Histopathological Alterations In Liver Research Articles

Protective effect of dietary vitamin E against fungicide copperoxychloride stress on Nile tilapia, Oreochromis niloticus (L.) fingerlings

A 2 × 3 factorial experiment was designed to study the effect of sublethal toxicity of technical grade copperoxychloride, dietary vitamin E and their interactions on growth performance, some blood parameters, DNA fragmentation and histopathological lesions of Nile tilapia (Oreochromis niloticus). The 96 h LC50 of copperoxychloride was found to be 129.21 mg/l. Four hundred and fifty fingerlings with an average initial body weight ranged from 1.92 to 2.04 ± 0.11 g were randomly distributed equally in six treatments (T1–T6) with each of triplicates. T4, T5 and T6 were exposed to sublethal concentration 0.25 LC50 of copperoxychloride. Fish of T1, T2 and T3 fed diet supplemented with different levels of vitamin E (0, 1 and 2 g/kg diet), respectively. While fish of T4, T5 and T6 fed diet supplemented with different levels of vitamin E (0, 1 and 2 g/kg diet), respectively. At the end of the experiment (90 days) the results indicated that fish exposed to 0.25 LC50 of copperoxychloride and fed diet with normal level of vitamin E, showed significantly lower values (P < 0.01) of all growth and feed utilization parameters, white blood cells and immunoglobulin M, but they showed significantly increased (P < 0.05) values of alanine aminotransferase, aspartate aminotransferase, hematocrit, hemoglobin, uric acid and creatinine. Fish fed with varied concentrations of vitamin E neutralized the toxic effect of copperoxychloride as well as vitamin E, significantly lowered the hematological and biochemical response and enhanced the growth parameters and feed utilization. The toxic effect of copperoxychloride exposure and vitamin E feeding on histopathological alterations of liver and gill of the same studied fish will be taken in concern. The results showed improvement in samples treated with vitamin E. This study suggests that vitamin E can be effectively used to decrease the toxic effect of copperoxychloride on O. niloticus and its amelioration through dietary vitamin E supplementation.

Enzymatic and histopathologic biomarkers in the flatfish Euryglossa orientalis from the northwestern Persian Gulf

Most of the chemicals in the petrochemical sewages cause oxidative stress in marine organisms. Antioxidant enzymes (catalase (CAT) and superoxide dismutase (SOD)) as biomarkers of oxidative stress and liver histopathological alterations were investigated in the current study to evaluate the toxic effects of petrochemical pollutions in flatfish, Euryglossa orientalis The enzymatic and histopathological changes were assessed in the liver of E. orientalis from Khowr-e Jafari (one of the creeks from Khowr-e Musa estuary) and Sajafi harbor as polluted and clean areas, respectively. A significant increase in the antioxidant enzyme activities was observed in response to aquatic pollutions of Khowr-e Jafari. Liver lesions were diagnosed and categorized using standard methods. The results of histopathological examinations showed more lesion scores in the fish from Khowr-e Jafari. Various histopathological changes including hepatocyte degeneration, inflammatory lesions, peliosis hepatis and pancreatic acinar cell adenoma, and increase in the number of pigmented macrophage aggregates were observed in the fish from polluted site. It is suggested that activities of CAT and SOD along with semi-quantitative histopathologic analysis of E. orientalis can be used for biomonitoring programs in Persian Gulf.

