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Experimental and Toxicologic Pathology 65 (2013) 489– 495

Contents lists available at SciVerse ScienceDirect

Experimental and Toxicologic Pathology

jo ur nal homepa ge: www.elsev ier .de /e tp

ffect of sub-lethal doses of Bacillus thuringiensis subsp. Aizawai and deltamethrinith regard to fertility and organ toxicity in pregnant albino rats

na Janaina J.M. Lemosa , Herbert A.A. Siqueirab , Valéria Wanderley-Teixeiraa,∗ , Frederico C.L. Maiac ,lvaro A.C. Teixeiraa, Edson J. Silvaa, José V. Oliveirab

Department of Animal Morphology and Physiology, University Federal Rural of Pernambuco, Av. Dom Manoel de Medeiros, s/n, Recife, PE, CEP 52171-900, BrazilAgronomy Department, University Federal Rural of Pernambuco, Av. Dom Manoel de Medeiros, s/n, Recife, PE, CEP 52171-900, BrazilDepartment of Veterinary Medicine, University Federal Rural of Pernambuco, Av. Dom Manoel de Medeiros, s/n, Recife, PE, CEP 52171-900, Brazil

a r t i c l e i n f o

rticle history:eceived 6 May 2010ccepted 21 February 2012

eywords:nsecticidesistopathologyiveridneysungs

a b s t r a c t

Products with Bacillus thuringiensis (Bt) and synthetic insecticides have been widely used against impor-tant vectors of human diseases. However, few studies have addressed the application of these substanceson the female reproduction apparatus during pregnancy at doses that do not cause clinical symptomsof intoxication. Seventy pregnant albino rats were analyzed with regard to fertility and histopathologyof the kidneys, liver and lungs as well as the morphology of the neonates. The rats were submitted tothree sub-lethal doses of the biological insecticide XenTari® WG (B. thuringiensis subsp. Aizawai) and thesynthetic insecticide deltamethrin (Decis® 25CE). After the confirmation of copulation, the insecticideswere administered orally for either seven days or during the entire pregnancy. The analysis revealedhistopathological alterations in all organs analyzed in both treatments. No miscarriages occurred and the

ats neonates did not exhibit signs of malformation of the head, limbs, thorax or abdomen. However, therewere a smaller number of pups in the groups that received higher doses of the insecticides in compari-son to the control group. Both insecticides produced similar lesions in the kidneys, liver and lungs andreduced the fertility of rats when administered at sub-lethal doses with no clinical signs of intoxication.Thus, this study suggests that sublethal doses of both insecticides can provide chronic toxicity in humans.

. Introduction

Formulations with Bacillus thuringiensis (Bt) have been widelysed as controlling agents of pests for more than 40 years, which novidence of harm to humans (Siegel, 2001; Juberg et al., 2009). Therotein crystals (Cry) are an excellent alterative for pests in agri-ulture as well as for important vectors of human diseases (Bravot al., 2005, 2007). However, there are case reports on allergenicffects as well as asthma, nausea and abdominal pain in work-rs and nearby residents following crop dusting with biologicalnsecticides made with the subspecies B. thuringiensis kurstaki and. thuringiensis israelensis (Tayabali and Seligy, 2000; Levin et al.,005). Tests on the release of Bt products and the developmentf toxicity are very superficial and there are no studies comparingregnant and non-pregnant females (Domingo, 2000; Janer et al.,

008).

Deltamethrin is one of the most commonly used synthetic insec-icides of the type II pyrethroid class. This product is considered

∗ Corresponding author. Tel.: +55 81 3320 6389.E-mail address: valeria@dmfa.ufrpe.br (V. Wanderley-Teixeira).

940-2993/$ – see front matter © 2012 Elsevier GmbH. All rights reserved.oi:10.1016/j.etp.2012.02.004

© 2012 Elsevier GmbH. All rights reserved.

important due to its low persistence and is applied to crops as wellas being used in veterinary medicine and public health (Anadónet al., 2009). Studies carried out on mammals mainly address theeffect on the central nervous system and the toxicity of theseproducts (Breckenridge et al., 2009; Elhalwagya and Zakib, 2009;Meeker et al., 2009). Moreover, these studies use doses based onLD50, whereas few studies have addressed the effect of these sub-stances on the female reproductive apparatus and pregnancy atdoses that do not cause clinical symptoms (Janer et al., 2008).

