Food and Chemical Toxicology 61 (2013) 121–126

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Food and Chemical Toxicology

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Comparative evaluation of oral and dermal cypermethrin exposureon antioxidant profile in Bubalus bubalis

0278-6915/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.fct.2013.04.017

⇑ Corresponding author. Tel.: +91 9815302213.E-mail address: rajdeepkaur@gadvasu.in (R. Kaur).

Rajdeep Kaur ⇑, Shabir Ahmad DarDepartment of Veterinary Pharmacology and Toxicology, College of Veterinary Science, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana 141 004, India

a r t i c l e i n f o

Article history:Available online 25 April 2013

Keywords:CypermethrinOralDermalOxidative stressBuffaloToxicity

a b s t r a c t

Cypermethrin, a type II synthetic pyrethroid insecticide, @ 0.5 mg/kg/day for 14 consecutive weeks pro-duced mild signs of toxicity in buffalo calves. Significant changes were observed in various antioxidantparameters in blood. There was a marked increase in the extent of lipid peroxidation (33.9%) and enzymicactivity of glutathione peroxidase (6.7%), superoxide dismutase (35.0%), catalase (43.7%), glutathione-S-transferase (64.4%), glutathione reductase (36.7%) and glucose-6-phosphate dehydrogenase (32.1%). Asignificant decrease in blood glutathione (16.7%), total antioxidant activity (45.4%) and vitamin E(40.8%) was observed and no significant effect was found on blood selenium levels. However, the extentof lipid peroxidation (42%) and the depletion of glutathione (28.8%) was greater after dermal sub-acutetoxicity of cypermethrin (0.25%) for 14 consecutive days. Similarly, it was observed that the incline inthe enzymic activity of glutathione peroxidase (29.7%), superoxide dismutase (38.3%) and glutathionereductase (38.3%) was higher in dermally cypermethrin exposed animals. Thus, the present investigationcontemplates that oxidative stress is the important mechanisms involved in cypermethrin-induced tox-icity and the oxidative insult produced by dermal route is more severe as compared to oral intoxication.

� 2013 Elsevier Ltd. All rights reserved.

1. Introduction

Over 98% of sprayed insecticides and 95% of herbicides reach adestination other than their target species, including non-targetspecies, air, water and soil (Miller, 2004). Pyrethroid pesticideshave gained popularity over other conventional pesticides due totheir high efficacy against target species, their relatively low mam-malian toxicity and rapid biodegradability. In the coming years, theuse of pyrethroids is predicted to increase further with the phasingout of the organophosphorus and organochlorine insecticides anddue to the emergence and re-emergence of mosquito-vectored dis-eases such as West Nile fever, Japanese encephalitis and dengue fe-ver. Owing to their excessive use, synthetic pyrethroids arepolluting the environment and water resources thereby endanger-ing aquatic, animal and human life.

It is known that after absorption, pyrethroids rapidly distributethroughout the body (Gray et al., 1980) and readily enter the brainbecause of their high lipophilicity and lack of exclusion by the mul-ti-drug transporter glycoprotein (Bain and LeBlanc, 1996) at theblood–brain barrier.

Cypermethrin, a type II pyrethroid, is being extensively recom-mended for agricultural and animal husbandry practices as an ect-oparaciticide. It has been shown to induce oxidative stress and lead

to generation of reactive oxygen species (ROS) in experimental sys-tems (Prasanthi et al., 2005). During the past few years, estimationof free radical generation and antioxidant defense has become animportant aspect of toxicological investigation in mammals. Induc-tion of oxidative stress during its metabolism is also based on theevidence that excitatory events may stimulate ROS productionduring the cleavage of cypermethrin (Grajeda-Cota et al., 2004).The present investigation was undertaken to further explore therole of oxidative damage in cypermethrin induced toxicity throughdifferent routes.