The involvement of Nrf2 in the protective effects of diallyl disulfide on carbon tetrachloride-induced hepatic oxidative damage and inflammatory response in rats

This study investigated the potential effect of diallyl disulfide (DADS) against carbon tetrachloride (CCl4)-induced oxidative hepatic damage and inflammatory response in rat liver. DADS at doses of 50 and 100mg/kg/day was administered orally once daily for 5days, prior to CCl4 administration. Pretreatment with DADS attenuated CCl4-induced elevated serum transaminase activities and histopathological alterations in liver. It prevented the hepatocellular apoptotic changes with induction of Bcl-2-associated X (Bax), cytochrome c, and caspase-3 caused by CCl4. An increase in the nuclear translocation of nuclear factor-kappaB (NF-κB) and phosphorylation of I kappaB alpha (IκBα) was observed in the livers of CCl4-treated rats that coincided with induction of inflammatory mediators or cytokines. In contrast, DADS inhibited NF-κB translocation and IκBα phosphorylation, and that subsequently decreased inflammatory mediators. Furthermore, DADS prevented CCl4-induced depletion of cytosolic nuclear factor E2-related factor 2 (Nrf2) and suppression of nuclear translocation of Nrf2, which, in turn, up-regulated phase II/antioxidant enzyme activities. Taken together, these results demonstrate that DADS increases the expression of phase II/antioxidant enzymes and simultaneously decreases the expression of inflammatory mediators in CCl4-induced liver injury. These findings indicate that DADS induces antioxidant defense mechanism by activating Nrf2 pathway and reduces inflammatory response by inhibiting NF-κB activation.

Ecological risk assessment of impacted estuarine areas: Integrating histological and biochemical endpoints in wild Senegalese sole

The analysis of multiple biomarker responses is nowadays recognized as a valuable tool to circumvent potential confounding factors affecting biomonitoring studies and allows a better understanding of the mechanisms underlying exposure to natural mixtures of toxicants. For the purpose of an environmental risk assessment (ERA) in an impacted estuary in SW Europe (the Sado, Portugal), juvenile Solea senegalensis from commercial fishing areas were surveyed for histopathological liver alterations and biochemical biomarkers. Although the findings revealed moderate differences in the patterns of histopathological traits between urban/industrial- and agricultural-influenced areas within the same estuary, no significant distinction was found between the cumulative alterations in animals from the two sites. The overall level of histopathological injury was low and severe traits like neoplasms or pre-neoplastic foci were absent. While metallothionein induction and lipid peroxidation could relate to histopathological condition indices, the activity of anti-oxidant enzymes appeared to be impaired in animals collected off the estuary's heavy-industry belt (the most contaminated site), which may partially explain some degree of hepatic integrity loss. Overall, the results are consistent with low-moderate contamination of the estuary and indicate that oxidative stress is the most important factor accounting for differences between sites. The study highlights the need of integrating multiple biomarkers when multiple environmental stressors are involved and the advantages of surveying toxicity effects in field-collected, foraging, organisms.

Biochemical and histopathological effects on liver due to acute oral toxicity of aqueous leaf extract of Ecliptaalba on female Swiss albino mice

Background:Limited data is available about the toxicity of herbal remedies used for self-medication. Since a popular medicinal plant Ecliptaalba contains various bioactive molecules, the present study aimed to observe the biochemical and histological changes in liver associated with acute oral toxicity (LD50) of aqueous extract of E. alba (L.) Hassk. in female Swiss albino mice.Materials and Methods:For the acute oral toxicity study, the animals were divided into six groups of 6 mice each. Group– I was normal control and the treatment groups were administered aqueous leaf extract of E. alba orally at different doses of 500 mg (group – I),1750 mg (group–III), 2000 mg (group- IV), 2500 mg (group- V) and 3000 mg/ kg/b.wt.(group- VI) for seven consecutive days. The mice were sacrificed on the eighth day and blood was collected for the analysis of ALP (alkaline phosphatase), SGPT (serum glutamic pyruvic transferase), total protein and albumin. The liver was dissected, weighed, and processed for histopathological analysis.Results:The LD50 was found to be 2316.626 mg/kg /body weight in female mice. Serum SGPT, total protein and albumin increased in treated group- IV (P < 0.05), V (P < 0.01), and VI (P < 0.01) as compared to the control (group- I). ALP level significantly decreased in the treated group- IV (P < 0.05), V (P < 0.01) and VI (P < 0.01). Histopathological changes were observed at dose of 2000 mg (group- IV), 2500 mg (group- V) and 3000 mg (group- VI).Conclusion:It was concluded that oral administration of aqueous leaf extract of E. alba had detrimental effects on biochemical parameters and induced histopathological alterations in liver of female Swiss albino mice at doses higher than 2000 mg/kg/day indicating that its indiscriminate use should be avoided.