When administered orally, deltamethrin is known to inhibitcytochrome P450, which is an enzyme involved in the metabolismof drugs and toxic substances. Cytochrome P450 may alter the hor-monal physiology of reproductive development and is involved inthe functioning of the tissues of the liver, kidneys, lungs, intestineand uterine endometrium in mammals (Miksys et al., 2003; Anandet al., 2006; Hodgson and Rose, 2007; Yang et al., 2009).

In Brazil, a large number of rural workers are exposed to insec-ticides (Garcia and Almeida, 1991). Female labor accounts for

approximately 60% of the total number of workers in the produc-tion of different crops, such as grapes, acerola and tomatoes (Brancoand Vainsencher, 2001), leading to increased exposure to pesticidesand herbicides. The present study sought to test the hypothesis that

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he administration of the insecticides XenTari® WG (B. thuringiensisubsp. Aizawai) and deltamethrin (Decis® 25CE) at concentrationshat do not cause clinical signs of intoxication can affect fertility asell as the histology of the kidneys, liver and lungs of rats in the

arly stage of pregnancy.

. Materials and methods

The experiment was conducted at the Histology Laboratoryf the Department of Animal Morphology and Physiology of theniversidade Federal Rural de Pernambuco (Brazil). Seventy Wis-

er albino rats (Rattus norvegicus albinus) with 90 days of age andeighing approximately 200 g were acquired from the animal lodg-

ng sector of the same department. The experimental protocol waspproved to the ethics institutional committee of the Federal Ruralniversity of Pernambuco, with number 23082.019868/2009.

.1. Bioassay

The animals were maintained in cages with chow and waterd libitum at a temperature of 22 ◦C and artificial light with a2-h photoperiod (light from 6 am to 6 pm). After an adaptationeriod, vaginal smears were collected for the determination of thestrous cycle. Rats that exhibited three regular cycles were ran-omly divided into seven groups of 10 females, five of which werereated through to the seventh day of pregnancy for the analy-is of the kidneys, liver and lungs and the other five were treatedhroughout the pregnancy for the fertility analysis:

Group I – pregnant rats that received a placebo.Group II – pregnant rats that received 18.5 mg of XenTari® WG(1 mg of protein toxin B. thuringiensis subsp. Aizawai)/100 g.Group III – pregnant rats that received 185 mg of XenTari® WG(10 mg of protein toxin)/100 g.Group IV – pregnant rats that received 370 mg of XenTari® WG(20 mg of protein toxin)/100 g.Group V – pregnant rats that received 1.0 mg of deltamethrin(0.4 ml of Decis® 25CE)/kg.Group VI – pregnant rats that received 2.0 mg of deltamethrin(0.8 ml of Decis® 25CE)/kg.Group VII – pregnant rats that received 4.0 mg of deltamethrin(1.6 ml of Decis® 25CE)/kg.

Following the analysis of the estrous cycle, ripe females werered at a proportion of one male to two females, always at theeginning of the night (6 pm). The following morning (6 am),olpocytological exams were performed for the confirmation ofopulation, using the presence of spermatozoids in the smearss reference. The samples were stained using the Shorr–Harrisethod.

.2. Administration of insecticides

Following the confirmation of copulation, the insecticidesenTari® WG and deltamethrin (Decis® 25CE) were administeredrally (gavage) in daily doses based on the modified methodescribed by Shaban et al. (2003) for the biological insecticide andhe method described by Andrade et al. (2002) for the syntheticnsecticide. The rats were weighed daily on a digital scale for theetermination of weight gain and conversion of the proportionaleasure of insecticide dose. The deltamethrin doses were estab-

ished from the No Observed Effect Level (NOEL) dose for maternaloxicity – the greatest dose that does not cause toxicity. Accord-ng to the US Environmental Protection Agency, the NOEL dose foreltamethrin in rats is 3.3 mg/kg (EPA, 2000).

cologic Pathology 65 (2013) 489– 495

2.3. Histopathological and macroscopic analysis

For the analysis of the organs, five rats from each groupwere anesthetized with an intra-muscle injection of Ketamine(80 mg/kg) and Xylazine (6 mg/kg) for sacrifice on the seventhday of pregnancy. The abdominal cavity was opened to the ribsand the thoracic cage was opened for the removal of the kid-neys, liver and lungs, which were immediately immersed in Bouin’ssolution for 48 h. The organs were then cleaved, dehydrated inincreasing concentrations of alcohol, diaphanized with xylol andembedded in paraffin. Blocks were cut on a Minot microtome (LeicaRM 2035) adjusted to 5 �m and submitted to hematoxylin–eosin(HE) staining for analysis under a light microscope andphotomicrography.

