 mg kg−1), CO or sunflower oil (SO) (400 and 800 mg kg−1). Treatments were given for 14 days. Rats were weighed before treatment and weekly thereafter. Rats were then killed and the prostates were removed and weighed. CO (400 and 800 mg kg−1), SPLE (400 mg kg−1) and SO at 800 mg kg−1, but not at 400 mg kg−1, significantly reduced the increase in prostate weight (PW) and PW:body weight (BW) ratio induced by testosterone (% inhibition 61.5%, 82.0%, 43.8% and 28.2%, respectively). Since CO and SPLE, but not SO, contain appreciable concentrations of lauric and myristic acids, these results could be attributed to this fact. In conclusion, this study shows that CO reduced the increase of both PW and PW:BW ratio, markers of testosterone-induced PH in rats.

Hypolipidaemic effects of fenofibrate and fasting in the herbivorous grass carp ( Ctenopharyngodon idella) fed a high-fat diet

We investigated whether the hypolipidaemic effect of fenofibrate and fasting observed in most omnivorous mammals may also apply to herbivorous fish. Grass carp (Ctenopharyngodon idella) fed a high-fat (8 %) diet exhibited a marked increase in blood lipids and body fat after 6 weeks. They were then treated with fenofibrate (100 mg/kg body weight) in the same high-fat diet for 2 weeks, followed by fasting for 1 week. Plasma lipid concentration, body fat amount, fatty acid composition, plasma thiobarbituric acid-reactive substances and some parameters related to hepatic fatty acid oxidation were measured, and liver samples were stained for histological examination. Fenofibrate treatment decreased TAG and cholesterol concentrations in plasma, total lipids of the whole body and liver, and EPA and DHA contents in tissues. Further, a mobilisation of mesenteric fat concomitant with an increase in hepatic peroxisomal fatty acid oxidation and lipid peroxidation was observed. Compared with fenofibrate treatment, fasting decreased body weight and plasma TAG, but not plasma cholesterol. It also reduced the fat content of the whole body and increased the EPA and DHA contents in the liver and other tissues. Fatty acid oxidation was stimulated by fasting in mitochondria, but not in peroxisomes. These data suggest that fenofibrate and fasting regulate the lipid metabolism in grass carp through different metabolic pathways. The grass carp is moderately responsive to a fibrate derivative in comparison with the well-known excess responsiveness of the rat model, and so it could be used for the study of lipid abnormalities as a herbivorous model.