Influence of rifampicin and tetracycline administration on some biochemical and histological parameters in albino rats

The present investigation was designed to evaluate the effect of two oral administered antibiotics (Rifampicin and Tetracycline) on some physiological parameters in the serum of male albino rats. Histopathological alterations in liver and kidney were also examined. Data showed that treatment of rats with rifampicin caused a significant increase in the total cholesterol, triglycerides and LDL-cholesterol levels, while HDL-cholesterol level showed a significant decrease. Moreover, significant increases in serum AST, ALT, bilirubin and urea were observed. Also, the levels of the total protein, albumin and alpha 1-globulin were significantly decreased. No significant changes were recorded in the rest of the globulin fractions (alpha 2-, beta- and gamma-globulin) and albumin/globulin ratio (A/G) as well as creatinine level.In the serum of tetracycline-treated rats, the triglycerides, LDL-cholesterol, AST, ALT, bilirubin, urea, creatinine and gamma-globulin levels increased significantly. On the other hand, HDL-cholesterol, total protein, albumin levels and A/G ratio showed significant decreases. No significant changes in the total cholesterol, alpha 2- and beta-globulin levels were detected.Histological examination of the liver and kidney in the rifampicin-treated rats indicated that the liver pathology includes necrosis of hepatocytes, cytoplasmic vacuolation, and distended sinusoids with some lymphatic aggregations. In the kidney, the glomeruli increased in size, the mesangial matrix was expanded and the renal tubules were degenerated. Histological analysis of liver samples of tetracycline – treated rats revealed high vacuolation of the cytoplasm of hepatic cells, sinusoidal dilation, hepatocellular necrosis and disappearance of the cell membrane in some hepatocytes. The kidney sections of rats treated with tetracycline showed shrinkage of the glomeruli, widening of the Bowman’s space, in addition to necrosis and vacuolation of the renal tubules.

Liver histopathology in Baltic eelpout (Zoarces viviparus) – A baseline study for use in marine environmental monitoring

The use of liver histopathology in various fish species as a biomarker in marine monitoring programmes to assess the biological effect of exposure to anthropogenic contaminants is well established. However, although the eelpout (Zoarces viviparus) has repeatedly been recommended as an appropriate bioindicator for monitoring purposes in the Baltic Sea, information on histopathological liver alterations of this species is scarce. In order to obtain an overview, a total of 1070 eelpout, collected in the period between spring 2001 and winter 2010 from 34 sampling sites distributed over large parts of the Baltic Sea, were histologically analyzed. Liver lesions were recorded and classified according to established liver lesion categories. A high prevalence of non-specific and early toxicopathic non-neoplastic hepatic lesions was recorded. In contrast, pre-neoplastic lesions were observed only in rare cases and neoplastic changes were absent. A comparison with published data on other fish species revealed that the observed alterations may indicate effects of environmental stressors including contaminants. The results of the present study, thus, support the application of eelpout liver histopathology in environmental monitoring.

Anti-apoptotic effects of tamarind leaves against ethanol-induced rat liver injury