For the morphological analysis of the neonates, the remainingrats were accompanied for a 21-day period until the birth of thepups, which were counted, weighed on an analytical scale, mea-sured from head to the tip of the tail and macroscopically analyzedfor visible malformations of the head, trunk and limbs. These datawere submitted to the non-parametric Kruskal–Wallis test. Meanvalues were compared using the Wilcoxon–Mann–Whitney test.The level of significance was set at p > 0.05.

3. Results

3.1. Histopathology

The results indicate that both insecticides affected the fertilityof the rats and histo-physiology of the kidneys, liver and lungs. Thealterations were dose dependent.

In the kidneys, hemosiderin depositing, necrosis and vacuo-lar degeneration of the convoluted tubules and collector ducts,membranous, proliferative glomerulonephritis and a significantreduction in Bowman’s spaces, compared to control (Fig. 1A–F)were found in the rats that received 4.0 mg of deltamethrin (1.6 mlof Decis® 25CE)/kg (Group VII) and those that received XenTari® at370 mg/100 g, which corresponds to a dose of 20 mg/100 g of theprotoxin (Cry subspecies Aizawai) (Group IV). In the latter group,accentuated hypertrophy and hyperplasia were observed, withstratification of the epithelium of the collector tubules (Fig. 2A),which are normally of the simple cubic type.

In the liver, there was a slight increase in the sinusoid spacesdue to congestion, coagulative nodular focal necrosis with anintense reaction of Kupffer cells and scarce mononuclear cells inthe rats treated with doses of 185 and 370 mg/100 g of XenTari®

WG, corresponding to 10 and 20 mg of the protein toxin, respec-tively, compared to control (Fig. 2B and C). In the rats treatedwith 2.0 and 4.0 mg of deltamethrin/kg, corresponding to 0.8and 1.6 ml of Decis® 25CE, respectively, there was congestion,vacuolar degeneration of hepatocytes, hyperplasia of the Kupffercells, with focal points in the portal triads exhibiting colangitis(Fig. 2D–F).

In the lungs, there was inflammatory reaction, with thepresence of macrophages and a predomination of polymorphonu-cleated cells, characterizing purulent bronchiolitis with exudatein the interior as well as peribronchiolitis and perivasculitis withinflammatory process by macrophages and lymphocytes in therats treated with doses of 185 and 370 mg/100 g de XenTari®

WG (Fig. 3B and C). In those treated with 2.0 and 4.0 mg ofdeltamethrin/kg, there was thickening of the septa, characterizingmoderate interstitial pneumonia, with an inflammatory reaction

around the bronchioles and vessels, exhibiting the characteristicperibronchiolar infiltrate; multi-focal pneumonia by macrophageswas also diagnosed, distributed in different areas of the lobule(Fig. 3D–F) in comparison to the control group (Fig. 3A).

A.J.J.M. Lemos et al. / Experimental and Toxicologic Pathology 65 (2013) 489– 495 491

Fig. 1. Kidneys of rats in experimental groups; (A) well-preserved cortical (c) and medullar (m) region (control group); HE ± 42X; (B) Hemosiderin depositing in collectortubules in rats treated with 185 mg/100 g of XenTari®; HE ± 428X; (C) necrosis of convoluted tubules (*) characterized by absence of nuclei and pale staining of cells in ratst onvolum (18.5m 70 m

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TMt

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reated with 370 mg/100 g of XenTari®); HE ± 428X; (D) vacuolar degeneration of cembranous proliferative glomerulonephritis, with reduction in Bowman’s spacesembranous proliferative glomerulonephritis, with absence of Bowman’s spaces (3

.2. Morphology of neonates and fertility

The macroscopic analysis of the neonates revealed no signs ofalformation of the head, limbs, thorax or abdomen. There were noiscarriages. Table 1 displays the data on the mean number, length

nd weight of the neonates. There were no statistically significant

able 1ean (± standard deviation) number, length and weight of neonates in experimen-

al groups.

