International Journal of Poultry Science 10 (4): 257-265, 2011 ISSN 1682-8356 © Asian Network for Scientific Information, 2011 Corresponding Author: Samuel Besong, Department of Human Ecology, Delaware State University, 1200 North DuPont HWY, John Price Bldg RM #103, Dover, DE 19901 257 Effect of Njangsa Oil Seeds (Ricinodendron heudelitii) on Expression of Stearoyl-coenzyme a Desaturase in Laying Hens Samuel Besong , Celestine Fosung , Ayasha Jones and Vincent Fondong 1 1 1,2 2 Department of Human Ecology, Delaware State University, 1200 North DuPont HWY, 1 John Price Bldg RM #103, Dover, DE 19901 Department of Biological Science, Delaware State University, 2 1200 North DuPont HWY, Dover, DE 19901 Abstract: Pathogenesis of liver steatosis in laying hen remains poorly understood. However, it has been suggested that regulation of the expression of Stearoyl-Coenzyme A Desaturase-1 (SCD-1) may alter hepatic lipid metabolism and prevent liver steatosis in laying hens. SCD-1 is an integral membrane protein that catalyzes the biosynthesis of monounsaturated fatty acids required for the synthesis of triglycerides, cholesterol esters and phospholipids. This study was conducted to determine whether Njangsa Oil Seed (NOS) (Ricinodendron heudelotii) which is rich in polyunsaturated fatty acids, specifically omega-3 fatty acids can regulate the expression of SCD-1 gene and lower hepatic lipid accumulation in laying hens. The experiment was carried out with seventy-two white leghorn hens (24 months old) which were randomly assigned to three layer diet supplemented with 0%, 10% or 20% NOS for 6 weeks. The mRNA levels in SCD- 1 gene was quantified using forward and reverse primers specific to chicken SCD-1 in real-time reverse transcription-PCR (RT-PCR) technique with SYBER Green detection. Histological studies with liver tissues were performed with oil red stain and electron transmission microscope. Results indicate that NOS supplementation at 10% level tended to increase (p>0.05) SCD-1 mRNA expression in hens. Histological examination revealed micro-vesicular fat accumulation in the liver of hen fed NOS diets, indicating that supplementation of NOS in the diet may not prevent development of fatty liver. Results from this study suggest that NOS supplementation may regulate genes involve in lipid biosynthesis but may not prevent liver steatosis. Key words: Njangsa oil seeds, stearoyl-coenzyme A desaturase-1, mRNA, laying hen, steatosis INTRODUCTION Fatty Liver Syndrome (FLS) is one of the most common metabolic disorders seen in laying hens in the period of high egg production. Liver cells distended with fat vacuoles and different size of hemorrhages (Riddell, 1997). Some studies have reported that the fat content of liver in the hen diagnosed with hepatic steatosis ranges from 40-70% dry weight (Riddell, 1997). Excess fat impairs liver functions and alters carbohydrate and protein metabolism and markedly impair glycogenesis and gluconeogenesis (Felig et al., 1970). Although the real cause of fatty liver disease in laying hens is not well understood, however excessive accumulation of lipids predominantly triacylglycerols in hepatocytes occur when VLDL transport is disrupted. Triacylglycerol secretion in the form of VLDL from liver cells is highly dependent on the activity of stearoyl- CoA desaturase, which converts saturated fatty acids into monounsaturated fatty acids, specifically oleic acids (Cook, 1991). Hepatic packaging and secretion of VLDL require synthesis of apoB-100 as well as sufficient amount of oleic acid (C18:1, n-9), originating from a diet or synthesized by stearoyl-CoA desaturase (Ntambi, 1999). Recent studies with mouse model have reported that SCD1-deficient (SCD1 ) mice showed reduced –/– synthesis of lipids, especially triglycerides (Miyazaki et al., 2001). SCD1 mice have low levels of triglycerides –/– in VLDL and increased plasma HDL-cholesterol levels (Cohen et al., 2002; Huuskonen et al., 2001). These observations suggest that regulating SCD-1 gene would be a novel intervention strategy to improve poultry health. Thus, we hypothesized that incorporating njangsa oil seed (Ricinodendron heudelotii), rich in omega-3 fatty acids in poultry ration would reduce hepatic triglyceride accumulation through its action on the expression of SCD-1 genes. Njangsa (Ricinodendron heudelotii; family Euphorbiaceae), a tropical shrub from which oil seeds are harvested, grows or cultivated in West and Central Africa-specifically in Cameroon. Ricinodendron heudelotii reaches maturity between 4-5 years before producing fruits. The fruits are usually manually shelled to collect the seeds and dried. The seeds are grinded and used for soup and as an ingredient for seasoning baked meats and fish. The oil seed is an economical