The leaf decoctions of Tamarindus indica (TI) have long been traditionally used in liver ailments. The aim of this study was to investigate the anti-apoptotic activity of TI leaf extract against acute ethanol (EtOH)-induced liver injury. The major constituents of the extract were also examined for standardization purposes. Rats (n = 5-7) were orally pretreated with TI leaf extract (25, 50 and 100 mg/kg) for seven days. Silymarin was used as a positive control. Liver tissue biochemical assays included key markers of apoptosis and its redox signalling. Serum enzyme levels were also determined. All graded doses of TI leaf extract mitigated the EtOH-induced liver caspase-3 activation (42, 57 and 64%) as well as DNA fragmentation (32, 47 and 50%), respectively. The highest dose of the extract demonstrated membrane-stabilizing (38%) in addition to glutathione-replenishing (88%) effects. Also, the leaves improved the liver histopathological alterations. Moreover, major plant bioactive polyphenolics, that might be responsible for the extract's observed effects, were isolated and identified. TI leaf extract demonstrated promising anti-apoptotic hepatoprotective effects in rats. The use of TI leaves in different liver diseases, having apoptosis as the underlying pathology, hence warrants further clinical investigation.

Responses of conventional and molecular biomarkers in turbot Scophthalmus maximus exposed to heavy fuel oil no. 6 and styrene

Several accidental spills in European coastal areas have resulted in the release of different toxic compounds into the marine environment, such as heavy fuel oil type no. 6 in the “Erika” and “Prestige” oil spills and the highly toxic styrene after the loss of the “Ievoli Sun”. There is a clear need to develop tools that might allow assessing the biological impact of these accidental spills on aquatic organisms. The aim of the present study was to determine the short-term effects and recovery after exposure of juvenile fish (Scophthalmus maximus) to heavy fuel oil no. 6 and styrene by using a battery of molecular, cell and tissue level biomarkers. Turbots were exposed to styrene for 7 days and to the diluted soluble fraction of the oil (10%) for 14 days, and then allowed to recover in clean seawater for the same time periods. cyp1a1 transcript was overexpressed in turbots after 3 and 14 days of exposure to heavy fuel oil, whereas ahr transcription was not modulated after heavy fuel oil and styrene exposure. pparα transcription level was significantly up-regulated after 3 days of treatment with styrene. Liver activity of peroxisomal acyl-CoA oxidase (AOX) was significantly induced after 14 days of oil exposure, but it was not affected by styrene. Hepatocyte lysosomal membrane stability (LMS) was significantly reduced after exposure to both treatments, indicating that the tested compounds significantly impaired fish health. Both AOX and LMS values returned to control levels after the recovery period. No differences in gamete development were observed between fuel- or styrene- exposed fish and control fish, and vitellogenin plasma levels were low, suggesting no xenoestrogenic effects of fuel oil or styrene. While styrene did not cause any increase in the prevalence of liver histopathological alterations, prevalence of extensive cell vacuolization increased after exposure to heavy fuel oil for 14 days. In conclusion, the suite of selected biomarkers proved to be useful to determine the early impact of and recovery from exposure to tested compounds in turbot.

Histopathological alterations observed in the liver of Poecilia vivipara (Cyprinodontiformes: Poeciliidae) as a tool for the environmental quality assessment of the Cachoeira River, BA

Histopathological alterations in liver have been widely used as a tool in studies for monitoring environmental quality. To evaluate the environmental quality in the Cachoeira river, five spots were monitored between the municipal districts of Itapé and Ilhéus, using liver histological analysis. The species chosen for analysis was Poecilia vivipara due to the fact that it is one of the most abundant in the sampling. The routine technique of inclusion and impregnation in paraffin was used, and the cuts were stained with Hematoxylin and Eosin (H & E). Histopathological alterations in the liver were evaluated semi-quantitatively and based on the severity of the lesions. The results of the histopathological alteration frequency together with the average taken from the Histopathological Alteration Index from points 1 (Vila de Itapé) and 2 (Fazenda Santa Amélia) showed that in this area the environment is more threatened because of some stressor agent, possibly contaminants that seem to be acting in the environment and endangering the health of fish. The statistic results demonstrated that there were no significant differences among points 1, 2 and 4, which means they are very similar to one another, and are ecologically endangered.

