Melatonin treatment prevents modulation of cell-mediated immune response induced by propoxur in rats.

The effect of melatonin, a major secretory product of the pineal gland, in attenuation of propoxur (2-isopropoxy phenyl N-methyl carbamate)-induced modulation of cell-mediated immune (CMI) response was studied in rats. Male Wistar albino rats were exposed to propoxur (a widely used pesticide) orally (10 mg/kg) and/or melatonin (10 mg/kg) orally for 4 weeks. CMI was measured by delayed-type hypersensitivity (DTH), leucocyte and macrophage migration inhibition (LMI and MMI) responses and estimation of cytokines TNF-alpha and IFN-gamma levels. Rats exposed to propoxur for 4 weeks showed significant decrease in DTH, LMI and MMI responses. Propoxur also suppressed TNF-alpha and IFN-gamma production significantly. Administration of melatonin alone caused a significant increase in DTH response. Although there were no changes in the LMI and MMI response, the cytokine levels were significantly increased, as compared to control. Co-administration of melatonin along with propoxur significantly nullified the effect of the pesticide on the CMI response, except DTH and reversed levels of cytokines to near control/normal values. Thus, melatonin treatment considerably attenuated immunomodulation caused by sub-chronic treatment of propoxur in experimental animals.

Impact of oral vitamin E supplementation on oxidative stress & lipid peroxidation in patients with polymorphous light eruption.

BACKGROUND & OBJECTIVES: Polymorphous light eruption (PMLE) is a photo-induced disease which clinically manifests in the form of pruritic eruptions on sun/light exposed parts. Little is known about lipid peroxidation and free radical scavengers in patients during PMLE. The present study was therefore undertaken to evaluate oxidative stress and levels of antioxidant enzymes in patients of PMLE. METHODS: The PMLE was diagnosed clinically by a consultant dermatologist and validated independently by another and through histopathologic findings. Blood samples were collected on day 1 and patients were given oral vitamin E supplementation (400 mg OD) along with topical sunscreen and advice for photo-protection. Samples were collected again after one week. The blood samples were evaluated for lipid peroxidation, oxygen free radical (OFR) scavenging enzymes, glutathione (GSH) and related enzymes such as glutathione reductase (GR), glutathione peroxidase (GPx), gamma glutamyl transpeptidase (GGT) and glutathione- S-transferase (GST) in erythrocytes and compared with healthy controls. RESULTS: The serum malondialdehyde (MDA) level was higher and GSH level was lower in PMLE cases as compared to controls. There was a significant decrease in superoxide dismutase (SOD) activity while activities of catalase (CAT) and glutathione related enzymes were increased in PMLE cases. Administration of oral vitamin E for one week, along with photoprotection resulted in a significant decrease in MDA levels and activities of all others enzymes except SOD. The GSH was replenished and returned to normal. INTERPRETATION & CONCLUSION: Oxidative stress and differential modulation of antioxidant enzymes in PMLE might play a pathogenic role in humans, which supports the incorporation of antioxidant drugs in the treatment protocol of the disease.

Immunotoxicity of phosphamidon following subchronic exposure in albino rats.

Effect of subchronic doses of phosphamidon exposure on humoral and cell mediated immune (CMI) responses were studied in male albino rats using SRBC, ovalbumin and KLH as antigens. Humoral immune responses were assessed by estimating antibody titre against antigen and splenic plaque forming cells (PFC) assay. CMI responses were studied by using leucocyte migration inhibition (LMI), macrophage migration inhibition (MMI) and delayed type hypersensitivity (DTH) response. Results obtained in the present study revealed marked suppression of humoral and CMI responses in a dose dependent pattern. Hence, suppression of immune responses by phosphamidon even at subchronic doses is clearly an important aspect for its safety evaluation.

Protective effect of melatonin against propoxur-induced oxidative stress and suppression of humoral immune response in rats.

Effect of melatonin in attenuation of propoxur induced oxidative stress and suppression of humoral immune response was studied in rats. Oral administration of propoxur (10 mg/kg) increased lipid peroxidation in serum after 28 days treatment. Superoxide dismutase, catalase and glutathione were also altered following propoxur exposure. In addition propoxur exposure markedly suppressed humoral immune response as assessed by antibody titre and plaque forming cell assay. Simultaneous treatment with melatonin (5 mg/kg, ip) markedly attenuated the effect of propoxur on (a) lipid peroxidation, (b) oxidative stress parameters and (c) immunotoxicity. Results have been discussed in the light of possible immunopotentiating and antioxidant effects of melatonin to understand the influence of oxidative stress on propoxur induced immunomodulation.