Group Number Length Weight

G I 12.00 ± 1.58a 6.17 ± 0.28a 6.14 ± 0.41aG II 11.60 ± 0.89a 5.92 ± 0.37a 5.57 ± 0.34aG III 8.60 ± 1.67ab 6.30 ± 0.05a 5.80 ± 0.31aG IV 6.20 ± 1.09b 6.16 ± 0.69a 5.97 ± 0.96aG V 8.20 ± 2.20ab 6.15 ± 0.95a 6.19 ± 0.56aG VI 7.80 ± 1.48ab 6.32 ± 0.26a 6.10 ± 0.30aG VII 4.80 ± 2.58b 6.52 ± 0.35a 6.31 ± 0.84aFP statistica 24.4890.0004 9.4890.1479 6.6060.3589

a Means followed by same letter do not differ significantly from one anotherWilcoxon–Mann–Whitney test; p < 0.05).

ted tubules (arrow) in rats treated with 370 mg/100 g of XenTari®; HE ± 428X; (E) and 185 mg/100 g of XenTari® and 1 and 2 mg/kg of deltamethrin); HE ± 428X; (F)g/100 g of XenTari® and 4 mg/kg of deltamethrin); HE ± 428X.

differences for the length and weight of the neonates. However,there were differences in the number of neonates, as higher dosesof the two insecticides led to a significant reduction in the numberof pups when compared to the control and group treated with adose of 18.5 mg of XenTari®.

4. Discussion

Contradictory data were found in the present study. Sub-lethaldoses of the biological insecticide produced substantial histopatho-logical alterations in the kidneys, liver and lungs of rats in earlypregnancy. Likewise, sub-lethal doses of the synthetic insecticidealso caused alterations in these organs, characterized by inflamma-tory processes. There was also a reduction in the number of pupsin the groups that received the highest doses of these insecticides.

The alterations in the kidneys caused by the biological insec-

ticide reflect the effect of toxins on the immune system throughthe proliferation of mesangial cells and their infiltration in the tis-sue. This led to either a reduction or absence of Bowman’s spaces,characterizing membranous proliferative glomerulonephritis and

492 A.J.J.M. Lemos et al. / Experimental and Toxicologic Pathology 65 (2013) 489– 495

Fig. 2. Kidney and liver of rats in experimental groups; (A) hypertrophy and hyperplasia with stratification of cells of collector tubules in kidneys of rats treated with370 mg/100 g of XenTari® . In detail, normal aspect of collector tubules, simple cubic epithelium. HE ± 428X; (B) well-preserved liver in control group; HE ± 428X; (C)coagulative nodular focal necrosis with intense reaction of Kupffer cells and scarce mononuclear cells (185 and 370 mg/100 g of XenTari®); HE ± 107X; (D) slight increasein sinusoid spaces characteristic of congestion (*) and diffuse hyperplasia of Kupffer cells [arrow] (370 mg/100 g of XenTari®); HE ± 428X; (E) vacuolar degeneration ofh riads [H

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epatocytes (2 and 4 mg/kg of deltamethrin); HE ± 428X; (F) colangitis in portal tE ± 107X.

hereby reducing the functional capacity of the nephrons. The effectf the Bt toxin on the immune system is reported by Hayakawat al. (2007), who found that strains of the Bt bacterium stimulatedhe activation of lymphocytes in human kidney cell cultures. Othertudies have also reported histological alterations in Bowman’sapsule and the diameter of the glomeruli, leading to a reduction inidney function in the third-generation offspring of rats fed trans-enic corn and Bt toxins during pregnancy and lactation (Séralinit al., 2007; Kilic and Akay, 2008).

Studies have also revealed that Bt toxins in mammal liver cellultures increase the production of lactate dehydrogenase (LDH),hich damages the endothelial cells of the sinusoids, leading toilation of the sinusoidal lumen at doses of approximately 2.0 ng/mlfter incubation for 24 and 48 h (Shimada et al., 2003; Sun et al.,001). This may explain the slight increase in the sinusoid spaces

n the present study, caused by the ingestion of sub-lethal dosesf XenTari® (185 and 370 mg/100 g). Other studies have demon-

trated that the insecticide Dipel® (B. thuringiensis var. kurstaki)as the ability to alter the defense behavior of liver cells, inducexidative stress, stimulate lipid peroxidation through the forma-ion of free radicals and damage the membranes of liver cells in

arrows] (2 and 4 mg/kg of deltamethrin) characteristic of inflammatory reaction;

rats, leading to an inflammatory reaction and activity of the Kupf-fer cells following the administration of the same dose used in thepresent study (Shaban et al., 2003; Ito, 2006).