Efecto de Gentianella alborosea en esteatosis hepática no alcohólica inducida por dieta hiperlipídica en ratas holtzman hembras

Objective: To determine the effect of the extract of Gentianella alborosea as a treatment for non-alcoholic fatty liver disease (NAFLD) induced by high-fat diet in female Holtzman rats. Methods: Design: An incomplete experimental study was developed. Location: National University of San Marcos, Lima, Peru. Participants: Female Holtzman rats. Interventions: 32 rats were divided into 4 groups: control -, control +, dose 1 (35mg/kg) and dose 2 (70mg/kg. NAFLD was induced by high-fat diet (carbohydrates: 26%, lipids: 59% and protein: 15% calories) for a period of 21 days, ad libitum. Then aqueous extract of Gentianella alborosea was administered for 4 days. Finally, the livers were removed to evaluate the histopatho logical alterations of liver parenchyma.Main outcome measures: We performed microscopic counting of hepatocytes affected by single large lipid droplets, and the results were compared using ANOVA (p <0.05) and Tukey’s HSD (p <0.05).Results: We found significant differences (p <0.05) in the percentage of hepatocytes affected between dose 1 (3.25 ± 2.27) and positive control groups (7.50 ± 3.76). Furthermore, no significant difference was found between dose 1 and dose 2 groups. Conclusion: We did not found any effect of the extract of Gentianella alborosea as a treatment for NAFLD. We strongly recommend further studies.

Naringin at a nutritional dose modulates expression of genes related to lipid metabolism and inflammation in liver of mice fed a high-fat diet

Epidemiological and clinical studies a role for flavanones (predominately found in citrus fruits) in the prevention of cardiovascular disease. Previously, we have shown that a nutritional dose of naringin exerts anti-atherogenic properties together with non HDL-cholesterol lowering effect in a murin model of dietary-induced hypercholesterolemia (1). The goal of the present study was to explore possible molecular mechanisms of naringin at the hepatic level. To this end, we analyzed the hepatic transcriptome using a microarray approach in response to naringin supplementation (0.02%) in mice fed a high-fat high- cholesterol diet. Naringin was observed to increase hepatic lipid content (triglyceride and cholesterol) without significant liver dysfunction (ALAT and ASAT activities) or histopathological alterations. Naringin supplementation also significantly improved insulin sensitivity as evaluated by the HOMA index and nutrigenomics revealed that naringin modulated the expression of 1,766 genes. These genes encode proteins involved in different cellular processes, such as lipid metabolism, inflammation and insulin signaling. In conclusion, this study revealed that the hypolipemic and anti-atherogenic effects induced by a nutritional- level naringin supplementation in high-fat high-cholesterol diet could be related to changes in hepatic lipid metabolism and inflammatory response, revealing new in vivo targets of this flavanone.

Histopathological liver alterations in juvenile rabbit fish ( Siganus canaliculatus) exposed to light Arabian crude oil, dispersed oil and dispersant

With the heavy transport of crude oil there is an increasing risk of a major oil spill in the Gulf waters; however, there have been few studies on the impact of oil spills and subsequent remedial action on Gulf fish. The aim of the experiment was to investigate the effects of acute exposure to water soluble fraction (WAF) of light Arabian crude oil, dispersed oil and dispersant on the liver of the juvenile rabbit fish ( Siganus canaliculatus), observing several histopathological biomarkers of the liver at different time points and different doses. The concentrations used (3–100 percent WAF) simulated a range of possible oil pollution events. The main alterations observed in this study include hepatocyte swelling and cytoplasmic vacuolisation, megalocytosis, coagulative dispersed necrosis, lymphocytic infiltration, melanomacrophage aggregates, spongiosis hepatis, pericholangiitis, and bile stagnosis. Treated livers showed significantly higher total index values than the control group ( p<0.01). According to the total liver index, liver exposed to WAF, dispersed oil or dispersant showed significant histopathologic alterations compared with the control fish (Mann–Whitney U-test; p<0.01). Components of the total liver index, (circulatory, degenerative, proliferative, and inflammatory changes) differed significantly from the control groups. There was a significant correlation between exposure time and the total liver index values and the different reaction pattern indexes of treated fish (Spearman correlation; p>0.05). The present study indicates that dispersed oil is not more toxic, to livers of juvenile rabbit fish, than crude oil or dispersant.

