Mariane G. Tadros

Neuroprotective effect of taurine in 3-nitropropionic acid-induced experimental animal model of Huntington's disease phenotype

An experimental animal model of Huntingtons disease (HD) phenotype was induced using the mycotoxin 3-nitropropionic acid (3-NP) and was well characterized behaviorally, neurochemically, morphometrically and histologically. Administration of 3-NP caused a reduction in prepulse inhibition (PPI) of acoustic startle response, locomotor hyper- and/or hypoactivity, bilateral striatal lesions, brain oxidative stress, and decreased striatal gamma-aminobutyric acid (GABA) levels. Taurine is a semi-essential beta-amino acid that was demonstrated to have both antioxidant and GABA-A agonistic activity. In this study, treatment with taurine (200 mg/kg daily for 3 days) prior to 3-NP administration reversed both reduced PPI response and locomotor hypoactivity caused by 3-NP injection. Taurine pretreatment also caused about 2-fold increase in GABA concentration compared to 3-NP-treated animals. In addition, taurine demonstrated antioxidant activity against oxidative stress induced by 3-NP administration as evidenced by the reduced striatal malondialdehyde (MDA) and elevated striatal glutathione (GSH) levels. Histochemical examination of striatal tissue showed that prior administration of taurine ahead of 3-NP challenge significantly increased succinate dehydrogenase (SDH) activity compared to 3-NP-treated animals. Histopathological examination further affirmed the neuroprotective effect of taurine in 3-NP-induced HD in rats. Taken together, one may conclude that taurine has neuroprotective role in the current HD paradigm due, at least partly, to its indirect antioxidant effect and GABA agonistic action.

Potential neuroprotective effects of hesperidin on 3-nitropropionic acid-induced neurotoxicity in rats

Huntingtons disease (HD) is a progressive neurodegenerative disorder with a spectrum of cognitive, behavioral, and motor abnormalities. The mitochondrial toxin 3-nitropropionic acid (3-NP) effectively induces specific behavioral changes, primarily manifested as prepulse inhibition (PPI) deficit of acoustic startle stimuli, and selective striatal lesions in rats and primates mimicking those in HD. The implications of nitric oxide in a variety of neurodegenerative diseases attract attention to study the possible role of flavonoids in interaction with nitric oxide pathways involved in HD. The present study investigates the potential effect of hesperidin, a flavanone group member, on 3-NP-induced behavioral, neurochemical, histopathological and cellular changes. Systemic administration of 3-NP to rats for 5 days (20 mg/kg) caused reduction of locomotor activity by days 2 and 5, 55% deficit of PPI response, elevation of cortical, striatal and hippocampal malondialdehyde (MDA) levels by 63%, 41% and 56%, reduction of respective catalase activity by 50%. Immunohistochemical staining of cortices, striata and hippocampi showed patches of iNOS positive cells. Electron microscopic ultrastructural examination showed marked mitochondrial swelling, perivascular edema and shrunken nerve cells. Pretreatment with hesperidin (100 mg/kg) ahead of 3-NP prevented any changes of locomotor activity or PPI response, slightly increased cortical, striatal and hippocampal MDA levels by 10% and reduced respective catalase activity by 22%, 20% and 5%. Only few iNOS positive cells were detected in sections from rats pretreated with hesperidin which also reduced cellular abnormalities induced by 3-NP. This study suggests a potential neuroprotective role of hesperidin against 3-NP-induced Huntingtons disease-like manifestations. Such neuroprotection can be referred to its antioxidant and anti-inflammatory activities.

Role of the phytoestrogenic, pro-apoptotic and anti-oxidative properties of silymarin in inhibiting experimental benign prostatic hyperplasia in rats.