2. Materials and methods

The experiments were performed on twelve healthy male buf-falo calves of 6–12 months age and weighing between 60 and120 kg, procured from the University Dairy Farm and local market.The animals were acclimatized in the animal shed of departmentunder uniform conditions for 2 weeks, prior to the commencementof study. The animals were dewormed, fed seasonal green fodderand wheat straw and water was provided ad libitum. The permis-sion to conduct the experiment was duely taken from the Univer-sity Animal Ethics Committee. The animals were randomly dividedinto three groups of four animals, each. Animals of group I servedas healthy control, group II animals were orally administeredcypermethrin at a dose rate of 0.5 mg/kg/day for 14 consecutiveweeks (oral drenching by dissolving the desired dose of

122 R. Kaur, S.A. Dar / Food and Chemical Toxicology 61 (2013) 121–126

cypermethrin in tap water) whereas group III animals were der-mally sprayed with 0.25% cypermethrin for 14 consecutive days.The doses were selected on the basis of previous work done inthe department as well as on the basis of the basis of recommen-dations for the use of cypermethrin in agricultural and animal hus-bandry practices. Blood samples were collected in heparinizedvials via jugular venipuncture at weekly interval in orally exposedanimals and on days 0, 3, 7, 10 and 14 in dermally exposedanimals.

Erythrocyte lysate was prepared for analyzing various biochem-ical parameters. Lipid peroxidation was estimated by determiningthe malonyl dialdehyde (MDA) produced using thiobarbituric acid(TBA) (Stocks and Dormandy (1971). The glutathione peroxidase(GPx) activity was measured by the method of Hafeman et al.(1974). Glutathione reductase was assayed spectrophotometricallyby measuring change in absorbance at 340 nm due to NADPH uti-lization (Carlberg and Mannervik, 1985). Glutathione-S-transferaseactivity was analyzed by measuring the amount of glutathioneconjugate formed with CDNB (Habig et al., 1974). Glucose-6-phos-phate dehydrogenase (G6PD) was estimated on the basis of its abil-ity to catalyze the conversion of glucose-6-phosphate and NADP to6-phosphogluconolactone and NADPH (Deutsch, 1978). Superoxidedismutase activity was assayed by the ability of the enzyme to in-hibit auto-oxidation of pyrogallol (Marklund and Marklund, 1974).Catalase activity was analyzed by the decomposition of hydrogenperoxide (Aebi, 1983). Glutathione levels were determined by themethod of Beutler et al. (1963). The total antioxidant activity, Vita-min E and blood selenium levels were estimated by the methodsdescribed by Koracevic et al. (2001), Kajden et al. (1973) and Annaet al. (1999), respectively. The data generated was analyzed by stu-dent’s t-test using SPSS� 16.0 software package. The significancewas assessed at P < 0.05 and P < 0.01 (Singh et al., 1991).

3. Results

Long term oral administration of cypermethrin at the dose rateof 0.5 mg/kg/day for 14 consecutive weeks resulted in a signifi-cant increase in the extent of lipid peroxidation. This inclinewas observed to be 33.9% on 9th week in orally treated groupand 42% on 14th day of dermal exposure as compared to controlgroup (Figs. 1 and 2). The values, however, returned to normal

0

2

4

6

8

10

12

14

16

0 2 3 4 5 6 7 8

Time (w

MDA

/g H

b/hr

Control (LPO)

Treatment (LPO)Control (GSH)Treatment (GSH)

Treatment

Fig. 1. Effect of repeated oral administration of cypermethrin @ 0.5 mg/kg/day o

during the observed post-treatment period in both the groups.Consecutively, a significant depletion of blood glutathione wasobserved up to an extent of 16.7% after 14 weeks of oral cyper-methrin exposure (Fig. 1) and 28.8% (Fig. 2) after dermalexposure.

The activity of antioxidant enzyme glutathione peroxidase(GPx), increased significantly from 10th week onwards and a max-imum increase of 6.7% was observed on 13th week of oral cyper-methrin exposure as depicted in Table 1. In the dermally exposedgroup, the activity of GPx increased significantly from 10th day on-wards and maximum increase was 29.7% on 14th day of cyper-methrin treatment (Table 4). The activity however returned tonormal in both the groups within the post treatment period. Sim-ilarly, the enzymic activity of superoxide dismutase and catalaseincreased by 35% and 43.7%, respectively, in orally treated group(Table 1) and by 38.3% and 34.4%, respectively, in dermally treatedgroup (Table 4).