Antioxidant potential ofCymbopogon citratusextract: alleviation of carbon tetrachloride-induced hepatic oxidative stress and toxicity

This study was aimed to evaluate the effect of Cymbopogon citratus against carbon tetrachloride (CCl(4))-mediated hepatic oxidative damage in rats. Rats were administrated with C. citratus extract (100, 200 and 300 mg/kg b.w.) for 14 days before the challenge of CCl(4) (1.2 ml/kg b.w. p.o) on 13th and 14th days. Hepatic damage was evaluated by employing serum biochemical parameters (alanine aminotransferase-ALT, aspartate aminotransferase-AST and lactate dehydrogenase-LDH), malondialdehye (MDA) level, reduced GSH and antioxidant enzymes (catalase: CAT, glutathione peroxidase: GPX, quinone reductase: QR, glutathione S-transferase: GST, glutathione reductase: GR, glucose-6-phosphate dehyrogenase: G6PD). In addition, CCl(4)-mediated hepatic damage was further evaluated by histopathological examination. However, most of these changes were alleviated by prophylactic treatment of animals with C. citratus dose dependently (p < 0.05). The protection was further evident through decreased histopathological alterations in liver. The results of the present study indicated that the hepatoprotective effect of C. citratus might be ascribable to its antioxidant and free radical scavenging property.

Biochemical and histopathological studies to assess chronic toxicity of triazophos in blood, liver and brain tissue of rats

Triazophos, O,O-diethyl-1-H-1,2,4-triazol-3-yl phosphorothioate, (TZ) is an organophosphorus pesticide which is extensively used in agriculture for controlling insect pests. Except a FAO/WHO report no study has investigated its short-term toxicity with respect to its potential to cause biochemical and histopathological alterations. The present study was designed to identify the effect of TZ at different doses (1.64, 3.2 and 8.2 mg/kg) on the oxidative stress parameters in blood as well as organs involved in xenobiotic metabolism (liver and brain) following chronic exposure for 90 days. Moreover, the study also delineates the effect of TZ on the histo-architecture of these organs. The results indicated a dose dependent induction ( p < 0.001) of oxidative stress, as evident by increased malondialdehyde (MDA) level and compromised antioxidant defense including glutathione S transferase (GST) activity, glutathione (GSH) content and ferric reducing ability of plasma (FRAP) in blood, and increased MDA level with concomitantly decreased GSH content in tissues, following chronic exposure to TZ. The ratio of MDA: FRAP in blood was found to be increased following chronic exposure to TZ and may serve as a suitable indicator of severity of oxidative damage. Onset of such biochemical alterations is one of the early adaptive responses to TZ exposure which leads to histopathological alterations in terms of diffuse fatty changes expanding from mid-zonal area to whole lobule in liver. However, increased oxidative stress did not bring any morphological alteration in brain. The present study concludes that induction of oxidative stress, leading to subsequent histopathological alterations in liver, is an important mechanism underlying the TZ induced chronic toxicity.

