PURPOSE: Borage oil (BO) and safflower oil (SO) are efficacious in reversing epidermal hyperproliferation, which is caused by the disruption of epidermal barrier. In this study, we compared the antiproliferative effect of dietary BO and SO. Altered metabolism of ceramide (Cer), the major lipid of epidermal barrier, was further determined by measurement of epidermal levels of individual Cer, glucosylceramide (GlcCer), and sphingomyelin (SM) species, and protein expression of Cer metabolizing enzymes. METHODS: Epidermal hyperproliferation was induced in guinea pigs by a hydrogenated coconut diet (HCO) for 8 weeks. Subsequently, animals were fed diets of either BO (group HCO + BO) or SO (group HCO + SO) for 2 weeks. As controls, animals were fed BO (group BO) or HCO (group HCO) diets for 10 weeks. RESULTS: Epidermal hyperproliferation was reversed in groups HCO + BO (67.6% of group HCO) and HCO + SO (84.5% of group HCO). Epidermal levels of Cer1/2, GlcCer-A/B, and beta-glucocerebrosidase (GCase), an enzyme of GlcCer hydrolysis for Cer generation, were higher in group HCO + BO than in group HCO, and increased to levels similar to those of group BO. In addition, epidermal levels of SM1, serine palmitoyltransferase (SPT), and acidic sphingomyelinase (aSMase), enzymes of de novo Cer synthesis and SM hydrolysis for Cer generation, but not of Cer3-7, were higher in group HCO + BO than in group HCO. Despite an increase of SPT and aSMase in group HCO + SO to levels higher than in group HCO, epidermal levels of Cer1-7, GlcCer-A/B, and GCase were similar in these two groups. Notably, acidic ceramidase, an enzyme of Cer degradation, was highly expressed in group HCO + SO. Epidermal levels of GlcCer-C/D and SM-2/3 did not differ among groups. CONCLUSION: Dietary BO was more prominent for reversing epidermal hyperproliferation by enhancing Cer metabolism with increased levels of Cer1/2, GlcCer-A/B, and SM1 species, and of GCase proteins.
Animals ; Borago* ; Carthamus tinctorius* ; Ceramidases ; Cocos ; Diet ; Epidermis* ; Glucosylceramidase ; Guinea Pigs* ; Guinea* ; Hydrogen ; Hydrolysis ; Metabolism* ; Safflower Oil* ; Serine C-Palmitoyltransferase ; Sphingomyelin Phosphodiesterase

This study was carried out to determine the effect of dietary gamma-linolenic acid on decreasing the plasma lipid levels and the thrombotic activity in rats. Sprague-Dawley male rats (B.W 120 g) were fed a experimental diet containing 5% lard (46.05% saturated fatty acids) , corn oil (51.36% linoleic acid) , evening primrose oil (EPO,72.80% linoleic acid and 9.16% gamma-linolenic acid) or borage oil (BO,40.29% linoleic acid and 24.25% gamma-liolenic acid) for 30 days. Although there were no significant differences in the food intake among the groups, the body weight gain of the BO group was significantly lower than that of the other groups. The bleeding time of the BO group was significantly longer than that of the other groups. There were significantly differences in the whole blood clotting time among the groups except for the EPO and corn oil groups, where the whole blood clotting time of the BO group was the highest among the groups, and that of the lard group was the lowest. The plasma triacyglyceride (TAG) , total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) concentrations were the lowest in the BO group, but highest in the lard group, and there were significant differences among the groups. The plasma HDL-C concentrations were in the following order: BO, EPO, corn oil and lard groups and there were significant differences among the groups. The excretions of fecal neutial steroids and acidic steroids of the BO group were the highest among the groups, and there were significant differences compared to the other groups. The results suggest that dietary EPO and BO containing gamma-linolenic acid has an antithrombotic activity, and inhibits the increasing of plasma TAG, TC and LDL-C concentrations compared to lard, which contains saturated fatty acids, or corn oil, which contains linoleic acid.
Animals ; Bleeding Time ; Blood Coagulation ; Body Weight ; Borago ; Cholesterol ; Cholesterol, LDL ; Corn Oil ; Diet ; Dietary Fats, Unsaturated* ; Eating ; Fatty Acids ; gamma-Linolenic Acid* ; Humans ; Linoleic Acid ; Male ; Oenothera biennis ; Plasma* ; Primula ; Rats* ; Rats, Sprague-Dawley ; Steroids