Decreased glycogen mobilization during ochratoxicosis in broiler chickens

Exosomes mediated the delivery of ochratoxin A-induced cytotoxicity in HEK293 cells

Ochratoxin A (OTA) is one of the mycotoxins, which widely pollutes food systems and seriously threatens human health. OTA's target organ is the kidney. Exosome, as one of the extracellular vesicles, could be secreted by all kinds of cells. It contains different proteins, nucleic acid, and lipid, which are decided by their donor cells and could be uptake by the recipient cells, release their contents, and affect the recipient cell's life activity. In this study, a 24 h-treatment with 5 μM OTA was found to significantly reduce the cell viability of HEK293 cells and meanwhile to provide a sufficient quantity of exosomes, thus this concentration and time were selected for subsequent experiments. In addition, exosomes extracted by ultracentrifugation had higher purity, fewer impurities, and uniform morphology than that by the ExoQuick-TC kit. Furthermore, these exosomes increased ROS levels and decreased mitochondrial membrane potential in HEK293 cells. By RNA-seq, the cytotoxicity mechanisms induced by OTA-treated HEK293 cell-derived exosomes (EXO-OTA) and OTA were mainly the metabolism of proteins and the cell cycle respectively. Also, it proved that exosomes deliver partial OTA-induced cytotoxicity.

Gene expression in the kidneys of broilers fed ochratoxin A for different time periods

Consumption of ochratoxin A (OTA) contaminated diets by broilers results in economic losses to the poultry industry. This experiment evaluated the effects of quantity and time of exposure to dietary OTA on performance, organ weights, serum biochemistry, and renal gene expression of chicks. Determination of genes expressed in response to OTA will allow for the identification of pathways that are influenced by OTA. 180-day old male broiler chicks were randomly assigned to a 3×3 factorial arrangement of treatments (3 levels of OTA; 0, 1 and 2 mg OTA/kg diet and 3 time periods; 7, 14 and 21 days) with 4 replicate pens of 5 birds each per treatment. For RNA-sequencing analysis (RNA-Seq), kidney samples were collected weekly from 3 controls and 3 chicks fed 1 mg OTA/kg. NextGENe software was used for read alignment and transcript quantification. Birds fed 2 mg OTA/kg diet had decreased feed intake and body weight gain, and increased serum uric acid on days 14 and 21. Compared to controls, birds fed 2 mg OTA/kg diet also had poorer feed conversion and increased kidney weights. On day 21, birds fed 1 mg OTA/kg diet had decreased albumin, and aspartate aminotransferase concentrations. Genes associated with carbohydrate and amino acid metabolism were downregulated, and genes associated with the immune system were upregulated at days 7 and 14. Genes associated with lipid metabolism and xenobiotic biodegradation were also downregulated on day 14. These changes disappeared on day 21 suggesting that the kidney and other related organs were repaired or the damage was contained. In conclusion, decreased performance and increased kidney weight and serum uric acid in birds fed 2 mg OTA/kg confirmed the effects of OTA. Supplementation of 1 mg OTA/kg diet caused time-dependent alterations in renal gene expression in chicks.

Ameliorative effects of L-carnitine and vitamin E (α-tocopherol) on haematological and serum biochemical parameters in White Leghorn cockerels given ochratoxin A contaminated feed

1. L-carnitine is a quaternary ammonium compound biologically synthesised from the amino acids methionine and lysine while vitamin E (α-tocopherol) is an important antioxidant. The objective of the present study was to evaluate the ameliorative effects of L-carnitine and vitamin E upon haematological and serum biochemical parameters in ochratoxin A intoxicated birds. 2. Day-old White Leghorn cockerels were acclimatised for 2 d, divided in 12 groups with 20 birds in each group. From d 3 of age, they were given different combinations of ochratoxin A (1.0 and 2.0 mg/kg), L-carnitine (1 g/kg) and vitamin E (200 mg/kg) in feed. Haematological (erythrocyte count, leucocyte count, haemoglobin concentration and haematocrit percentage) and serum biochemical parameters (serum urea, creatinine, albumin, total proteins and alanine aminotransferase) were evaluated. 3. Results confirmed that L-carnitine and vitamin E given alone or combined with 1.0 mg/kg ochratoxin A ameliorated toxin induced alterations in haematological and serum biochemical parameters. This amelioration, however, did not occur when ochratoxin of 2.0 mg/kg was given. 4. L-carnitine and vitamin E in combination have the ability to ameliorate ochratoxin altered haematological and serum biochemical parameters. However, the optimum ratio of L-carnitine + vitamin E, to be used to assure such mitigation of ochratoxin A altered changes in haematological and serum biochemical parameters in cockerels, has yet to be determined. The combination used in this study was indeed sufficient to ameliorate the alterations induced by ochratoxin A up to 1.0 mg/kg feed.