Androgen and estrogen play an important role in the pathogenesis of benign prostatic hyperplasia (BPH). Estrogen exerts its action through two distinct estrogen receptors (ERs) either ER-α or ER-β. The phytoestrogenic property of silymarin (SIL) has been previously characterized. Thus, this study examined the protective effect of SIL against testosterone-induced BPH in rats. In an initial dose-response study, SIL in a dose of 50mg/kg was the most effective in preventing the rise in prostate weight, prostate weight/body weight ratio and histopathologic changes induced by testosterone. Testosterone significantly decreased ER-β and increased ER-α and AR expressions as compared to the control group and these effects were significantly ameliorated by SIL. Furthermore, SIL significantly protected against testosterone-provoked decline in mRNA expression of P21(WAF1/Cip1) and Bax/Bcl-xl ratio as well as caspase-3 activity. SIL minimized the number of proliferating cell nuclear antigen (PCNA) positive cells as compared to testosterone-treated group. Moreover, SIL significantly blunted the inducible NF-κB expression and restored the oxidative status to within normal values in the prostatic tissues. Collectively these findings elucidate the effectiveness of SIL in preventing testosterone-induced BPH in rats. This could be attributed, at least partly, to its phytoestrogenic, pro-apoptotic and anti-oxidative properties.

The effect of Ginkgo biloba extract on 3-nitropropionic acid-induced neurotoxicity in rats.

3-Nitropropionic acid (3-NP), an irreversible inhibitor of succinate dehydrogenase enzyme (SDH), induces neurodegeneration similar to that observed in Huntingtons disease (HD). Reduction of prepulse inhibition (PPI) of acoustic startle response, locomotor hypoactivity, bilateral striatal lesions as well as brain oxidative stress are major features of HD. The present study was designed to investigate neuroprotective effect of Ginkgo biloba extract (EGb 761) on 3-NP induced neurobehavioral changes and striatal lesions. Rats administered 3-NP (20mg/kg, s.c.) for five consecutive days exhibited PPI deficits and locomotor hypoactivity whereas, pretreatment of animals with EGb 761 (100mg/kg, i.p. for 15 days) ahead of and during the induction of HD by 3-NP (20mg/kg for 5 days starting at day 8) ameliorated 3-NP-induced neurobehavioral deficits. Administration of 3-NP increased the level of striatal malondialdehyde (MDA). This effect was prevented in animals pre-treated with EGb 761. Changes in the level of apoptotic regulatory gene expressions, following 3-NP treatment, were demonstrated as both an up-regulation and a down-regulation of the expression levels of striatal Bax and Bcl-xl genes, respectively. In addition, an up-regulation of the expression level of striatal glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was also observed. Pre-treatment with EGb 761 caused a down-regulation in striatal GAPDH and Bax together with an up-regulation of striatal Bcl-xl expression level as compared to the 3-NP treated group. Histochemical examination of striatal tissue showed that EGb 761 significantly prevented 3-NP induced inhibition of SDH activity. Histopathological examination further affirmed the neuroprotective effect of EGb 761 against 3-NP toxicity. Taken together, these results suggest that EGb 761 has a neuroprotective role in the current HD paradigm, which may be related to improvement of energy metabolism, antioxidant properties and antiapoptotic effects.

Genistein improves 3-NPA-induced memory impairment in ovariectomized rats: impact of its antioxidant, anti-inflammatory and acetylcholinesterase modulatory properties.

Huntington’s disease (HD) is a progressive neurodegenerative disorder. The pre-motor symptomatic stages of the disease are commonly characterized by cognitive problems including memory loss. 3-Nitropropionic acid (3-NPA) is a mitochondrial toxin that produces selective lesions in the brain similar to that of HD and was proven to cause memory impairment in rodents. Phytoestrogens have well-established neuroprotective and memory enhancing effects with fewer side effects in comparison to estrogens. This study investigated the potential neuroprotective and memory enhancing effect of genistein (5, 10 and 20 mg/kg), a phytoestrogen, in ovariectomized rats challenged with 3-NPA (20 mg/kg). These potential effects were compared to those of 17β-estradiol (2.5 mg/kg). Systemic administration of 3-NPA for 4 consecutive days impaired locomotor activity, decreased retention latencies in the passive avoidance task, decreased striatal, cortical and hippocampal ATP levels, increased oxidative stress, acetylcholinesterase (AChE) activity, cycloxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions. Pretreatment with genistein and 17β-estradiol attenuated locomotor hypoactivity, increased retention latencies in the passive avoidance task, increased ATP levels, improved the oxidative stress profile, attenuated the increase in AChE activity and decreased the expression of COX-2 and iNOS. Overall, the higher genistein dose (20 mg/kg) was the most effective. In conclusion, this study suggests neuroprotective and memory enhancing effects for genistein in a rat model of HD. These effects might be attributed to its antioxidant, anti-inflammatory and cholinesterase inhibitory activities.