Study of some toxicological aspects of Alfa-cypermethrin in rabbits

This study was conducted to evaluate the immediate alterations that occur in rabbitsafter acute toxicity with single oral dose of cypermethrin. Twenty one rabbits were randomlydivided into three equal groups: treated groups (A1), (A2) and control group used in thisstudy. Groups (A1), (A2) received orally cypermethrin in dose of (25, 50 mg/kg body weight)respectively, While control group received normal saline at same time. Most obvious clinicalsings in the treated groups were Restlessness, salivation, licking of legs and face, frequenturination, muscular tremor, incoordination, and ataxia appeared in dose dependent manner. Inaddition, significantly increased in respiratory rate and heart rate in treated groups comparedwith control group and appeared petechial hemorrhage and congestion in the conjunctiva intreated groups. The blood samples were taking to evaluate some of blood parameters includes(RBC counts, WBC counts, PLT counts, Hb concentration, PCV, RBCs indices (MCV, MCH,MCHC, RDW -CV and RDW - SD), PDW, MPV, P-LCR and some biochemical study asALT and AST. Two rabbits from each group were killed to evaluate the histopathologicalalteration in liver. The statistical analysis revealed that there were significant decreased inRBC counts and Hb concentration (P&lt;0.05) in treated groups (A1), (A2) as compared withcontrol group. The PCV percentage, platelet counts and MCHC values revealed significantdecreased (P&lt;0.05) between group (A2) and control group. The RDW-SD, RDW-CV valveswere significantly increased (p&lt;0.05) between group (A1) and control group. Other parameterstudied did not show significant differences between treated groups and control group. Thestatistical analysis revealed that the levels of ALT and AST were significantly elevated(P&lt;0.05) in (A1 and A2) groups as compared with control group. In gross appearance therewere petechial hemorrhage and erosion of liver parenchyma. Histopathological study revealedthat there were engorgement of hepatic vein with presence of extravasated RBCs between thehepatocytes in group (A1), while group (A2) the hepatocytes undergo atrophy and severenecrosis and destruction with infiltration of polymorphnuclear leukocytes and engorgement ofsome portal trait with bile secretion

Some clinical, microbiological and molecular characteristics of Aeromonas hydrophila isolated from various naturally infected fishes

Heat-stable cytotonic enterotoxin gene (Ast) was detected by polymerase chain reaction (PCR) of twenty isolates of Aeromonas hydrophila isolated from various naturally infected fishes collected from both fresh and brackish water. These fishes were Nile tilapia and meagre, mullet and sea bream, respectively. Antibiotic susceptibility, pathogenic characteristics of these isolates and histopathological alterations of liver from experimentally infected tilapia fish with A. hydrophila which contained Ast gene were investigated. PCR technique for the detection of Ast as specific gene for A.hydrophila genomes showed that 90% of tested A. hydrophila (18/20) contained Ast gene, which is specific for A. hydrophila(SSU).The in vitro susceptibility of 18 strains of A. hydrophila (SSU) to 9 antibiotics was evaluated. Oxytetracycline only was an effective antibiotic for all tested isolates. On contrast, all these isolates were resistant to amoxicillin, ampicillin and penicillin. Pathogenicity assay in this study proved that 33.3% of the tested A. hydrophila (6/18) were pathogenic for tilapia in vitro with various levels of virulence where 2/6 were classified as strongly virulent according to the severity of mortality rate. Microscopically, A. hydrophila toxins apparently cause irreparable systemic damage to liver which leads to death.

Transient disruption of liver gap junctional intercellular communication and induction of apoptosis after administration of 1,4-bis[2-(3,5 dichloropyridyloxy)]benzene in mice

Gap junctional intercellular communication (GJIC) and connexin expression (Cx26 and Cx32) in mouse liver were studied after administration of 4-bis[2-(3,5 dichloropyridyloxy)]benzene (TCPOBOP), a phenobarbital-like enzyme inducer. Female C57Bl/6 mice were administered TCPOBOP (5.8 mg/kg BW) and euthanized 0, 24, 48 and 72 hours later. Liver samples were snap frozen, or fixed in formalin, or submitted to GJIC analysis. The proliferating cell nuclear antigen (PCNA) immunohistochemistry and the Western blotting for Cx26 and Cx32 were performed. After 48 and 72 h of drug administration the liver-to-body weight ratio was increased 70% and 117% ( p<0.0001), respectively. There were temporal-dependent alterations in liver histopathology and a significant increase in cell proliferation was noted after 48 h and sustained after 72 h, though to a lesser extent ( p<0.0001). In addition, TCPOBOP administration induced apoptosis, which appeared to be time-dependent showing statistical significance only after 72 h ( p<0.0001). Interestingly, a transient disruption by nearly 50% of GJIC capacity was detected after 48 h of drug ingestion, which recovered after 72 h ( p=0.003). These GJIC changes were due to altered levels of Cx26 and Cx32 in the livers of TCPOBOP-treated mice. We concluded that a single administration of TCPOBOP transiently disrupted the levels of GJIC due to decreased expression of connexins and increased apoptotic cell death in mouse liver.

