| Egg yolk contains large amount of cholesterol and was suspected to be closely related to hyperlipidemia after long time consumption.The present research aims to evaluate the effect of egg white(EW)and egg yolk(EY)supplementation on brain cognition of male Sprague Dawley(SD)rats.Sixty three rats were divided into seven groups with 3 replicates in each group(3 rats per replicates).The rats were kept and fed of normal diet for three days to adapt to the new environment.Rats divided in seven groups were fed: normal diet(NC with 3%whole egg),1.60%,4% and 7.20% of egg yolk supplemented to diet and 2.80%,7.20% and13.20% of egg white supplemented to diet for 4 weeks.The feeding condition(change in body weight,feed intake and feed conversion ratio),blood serum levels,liver function,morphology of the hippocampus in the CA1 region and the expression levels of BDNF and trk B in brain responsible for underlying changes of behavior were determined by RT-PCR.The body weight was significantly higher(p<0.05)in the group of rats fed diet containing 13.20% egg white while there was a significant decrease in body weight of group fed diet containing4% egg yolk as compared with the rats from control group.However,feed intake was significantly higher in rats from 13.20% egg white addition group(p<0.05)while the feed intake was significantly lowerin rats from 4%EY group.The ratio of feed to gain(F/G)was significantly increased in rats feddiet with 4% egg yolk addition,while F/G was remarkably decreased(p<0.05)in rats fed diet containing2.80% and 7.20% egg white addition as compared with rats from control group.In addition,rats fed diet containing egg white(2.80%,7.20% and 13.20%)showed a decreased F/G whereas rats from egg yolk group exhibited an increased F/G as compared with control group.Serum concentration of triglycerides was significantly higher in group fed 7.20% egg white(p<0.05)while serum triglycerides was significantly lower in group fed2.80% egg white addition.Serum level of total lipids was significantly increased(p<0.05)in 7.20% egg white addition group whereas there was a significant decrease(p<0.05)in serum concentration of total lipids of the group of normal control,1.6% and 4%egg yolk addition.There was a significant increase in serum levels of LDL-C of groups of 7.20% and 13.20%egg whites addition while there was a significant decrease in rats from control group,1.6%,4%and 7.20% egg yolk addition group and 2.80% egg white addition group.The HDL-C concentration was significantly higher in the control group and 4% egg yolk addition group while there was a significant decrease in 7.20% egg white addition group(p < 0.05).The serum glucose concentration was only significantly higher in group of 7.20% egg white addition(p<0.05).Serum free fatty acids was significantly higher(p<0.05)in group of 7.20%egg white addition and a significant decline in control and 1.6%egg yolk addition group.The serum AST and ALT concentrations exhibited no significant difference among groups.The diet of(1.6% and 4%)egg yolk protected the brain and are resulted in an abundant neurons in CA1 hippocampal areas when compared with the normal control group.In addition,the diets of higher percentage egg yolk(7.20%)affected the brain and are resulted in a formation of apoptotic neurons and a reduction in the number of neurons in the hippocampus.However,in the diet of lower egg white(2.80%)group,revealed a formation of neuronal apoptosis in CA1 hippocampal areas of rats.In the group of rats fed of 7.2% EW added to normal diet,the brain sections showed abnormal and large neurons with apoptosis in the CA1 region of the hippocampus.The diets of higher percentage egg white(13.20%)affected the brain and exhibited a degenerative change leading to a reduced CA1 hippocampal neuron and a considerable loss of neurons.BDNF and its high affinity receptor trk B,exhibited significantly higher expression level in rats fed diet containing egg yolk as compared with rats fed diet containing egg white.Egg yolk consumption reduced weight,glucose level,and increased HDL level in rats.However,egg white consumption increased body weight and decreased HDL level.Rats fed diet containing 4% EY exhibited rich neuron development from hippocampus and high expression level of trkB. |
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