Insights antifibrotic mechanism of methyl palmitate: Impact on nuclear factor kappa B and proinflammatory cytokines

Fibrosis accompanies most chronic liver disorders and is a major factor contributing to hepatic failure. Therefore, the need for an effective treatment is evident. The present study was designed to assess the potential antifibrotic effect of MP and whether MP can attenuate the severity of oxidative stress and inflammatory response in chronic liver injury. Male albino rats were treated with either CCl(4) (1 ml/kg, twice a week) and/or MP (300 mg/kg, three times a week) for six weeks. CCl(4)-intoxication significantly increased liver weight, serum aminotransferases, total cholesterol and triglycerides while decreased albumin level and these effects were prevented by co-treatment with MP. As indicators of oxidative stress, CCl(4)-intoxication caused significant glutathione depletion and lipid peroxidation while MP co-treatment preserved them within normal values. As markers of fibrosis, hydroxyproline content and α-SMA expression increased markedly in the CCl(4) group and MP prevented these alterations. Histopathological examination by both light and electron microscope further confirmed the protective efficacy of MP. To elucidate the antifibrotic mechanisms of MP, the expression of NF-κB, iNOS and COX-2 and the tissue levels of TNF-α and nitric oxide were assessed; CCl(4) increased the expression of NF-κB and all downstream inflammatory cascade while MP co-treatment inhibited them. Collectively these findings indicate that MP possesses a potent antifibrotic effect which may be partly a consequence of its antioxidant and anti-inflammatory properties.

The effect of pomegranate fruit extract on testosterone-induced BPH in rats

Benign prostatic hyperplasia (BPH) affects many men after the age of 50 years. Inflammation and oxidative stress along with apoptotic changes are thought to play an important role in the pathology of BPH. Pomegranate contains a variety of polyphenolic compounds that have been studied in a medley of diseases for their anti‐oxidant, anti‐inflammatory and pro‐apoptotic properties. Therefore, this study examined the effect of Pomegranate Fruit Extract (PFE) on the development of BPH using a testosterone‐induced BPH model in rats.

ADIOL protects against 3-NP-induced neurotoxicity in rats: Possible impact of its anti-oxidant, anti-inflammatory and anti-apoptotic actions

Huntingtons disease (HD) is a progressive neurodegenerative disorder with a wide spectrum of cognitive, behavioral and motor abnormalities. The mitochondrial toxin 3-nitropropionic acid (3-NP) effectively induces specific behavioral changes and selective striatal lesions similar to that observed in HD. Some neurosteroids, synthesized in neurons and glial cells, previously showed neuroprotective abilities. 5-Androstene-3β-17β-diol (ADIOL) is a major metabolite of dehydroepiandrosterone (DHEA) with previously reported anti-inflammatory, anti-apoptotic and neuroprotective activities. The neuroprotective potential of ADIOL in HD was not previously investigated. Therefore, the present study investigated the neuroprotective effects of ADIOL against 3-NP-induced behavioral changes, oxidative stress, inflammation and apoptosis. Intraperitoneal administration of 3-NP (20mg/kg) for 4 consecutive days in rats caused significant loss in body weight, reduced prepulse inhibition (PPI) of acoustic startle response, locomotor hypoactivity with altered cortical/striatal histological structure, increased cortical/striatal oxidative stress, inflammation and apoptosis. Administration of ADIOL (25mg/kg, s.c.) for two days before 3-NP significantly attenuated the reduction in body weights and PPI, increased locomotor activity and restored cortical/striatal histological structure nearly to normal. Moreover, it displayed anti-oxidant, anti-inflammatory and anti-apoptotic activities as evidenced by the elevation of cortical and striatal reduced glutathione levels, reductions of cortical and striatal malondialdehyde, striatal tumor necrosis factor alpha and interleukin-6 levels. Only a small number of iNOS and caspase-3 positive cells were detected in sections from rats pretreated with ADIOL. This study suggests a potential neuroprotective role of ADIOL against 3-NP-induced Huntingtons disease-like manifestations. Such neuroprotection can be attributed to its anti-oxidant, anti-inflammatory and anti-apoptotic activities.

