Protective effects of melatonin in endosulfan induced immunomodulation and their association with oxidative stress markers in rats

Endosulfan toxicity affects the nervous system as well as immunological functions. It also causes oxidative stress and subsequent mitochondrial dysfunction. In the present study, we tried to evaluate the protective effects of melatonin on endosulfan (END) induced immunological and biochemical changes in rats. Wistar rats (200-250 g, n=8/group) were immunized with fresh SRBC (0.5×109 cells/kg) and were exposed to END (4-16 mg/kg, orally), simultaneously exposed animals were treated with vehicle or melatonin (10 and 50 mg/kg) for 14 days. On day 15, their blood and spleen was collected for immunological assays and oxidative stress markers. Endosulfan (8 and 16 mg/kg) significantly suppressed (i) anti-SRBC antibody titer; (ii) footpad thickness; (iii) spleen PFC counts; and (iv) Th1 (IFN-γ) & Th2 (IL-4) and significantly increases serum TNF-α level as compared to controls (P <0.05 in all parameters). Endosulfan induced immunological changes were found associated with changes in oxidative stress markers as evidenced by the results of this study. Endosulfan, while significantly decreased GSH, SOD and CAT activity (P <0.05), it increased serum TBARS activities (P <0.001). These endosulfan induced changes in immunological and biochemical parameters were found significantly reversed by the treatment with melatonin (10 and 50 mg/kg) in a dose dependent manner by differential degrees. Results of the present immunological and biochemical data suggest the protective role of melatonin in endosulfan induced immunomodulation which is associated with oxidant/antioxidant imbalance.

Cellular and molecular mechanisms of action of polyherbal preparation UNIM-352 in experimental models of bronchial asthma.

Bronchial asthma is a chronic inflammatory disorder of the airways and pharmacotherapy is dependent on anti-inflammatory and bronchodilator agents. However, adverse effects of these agents on chronic administration and sometimes non-responsiveness to these drugs have prompted the search for viable alternatives from medicinal plant sources. UNIM-352 is a polyherbal preparation traditionally used in the Unani system of Indian medicine for the treatment of bronchial asthma. The present study defines the possible cellular and molecular mechanisms of action of UNIM-352 in experimental models of bronchial asthma and validates the observed therapeutically beneficial effects. Wistar rats were immunized and challenged with ovalbumin, and blood and bronchoalveolar lavage (BAL) fluid were assayed for cytological and biochemical markers. UNIM-352 (200 and 400 mg/kg) markedly reduced the eosinophil and neutrophil counts in both blood and BAL compared to control. The polyherbal agent also attenuated the levels of TNF-α, IL-4, GM-CSF and NF-κB whereas histone deacetylase (HDAC) levels were elevated, in both blood and BAL fluid. All effects of UNIM-352 were comparable with the standard drug, prednisolone. The results demonstrated possible cellular and molecular mechanisms of UNIM-352 and thus explain its beneficial effects in bronchial asthma.

Effects of diesel exhaust, heavy metals and pesticides on various organ systems: Possible mechanisms and strategies for prevention and treatment.

Environmental pollutants have a significant impact on the ecosystem and disrupt balance between environment, human and non-human components that result in deleterious effects to all forms of life. Identifying environmental factors for potential imbalance are extremely crucial for devising strategies for combating such toxic dysregulation. Automobile exhaust (in air), heavy metals (in food and water) and pesticides (in air, food, soil and water) are the most common environmental pollutants and their short and long term exposures can cause hazardous effects in humans leading to systemic disorders involving lungs, kidney and immune systems. Mechanisms involved in genesis of such toxic effects have revealed complex, interactive pathways. Strategies for the protection of homeostasis and health, viz., general preventive measures, nutritional supplements and herbal agents have been described, to counter these pollutants induced damaging effects on various body systems.

Assessment of protective role of polyherbal preparation, Livina, against anti-tubercular drug induced liver dysfunction.

The present study evaluated the possible protective role of Livina (a polyherbal preparation) against anti-tubercular therapy (ATT)-induced liver dysfunction in patients of pulmonary tuberculosis. Patients were given intensive phase treatment with 4-drugs (rifampicin, INH, pyrazinamide and ethambutol) used for anti-tubercular therapy for 2 months, followed by a 4-month continuous phase treatment with 2 drugs (rifampicin and INH) under clinical advice and supervision. Both qualitative and quantitative measures of liver function were assessed, at different time intervals, before and after ATT. Analysis of data showed that the incidence of qualitative manifestations of liver dysfunction were greater in the placebo treated group as compared to the test drug group. None of the patients of either group showed clinical jaundice. Most signific changes ant were observed in the SGOT and SGPT levels in the placebo group, wherein the levels of both enzymes were higher at 4 and 8 weeks post–ATT, as compared to the respective baseline (0 week) values. When Livina (2 capsules twice daily) was given with ATT drugs, incidence of qualitative manifestation of liver dysfunction was insignificant and SGOT and SGPT levels were also significantly lower than the placebo+ATT drugs treated group. These results indicate that the test drug (Livina) was efficacious, against ATT-induced hepatic dysfunction in patients of pulmonary tuberculosis.

