Fipronil induced oxidative stress involves alterations in SOD1 and catalase gene expression in male mice liver: Protection by vitamins E and C.

In the present investigation, hepatic oxidative stress induced by fipronil was evaluated in male mice. We also investigated whether pretreatment with antioxidant vitamins E and C could protect mice against these effects. Several studies conducted in cell lines have shown fipronil as a potent oxidant; however, no information is available regarding its oxidative stress inducing potential in an animal model. Out of 8 mice groups, fipronil was administered to three groups at low, medium, and high dose based on its oral LD50 (2.5, 5, and 10 mg/kg). All three doses of fipronil caused a significant increase in the serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) level with concomitant increase in the absolute and relative weight of liver. High dose of fipronil caused significant down-regulation in the hepatic mRNA expression of superoxide dismutase 1 (SOD1) and catalase (0.412 ± 0.01 and 0.376 ± 0.05-fold, respectively) as well as an increase in the lipid peroxidation (LPO). Also, decrease in the activity of antioxidant enzymes; SOD, catalase, and glutathione-S-transferase (GST) and the content of nonantioxidant enzymes; glutathione and total thiol were recorded. Histopathological examination of liver revealed dose dependant changes such as severe fatty degeneration and vacuolation leading to hepatocellular necrosis. Prior administration of vitamin E or vitamin C against fipronil high dose caused decrease in lipid peroxidation and increased activity of antioxidant enzymes. Severe reduction observed in functional activities of antioxidant enzymes was aptly substantiated by down-regulation seen in their relative mRNA expression. Thus results of the present study imply that liver is an important target organ for fipronil and similar to in vitro reports, it induces oxidative stress in the mice liver, which in turn could be responsible for its hepatotoxic nature. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1147-1158, 2016.

Metagenomics in animal gastrointestinal ecosystem: a microbiological and biotechnological perspective.

Metagenomics- the application of the genomics technologies to nonculturable microbial communities, is coming of age. These approaches can be used for the screening and selection of nonculturable rumen microbiota for assessing their role in gastrointestinal (GI) nutrition, plant material fermentation and the health of the host. The technologies designed to access this wealth of genetic information through environmental nucleic acid extraction have provided a means of overcoming the limitations of culture-dependent microbial genetic exploitation. The molecular procedures and techniques will result in reliable insights into the GI microbial structure and activity of the livestock gut microbes in relation to functional interactions, temporal and spatial relationships among different microbial consortia and dietary ingredients. Future developments and applications of these methods promise to provide the first opportunity to link distribution and identity of rumen microbes in their natural habitats with their genetic potential and in situ activities.

Lymphoproliferative response and its relationship with histological lesions in experimental ovine paratuberculosis and its diagnostic implications.

Lymphoproliferative response (LPR) was studied in 19 lambs orally infected (Group I) with Mycobacterium avium subsp. paratuberculosis (MAP) with in vitro lymphocyte stimulation test using MTT dye reduction assay. The non-specific LPR against Con A and specific LPR against sonicated antigen and johnin PPD (purified protein derivatives) were estimated on preinfection (0 day) and various days postinfection period (15 to 330 dpi) in the animals, which were classified according to histological and bacteriological evidence of paratuberculosis infection. Of the two antigens used, johnin PPD was found to be superior in terms of consistency and uniformity of response over an observation period of about a year. Significantly (P<0.05) higher LPR were observed in the infected sheep during postinfection period, as compared with preinfection values and values from uninfected control sheep. It was evident from the present study that the LPR in histologically infected animals fluctuated during the long course of infection and had a definite relationship with the gut pathology and the mycobacterial load. The LPR were stronger but variable in sheep with grades 1, 2 and 3 lesions (paucibacillary) and increased progressively from 30 dpi onwards. The sheep with the advanced lesions (grade 4, multibacillary) showed progressive decline in LPR till 120 dpi after initial stronger response at 30 dpi. Most of the animals were detected by LPR before initiation of faecal shedding of MAP. The results suggested that repeated testing was required while screening an infected flock for detecting most of the positive animals.

Sequential development of histologic lesions and their relationship with bacterial isolation, fecal shedding, and immune responses during progressive stages of experimental infection of lambs with Mycobacterium avium subsp. paratuberculosis.