The chemomodulatory effects of resveratrol and didox on herceptin cytotoxicity in breast cancer cell lines

Herceptin is considered an essential treatment option for double negative breast cancer. Resveratrol and didox are known chemopreventive agents with potential anticancer properties. The aim of the current study is to investigate the influence of resveratrol and didox on the cytotoxicity profile of herceptin in HER-2 receptor positive and HER-2 receptor negative breast cancer cell lines (T47D and MCF-7 cell lines, respectively). The IC50’s of herceptin in T47D and MCF-7 were 0.133 ± 0.005 ng/ml and 23.3795 ± 1.99 ng/ml respectively. Equitoxic combination of herceptin with resveratrol or didox in T47D significantly reduced the IC50 to 0.052 ± 0.001 and 0.0365 ± 0.001 ng/ml, respectively and similar results were obtained in MCF-7. The gene expression of BCL-xl was markedly decreased in T47D cells following treatment with herceptin/resveratrol compared to herceptin alone. Immunocytochemical staining of HER-2 receptor in T47D cells showed a significant reduction after treatment with herceptin/resveratrol combination compared to herceptin alone. On the contrary, herceptin/didox combination had no significant effect on HER-2 receptor expression. Cell cycle analysis showed an arrest at G2/M phase for both cell lines following all treatments. In conclusion, herceptin/resveratrol and herceptin/didox combinations improved the cytotoxic profile of herceptin in both T47D and MCF-7 breast cancer cell lines.

Proapoptotic and prepulse inhibition (PPI) disrupting effects of Hypericum perforatum in rats

ETHNOPHARMACOLOGICAL RELEVANCE St. Johns wort extract is commonly used as a wound healing, anti-inflammatory, anxiolytic, diuretic, antibiotic, antiviral and cancer chemoprotective agent. It also has nootropic and/or antiamnestic effects. AIM OF THE STUDY Prepulse inhibition (PPI) of startle response is a valuable paradigm for sensorimotor gating processes. A previous study indicated that single administration of St. Johns wort extract (500 mg/kg) caused PPI disruption in rats. The effect of antiamnestic doses of the extract on PPI has not been investigated despite the coexistence of impaired memory and PPI deficit in some neurological disorders. MATERIALS AND METHODS The effects of acute (500 mg/kg) and chronic (200mg/kg for 3 days) administration of St. Johns wort extract were investigated for its antiamnestic activity. The effects of administration of the antiamnestic dose of the extract and hyperforin, its main active component, were tested on PPI of an acoustic startle response in rats. This study also investigated the proapoptotic effect of hyperforin in animals, demonstrating PPI deficit, by electrophoresis of DNA isolated from selected brain areas. RESULTS Disruption of PPI resulted after treatment of rats with an antiamnestic dose of the extract (200mg/kg for 3 days) and with hyperforin. Gel electrophoresis showed DNA fragmentation of the cortices of hyperforin-treated animals exhibiting PPI deficit. CONCLUSIONS The exacerbating effect of St. Johns wort extract on PPI deficit may provide a limitation for using the extract to manage cognitive disturbance in psychotic and Huntingtons disease patients manifesting PPI deficit.