Dorsaf Hallegue

Mechanisms of chromium hexavalent-induced apoptosis in testis rats

Hexavalent chromium (CrVI)-containing compounds, present in industrial settings and in the environment, are known as carcinogens and mutagens. The present study is designed to test the hypothesis that oxidative stress mediates CrVI-induced apoptosis in testis. Male Wistar rats received an intraperitoneal injection of potassium dichromate at doses of 1 and 2 mg kg−1. Superoxide anion production was assessed by the determination of the reduction of cytochrome c and iodonitrotetrazolium, lipid peroxidation (LPO), metallothioneins (MTs), and catalase (CAT) activity. Apoptosis was evaluated by DNA fragmentation detected by agarose gel electrophoresis. Germinal cells apoptosis was detected by toluidine blue staining. The expression of Bax and Bcl-2 proteins (Pts) was also investigated. After 15 days of treatment, an increase of LPO and MT levels occurred, while CAT activity was decreased. Testicular tissues of treated rats showed pronounced degradation of the DNA into oligonucleotides as seen in the typical electrophoretic DNA ladder pattern. Intense apoptosis was observed in germinal cells of Cr-exposed rats. Bax Pt expression was induced in spermatogonia and spermatocytes cells of CrVI-treated rats. In contrast, Bcl-2 Pt was occasionally observed in germ cells of CrVI-exposed rats. These results clearly suggest that CrVI subacute treatment causes oxidative stress in rat testis leading to apoptosis.

p,p’-DDT induces testicular oxidative stress-induced apoptosis in adult rats

BackgroundThe 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (p,p’-DDT) is a known persistent organic pollutant and male reproductive toxicant. The present study is designed to test the hypothesis that oxidative stress mediates p,p’-DDT-induced apoptosis in testis.MethodsMale Wistar rats received an intraperitoneal (ip) injection of the pesticide at doses of 50 and 100mg/kg for 10 consecutive days. The oxidative stress was evaluated by biomarkers such lipid peroxidation (LPO) and metallothioneins (MTs) levels. Antioxidant enzymes activities was assessed by determination of superoxide dismutase (SOD), catalase (CAT) and hydrogen peroxide (H2O2) production. In addition, glutathione-dependent enzymes and reducing power in testis was evaluated by glutathione peroxidase (Gpx), glutathione reductase (GR), glutathione S-transferase (GST) activities and reduced and oxidized glutathione (GSH - GSSG) levels. Apoptosis was evaluated by DNA fragmentation detected by agarose gel electrophoresis. Germinal cells apoptosis and the apoptotic index was assessed through the TUNEL assay.ResultsAfter 10 days of treatment, an increase in LPO level and H2O2 production occurred, while MTs level, SOD and CAT activities were decreased. Also, the Gpx, GR, GST, and GSH activities were decreased, whereas GSSG activity was increased. Testicular tissues of treated rats showed pronounced degradation of the DNA into oligonucleotides as seen in the typical electrophoretic DNA ladder pattern. Intense apoptosis was observed in germinal cells of DDT-exposed rats. In addition, the apoptotic index was significantly increased in testis of DDT-treated rats.ConclusionsThese results clearly suggest that DDT sub-acute treatment causes oxidative stress in rat testis leading to apoptosis.

Hepatoprotective activity of Rhus oxyacantha root cortex extract against DDT-induced liver injury in rats

The present investigation aimed to study the antioxidant activity and hepatoprotective effects of ethyl acetate extract of R. oxyacantha root cortex (RE) against DDT-induced liver injury in male rats. The RE exhibited high total phenolic, flavonoid and condensed tannins contents. The antioxidant activity in vitro systems showed a significant potent free radical scavenging activity of the extract. The HPLC finger print of R. oxyacantha active extract showed the presence of five phenolic compounds with higher amounts of catechol and gallic acid. The in vivo results showed that a single intraperitoneal administration of DDT enhanced levels of hepatic markers (ALT, AST and LDH) in serum of experimental animals. It also increased the oxidative stress markers resulting in increased levels of the lipid peroxidation with a significant induction of SOD and GPx, metallothioneins (MTs) and a concomitant decrease of non protein thiols (NPSH) in liver. However, pretreatment of rats with RE at a dose of 150 and 300mg/kg body weight significantly lowered serum transaminases and LDH in treated rats. A significant reduction in hepatic thiobarbituric reactive substances and a decrease in antioxidant enzymes activities and hepatic MTs levels by treatment with plant extract against DDT, were observed. These biochemical changes were consistent with histopathological observations, suggesting marked hepatoprotective effect of RE with the two doses used. These results strongly suggest that treatment with ethyl acetate extract normalizes various biochemical parameters and protects the liver against DDT-induced oxidative damage in rats and thus help in evaluation of traditional claim on this plant.

Adverse Haemato-Biochemical Effects of Chlorinated Insecticide in Adult Male Rats.

