Short chain fatty acids stimulate feline colonic smooth muscle contraction

The effect of short chain fatty acids (SCFA) on feline colonic smooth muscle contraction was evaluated in vitro. Colonic tissue was obtained from seven healthy male and female adult cats and seven healthy male and female kittens. Longitudinal and circular colonic smooth muscle strips from proximal and distal colon were incubated with SCFA (acetate, butyrate and propionate; 1-100mM). SCFA-induced contractions were compared to responses obtained using maximal concentrations (10(-4)M) of acetylcholine (ACh). The calcium dependence of the SCFA response was investigated by incubating with nifedipine (1 microM) or verapamil (1 microM). Acetate, butyrate and propionate elicited isometric stress responses (0.25-1.98 x 10(4)N/m(2)) in longitudinal, but not circular, smooth muscle from both the proximal and distal colon of adult cats. Maximal responses were attained at 50 and 100mM SCFA. Maximal butyrate and propionate responses were 29 and 19% of the maximal ACh response (10(-4)M), respectively. Acetate was least effective in stimulating contractile responses. Nifedipine and verapamil abolished all responses. Contractile responses in kittens were similar to those observed in adult cats, but were smaller in amplitude.Results of these studies have shown that SCFA stimulate longitudinal colonic smooth muscle contractions in kittens and adult cats in vitro. These SCFA-induced contractions involve activation of calcium influx. These in vitro findings may account for some of the effects of dietary fiber on feline colonic motility in vivo.     

Effect of omega-3 fatty acids on canine atopic dermatitis

Twenty-nine dogs were included in a double-blinded, placebo-controlled, randomised trial and were orally supplemented for 10 weeks with either flax oil (200 mg/kg/day), eicosapentaenoic acid (50 mg/kg/day) and docosahexaenoic acid (35 mg/kg/day) in a commercial preparation, or mineral oil as a placebo. For each dog, clinical scores were determined based on a scoring system developed prior to the trial. Total omega-6 and omega-3 intake and the ratio of omega-6:omega-3 (omega-6:3) were calculated before and after the trial. The dogs' clinical scores improved in those supplemented with flax oil and the commercial preparation, but not in the placebo group. No correlation was identified between total fatty acid intake or omega-6:3 ratio and clinical scores. Based on the results of this study, the total intake of fatty acids or the omega-6:3 ratio do not seem to be the main factors in determining the clinical response.     

Cecal short-chain fatty acids in experimental rabbit mucoid enteropathy

Short-chain fatty acid concentrations were measured in the cecal contents of 9 healthy rabbits and 20 rabbits with experimentally induced mucoid enteropathy. In control rabbits, cecal concentration of acetate was the most abundant, followed by that of butyrate and propionate--a feature distinguishing rabbits from most other mammals. In mucoid enteropathy, cecal acetate and butyrate concentrations were lower, whereas propionate, isobutyrate, valerate, and isovalerate were increased. The results indicated that there were abnormal fermentation and cecal maldigestion in rabbits with mucoid enteropathy.     

短链脂肪酸在生猪产业的研究与应用

短链脂肪酸是肠道微生物发酵产物,其对机体健康的影响已被广泛研究。本文就短链脂肪酸在国内外的研究进展,综述了其对猪肠道健康和代谢健康的有益影响以及在生猪养殖中的应用,旨在为新型饲料添加剂的开发与利用提供应用和理论依据。     

Effects of short-chain fatty acids and lactic acids on survival of Oesophagostomum dentatum in pigs

The direct influence of intracaecal infusion of short-chain fatty acids (SCFA) and lactic acids (LA) on already established Oesophagostomum dentatum infection in cannulated pigs was investigated. We tested the hypothesis that the previously discovered anti-parasitic effect of inulin is mediated through its metabolic products SCFA and LA by infusing into cannulated pigs these compounds in amounts approximating to those produced in the pigs large intestine and caecum during the metabolism of inulin. The experiment comprised of 18 pigs--2 groups of 9 pigs in each. The normal diet used in the experiment was based on barley flour with insoluble fibre from oat husk with added soybean meal, vitamins and minerals. After 2 weeks of adaptation to the diet all the pigs were inoculated with 6,000 infective larvae of O. dentatum. Six weeks later, surgery on all pigs was performed to install cannulas into caeci. At 7 weeks post-infection (p.i.) the SCFA and LA infusion was initiated in Group 1 (experimental) pigs; at the same time pigs in Group 2 (controls) were infused with saline. At week 10 p.i., all pigs were killed and their worm burdens determined. SCFA and LA infused pigs exhibited markedly reduced fecal egg counts and worm recoveries (98 and 92% reduction, respectively, compared to saline controls). The results from this study demonstrate that SCFA and LA have a significant negative influence on established O. dentatum infection in growing pigs. The results also show that the type of dietary carbohydrates fed and its intestinal degradation can yield metabolic by products that profoundly influence helminth survival.     