The coagulative nodular focal necrosis with an intense reac-tion and diffuse hyperplasia of the Kupffer cells resulted fromthe inflammatory action the Bt toxins, as these cells are residentmacrophages, the function of which is to metabolize old eryth-rocytes, digest hemoglobin and secrete proteins related to theimmune system. In other words, they act as defense cells in theliver (Takiya and Borojevic, 2005).

Regarding the synthetic insecticide, the literature reports tox-icological tests of much higher doses than those used in thepresent study, emphasizing physiopathological aspects withouttaking morphological alterations into consideration. For example,Manna et al. (2004) report an increase in the number of neutrophils,lymphocytes and monocytes in the kidneys, subsequently leadingto glomerulonephritis and hemorrhage in rats submitted to a cyper-

methrin (a pyrethroid from the same class as deltamethrin) at adose of 14.5 mg/kg (1/10 da DL50) for 30 days. Oral deltamethrindoses of 5.6 mg/kg and 18 mg/kg for 15 days also led to areduction in glutathione (GSH), which is extremely important to

A.J.J.M. Lemos et al. / Experimental and Toxicologic Pathology 65 (2013) 489– 495 493

Fig. 3. Lungs of rats in experimental groups; (A) normal vascular region and alveoli in control group; HE ± 107X; (B) purulent bronchiolitis, showing exudate with polymor-phonucleated cells (arrow) and peribronchiolitis (*) (185 and 370 mg/100 g of XenTari®); HE ± 428X; (C) peribronchiolitis (*) and perivasculitis [arrow] (185 and 370 mg/100 go ia (2.0( risk] (

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f XenTari®); HE ± 107X; (D) thickening of septa characterizing interstitial pneumon2.0 and 4.0 mg/kg of deltamethrin); HE ± 107X; (F) detail of focal pneumonia [aste

etoxification in the kidneys, liver and lungs. This reduction in GSHs reflected in an increase in lipid peroxidation and vulnerabilityf the organism regarding the functioning of the immune system,hereby leading to the occurrence of opportunistic diseases andxidative stress (Rehman et al., 2006). It should be mentioned that,long with the reduction in GSH, Eraslan et al. (2007) found anncrease in creatinine and phosphorus in the blood of rats sub-

itted to 7.5–30 mg/kg of deltamethrin in the feed. The increasedlood concentration of creatinine corresponds to a reduction in thelomerular filtration rate and nephron dysfunction. Deltamethrinlso causes a change in the potential difference of the sodium chan-els in the cell membranes, thereby causing kidney dysfunctionMeacham et al., 2008; Peng et al., 2009).

Using an intraperitoneal injection of deltamethrin at a dose of68 ppm (1/10 of DL50), Fetoui et al. (2009) found dilation of the

umen of the sinusoids, inflammatory cell infiltration, liver cellegeneration and an increase in LDH. These effects of deltamethrinxplain the colangitis of the portal triads, which are aggregationsf inflammatory cells, especially around biliary ducts, and the pres-

nce of fibrosis, which occurs in the liver as a response to necrosisnd inflammation and may be followed by fibrosis as a consequencef toxic or inflammatory aggression (Maclachlan and Cullen, 1995).nother theory for explaining these lesions in the liver due to

and 4.0 mg/kg of deltamethrin); HE ± 107X; (E) multifocal pneumonia [long arrows]2.0 and 4.0 mg/kg of deltamethrin); HE ± 107 and 428X.

deltamethrin involves alterations in hydrolases and the biotrans-formation of microsomal vesicles as well as an increase in aspartatetransaminase (AST), alanine transaminase (ALT) and LDH, whichare substances that indicate symptoms of intoxication, damage ordysfunction in liver tissue or pneumocytes. These substances havebeen found in rats submitted to oral doses of 12 mg/kg four timesa week for three weeks and when goats were bathed in 0.8–1.6%solutions once a day for 75 days (Lamfon, 2007; Khan et al., 2009).Moreover, low oral doses of deltamethrin (1.28 mg/kg orally) in ratsfor 30 days were found to cause liver failure, leading to a reduc-tion in albumin and globulin, which transport hormones and othersubstances that are fundamental to the normal functioning of theorganism (Yousef et al., 2006).

In the rats treated with doses of 185 and 370 mg/100 gof XenTari® WG and those treated with 2.0 and 4.0 mg ofdeltamethrin/kg, the histopathological alterations in the lungswere quite substantial, characterized by purulent bronchiolitis,peribronchiolitis, perivasculitis, interstitial pneumonia, peribron-chiolar infiltrate and multifocal pneumonia by macrophages.