Khemais Ben Rhouma. The 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (p,p’-DDT) is a highly toxic organochlorine pesticide and posing adverse effects on the environment and public health due to its frequent usage in developing countries. The present study is aimed to investigate the effects of p,p’-DDT exposure on some hematological and biochemical parameters, as well as, histopathological changes in liver. Male Wistar rats received an intraperitoneal (ip) injection of the pesticide at doses of 50 and 100mg/kg for 10 consecutive days. The hematological parameters were evaluated by the level of red blood cells (RBC), white blood cells (WBC), platelet count (PLT), hemoglobin (Hb) and hematocrit (Ht). The biochemical parameters such as liver glycogen, blood glucose, triglycerides (TG) and plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels were determined. In addition, histological changes in the liver, proliferating cell nuclear antigen (PCNA) and proliferation index (PI) were analyzed. After 10 days of treatment, hematological analysis revealed a significant increase of RBC, Hb and Ht levels while WBC and PLT counts were significantly decreased. Also, the liver glycogen and TG contents were decreased, whereas blood glucose, ALT, AST and LDH levels were increased. Histopathological examination of the liver revealed pronounced morphological alterations with cytoplasmic vacuolation, focal necrosis, sinusoidal congestion, infiltration of inflammatory leucocytes and loss of hepatic structure in periportal areas of treated rats. Immunohistochemical staining showed an increase in PCNApositive cells in liver of treated rats. In addition, the PI and the percentage of binucleated hepatocytes cells were significantly increased in liver of DDTtreated rats. These results clearly suggest that DDT sub-acute treatment causes extensive changes in hematological and biochemical parameters leading to liver damage.

Impact of dieldrin on liver morphological and biochemical parameters of rats

The current study deals with the effect of the organochlorine insecticide on the liver of Wistar rats. The dieldrin effect on rats was tested after a single intraperitoneal (i.p.) injection of two doses: 3 and 6 mg/kg and observations were made 4 days later. Animals showed a significant dose-dependent increase in relative liver weight. Elevations of transaminases (aspartate aminotransferase [AST], alanine aminotransferase [ALT]), bilirubin and total activity of lactate dehydrogenase (LDH) were recorded in the sera of treated rats. Serum LDH-5 isoenzyme activity increases in a dose-dependent manner. In contrast, LDH-1 activity does not show any significant variations with respect to controls. Histological examination of the liver of dieldrin-treated animals revealed cytoplasmic vacuolation, focal necrosis and nuclear enlargement of hepatocytes. This study suggests that biochemical assessment (transaminases, LDH and bilirubin activity) and LDH (LDH-1 & LDH-5) isoenzyme profiles can be very helpful in defining the border of the liver injury, dieldrin damaged liver would be a valuable addition to histological analysis in evaluating histopathological liver changes.

DDT-Induced Hypothyroidism Mechanisms in Rats

DDT and many of its metabolites have been linked to endocrine disruptions because of their capacity for mimicking or interfering with endogenous hormones and other signaling chemicals of the endocrine system.

Pituitary Adenylate Cyclase Activating Peptide (1-38) and its analog (Acetyl-[Ala15, Ala20] PACAP 38-polyamide) reverse methacholine airway hyperresponsiveness in rats

O objetivo deste estudo foi investigar funcionalmente e estruturalmente efeito broncodilatador do peptideo ativador da adenilato ciclase pituitaria (PACAP1-38) e da acetil-[Ala15, Ala20]PACAP 38-poliamida, potente analogo do PACAP-38, nos ratos desafiados pelo metacolina (MeCh). Ratos Wistar machos foram aleatoriamente divididos em cinco grupos. Grupos 1 e 2, inalando aerossois de solucao salina ou doses crescentes de MeCh (0,5, 1, 2,12, 4,25, 8,5, 17, 34 e 68 mg/L). Os outros grupos recebendo terbutalina (Terb) (250 µg/rato) (10-6M), PACAP-38 (50 µg/rato) (0.1 mM) ou analogo do PACAP-38 (50 µg/rato) associados a MeCh na dose de 4,25 mg/L. A resistencia pulmonar total (RL) foi registrada antes e 2 min apos a administracao de Mech pelo equipamento pneumomultiteste. A administracao MeCh induziu aumento significativo e dose dependente (p<0,05) de RL em comparacao com ratos do grupo controle. Terb e PACAP1-38 e analogo do PACAP-38 reverteram, significativamente, a constricao bronquica induzida por Mech, a espessura do musculo liso (SM) e abundância de muco do lume bronquico. O analogo PACAP-38 do mesmo modo que a Terb impediu a responsividade bronquica a MeCh e pode se constituir em um importante regulador no desenvolvimento da doenca inflamatorio pulmonar. Contudo, o uso do peptideo nativo para aplicacoes terapeuticas e limitado por sua baixa estabilidade metabolica. Consequentemente, o analogo metabolicamente estavel representa ferramenta promissora no tratamento de doencas pulmonares inflamatorias.