Studies on some feed additives giving partial protection against ochratoxin A toxicity in chicks

Significant protective effects of the feed additives: water extract of artichoke, sesame seed, Roxazyme-G and L-beta phenylalanine against the growth inhibitory effect of ochratoxin A (OTA) and associated pathomorphological changes were seen. Similarly, there was less OTA-induced decrease in serum total protein and increase of serum creatinine and urea in the chicks. Whereas OTA induced strong degenerative changes and an increase in weight of kidneys and liver as well as a decrease of the weight of lymphoid organs the additives variously gave protection against these changes. The protection of Roxazyme-G and sesame seed was better expressed in kidneys and liver, whereas the phenylalanine better protected the weight changes in gizzard, heart and the changes in differential WBC count. Notably, sesame seed gave strong protection against 5 ppm OTA-induced suppression of humoral immune response, for which artichoke also had some beneficial effect, whereas phenylalanine had hardly any effect.

Toxicological evaluations of cyclopiazonic acid and ochratoxin A in broilers

The individual and combined effects of ochratoxin A (OA) and cyclopiazonic acid (CPA) were evaluated in Petersen x Hubbard broiler chickens from 1 d to 3 wk of age. The experimental design was a 2 x 2 factorial with treatments of 0 and 2.5 mg OA/kg feed and 0 and 34 mg CPA/kg feed. Production performance, serum biochemistry, and gross pathological observations were evaluated. Body weight gain was reduced (P < 0.05) by OA, CPA, and OA-CPA in combination at the end of 3 wk. Ochratoxin A significantly increased the relative weight of the kidney and serum concentrations of uric acid and triglycerides and decreased total protein, albumin, and cholesterol. The toxicity of CPA was expressed primarily through increased relative weights of the proventriculus and increased activity of creatine kinase. Exposure to OA-CPA was characterized by increased relative weights of the liver, kidney, pancreas, and proventriculus; decreased concentrations of serum albumin, total protein, and cholesterol; increased activity of creatine kinase; and increased concentrations of triglycerides and uric acid. Postmortem examination revealed that the chickens fed CPA or OA-CPA had thickened mucosa and dilated proventricular lumen. Data from this study demonstrate that OA, CPA, and the OA-CPA combination can limit broiler performance and adversely affect broiler health. The interaction of the compounds was primarily additive or less than additive in the parameter in which the interaction occurred.

Haematological and biochemical studies in broiler chicks fed ochratoxin and inoculated with inclusion body hepatitis virus, singly and in concurrence

Day-old broiler chicks, which had been shown to be negative for maternal antibodies against inclusion body hepatitis (IBH) virus and for viral antigen in cloacal swabs, were divided into four groups of 20 chicks each. One group was fed ochratoxin-A at 0.5 ppm from 3 to 38 days of age, another group was inoculated with 1 ml of IBH virus containing 10(6.5) EID50 per 0.2 ml. A third group was given both ochratoxin-A and infected with IBH virus. The fourth group served as the control. Anaemia was observed in all three treated groups but the changes were more pronounced in the combined group. The biochemical changes also suggested a cumulative damaging effect by ochratoxin-A and IBH virus.

Progression of ochratoxicosis in broiler chickens

The progression of effects induced by administration of ochratoxin A were characterized in young male broiler chickens (Hubbard x Hubbard). The experimental design consisted of four dietary treatments of ochratoxin A (0, 1.0, 2.0, and 4.0 micrograms ochratoxin A/g feed) and 11 replicates of 10 broilers/replicate. Broilers were housed in electrically heated batteries with feed and water available ad libitum. Broilers were weighed, bled, killed by cervical dislocation, and necropsied at 3, 6, 9, 12, 15, 18, and 21 days of age. Toxicity of ochratoxin A to broilers was evident as early as 6 days of age, when significant (P less than .05) growth depression occurred at 4.0 micrograms dietary ochratoxin A/g feed. Dietary ochratoxin A significantly increased the relative weights of the liver, kidney, spleen, pancreas, and gizzard. Anemia, characterized by a significant decrease in packed-cell volume and hemoglobin levels, was present during ochratoxicosis. Hepatotoxicity of dietary ochratoxin A was evident through an observed significant reduction in serum levels of total protein, albumin, globulin, cholesterol, triglyceride, and blood urea nitrogen, and a significant increase in the serum activities of gamma glutamyl transferase and cholinesterase. A significant increase in serum uric acid and creatinine levels was indicative of nephrotoxicity. These data provide a description of the progression of ochratoxicosis in broilers that should be useful in diagnosis and in improved understanding of ochratoxicosis.