Role of free radicals in stress-induced neurobehavioural changes in rats.

Effect of restraint stress (RS) and its modulation by antioxidants were evaluated on elevated plus maze (EPM) and open field (OF) tests in rats. Restraint stress (RS for 1 hr) reduced the number of open arm entries, as also the time spent on open arms indicating enhanced anxiogenic response in the EPM test as compared to normal non RS group of rats. Pretreatment with ascorbic acid (100 and 200 mg/kg) and alpha-tocopherol (30 and 60 mg/kg) attenuated these RS-induced effects. In the OF test, RS-reduced (a) ambulations; and (b) rearings, whereas an increase was seen in (a) latency of entry and (b) number of fecal boluses. The RS-induced changes in OF parameters were reversed after pretreatment with the antioxidants, (ascorbic acid and alpha tocopherol). Biochemical data showed that RS enhanced MDA levels in both serum and brain, and these were attenuated after pretreatment with the antioxidants. The pharmacological and biochemical results indicate that free radicals might be involved in such stress-induced neurobehavioural effects.

Involvement of nitric oxide (NO) in the regulation of stress susceptibility and adaptation in rats.

The present study evaluated the regulatory role of nitric oxide (NO) in stress susceptibility and adaptation in rats. Acute restraint stress (RS x1) reduced the number of entries and time spent in the open arms in the elevated plus maze (EPM) test and raised plasma corticosterone levels. RS (x1)-induced neurobehavioral suppression and raised corticosterone levels were attenuated by pretreatment with the NO precursor, L-arginine (500 and 1000 mg/kg)and unaffected or further aggravated by NO synthase inhibitor, L-NAME or 7-nitroindazole (10 and 50 mg/kg). Biochemical assay of plasma and brain homogenates showed that these RS - induced behavioral and neuroendocrinal changes were associated with lowered levels of plasma and brain total nitrates/nitrites (NOx). L-Arginine attenuated the RS-induced suppression of NOx levels in plasma and brain, whereas, the NO synthase inhibitors tended to produce reverse effects. In the experiments involving repeated stress i.e. RS (x5), exposure resulted in attenuation/reversal of (a) neurobehavioral suppression in the EPM test and (b) lowered brain NOx, that was seen after RS (x1). The RS (x5)-induced changes in EPM parameters and brain Nox were further potentiated after L-arginine pretreatment, whereas, the NO synthase inhibitors were less effective. Rats were screened as high and low emotional in the open-field test, and high emotional rats showed greater(a) behavioral suppression in the EPM, (b) corticosterone responses (c) brain NOx suppression, and (d) cold-restraint stress (CRS) induced gastric mucosal lesions as compared to their low emotional counterparts. L-Arginine pretreatment was more effective in modulating the above RS induced stress responses/markers in the high emotional group of rats. Our data suggest that NO plays a differential role during exposure to acute and repeated stress situations, and that the relationship between stress and emotionality status may be under the regulatory influence of NO.

Pharmacological studies on mechanisms of aminophylline-induced seizures in rats.

In the present study, the possible role of free radicals in aminophylline-induced seizures was evaluated in albino rats. Aminophylline (theophylline in ethylene diamine; 50 - 300 mg/kg) induced convulsions in rats in a dose-dependent manner, and both incidence of seizure and mortality were maximum at 300 mg/kg. Conventional anti-epileptics, diphenylhydantoin and dizocilpine, as well as adenosine agonists were ineffective in antagonizing these seizures. On the other hand, phosphodiesterase inhibitors, pentoxyphylline and rolipram, showed insignificant seizurogenic effects. Pretreatment with antioxidants (ascorbic acid, alpha-tocopherol, and melatonin) showed differential attenuating effects on aminophylline seizures and lethality. Further, prior administration of 1-buthionine sulfoxamine (BSO, glutathione depletor) and triethyltetramine (TETA, superoxide dismutase inhibitor), precipitated seizures and enhanced lethality in response to subthreshold doses of aminophylline. The present results suggested of the possible involvement of oxidative stress during aminophylline-induced seizures.