Experimentally induced citrinin and endosulfan toxicity in pregnant Wistar rats: histopathological alterations in liver and kidneys of fetuses

In the present investigation, citrinin (CIT) (10 mg kg(-1) feed) and endosulfan (1 mg kg(-1) body weight) were administered orally alone and in combination to pregnant Wistar rats from gestational day 6 to 20 and their fetuses were collected to evaluate the histopathological alterations in hepatic and renal tissues. In CIT-fed group fetal liver, the changes were less marked, showing only sinusoidal dilation and mild vacuolar degeneration, whereas the consistent changes in the fetal kidney included tubular degeneration, medullary tubular necrosis, cystic dilatation of tubules, distortion of glomerulur capillary tuft and interstitial fibroblastic proliferation which separated clusters of tubules. In the endosulfan group, the liver was predominantly affected, showing vacuolar degeneration, karyomegaly and severe sinusoidal dilation, whereas the renal changes were mainly confined to tubular degeneration and varying degree of interstitial fibrosis. In the combination group, the hepatic and renal histopathological alterations in the fetus, though of similar nature to those of the individual groups, were more severe.

Physiological stress and pathology in European whitefish ( Coregonus lavaretus) induced by subchronic exposure to environmentally relevant densities of Planktothrix rubescens

Planktothrix rubescens belongs to the most ubiquitous cyanobacterial species in mesotrophic and oligotrophic lakes in the pre-alpine regions. In most of these lakes, coregonids are among the dominant species of the ichthyofauna with great importance for the professional fishery. A possible link between the occurrence of toxic Planktothrix blooms and the recurrent slumps in coregonid yields has been suggested. Indeed, acute toxic effects of microcystins and other cyanobacterial toxins have been shown for various fish species. However, chronic exposure scenarios appear to be more common and thus more environmentally realistic than acute intoxications. The aim of this study was therefore to investigate the physiological stress response and organ pathology in coregonids sub-chronically exposed to ambient water containing low, medium and high P. rubescens densities, known to be typical of pre-alpine lakes. Coregonid hatchlings were exposed in four tanks containing 0 (sham-control) and approximately 1500 (low), 15,000 (medium) and 55,000 (high) P. rubescens cells/ml for up to 28 days. Temperature, oxygen concentration, pH-value, P. rubescens cell density and microcystin concentration were recorded and the fish were observed for behavioural changes and examined for parasite infestations. Gill ventilation rates, general condition factors and mortalities were determined and liver, kidney, gut and gill were assessed histopathologically and immunhistologically. Depending on the cell density, exposed fish showed behavioural changes, including increased ventilation rates possibly representing a physiological stress response. Susceptibility to ectoparasitic infestation and increased mortality in exposed fish suggested P. rubescens associated effects on fish fitness. Histopathological alterations in liver, gastrointestinal tract and kidney, which were also immunopositive for microcystin suggested causality of tissue damage and the presence of microcystins. In contrast, observed gill pathology appeared to result primarily from mechanical abrasion and irritation due to ectoparasitic infestation. The current exposure experiment confirmed the hypothesis that subchronic and chronic exposure to low cyanobacterial cell densities and hence microcystins can exacerbate physiological stress and sustained pathological alterations in exposed coregonids. The study therefore supports the theory that P. rubescens blooms may be causal to the observed weight reduction and hence fitness of coregonids in pre-alpine lakes such as Lake Ammersee (Germany).