Maternal protein deprivation enhances the teratogenicity of ochratoxin A in mice

Teratogenic effects of the mycotoxin ochratoxin A (OA) were investigated in protein-deprived mice. Pregnant CD-1 mice were assigned to control (26%), 16%, 8%, and 4% protein diet groups and treated by gavage with 0, 2, or 3 mg/kg OA on gestation day 8 (plug = day 1). They were killed on day 18 and subjected to teratological examination. OA treatment decreased prenatal survival, particularly at the two lowest dietary protein levels. OA at the higher dose also inhibited fetal growth in all groups, with a similar effect at the low dose in the 16% and 4% protein groups. Gross malformations associated with OA were inversely related to dietary protein levels; for example, 26% and 100% of the litters were affected in the 26% and 4% protein groups, respectively, at the high OA dose. A similar trend was also seen for skeletal malformations and variations. Thus maternal protein deprivation was seen to exacerbate adverse effects of OA in a developing mammal. Such results may have implications for areas where lack of adequate food supply may cause consumption of moldy grain by women or domestic animals already living on a protein-deficient diet.

Effects of acute ochratoxicosis on blood pressure and heart rate of broiler chickens

Male broiler chickens (Hubbard X Hubbard) were placed at hatching into electrically heated batteries with feed and water available ad libitum and maintained to 3 weeks of age under continuous lighting. In Trial 1, two replicate pens of 10 broilers per replicate were fed ochratoxin A from day-old to 3 weeks of age with treatments of 0, 2.0, and 4.0 micrograms/g ochratoxin A in feed (ppm). Trial 2 was identical to Trial 1 except that when the broilers reached 3 weeks of age they were administered an additional intravenous dose of either ochratoxin A, methoxamine, or isoproterenol. Trial 3 broiler chickens were maintained on control feed until they reached 3 weeks of age at which time they were taken off of feed for 2.5 hr and then placed on either control feed or feed containing 4.0 ppm ochratoxin A, and heart rate and blood pressure were measured every half hour through 7 hr. In Trial 1, no effect of ochratoxin A was seen in any treatment on heart rate or diastolic, systolic, or mean blood pressure. However, when an intravenous dose of ochratoxin A was administered to these broilers, a significant (P less than .05) decrease in heart rate and diastolic, systolic, and mean blood pressure occurred. The severity and duration of intravenous ochratoxin A administration were significantly (P less than .05) enhanced as the level of dietary ochratoxin A increased. The response of broilers to isoproterenol was significantly (P less than .05) altered by dietary ochratoxin A, whereas the broilers responded in a predictable manner to methoxamine without significant (P less than .05) ochratoxin A treatment effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycogen storage diseases in animals and their potential value as models of human disease

Glycogen storage diseases (GSD) are inborn errors of glycogen metabolism. Of the eight human GSD types in which the enzymatic deficiency has been identified, spontaneous animal counterparts have been reported for GSD I (glucose-6-phosphatase deficiency) in the mouse, for GSD II (acid alpha-glucosidase deficiency) in the dog, in cattle and in the quail, for GSD III (debrancher enzyme deficiency) in the dog and for GSD VIII (phosphorylase kinase deficiency) in the rat and the mouse. Experimentally induced GSD-like conditions have been described in the rat (Acarbose-induced GSD II-like conditions, iodoacetate-induced symptoms of myophosphorylase (GSD V) and myophosphofructokinase (GSD VII) deficiency) and the chicken (ochratoxin A-induced symptoms of cyclic AMP-dependent protein kinase deficiency). Enzymatic defects that are typical of the human GSD types have not been clearly identified in the induced animal conditions. The homology of animal and human GSD types is discussed. It is concluded that clinical, pathogenic and therapeutic studies of GSD may benefit from the use of animal models. For genetic studies of human GSD these models may prove to be of limited value, as the picture of several human GSD types is already obscured by genetic heterogeneity.

Eimeria acervulina and Eimeria tenella infections in ochratoxin A-compromised broiler chickens

A 2 x 6 factorial experimental design was used to evaluate the effects of coccidial infections in ochratoxin A-compromised chicks. Ochratoxin A was incorporated into the feed at the dose levels of 0, .5, 1.0, 2.0, 4.0, and 8.0 micrograms/g toxin in feed (ppm), and fed to the birds from 1 day of age. Birds from each treatment were inoculated with either Eimeria acervulina or Eimeria tenella at 14 days of age. Ochratoxin A decreased the severity of lesions caused by both E. acervulina and E. tenella but did not prevent infection. Packed cell volume, hemoglobin concentration, relative weight of the kidney, and plasma protein levels were altered in a manner consistent with the independent effects of ochratoxicosis and coccidiosis. A combination of ochratoxin A and either species of coccidia produced a greater decrease in body weights, increase in feed conversions, and decrease in plasma carotenoid levels than either disease alone. The relative weight of the liver and level of plasma uric acid were altered in a manner that was dependent on the species of coccidia used. These data indicate that ochratoxin A and coccidial infections can interact to limit broiler performance and that some responses are directly related to the species of coccidia.

