ABSTRACT
Objective To detect the glycomacropeptide (GMP) content of human breast milk,and take it as reference of newborn infant formula milk powder to optimize the nutritional content of infant formulas.Methods Thirty primiparas who fit the following conditions were selected:healthy,no special diet habits,living stably,having adequate milk,aged between 25 to 39 years old,and term delivery,were selected.Then they were divided into 2 groups,the colostrum group and mature milk group,and each group had 15 cases.Each case had been collected of breast milk 5 mL(front milk).The gathering time of colostrum group was the 2nd day postpartum and mature milk group was the 42nd day postpartum.Hydrolyzing the breast milk by chymosin at 37 ℃,then the sialic acid(SA) content was detected by a sialic acid detection kit,and GMP content was represented by SA content.In addition,6 brands of formula milk powder were detected in the same way as breast milk after being made into standard liquid milk.The differences between groups were compared by analysis of variance (ANOVA).Results Best conditions for enzymolysis were:chymosin concentration 0.25 g/L,hydrolysis time 120 min.SA content of colostrum group was (3486.98 ± 406.70) mg/L,while mature milk group was (2687.95 ± 375.85) mg/L,as the former was significantly higher than the latter (P ＜ 0.01),but the differences between individuals within each group were small (CVco1 =0.12,CVma ilk =0.14).The average level of SA content of various infant formulas was (1196.93 ± 608.40)mg/L,which was significantly lower than colostrum and mature milk(all P ＜ 0.01).SA contents of various brands of formulas were various,and the difference among these brands was relatively big(CV =0.63).Conclusions The content of GMP in human colostrum was higher than that of the mature milk.The contents of the GMP in different brands of infant formula milk powder were uneven,and the measured values were quite different with human milk.However,because of the difference of the molecular weight of GMP and the number of amino acid residues between human milk and bovine milk,the amount of GMP required to achieve the same physiological effects may be different in breast milk and bovine milk.In order to optimize the nutritional content of infant formula,and make it even closer to human milk,it is necessary to further explore the best GMP content relative to human milk.
ABSTRACT
<p><b>OBJECTIVE</b>To establish an appropriate neonatal rat model of necrotizing enterocolitis (NEC) and to investigate the protective effects of glycomacropeptide (GMP) on the gut from injury in neonatal rats with NEC.</p><p><b>METHOD</b>A total of 36 neonatal SD rats were randomly divided into 3 groups: NEC model group (Group M), NEC + GMP group (Group G) and normal control group (Group N), each group had 12 rats. All the neonatal rats were fed with breast milk in the first 3 days after birth. During the second 3 days after birth, the rats of Group N were still maternal breast-fed, but the rats of Group M and Group G were separated from their mothers and lived in incubator and began to be formula fed, and were subjected to cold exposure shortly after hypoxic-reoxygenation treatment. After being fed in such means for 6 days, all the neonatal rats were placed into the incubator and fasted for 24 hours. Then all the rats were sacrificed by cervical dislocation. Intestinal tissue located at the boundary of ileum and cecum was obtained for: (1) histological examination after HE staining, (2) TUNEL detection, (3) electron microscopic observation; and the tissue homogenate was obtained for checking TNF-α and IL-1β levels by ELISA and platelet activating factor (PAF) mRNA expression by quantitative fluorescence (QF)-PCR.