Effects Of Sodium Butyrate On Intestine Cell Proliferation And Protein Metabolism In Carassius Auratus And Its Molecular Mechanism

In this paper, a growth experiment was conducted to evaluate the effects of dietary sodium butyrate on growth performance, apparent digestibility, intestine cell proliferation, serum biochemical index and serum free amino acids in Carassius auratus. Furthermore, the real-time RCR was applied to evaluate effects of sodium butyrate on the expression levels of a few intestine cell proliferation and protein metabolism relative genes in intestine, reveals the sodium butyrate on intestinal cell proliferation and protein metabolism mechanism in Carassius auratus. The summary of research contents are as follows:1. Effects of sodium butyrate on growth and intestinal cell proliferation of Carassius auratus. A7-week feeding experiment was conducted to evaluate the effects of dietary sodium butyrate on growth performance and expression of intestinal development related genes in Carassius auratus. A grade levels of sodium butyrate at0.0(control),1.0,2.5,5.0and7.5g/kg were added to the basic diets respectively. Each diet was randomly fed to a group of30fishes per tank in triplicates. Fish were fed three times daily by hand at a rate of3%-5%of body weight for seven weeks. The results showed that dietary sodium butyrate significantly affected growth, foregut villus height and crypt depth, and the expression levels of CREB and CDX2in Carassius auratus (P<0.05). Compared with the control group, the weight gain(WG),special growth rate(SGR), protein efficiency rate(PER), as well as the condition factor(CF) were the highest in fish fed with diet supplemented with2.5g/kg sodium butyrate and they were increased at25.76%,16.46%,28.91%and8.37%respectively, and it also shows an increase of the apparent digestibility coefficients of dry matter and protein, foregut villus height at8.36%,6.21%and34.22%. Further, the sodium butyrate apparently up-regulated the CREB and CDX2gene expression at51.11%and42.13%(P<0.05). Overall of the results demonstrated that sodium butyrate may promote the growth of Carassius auratus via affecting intestinal villus height,CREB and CDX2genes’ expression and the optimun sodium butyrate supplementary concentration is2.5g/kg for Carassius auratus.2. Effects of sodium butyrate on protein metabolism and its relative genes expression of Carassius auratus. After the feeding experiment, the serum and intestinal samples were collected. The serum biochemical index and free amino acids in serum as well as APN、GDH and LAT2mRNA expression in intestinal were measured. Theresults showed that dietary sodium butyrate significantly affected the content of serum total protein(TP), albumin(ALB), globulin(GLB), aspartate aminotransferase(AST) and gtucose(GLU) in Carassius auratus (P<0.05). Compared with the control group, the serum ALB/GLB and AST were the highest in fish fed with diet supplemented with2.5g/kg sodium butyrate and they were increased at52.38%and146.91%respectively (P<0.05), and it also shows an increase of the serum free amino acids, however, the high concentration group were reduced its content. Only the serum Lys content was continued decreasing. Further, the sodium butyrate apparently up-regulated the GDH gene expression, meanwhile down-regulated the APN and LAT2gene expression (P<0.05). The results demonstrated that sodium butyrate significantly influenced the protein metabolism and its related gene expression of Carassius auratus.3. Effects of sodium butyrate on PepTl genes expression in intestinal of Carassius auratus were detected. After feeding experiment, the PepTl mRNA and protein expression levels in intestinal were measured7.5g/kg of sodium butyrate group and the control group were set up to feeding crucian carp for7weeks, the intestinal sample were collected after crucian carp intaking diets for0days,3days,7days,12days,18days,25days,33days,42days and49days, respectively. The same as above, PepT1mRNA expression levels in intestinal were measured. The results showed thatdietary sodium butyrate significantly affected the expression of PepTl mRNA and protein levels in Carassius auratus (P<0.05) and exhibiting dosage-depended also. Compared with the control group, the PepTl mRNA expression levels in intestinal were apparently up-regulated in fish fed with diet supplemented with2.5g/kg sodium butyrate (P<0.05), and the average optical density increased at115.45%in7.5g/kg of sodium butyrate group. But the longitudinal experiment showed that with the extension of breeding period, the PepTl mRNA expression levels in intestinal of Carassius auratus hasn’t been raising affected by sodium butyrate, exhibiting the first rise then in decline, after the rise and fall again of trend. This study also found the PepT1protein in intestinal of Carassius auratus mainly expression in the intestinal villus of brush border cells.