There was significant elevation in the activity of GST, to thetune of 64.4% (Table 2) and 53.9% (Table 4) in orally and dermallytreated groups, respectively. A similar trend was seen in the activ-ity of antioxidant enzyme glutathione reductase (GR), which in-clined by 36.7% after 9th week of oral cypermethrin exposureand by 38.3% on 14th day of dermal exposure as observed in Tables2 and 4. A consonant increase in G6PD was observed in orally ex-posed (32.1%) (Table 2) and dermally exposed (27%) (Table 5) buf-falo calves. Contrastly, there was a significant decline in the totalantioxidant activity from 7th week onwards in orally exposed ani-mals (Table 3). The decrease was observed to be 45.4% on13th week of cypermethrin treatment. Short term dermal cyper-methrin exposure caused significant decrease in total antioxidantactivity 10th onwards in buffalo calves as presented in Table 5.The maximum decrease was found to be 36% on 14th day of cyper-methrin treatment.

Cypermethrin exposure (@ 0.5 mg/kg; 14 weeks) caused a sig-nificant decline (40.8%) in vitamin E content (Table 4), which re-mained significantly lower even after 2 weeks of post-treatmentperiod. Similarly, dermal spray of cypermethrin (0.25%; 14 days)also caused a significant decrease in non-enzymatic antioxidant,vitamin E, from 7th day onwards as shown in Table 5. However,cypermethrin exposure by either the oral or dermal routeproduced no significant change in blood selenium levels of the ex-posed buffalo calves (Tables 3 and 5).

9 10 12 13 14 2

eeks)

450

500

550

600

650

700

µg/ml

Post-treatment

n lipid peroxidation and blood gluthathione concentration in buffalo calves.

Table 1Effect of repeated oral administration of cypermethrin @ 0.5 mg/kg/day on glutathione-peroxidase, superoxide dismutase and catalase in buffalo calves.

Time (weeks) Control Treatment Control Treatment Control Treatment

Treatment Glutathione peroxidase Superoxide dismutase Catalase

0 2.56 ± 0.10 2.59 ± 0.06 7.2 ± 0.62 7.1 ± 0.33 3221.01 ± 142.75 3205.74 ± 148.62 2.54 ± 0.10 2.59 ± 0.06 9.7 ± 0.78 9.1 ± 0.61 3208.38 ± 197.18 3221.01 ± 142.753 2.59 ± 0.09 2.62 ± 0.06 6.3 ± 0.85 6.4 ± 0.49 3482.60 ± 184.21 3360.35 ± 149.814 2.52 ± 0.08 2.61 ± 0.06 5.6 ± 0.36 5.1 ± 0.81 3403.48 ± 134.61 3427.52 ± 152.815 2.56 ± 0.05 2.62 ± 0.05 5.8 ± 0.45 6.5 ± 0.52 3561.32 ± 183.84 3452.65 ± 169.156 2.55 ± 0.03 2.61 ± 0.06 5.7 ± 0.51 5.4 ± 0.39 3347.74 ± 155.72 3415.49 ± 173.797 2.57 ± 0.03a 2.61 ± 0.04 6.7 ± 0.45a 6.5 ± 0.49 3326.52 ± 148.29a 3576.47 ± 129.218 2.59 ± 0.05a 2.63 ± 0.06 6.7 ± 0.54a 7.5 ± 0.71 3374.48 ± 168.38a 3707.98 ± 174.689 2.57 ± 0.06a 2.66 ± 0.04 8.0 ± 0.64a 8.9 ± 0.60 3618.08 ± 161.51a 3952.84 ± 169.51

10 2.58 ± 0.04a 2.68 ± 0.04* 8.4 ± 0.62a 9.4 ± 0.50 3558.44 ± 158.13a 4187.10 ± 174.90**

12 2.58 ± 0.06a 2.72 ± 0.06** 8.3 ± 0.55a 10.9 ± 0.43** 3829.34 ± 165.05a 4547.76 ± 165.21**

13 2.55 ± 0.05a 2.72 ± 0.09** 8.3 ± 0.35a 11.2 ± 0.62** 3424.76 ± 193.16a 4692.17 ± 162.63**

14 2.56 ± 0.06a 2.72 ± 0.06** 8.2 ± 0.59a 11.1 ± 0.56** 3646.40 ± 142.18a 4607.03 ± 158.55**

Post-treatment2 2.57 ± 0.03a 2.61 ± 0.04 8.6 ± 0.43a 9.2 ± 0.63 3454.44 ± 156.30a 3679.01 ± 172.67

Values given represent the Mean ± SE of five animals unless otherwise stated.Values with superscript in a given row differs significantly from each other.* P < 0.05.** P < 0.01.

a Mean ± SE of four animals.

