Effect of hexachlorocyclohexane (HCH) on testicular plasma membrane of rat

Pesticide residues in honey and their potential reproductive toxicity

Honey is the sweet natural substance produced by honeybees. It may be contaminated with pesticide residues due to its intensive use. Almost no reviews have addressed pesticide residues in honey, calculated a hazard index or discussed their potential reproductive toxicity. The focus of this article is primarily to summarize advances in research related to pesticide residues, estimate daily intake of pesticide residues from consuming honey only and discuss the potential reproductive toxicity associated with those residues. The results showed that 92 pesticide residues were found in honey samples from 27 countries. Six residues belong to class IA toxicity, eight residues belong to class IB toxicity, 42 residues belong to class II, 35 residues belong to class III and one residue belong to class IV toxicity. The calculated hazard indices (HIs) suggest high potential health risk by consuming honey. In addition, residues found in honey are known to impair semen quality among exposed individuals and experimental animal models. In conclusion, consumption of honey as one of many food items contaminated with pesticide residues may induce male and female reproductive toxicity in consumers.

Stereospecificity in the cytotoxic action of hexachlorocyclohexane isomers

Hexachlorocyclohexane (HCH) is a highly recalcitrant organochlorine insecticide known for its chronic toxicity. In spite of many isolated studies a clear mechanism of cytotoxic action of HCH and the structure-toxicity relationship of its isomers is not well understood. We have investigated the toxicity of HCH isomers and its mechanism in Ehrlich Ascites tumor (EAT) cells. Our studies show differential cytotoxicity of HCH isomers (alpha, beta, gamma, and delta), delta isomer being most toxic and beta the least. HCH-induced cell death was associated with induction of reactive oxygen species (ROS) formation, lipid peroxidation (LPO), and depletion of glutathione (GSH). The increase in oxidative stress was linked with increased NAD(P)H oxidase activity. HCH inhibited Na(+),K(+)-ATPase, which could be involved in raising the intracellular calcium and increased Ca(2+),Mg(2+)-ATPase activity. HCH lead to apoptotic as well as necrotic cell death as it was marked by increased caspase-3 activity and lactate dehydrogenase (LDH) leakage, respectively. Based on the results it is concluded that the HCH isomers inflict differential cytotoxicity which was highest by delta and lowest by beta. Further, this study demonstrates for the first time a clear link between Na(+),K(+)-ATPase, i[Ca(2+)] level, and oxidative stress in HCH-induced cytotoxicity.

Lindane induces testicular apoptosis in adult Wistar rats through the involvement of Fas-FasL and mitochondria-dependent pathways

Lindane, an organochlorine pesticide, is known to impair testicular functions and fertility. To elucidate the mechanism(s) underpinning the gonadal effects of lindane, we sought to investigate the levels of apoptosis-related proteins, namely cytochrome c, caspase-3 and-9, Fas and FasL in the testis of adult rats. Furthermore, the study aims to delineate whether nuclear factor kappa B (NF-kappaB) is involved in meditating the testicular effects of lindane. Animals were administered with a single dose of lindane (5mg/kg body weight) and sacrificed at specific post-treatment intervals (0, 3, 6, 12, 24 and 72h). Significant elevations in the levels of cytosolic cytochrome c with a parallel increase in pro-caspase-9 were observed as early as 6h following exposure. Time-dependent elevations in the levels of Fas, FasL and caspase-3 were observed. Immunofluorescence studies revealed increased colocalization of Fas and caspase-3 in peritubular germ cells. FasL levels were increased in Sertoli and peritubular germ cells. The cytoplasmic levels of NF-kappaB p65 decreased from 3h following exposure with a maximal decline at 12 and 24h. Changes in the localization of NF-kappaB were observed with maximal nuclear translocation in germ cells at 12 and 24h. Terminal deoxynucleotidyl transferase-mediated dUTP nickend-labeling (TUNEL) assay revealed a time-dependent increase in the number of apoptotic cells. Taken together, the data illustrate induction of testicular apoptosis in adult rats following exposure to a single dose of lindane. Early activation of NF-kappaB in contrast to late increase in Fas expression suggests a pro-apoptotic role of NF-kappaB in testicular response to lindane.

Cytotoxic effects induced by hexachlorobenzene in Squilla mantis (L.) (Crustacea, Stomatopoda)

Contamination of marine environments by hexachlorobenzene (HCB) represents a serious concern for potential consequences on ecosystem and human health. Despite this, information on cytotoxic effects on marine organisms is still largely lacking. In this study, we investigated cytotoxic effects induced by HCB on gonads and muscular tissue of Squilla mantis by analysing Na(+)/K(+)-ATPase activity and plasma membrane fluidity. This crustacean species was selected as a model for its habitat, trophic level, feeding behavior, and commercial exploitation for human consumption. Time course experiments revealed that low concentrations of HCB (i.e. 50 nM) determine an exponentially decrease of Na(+)/K(+)-ATPase activity and a significant modification of cellular membrane fluidity. Significant negative relationships between Na(+)/K(+)-ATPase activity and membrane fluidity were observed, suggesting that changes in the structure and packing of cellular membranes induced by HCB may be the primary factor affecting the activity of essential bilayer-associated enzymes. Overall these findings suggest that even small concentrations of HCB may determine important changes on cell metabolism with potential cascade effects on recruitment of this commercial species.