Analysis of liver glycogen in chicks

The glycogen levels in homogenates from livers from 3- to 4-week-old broilers were measured using alkaline digestion and ethanol precipitation followed by direct hydrolysis with amyloglucosidase. Glycogen was determined with glucose oxidase. Glycogen levels were not affected by rapid freezing in liquid nitrogen and storage at -10 C. Glycogen was stabile at 4 C for at least 1 hr; however, at room temperature, over 50% of the glycogen was lost within 1 hr. Homogenization with .05 M ethylenediaminetetraacetate (EDTA) prevented this loss. Liver glycogen decreased rapidly (within 1 hr) after feed withdrawal and was sometimes undetectable within 2 hr. There was considerable variation in glycogen levels among individual birds. Liver glycogen levels were up to 50% higher at 1100 than at 0800 hr.

Synergism between aflatoxin and ochratoxin A in broiler chickens

A 2 X 2 factorial experimental design consisting of four treatments (0, 2.5 microgram/g aflatoxin, 2.0 microgram/g ochratoxin A, and 2.5 microgram/g aflatoxin + 2.0 microgram/g ochratoxin A) with six replicates of 10 birds each was used to evaluate the synergism between aflatoxin and ochratoxin A. The chicks (Hubbard X Hubbard) were maintained on these dietary treatments from hatching until they reached 3 weeks of age, when the experiment was terminated. The size of the liver, spleen, pancreas, and proventriculus was significantly (P less than .05) altered by the individual toxins; however, a synergistic effect on the size of these organs was not observed. The kidney and gizzard were sensitive to the coincident exposure to these mycotoxins and were significantly (P less than .05) enlarged. The kidney was the most sensitive organ to the combined toxicity of aflatoxin and ochratoxin A, and nephropathy was the most important characteristic of this interaction. The synergism between aflatoxin and ochratoxin A significantly (P less than .05) decreased growth rate and numerically increased mortality, demonstrating the enhanced toxicity of cocontaminated feed. Liver lipid levels were significantly (P less than .05) increased by aflatoxin and decreased by ochratoxin A. The interaction of both mycotoxins on this parameter was significant (P less than .05) and the combined effect demonstrates that ochratoxin A inhibited lipid accumulation normally induced by aflatoxin. The data show that toxicity-enhancing synergisms exist between mycotoxins and that symptom patterns are altered during multiple mycotoxicoses. The data also demonstrate that nephropathy is the primary effect of this interaction and, thus, is of diagnostic importance.

Glycogen storage disease type X caused by ochratoxin A in broiler chickens

Day-old broiler chickens fed graded concentrations of ochratoxin A (0, .5, 1.0, 2.0, 4.0, and 8.0 micrograms/g of diet) for 3 weeks were examined histopathologically for glycogen accumulation in muscle tissue using both formalin and ethanol fixatives with periodic acid-Schiff stain in a duplicate diastatic slide technique. However, glycogen could not be visualized in chicken muscle by these techniques which work with human muscle. Quantitative analysis for the glycogen itself permitted demonstration of a significant (P less than .05) fourfold increase in birds fed 8 micrograms/g. Using startled birds demonstrated that this accumulated glycogen was about 99% physiologically available. These findings coupled with prior reports permit the assignment on morphologic criteria of the hyperglycogenation of ochratoxicosis as a type X glycogen storage disease.

Inhibition of the glycogen phosphorylase system during ochratoxicosis in chickens

Graded doses of ochratoxin A incorporated into the diet (0, 0.5, 1.0, 2.0, 4.0, and 8.0 micrograms/g) of broiler chickens significantly (P < 0.05) inhibited activity of protein kinase, the initiator enzyme of the glycogen phosphorylase system, in the livers at all dose levels. Only the highest dose, 8.0 micrograms/g, significantly reduced the total activity of phosphorylase kinase, which is activated by protein kinase. The total activity of phosphorylase, which is activated by phosphorylase kinase, was unaltered by ochratoxin A at any level. Additon of ochratoxin A to liver extracts control birds inhibited protein kinase but not phosphorylase kinase. When added to extracts of livers from control birds, cyclic adenosine 3',5'-monophosphate stimulated protein kinase but not phosphorylase kinase. The cyclic adenosine 3',5'-monophosphate had no effect when added to extracts from birds fed ochratoxin A. These results suggest that ochratoxin A affects primarily the cyclic adenosine 3',5'-monophosphate-dependent protein kinase which initiates the enzymatic cascade leading to glycogenolysis. Furthermore, these results conform an earlier assignment on morphological criteria of the glycogenosis of ochratoxicosis as a type X glycogen storage disease.