0

2

4

6

8

10

12

14

16

18

0 3 7 10 14 7

Time (days)

MD

A/b

Hb/

hr

250

300

350

400

450

500

550

600

650

700

750

µg/ml

Control (LPO)Treatment (LPO)Control (GSH)Treatment (GSH

Treatment Post-treatment

Fig. 2. Effect of repeated dermal exposure of 0.25% cypermethrin on lipid peroxidation abd blood glutathione concentration in buffalo calves.

R. Kaur, S.A. Dar / Food and Chemical Toxicology 61 (2013) 121–126 123

4. Discussions

The cellular peroxidation states indicate oxidation of lipids andother biomolecules (Gebicki et al., 2000). Determination of extentof lipid peroxidation indirectly reflects the degree to which cell li-pid membranes are attacked by free radicals. Thus, the increase inextent of lipid peroxidation in the present investigation couldpossibly be due to the formation of free radicals, particularlysuper-oxide released following pyrethroid treatment, which in-duce alterations in the plasma membrane by producing increasedlipid peroxidation.

Glutathione possess highly reactive sulfhydryl (-SH) group,which like other thiols, acts non-enzymatically as a free radicalacceptor to counteract oxidative damage. Glutathione concentra-tion is considered to be a good indicator of antioxidant status oroxidative stress (Gurbay and Hincal, 2004). Significant decreasein GSH levels in this study may be either due to the inhibition of

GSH synthesis or increased utilization of GSH for detoxificationof toxicant-induced free radicals as observed by Singh et al.(2001). The decline in the levels of blood glutathione in the presentstudy indicate towards cypermethrin induced oxidative stress andare in agreement with Giray et al. (2001) and Sushma andDevasena (2011) who reported that cypermethrin treatmentcaused significant decrease in non-enzymatic antioxidant, like glu-tathione (GSH) and increased mechanical fragility of cells in rats.Additionally, the decline in glutathione levels in the present studycould be attributed to the increased utilization of this intracellularantioxidant by GST or GPx. Furthermore, it has been suggested byJin et al. (2011) that the mRNA levels for the genes encoding anti-oxidant proteins, such as GPx-1, GPx-2, SOD-1 and SOD-2 are alsoup-regulated significantly in cypermethrin treated mice. Similarly,an increase in the concentration of superoxide radical, released fol-lowing pyrethroid treatment (Kale et al., 1999) upregulated theactivity of catalase, as observed in the present study.

Table 2Effect of repeated oral administration of cypermethrin @ 0.5 mg/kg/day on glutathione-S-transferase, glutathione reductase and glucose-6-phosphate dehydrogenase in buffalocalves.

Time (weeks) Control Treatment Control Treatment Control Treatment

Treatment Glutathione-S-transferase Glutathione reductase Glucose-6-phosphate dehydrogenase

0 655.79 ± 49.40 740.38 ± 102.51 9.97 ± 0.25 9.87 ± 0.56 1190.34 ± 47.21 1118.84 ± 54.262 646.08 ± 86.51 625.33 ± 73.12 11.43 ± 1.17 11.13 ± 1.16 1155.29 ± 57.50 1130.62 ± 43.413 692.01 ± 76.58 802.23 ± 125.22 11.07 ± 0.34 10.50 ± 1.16 1143.27 ± 55.98 1136.82 ± 37.494 650.17 ± 87.58 796.81 ± 61.58 11.62 ± 0.93 11.63 ± 0.51 1131.34 ± 58.97 1208.46 ± 46.895 714.01 ± 68.70 859.45 ± 120.65 10.95 ± 0.36 11.44 ± 1.05 1148.34 ± 82.09 1130.72 ± 69.156 722.42 ± 90.73 882.50 ± 79.41 11.02 ± 1.00 11.92 ± 0.53 1157.07 ± 69.80 1181.19 ± 57.807 621.96 ± 41.45a 980.93 ± 102.32** 11.21 ± 0.76a 12.97 ± 1.05 1102.08 ± 46.10a 1188.32 ± 55.078 716.33 ± 57.22a 1089.37 ± 95.91** 10.59 ± 0.86a 13.59 ± 0.74** 1089.11 ± 79.32a 1148.21 ± 68.949 765.03 ± 55.52a 1053.29 ± 88.34** 11.32 ± 0.59a 15.48 ± 1.40* 1098.82 ± 65.89a 1186.38 ± 62.61