Effect of feeding selected short-chain fatty acids on the in vivo attachment of Salmonella typhimurium in chick ceca.

Two groups of 20 chicks each were fed 1% fatty acid continuously starting at 1 day of age, while a control group of 20 chicks received unsupplemented feed. At 2 days of age, chicks were inoculated orally with 1 ml of Salmonella typhimurium (1 x 10(6) colony-forming units/ml). Ceca were obtained from six chicks of each group at 7, 14, and 21 days of age. At 14 days of age, formic and propionic acids had statistically reduced Salmonella recovery by 2.56 logs and 3.09 logs, respectively, compared with controls. At 21 days of age, both test groups showed significant reductions of approximately 3.6 logs compared with controls. There were no statistical differences in body weights among the groups at 21 days of age.     

Effect of short-chain fatty acids on pancreatic exocrine secretion in calves aged 2 weeks and 13 weeks

Effects of short-chain fatty acids on pancreatic exocrine secretion were studied under anesthesia in calves within 2 weeks of age (2-wks calves) given only whole milk and milk replacement and in which rumen fermentation has not begun yet, and in calves at 13 weeks of age (13-wks calves) weaned at 40 days of age and in which rumen fermentation has already begun. Basal rate of juice flow and protein concentration and amylase activity in pancreatic juice under basal condition were significantly lower in the 2-wks calves than those in the 13-wks calves. Intravenous administrations of acetate, propionate and butyrate stimulated pancreatic juice secretion and protein and amylase output in both groups of calves. Those responses were increased with increasing carbon number in the molecule of fatty acids. Although the response of amylase output (/kg of body weight) in the 2-wks calves was significantly less than that in the 13-wks calves, the response of juice flow and protein output (/kg of body weight) in the 2-wks calves were equivalent to or greater than those in the 13-wks calves. These results indicate that the characteristic of pancreas, being stimulated by short-chain fatty acids, in calves and probably in other ruminants is not generated on the process of postnatal development, but has been already acquired before rumen fermentation begins.     

大豆寡糖对肉仔鸡肠道pH值和盲肠短链脂肪酸的影响

在玉米-大豆浓缩蛋白型低寡糖基础日粮中分别添加0、0.50%、1.00%或2.00%的大豆寡糖,研究了不同添加量大豆寡糖对肉仔鸡肠道pH值和盲肠短链脂肪酸的影响。选用192只1日龄AA肉公鸡,随机分成4个处理组,每个处理设6个笼(重复),每笼8只鸡。结果表明:大豆寡糖对18、36日龄肉仔鸡十二指肠和空肠食糜pH值的影响无明显规律,各处理组之间无显著性差异(P0.05);随着大豆寡糖水平的增加,盲肠食糜pH值呈下降的趋势(P0.05),1.00%大豆寡糖添加组18、36日龄肉仔鸡盲肠食糜pH值为最低水平,且显著低于对照组(P0.05)。低寡糖日粮中添加不同剂量大豆寡糖,大幅度增加肉仔鸡盲肠食糜中乙酸和短链脂肪酸总量的浓度(P0.05);添加1.00%或2.00%大豆寡糖,显著增加18日龄肉仔鸡盲肠食糜中丁酸占短链脂肪酸总量的摩尔百分比(P0.05)。     

孕酮、雌二醇对奶牛离体真胃平滑肌收缩的影响

随着奶牛集约化饲养规模的扩大和产奶量的提高,奶牛真胃变位(DA)的发病率逐渐增加.研究表明,DA多发生在奶牛围产期,而围产期母牛体内雌二醇和孕酮含量改变明显.本试验进行了不同浓度的孕酮、雌二醇对离体真胃平滑肌收缩影响的研究,表明0.4～12.8 μg/L的孕酮能使真胃平滑肌收缩强度显著降低(P＜0.01),且呈剂量-效应关系.50.0 ng/L～101.2 μg/L的雌二醇能显著抑制真胃平滑肌的收缩强度(P＜0.01),但不呈现剂量效应关系.     