Causal relationship between Hexachlorocyclohexane cytotoxicity, oxidative stress and Na+, K+-ATPase in Ehrlich Ascites Tumor cells

Role of oxidative stress and Na+,K+-ATPase in the cytotoxicity of hexachlorocyclohexane (HCH) on Ehrlich Ascites tumor (EAT) cells has been studied. HCH caused dose dependent cell death as measured by trypan blue exclusion and lactate dehydrogenase (LDH) leakage from the cells. HCH induced oxidative stress in EAT cells which was characterized by glutathione depletion, lipid peroxidation (LPO), reactive oxygen species (ROS) production and inhibition of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT). Protective effect of antioxidants on HCH induced oxidative stress was assessed, among the antioxidants used only quercetin inhibited HCH-induced LPO and ROS production as well as cell death whereas alpha -tocopherol, ascorbic acid and BHA inhibited LPO but not cell death. Inhibition of membrane bound Na+,K+-ATPase was a characteristic feature of HCH cytotoxicity in EAT cells. Experimental evidence indicates that HCH-induced cell death involves oxidative stress due to ROS production and membrane perturbation in EAT cells.

A novel aspect of lindane testicular toxicity: in vitro effects on peritubular myoid cells

The in vitro effects of the insecticide lindane have been investigated in rat testis peritubular myoid cells (PMCs). Upon PMC exposure to lindane, polarity increase and decrease of dipole dynamics were seen at the membrane level (EC50 20 microM), leading to a partial dissipation of the membrane intrinsic dipole potential. The initial membrane depolarization was increased by Cl- efflux and limited by Ca(2+)-activated repolarizing currents. Concomitantly, lindane produced an increase in [Ca2+]i (EC50 125 microM) resulting from both Ca2+ release from an inositol 1,4,5-trisphosphate-sensitive intracellular store and a voltage-dependent Ca2+ influx from the extracellular medium. Of particular interest from a toxicologic point of view, insecticide concentrations well below those effective in altering ion homeostasis potently inhibited both [Ca2+]i increase and contraction induced by the natural agonists vasopressin and endothelin-1 (IC50s < 10 microM). These data demonstrate that PMCs are highly susceptible to lindane and suggest that the insecticide may exert testicular toxicity by interfering with hormone-regulated PMC function.

Hexachlorocyclohexane-induced behavioural and neurochemical changes in rat

Effect of chronic oral exposure (10 and 20 mg kg(-1) body wt. for 7, 15 and 30 days) to hexachlorocyclohexane (HCH) on open-field behaviour and activities of cerebral Na+,K+-ATPase, Mg2+-ATPase and acetylcholinesterase (AChE) of rat was evaluated. Motor and grooming activities were altered, whereas vertical exploratory activity was unaffected by HCH. Activities of Na+,K+-ATPase, Mg2+-ATPase and AChE were inhibited significantly by the pesticide. The results suggest that HCH induces impairment of the enzymes involved in synaptic activity, resulting in behavioural alterations.

Comparison of hexachlorocyclohexane-induced oxidative stress in the testis of immature and adult rats

1. The acute effect of hexachlorocyclohexane (HCH) administration (i.p.) on testicular antioxidant system and lipid peroxidation (LPX) in immature and mature rats (15- and 90-day-old, respectively) were compared. 2. In both the age groups, the level of LPX in crude homogenate of testis (endogenous, as well as FeSO4, and ascorbic acid-stimulated) was increased after 6 hr of HCH treatment and remained high till 24 hr. However, FeSO4 and ascorbic acid-stimulated LPX was higher in 90-day-old rats in comparison to 15-day-old rats. HCH treatment also resulted in elevation of LPX level in testicular subcellular (nuclear, mitochondrial and microsomal) fractions by 6 hr of treatment. However, the magnitude of increase was greater in case of 90-day-old rats. 3. Activities of testicular cytosolic superoxide dismutases (total and CN(-)-resistant) of rats of 15- and 90-day-old age groups decreased significantly after 6 hr of HCH treatment, and remained decreased till 24 hr of the pesticide treatment. The percentage of decrease was higher in 15-day-old rats than 90-day-old rats. CN(-)-sensitive SOD activity of testis was found to decrease by 12 and 24 hr after the pesticide treatment in 15- and 90-day-old rats, respectively. The activity of catalase decreased 6 hr after the pesticide treatment in both the age groups. However, the magnitude of decrease was similar for both age groups of rats. 4. Testicular glutathione content, as well as levels of glutathione metabolizing enzymes (glutathione peroxidase and glutathione reductase), did not change in response to HCH treatment, whereas ascorbic acid content decreased by 12 and 6 hr after HCH treatment in 15- and 90-day-old rats, respectively. The level of H2O2 was found to be elevated after 6 hr of the pesticide treatment in both age groups. 5. Total epididymal sperm number was comparable in all experimental groups. However, the percentage of dead and damaged spermatozoa was significantly enhanced in HCH treated rats. 6. Acute HCH administration to rats results in induction of oxidative stress in the testis which depends upon the age of the animal.