10 726.77 ± 66.99a 1194.82 ± 113.67** 11.35 ± 0.71a 14.94 ± 0.94** 1023.56 ± 83.33a 1256.16 ± 52.23**

12 714.54 ± 42.09a 1100.45 ± 100.45* 10.76 ± 0.65a 14.64 ± 1.25* 1043.25 ± 83.33a 1378.33 ± 91.41**

13 747.83 ± 46.58a 1114.15 ± 79.54** 11.44 ± 0.86a 13.25 ± 1.13 1088.23 ± 75.26a 1305.07 ± 85.55**

14 727.43 ± 44.90a 1096.08 ± 98.58** 12.13 ± 1.02a 13.26 ± 0.73 1052.75 ± 69.30a 1213.35 ± 68.78**

Post-treatment2 682.14 ± ± 63.01a 820.69 ± 58.10 10.94 ± 0.52a 10.87 ± 0.86 1075.37 ± 67.72a 1160.12 ± 45.44

Values given are expressed as lmole of conjugate of GSH and CDNB/min/g Hb for glutathione-S-transferase, as oxidation of 1 lmol of NADPH/min for glutathione reductaseand as EU for glucose-6-phosphate dehydrogenase and represent the Mean ± SE of 5 animals unless otherwise stated.Values with superscript in a given row differs significantly from each other.* P < 0.05.** P < 0.01.

a Mean ± SE of four animals.

Table 3Effect of repeated oral administration of cypermethrin @ 0.5 mg/kg/day on total antoxidant activity, vitamin E and blood selenium in buffalo calves.

Time (weeks) Control Treatment Control Treatment Control Treatment

Treatment Total antioxidant activity Vitamin E Blood selenium

0 0.99 ± 0.06 1.01 ± 0.05 8.55 ± 0.81 8.48 ± 0.81 111.65 ± 1.26 111.66 ± 1.292 0.99 ± 0.04 1.03 ± 0.05 8.66 ± 0.84 8.70 ± 0.71 112.22 ± 1.18 112.36 ± 1.313 0.99 ± 0.04 0.98 ± 0.05 8.71 ± 0.58 9.11 ± 0.784 0.99 ± 0.05 1.00 ± 0.03 8.27 ± 0.85 8.44 ± 0.56 111.74 ± 0.79 111.17 ± 1.475 1.03 ± 0.04 0.97 ± 0.06 8.58 ± 1.01 8.00 ± 0.436 0.99 ± 0.05 0.89 ± 0.07 8.08 ± 0.68 7.42 ± 0.88 111.44 ± 1.22 110.82 ± 1.017 1.02 ± 0.06a 0.78 ± 0.08** 8.87 ± 0.63a 6.84 ± 1.13**

8 0.98 ± 0.08a 0.68 ± 0.12** 8.71 ± 1.08a 6.29 ± 1.05* 113.31 ± 2.11a 112.99 ± 1.819 0.99 ± 0.07a 0.63 ± 0.10** 8.74 ± 0.91a 5.49 ± 1.04**

10 1.06 ± 0.11a 0.62 ± 0.12** 8.44 ± 0.90a 5.23 ± 0.94** 111.11 ± 1.09a 109.84 ± 1.1112 1.00 ± 0.08a 0.62 ± 0.08** 8.23 ± 0.89a 5.09 ± 0.86** 110.58 ± 1.78a 109.91 ± 0.7713 1.10 ± 0.06a 0.60 ± 0.07** 8.22 ± 0.80a 4.95 ± 0.68**

14 0.96 ± 0.07a 0.59 ± 0.06** 8.21 ± 0.80a 4.86 ± 0.75** 110.91 ± 1.20a 110.44 ± 1.23

Post-treatment2 0.96 ± 0.07a 0.96 ± 0.05 8.51 ± 0.73a 5.90 ± 0.60** 111.91 ± 1.75a 111.58 ± 1.20

Values given are expressed as mmol/L for total antioxidant activity, as lmol/L of plasma for vitamin E and as lg/dl of blood for selenium and represent the Mean ± SE of fiveanimals unless otherwise stated.Values with superscript in a given row differs significantly from each other.* P < 0.05.** P < 0.01.

a Mean ± SE of four animals.