Effects of bethanechol on canine urinary bladder smooth muscle function

We studied whether the effects of bethanechol are mediated via a muscarinic receptor, the role of extracellular calcium on bladder contraction, and down-regulation of bladder contraction by bethanechol after activation with potassium chloride (KCl) and acetylcholine (Ach). Smooth muscle strips of normal urinary bladder were studied with standard methods to measure isometric force. Bethanechol caused a dose-dependent increase in bladder contraction. The potency of bethanechol is higher than Ach, as shown by higher peak active isometric stress (P(max)) and lower half-maximal contraction (ED(50)) (P< 0.01). The contractile responses to bethanechol were diminished in the presence of atropine, nifedipine and in calcium-free medium as shown by P(max) decreased by 58%, 87% and 65% and ED(50) increased by 314-, 24- and 16-fold, respectively. When bladder strips were stimulated with KCl and Ach, pre-treatment with bethanechol reduced the responses to KCl by 116-242% (P<0.05), while the contractile responses to Ach were unaltered. Thus, bethanechol induces bladder contraction via muscarinic receptor activation while both intracellular and extracellular calcium play a crucial role on bladder smooth muscle contraction. The mechanisms of down-regulation by bethanechol may be related to interference with calcium influx into the smooth muscle cells, rather than the desensitisation of muscarinic receptors or post-receptor steps of signal transduction following bethanechol binding to the receptor.     

Evaluation of the effects of short-chain fatty acids and extracellular pH on bovine neutrophil function in vitro

OBJECTIVE: To investigate the effects of short-chain fatty acids (SCFAs) and pH on neutrophil oxidative burst, phagocytosis, and morphology after exposure to acetate, propionate, butyrate, or succinate at pH 5.5 and 6.7. SAMPLE POPULATION: Neutrophils isolated from bovine blood samples and Porphyromonas levii, Prevotella spp, and Bacteroides fragilis isolated from lesions of cattle with acute interdigital phlegmon (foot rot). PROCEDURES: Bacteria were cultured in strictly anaerobic conditions. Bacterial SCFA production was measured with high-performance liquid chromatography. Neutrophils were isolated, stimulated with phorbol 12-myristate 13-acetate (PMA) or opsonized zymosan (OZ), and incubated with dihydroethidium or dichlorofluorescein diacetate to measure production of O(2)and H(2)O(2), respectively. Phagocytosis was assessed after exposure to serum-opsonized bacteria. Cellular morphology was assessed with differential staining. RESULTS: All bacteria produced at least 3 of the 4 SCFAs. Production of both O(2) and H(2)O(2) was markedly curtailed in PMA-stimulated neutrophils exposed to SCFA at pH 5.5, compared with production at pH 6.7. Succinate caused a significant dose-dependent decrease in O(2) production at pH 6.7 in OZ-stimulated neutrophils. Monoprotic SCFAs elicited a significant increase in H(2)O(2) production in OZ-stimulated neutrophils at pH 6.7 but a significant decrease at pH 5.5. Monoprotic SCFAs significantly increased phagocytosis at pH 6.7 but decreased phagocytic activity at pH 5.5. Cellular necrosis was observed in cells exposed to SCFAs at pH 5.5. CONCLUSIONS AND CLINICAL RELEVANCE: Establishment and persistence of anaerobic bacteria in cattle with foot rot infection may result in part from neutrophil dysfunction secondary to the effects of bacterially secreted SCFA in acidotic microenvironments.     