Similar alterations have also been found in the lungs of ratssubmitted to intra-tracheal colony-forming units of 3.9 × 105 to1.2 × 107 of purified Bt protein at doses of 0.4–9.6 mg/kg in a sin-gle dose, resulting in dose-dependent histological alterations and

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nflammation in the bronchioles and alveoli with cell infiltrationnd agglomerates of neutrophils (Tsai et al., 2003; Ghelardi et al.,007). The toxins of the bacterium are also known to lead to aerum increase in pro-inflammatory substances, even leading tohe death of animals when spore doses of greater than 108 wereiven intranasally and induced pulmonary hemorrhage and inflam-atory infiltration (Hernandez et al., 1999; Tsai et al., 2006).The synthetic insecticide is reported to have pro-inflammatory

ctivity and cause alterations in type II pneumocytes, leading toyperplasia of these cells, which are responsible for the produc-ion of pulmonary surfactant and are involved in the cleaning ofhe tissue. The administration of a deltamethrin spray aerosol for0 min a day for 45 days at doses of 6 and 12 mg/m3 was foundo cause interstitial pneumonia and lead to respiratory bronchiolesith vascular substance, perivascular edema and peribronchiolaryperplasia of the lymphoid tissue (Erdogan et al., 2006). Thesendings are similar to those of the present study at doses of 2.0 and.0 mg/kg administered orally for just seven days. Other studieseveal alteration in the pneumocytes and pro-inflammatory symp-oms when administered at nearly acute doses of 125–225 mg/kg,eading the authors to conclude that deltamethrin causes emphy-ema after 30 days of study and is able to raise the levels of AST, LDH,LT, etc., which are substances that indicate intoxication (Mannat al., 2005), thereby explaining the presence of peribronchiolarnfiltrate and multifocal pneumonia by macrophages in the pul-

onary lobules.It should be mentioned that a recent study found differences

n the depositing of deltamethrin in the tissues and the substanceas dose dependent with regard to its distribution throughout

he tissues, but not proportional to the dose. To some extent, thisxplains the similar reactions between different treatments whennvestigating adipose tissue, skeletal muscle, epithelial tissue andastrointestinal tissue in rats at intravenous doses of 0.4, 2 and0 mg/kg (Kim et al., 2008).

The inflammatory process occurred in the kidneys, liver andungs of the animals submitted to both the synthetic and biolog-cal insecticides. There were also a lower number of pups in theroups that received higher doses of the insecticides throughouthe entire pregnancy. This reduction may be explained by the facthat the insecticides caused a pro-inflammatory process in the rats.

oreno-Fierros et al. (2002) found Bt Cry1Ac protein toxins toause immune system responses on the systemic level in differentites, such as the reproductive apparatus, immediately followinghe intraperitoneal and intravaginal administration of 100 �g. Thisame toxin has been found to be a potent specific inducer of themmune response in mucous tissue (Vázquez-Padrón et al., 2000).

Just as type II pyrethroid Bt-based biological insecticides areonsidered pro-inflammatory, researchers have demonstrated thathese insecticides may lead to a change in corticoidsteroid hormoneevels in the plasma at doses of 3 mg/kg of cyhalothrin in rats foreven days (Righi and Palermo-Neto, 2003). These insecticides canlso alter sex hormone levels, such as FSH and LH, proportionatelyn relation to the amount of pyrethroid substances eliminated byrine and on the serum level in adult humans (Meeker et al., 2009),hereby demonstrating the ability of these substances to affect theeproductive system.

The success of implantation is known to depend on diverseactors, including the temporarily defined expression of specific

olecules. The implantation of blastocysts is always preceded by anncrease in vascular permeability for the formation of the implan-ation sites, which increases the contact of the uterus with allubstances present on the vascular level. Hormonal function is also

mportant, such as progesterone in the maintenance of the decidu-lization and development of the implantation process, as all theseactors are essential to the adequate establishment of pregnancy innimals (Zorn, 2005).

cologic Pathology 65 (2013) 489– 495

In conclusion, both the biological and synthetic insecticidescaused lesions characterized by inflammatory reactions and led toa lower number of offspring. This indicates that both insecticidesact similarly on fertility as well as in the kidneys, liver and lungswhen administered at doses that do not cause clinical symptoms ofintoxication in albino rats. Thus, this study suggests that sublethaldoses of both insecticides can provide chronic toxicity in humans.

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