124 R. Kaur, S.A. Dar / Food and Chemical Toxicology 61 (2013) 121–126

Glutathione reductase enzyme is essential for reduction of glu-tathione disulfide (GSSG) to the reduced form glutathione (GSH),necessary for protection of cells against oxidative stress (Tekmanet al., 2008) whereas glucose 6-phosphate dehydrogenase is thefirst enzyme of the pentose phosphate pathway (Beydemir et al.,2003), whose principal physiological function is the productionof NADPH and ribose 5-phosphate. NADPH participates in cellmembrane protection and cell detoxification from xenobioticsthrough the gluthatione reductase–peroxidase system and themixed-function oxidases (Barroso et al., 1999). The major role ofNADPH in erythrocytes is the regeneration of reduced glutathione,which prevents haemoglobin denaturation, preserves the integrityof erythrocytic cell membrane sulfhydryl groups and detoxifieshydrogen peroxide and oxygen radicals in and on the red bloodcells (Weksler et al., 1990). In cells exposed to high levels of

oxidative stress, like red blood cells, up to 10% of the glucose con-sumption may be directed to the pentose phosphate pathway (PPP)for production of the NADPH needed for this reaction. In erythro-cytes, if the PPP is non-functional, then the oxidative stress inthe cell leads to cell lysis and anemia (Champe et al., 2008). The in-crease in the activity of these enzymes in the present investigationhowever failed to mitigate the extent of lipid peroxidation.

The efficiency of antioxidants is expressed as total antioxidantcapacity (TAC), a parameter summarizing overall activity of alltypes of antioxidants in living systems, which was significantly re-duced in both the groups exposed to cypermethrin. In addition,Vitamin E, considered to play a pivotal role in the prevention ofoxidative damage by blocking the oxidation of polyunsaturatedfatty acids (Aldana et al., 2001), was significantly depleted whereasanother antioxidant Se was non-significantly depleted. This

Table 4Effect on glutathione peroxidase, superoxide dismutase, catalase, glutathione-S-transferase and glutathione reductase activity after dermal exposure of 0.25% cypermethrin inbuffalo calves.

Time (days) 0 3 7 10 14 7Treatment Post-treatment

Glutathione peroxidase (EU/mg Hb)Control 1.80 ± 0.21 1.86 ± 0.31 1.71 ± 0.26 1.74 ± 0.27 1.78 ± 0.25 2.02 ± 0.36Treatment 1.65 ± 0.17 1.74 ± 0.26 2.10 ± 0.23 2.25 ± 0.23** 2.31 ± 0.25** 1.95 ± 0.26

Superoxide dismutase (EU/mg Hb)Control 2.52 ± 0.45 4.25 ± 0.42 4.33 ± 0.39 4.57 ± 0.42 4.23 ± 0.45 3.14 ± 0.63Treatment 2.47 ± 0.27 5.21 ± 0.52 6.06 ± 0.42* 6.32 ± 0.51** 5.57 ± 0.44** 3.19 ± 0.62

Catalase (EU/mg Hb)Control 1689.99 ± 128.54 1694.13 ± 144.88 1596.95 ± 192.34 1702.12 ± 205.39 1764.87 ± 169.10 1896.77 ± 147.25Treatment 1859.91 ± 114.83 1811.41 ± 103.94 1891.74 ± 133.25 2017.07 ± 141.12 2372.83 ± 137.69** 2178.36 ± 173.745