Exogenous infusion of short-chain fatty acids can improve intestinal functions independently of the gut microbiota

The present experiment was conducted to investigate the effects of exogenously infused short-chain fatty acids (SCFAs) on the growth development and intestinal functions in a germ-free (GF) pig model. Twelve hysterectomy-derived newborn piglets were reared in six sterile isolators. All piglets were hand-fed Co60-γ-irradiated sterile milk powder for 21 d and then were switched to sterile feed for another 21 d. During the second 21-d period, GF piglets (n = 6) were orally infused with 25 mL/kg sterile saline per day, and SCFA piglets (n = 6) were orally infused with 25 mL/kg SCFAs mixture (acetic, propionic, and butyric acids, 45, 15, and 11 mM, respectively) per day. We observed the concentrations of SCFAs in serum and intestine, and the messenger ribonucleic acid (mRNA) abundance of G-protein-coupled receptor-43 in the ileum was increased (P < 0.05) in the SCFA group. Meanwhile, oral infusion of SCFAs enhanced (P < 0.05) the contents of glucagon-like peptide-2 in the jejunum and serum and tended to increase the villi height in the ileum (P < 0.10). Besides, the activities of lipase, trypsin, sucrase, lactase, Na⁺-K⁺-adenosine triphosphatase ([ATPase] P < 0.05), and Ca²⁺-Mg²⁺-ATPase (P < 0.10) were stimulated and the mRNA expressions of solute carrier family 7 (SLC₇A₁) and regeneration protein (REG)-ΙΙΙ γ in the jejunum (P < 0.05) were upregulated in the SCFA group. Additionally, SCFAs infusion downregulated the mRNA abundances of interleukin (IL)-1β and IL-6 in the jejunum, ileum, or colon (P < 0.05) and increased the counts of white blood cell, neutrophils, and lymphocyte in the blood (P < 0.05). Collectively, exogenous infusion of SCFAs might improve intestinal health through promoting intestinal development and absorption function, and enhancing intestinal immune function, and these effects were occur independently of the gut microbiota.     

饲粮大麦粉碎粒度对湖羊瘤胃微生物组成及肌肉脂肪酸的影响

将大麦进行不同粒度粉碎处理改变瘤胃可降解淀粉的含量,研究其对湖羊血常规、瘤胃微生物组成及肌肉脂肪酸的影响.试验选取54只健康3月龄湖羊公羔,随机分为3个处理,分别为大麦经2、3和4 mm的筛片粉碎,每个处理18个重复,每个重复1只羊.整个试验期包括预饲期7 d,正试期63 d和采样期1 d.试验结果表明:1)大麦粉碎处理对湖羊血液的红细胞总数、血红蛋白浓度、红细胞压积、血小板总数、淋巴细胞计数、单核细胞计数、嗜酸性粒细胞计数、嗜中性粒细胞计数和嗜碱性粒细胞计数等血常规指标均无显著影响(P>0.05).2)大麦4 mm粉碎组总菌和溶纤维丁酸弧菌数量显著高于3 mm粉碎组(P<0.05),反刍兽新月形单胞菌数量显著低于2和3 mm粉碎组(P<0.05),产琥珀酸丝状杆菌数量显著高于2 mm粉碎组(P<0.05).普雷沃氏菌、白色瘤胃球菌和黄色瘤胃球菌等微生物的数量各组间差异不显著(P>0.05).3)大麦4 mm粉碎组湖羊肌肉中的C10:0、C12:0、C14:0和C14:1含量均显著高于2 mm粉碎组(P<0.05),C18:2n-9t11t和共轭亚油酸(conjugated linoleic acid,CLA)含量显著高于3 mm粉碎组(P<0.05),肌肉中anteiso C15:0、C16:1、C18:2n6t和C18:2n-9c11t的含量随着粉碎粒度的增加有增加的趋势(0.05≤P<0.10).综上,当饲喂湖羊4 mm粉碎大麦的饲粮时,湖羊瘤胃内容物中纤维分解菌数量增加,反刍兽新月形单胞菌数量减少,肌肉脂肪酸中CLA含量增加,因此,4 mm粉碎处理对湖羊瘤胃微生物区系和肌肉脂肪酸CLA合成的影响效果最佳.     

中药产复康对大鼠离体子宫平滑肌收缩功能的影响

为了观察中药制剂产复康对离体子宫平滑肌的收缩功能,测定了产复康对大鼠离体子宫平滑肌收缩功能和催产素引起的大鼠离体子宫平滑肌收缩功能的影响。结果发现低剂量产复康可以促进大鼠离体子宫平滑肌的收缩功能,提高子宫的活动性,高剂量则对子宫呈抑制作用;产复康对催产素引起的大鼠离体子宫平滑肌收缩功能具有抑制作用,且呈剂量-效应关系。产复康对大鼠离体子宫具有双向调节作用。