Understanding pathogenesis during progressive stages of infection by Mycobacterium avium subsp. paratuberculosis (MAP) and finding suitable methods for its diagnosis are key to the control of Johne's disease in animals. Paratuberculosis was experimentally produced in 20 crossbred lambs by oral administration of MAP to study the sequential development of lesions between 10 and 330 days postinfection and to assess commonly used diagnostic methods such as bacterial culture, lymphocyte stimulation test (LST), and enzyme-linked immunosorbent assay (ELISA) during progressive stages of infection. Histologic lesions were classified into four grades from grade 1 (least severe) to grade 4 (most severe) on the basis of location of granulomatous lesions in different regions and layers of intestines, their association with intestinal lymphoid tissues, pattern and distribution of lesions, types of cellular infiltration, and presence of acid-fast bacilli. It is evident that infection first establishes in lymphoid tissues of the small intestine, possibly at multiple sites, producing segmental lesions and from there spreads to lamina propria and local lymph nodes. Wide variability in the histologic lesions in relation to postinfection periods and initial tropism of MAP to the intestinal lymphoid tissues (Peyer's patches) suggests a differential susceptibility of young animals, possibly because of compositional phenotypic variation of Peyer's patches influencing subsequent course of infection. Histopathology was found to be a better indicator of paratuberculous infection than bacteriology in sheep. The LST (reflecting the cellular immune response) and ELISA (reflecting the humoral immune response) had overall sensitivities of 65% (11 of 17) and 42% (8 of 19), respectively, in sheep with different types of pathology but when employed together could detect about 88% of infected animals.

Exposure to the fern Onychium contiguum causes increase in lipid peroxidation and alters antioxidant status in urinary bladder.

The status of lipid peroxidation, glutathione, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, superoxide dismutase, catalase, ascorbic acid, and alpha-tocopherol was studied in the urinary bladder of guinea pigs exposed to the carcinogenic fern Onychium contiguum. There was significant increase in the preformed lipid peroxides in the urinary bladders from fern exposed animals. The amount of lipid peroxides produced on incubation of urinary bladder homogenates with or without catalyst was significantly higher in the fern exposed animals. The concentrations of glutathione and alpha-tocopherol and the activities of glutathione reductase and catalase were elevated in the urinary bladders of the animals exposed to the fern. No effect was observed on the concentration of ascorbic acid and the activities of glutathione peroxidase, glutathione-S-transferase, and superoxide dismutase. It is summarized that the fern toxins increased oxidative stress in the urinary bladder and antioxidant status was altered. However, the altered antioxidant status did not provide protection from the toxin induced injury. Histopathology of the urinary bladder in the fern exposed animals revealed oedema, haemorrhages, and congestion. This is the first study to show increase in lipid peroxidation along with altered antioxidant status in the urinary bladder of fern exposed animals.

An enzyme-linked immunosorbent assay using immonoaffinity-purified antigen in the diagnosis of caprine paratuberculosis and its comparison with conventional ELISAs.

An enzyme-linked immunosorbent assay (APA-ELISA) using an immunoaffinity-purified antigen was developed and compared with the unabsorbed and absorbed ELISA procedures, using a crude antigenic preparation, for its efficacy in detecting antibodies in goat sera against Mycobacterium ovium paratuberculosis. Serum samples from 89 goats belonging to three different flocks, two with a history and evidence of paratuberculosis and one without it, were subjected to each ELISA, which had been standardized on known positive sera from goats experimentally infected with paratuberculosis. Faecal culture, faecal examination and histopathology were used as indicators of infection. The diagnostic sensitivities of the unabsorbed, absorbed and APA-ELISA were 81.8%, 77.3% and 77.3% and the specificities were 90.6%, 93.7% and 96.8%, respectively. The positive predictive values of APA-ELISA (94.4%) was the highest, followed by absorbed ELISA (80.9%) and unabsorbed ELISA (72.0%). The negative predictive values for APA-ELISA, absorbed ELISA and unabsorbed ELISA were 93.0%, 92.7% and 93.8%, respectively. The results indicated the value of APA-ELISA in avoiding the need to absorb individual test sera with Mycobacterium phlei and giving more consistent results than the absorbed ELISA. The APA-ELISA was also better than the other two procedures in terms of specificity and positive predictive values.

Biochemical alterations in the blood plasma of rats associated with hepatotoxicity induced by Eupatorium adenophorum.