Glutathione-S-transferase (EU/mg Hb)Control 127.78 ± 16.32 154.74 ± 17.60 144.35 ± 15.52 149.26 ± 16.54 139.85 ± 20.61 146.10 ± 27.30Treatment 134.99 ± 16.81 147.13 ± 18.77 189.25 ± 20.25* 208.69 ± 24.07** 215.26 ± 28.72** 129.45 ± 10.24

Glutathione reductase (EU/mg Hb)Control 6.79 ± 0.49 6.44 ± 0.52 7.48 ± 0.49 7.52 ± 0.66 7.86 ± 0.64 5.96 ± 0.48Treatment 5.53 ± 0.59 5.78 ± 0.56 7.40 ± 0.41 8.62 ± 0.71 10.87 ± 0.68** 5.71 ± 0.44

Values are the Mean ± SE of five animals.Values with superscript in a given column differs significantly from each other.* P < 0.05.** P < 0.01.

Table 5Effect of repeated dermal exposure of 0.25% cypermethrin on glucose-6-phosphate dehydrogenase, total antioxidant activity, vitamin E and blood selenium activity in buffalocalves.

Time (days) 0 3 7 10 14 7Treatment Post-treatment

Glucose-6-phosphate dehydrogenase (EU/mg Hb)Control 507.85 ± 25.23 592.31 ± 20.31 610.16 ± 32.18 602.86 ± 16.04 622.94 ± 20.81 598.13 ± 99.89Treatment 530.30 ± 20.51 600.85 ± 23.83 658.65 ± 25.35 714.24 ± 31.73** 791.17 ± 33.62** 589.91 ± 15.68

Total antioxidant activity (mmol/L)Control 0.940 ± 0.065 0.868 ± 0.068 0.830 ± 0.049 0.834 ± 0.069 0.805 ± 0.058 0.826 ± 0.051Treatment 0.995 ± 0.0595 0.820 ± 0.074 0.756 ± 0.064 0.573 ± 0.076** 0.514 ± 0.051** 0.748 ± 0.053

Vitamin E (lmol/L)Control 9.40 ± 0.46 9.03 ± 0.69 9.56 ± 0.59 9.14 ± 0.76 9.26 ± 0.69 8.93 ± 0.85Treatment 9.76 ± 0.56 11.13 ± 0.61 7.64 ± 0.70** 6.82 ± 0.65** 6.93 ± 0.63** 7.76 ± 0.68

Blood selenium (lg/dl)Control 111.64 ± 0.80 112.54 ± 1.04 110.92 ± 1.46 111.15 ± 1.21 110.92 ± 1.26 110.61 ± 1.33Treatment 111.71 ± 1.03 113.45 ± 1.20 111.37 ± 0.89 109.84 ± 1.02 110.04 ± 1.17 111.08 ± 1.27

Values given represent the Mean ± SE of five animals unless otherwise stated.Values with superscript in a given column differs significantly from each other.�P < 0.05.** P < 0.01.

R. Kaur, S.A. Dar / Food and Chemical Toxicology 61 (2013) 121–126 125

indicates that plasma during cypermethrin treatment possessedless antioxidant holding capacity and was more susceptible to freeradicals. These observations assert the hypothesis that the produc-tion of oxidative damage is one of the principal mechanism in-volved in both oral and dermal toxicity of cypermethrin.

Consistent with its lipophilic nature, cypermethrin has beenfound to accumulate in body fat and skin, which could be a possi-ble reason for the relatively higher degree of oxidative insult bycypermethrin in dermally exposed animals. In addition, cyper-methrin binds to bovine serum albumin (BSA) and bovine haemo-globin (BHb) (Yong et al., 2006). Cypermethrin bonding with BSA issignificantly stronger than its bonding with BHb. Binding with pro-teins will effectively decrease the concentration of free insecticide,benefit its metabolic modification and transport it to the disposalsites thereby alleviating the corresponding toxicity (Silva et al.,2004). In other words, binding of cypermethrin with proteins, isa contrasting factor for higher toxicity of cypermethrin via dermalroute, which requires further investigation.

Therefore, on the basis of present study, it can be contemplatedthat oxidative stress is one of the important mechanisms involvedin cypermethrin-induced toxicity, both via oral and dermal expo-sure. However, the oxidative insult produced by dermal route ismore severe as compared to oral intoxication.

Conflict of Interest

The authors declare that there are no conflicts of interest.

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