</p><p><b>RESULT</b>(1) The pathological scores of the 3 groups were 2.17 ± 0.83 (Group M), 0.92 ± 0.79 (Group G) and 0.17 ± 0.39 (Group N) separately. There was significant difference between Group M and Group G (H = 8.819, P = 0.003). (2) TNF-α levels of 3 groups were (41.94 ± 13.51) pg/ml (Group M), (31.69 ± 11.68) pg/ml (Group G) and (17.42 ± 7.18) pg/ml (Group N) separately, and TNF-α level in Group G was significantly lower than that of Group M (F = 3.959, P = 0.030). (3) IL-1β levels of 3 groups were (150.33 ± 36.41) pg/ml (Group M), (118.36 ± 33.00) pg/ml (Group G) and (28.44 ± 15.04) pg/ml (Group N) separately, and IL-1β level in Group G was lower than that of Group M (F = 5.080, P = 0.013). (4) Expression levels of intestinal PAF mRNA (2(-ΔΔCt) value): 3.01 ± 0.96 (Group M), 1.56 ± 0.29 (Group G), 1.01 ± 0.13 (Group N), the level of Group G was significantly lower than that of Group M (F = 25.251, P = 0.000). (5)Electron microscopy: Group N showed that its cell volume was mostly occupied by the nucleus, the structure was clear, nuclear membrane existed, suggesting the normal phase of cell; Group M showed that apoptotic body existed, suggesting that the advanced stage phase of apoptosis; Group G showed that condensed chromatin marginated around the nuclear envelope, nuclear pores expanded, suggesting the early phase of apoptosis. (6) The apoptosis rate of intestinal epithelial cells by TUNEL detection: 38.79 ± 9.79 (Group M), 29.54 ± 7.30 (Group G), 6.37 ± 1.96 (Group N); the apoptosis rate of intestinal epithelial cells of Group G was significantly lower than that of Group M (F = 6.888, P = 0.003).</p><p><b>CONCLUSION</b>GMP has protective effects on guts of neonatal rats with NEC, which may probably work by reducing TNF-α, IL-1β and PAF expression, inhibiting the apoptosis of intestinal epithelial cells and reducing intestinal tissue injury.</p>
Subject(s)
Animals , Female , Male , Rats , Animals, Newborn , Apoptosis , Caseins , Pharmacology , Cold Temperature , Enterocolitis, Necrotizing , Drug Therapy , Metabolism , Pathology , Epithelial Cells , Metabolism , Pathology , Hypoxia , Interleukin-1beta , Metabolism , Intestinal Mucosa , Metabolism , Pathology , Intestines , Metabolism , Pathology , Peptide Fragments , Pharmacology , Platelet Activating Factor , Genetics , Metabolism , RNA, Messenger , Genetics , Metabolism , Random Allocation , Rats, Sprague-Dawley , Tumor Necrosis Factor-alpha , MetabolismABSTRACT
<p><b>OBJECTIVE</b>To study the expression of Toll-like receptor 4 (TLR-4) and caspase-3 in the intestine of neonatal rats with necrotizing enterocolitis (NEC), and explore the protective effects and possible regulatory mechanisms of glutamine (Gln) in NEC.</p><p><b>METHODS</b>Sixty premature rats were randomly divided into three groups (n=20 each): control, NEC model and Gln intervention group. NEC model was prepared by formula feeding, hypoxia and cold stress. The Gln intervention group was also subjected to hypoxia and cold stress but was fed with formula containing Gln (0.3 g/kg). Two days later, the rats were sacrificed and the intestine tissues were obtained. The histological changes of ileal tissues were observed by hemetoxylin and eosin staining. The expression of caspase-3 and TLR-4 protein in the jejunum, ileum and colon were detected by inmunohistochemistry. The expression of TLR-4 mRNA in the jejunum, ileum and colon were detected by RT-PCR.</p><p><b>RESULTS</b>Compared with the control group, the histological score of ileal tissues, and the expression of caspase-3, TLR-4 protein and TLR-4 mRNA in the NEC model group increased significantly (P<0.01). Gln intervention decreased significantly the histological score of ileal tissues, and the expression of caspase-3, TLR-4 protein and TLR-4 mRNA compared with the NEC model group (P<0.05).</p><p><b>CONCLUSIONS</b>TLR-4 might be involved in the pathogenesis of NEC. Gln may provide protective effects on intestine possibly through reducing the TLR-4 expression and then decreasing the apoptosis of intestinal epithelial cells.</p>