Eupatorium adenophorum (Crofton weed), a native of Central America. has appeared as a major weed in several areas in different parts of the world. Horses that eat this plant are poisoned on prolonged exposure. Toxicity due to consumption of this plant by other grazing animals is not clear. Administration of freeze-dried leaf powder to mice results in hepatotoxicity. Earlier attempts to produce toxicity in rats using the leaves of this plant were not successful. In the present study, administration of oven-dried E. adenophorum leaves collected at the flowering stage elicited hepatotoxicity in rats. The affected animals had a marked increase in the concentration of plasma bilirubin and in the activities of 5'-nucleotidase, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase. There were no significant differences in plasma creatinine, urea or total protein values in the affected animals compared to controls. The livers of the affected animals had focal areas of necrosis throughout the parenchyma and hepatocytes showed megalocytosis. The bile ducts were dilated and the epithelium showed degenerative to necrotic changes. The alterations in bilirubin, enzymes and histopathological changes imply cholestasis and liver injury.

Detoxification of lantana hepatotoxin, lantadene A, using Alcaligenes faecalis.

Detoxification of lantadene A (LA), the hepatotoxin from Lantana camara var. aculeata, by the bacterial strain Alcaligenes faecalis has been investigated. Lantadene A induced hepatotoxicity concomitant with increases in plasma bilirubin, blood plasma enzymes and histopathological lesions that typify lantana toxicity. The extract of fermentation broth in which LA was incubated with A. faecalis did not elicit any alterations in blood enzyme prolife or liver histopathology, which were comparable with the control group. It is concluded that A. faecalis detoxified LA and no noxious product was formed on incubation of LA with A. faecalis.

Hepatotoxicity and cholestasis in rats induced by the sesquiterpene, 9-oxo-10,11-dehydroageraphorone, isolated from Eupatorium adenophorum.

Eupatorium adenophorum leaves cause hepatotoxicity and cholestasis in rats. The hepatotoxicant has been characterized as 9-oxo-10,11-dehydroageraphorone (ODA), a cadinene sesquiterpene. Oral administration of ODA, mixed in feed to rats, caused jaundice in 24 h. The liver of the intoxicated animals had focal areas of hepatocellular necrosis, proliferation, and dilation of bile ducts with degenerative changes in the lining epithelium. There was marked increase in the conjugated form of plasma bilirubin and in the activities of the enzymes glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, alkaline phosphatase, lactate dehydrogenase, gamma-glutamyltranspeptidase, glutamate dehydrogenase, and 5'-nucleotidase. The histopathological lesions in liver and biochemical profile of marker enzymes show that ODA induced hepatotoxicity and cholestasis in rats. This is the first report on the toxicity of a cadinene sesquiterpene in rats.

Hepatotoxicity in rat induced by partially purified toxins from Eupatorium adenophorum (Ageratina adenophora).

A group of rats were administered a methanolic extract of Eupatorium adenophorum (Ageratina adenophora) oven-dried (60 degrees C) leaf powder and a partially purified fraction from the methanolic extract. Administration of the methanolic extract and the partially purified fraction elicited a significant increase in total and conjugated bilirubin, alkaline phosphatase, 5'-nucleotidase and transaminases. Histopathology of the livers from these animals revealed dilated bile ducts and proliferative changes. Hepatocytes around the bile ducts showed necrotic changes. Biochemical and histopathological changes resembled those observed in response to administration of whole leaf powder. The hepatotoxin present in E. adenophorum leaves can be extracted with methanol and partially purified further using the procedure described.

Hepatotoxicity of Eupatorium adenophorum to rats.

Freeze dried Eupatorium adenophorum leaf powder mixed in rat feed at a level of 25% elicited hepatotoxicity. The affected animals were jaundiced and had marked increase in plasma bilirubin levels and activities of alkaline phosphatase, glutamate oxaloacetate transaminase and glutamate pyruvate transaminase. The liver of intoxicated animals had focal areas of necrosis and bile duct proliferation. Elevation in plasma bilirubin concomitant with alterations in enzyme profile and histopathological lesions are consistent with liver injury and cholestasis. This is the first report of the toxicity of E. adenophorum to rats.

A review of the toxicosis and biological properties of the genus Eupatorium.

Eupatorium genus grows wild in many parts of the world. A number of species of Eupatorium are toxic to grazing animals. Milk sickness in humans is caused by ingestion of milk of the animals reared on the pastures infested with Eupatorium rugosum (white snakeroot). While some information is available on the toxins in various species of Eupatorium, ambiguities still persist in extrapolation of the data to field incidence of toxicosis. Eupatorium genus has been used for its medicinal properties for many decades. A number of bioactive natural products have been reported in the extracts of Eupatorium spp. and the genus is a promising bioresource for preparation of drugs and value-added products.