Cytoskeleton involvement in lithium-induced SH-SY5Y neuritogenesis and the role of glycogen synthase kinase 3ß.

Lithium modulates signals impacting on the cytoskeleton, a dynamic system contributing to neural plasticity at multiple levels. In this study, SH-SY5Y human neuronal cells were cultured in the absence (C) or in presence (Li) of a 0.5 mM Li2CO3 (i.e. 1 mM lithium ion) for 25-50 weeks. We investigated the effect of this treatment on (1) morphological changes of cells observed using Hemalun eosin staining assay, (2) cytoskeletal changes by indirect immunofluorescence (IIF) staining of microtubules (α-tubulin) and heavy neurofilaments subunits (NF-H) and by measuring the expression rate changes of genes coding for receptor for activated C kinase (RACK1), casein kinase2 (CK2) and thymosine beta-10 using cDNA arrays technology, (3) cell adhesion properties by IIF staining of ß-catenin protein. Besides, we have tried to understand the molecular mechanism of lithium action that triggers changes in cytoskeleton and neurites outgrowth. Thus, we examined the effect of this treatment on glycogen synthase kinase 3 (GSK3) expression and activity using western blotting of GSK3 and phosphorylated ß-catenin, a downstream GSK3 target protein. Our results showed that lithium treatment reduces axon length, increases axonal spreading, enhances neurites growth and neurites branching with an increase of growth cone size. Moreover, genes coding for CK2 and thymosine beta-10 were significantly up-regulated, however, that coding for RACK1 was down-regulated. The most interesting result in this work is that mechanism underlying lithium action was not related to the inhibition of GSK3 activity. In fact, neither expression rate nor activity of this protein was changed.

Chronic neuroprotective effects of low concentration lithium on SH-SY5Y cells: possible involvement of stress proteins and gene expression.

To investigate the molecular mechanism underlying the neuroprotective effect of lithium on cells, in this study, we exposed SH-SY5Y cells to 0.5 mmol/L lithium carbonate (Li2CO2) for 25-50 weeks and then detected the expression levels of some neurobiology related genes and post-translational modifications of stress proteins in SH-SY5Y cells. cDNA arrays showed that pyruvate kinase 2 (PKM2) and calmodulin 3 (CaM 3) expression levels were significantly down-regulated, phosphatase protein PP2A expression was lightly down-regulated, and casein kinase II (CK2), threonine/tyrosine phosphatase 7 (PYST2), and dopamine beta-hydroxylase (DBH) expression levels were significantly up-regulated. Besides, western blot analysis of stress proteins (HSP27, HSP70, GRP78 and GRP94) showed an over-expression of two proteins: a 105 kDa protein which is a hyper-phosphorylated isoform of GRP94, and a 108 kDa protein which is a phosphorylated tetramer of HSP27. These results suggest that the neuroprotective effects of lithium are likely related to gene expressions and post-translational modifications of proteins cited above.

Neuroprotective effects of chronic exposure of SH-SY5Y to low lithium concentration involve glycolysis stimulation, extracellular pyruvate accumulation and resistance to oxidative stress.

Recent studies suggest that lithium protects neurons from death induced by a wide array of neurotoxic insults, stimulates neurogenesis and could be used to prevent age-related neurodegenerative diseases. In this study, SH-SY5Y human neuronal cells were cultured in the absence (Con) or in the presence (Li+) of a low lithium concentration (0.5 mm Li2CO3, i.e. 1 mm lithium ion) for 25-50 wk. In the course of treatment, growth rate of Con and Li+ cells was regularly analysed using Alamar Blue dye. Resistance to oxidative stress was investigated by evaluating: (1) the adverse effects of high concentrations of lithium (4-8 mm) or glutamate (20-90 mm) on cell growth rate; (2) the levels of lipid peroxidation (TBARS) and total glutathione; (3) the expression levels of the anti-apoptotic Bcl-2 protein. In addition, glucose metabolism was investigated by analysing selected metabolites in culture media and cell extracts by 1H-NMR spectroscopy. As compared to Con, Li+ cells multiplied faster and were more resistant to stress, as evidenced by a lower dose-dependent decrease of Alamar Blue reduction and dose-dependent increase of TBARS levels induced by toxic doses of lithium and glutamate. Total glutathione content and Bcl-2 level were increased in Li+ cells. Glucose consumption and glycolytic activity were enhanced in Li+ cells and an important release of pyruvate was observed. We conclude that chronic exposure to lithium induces adaptive changes in metabolism of SH-SY5Y cells involving a higher cell growth rate and a better resistance to oxidative stress.

Lipid peroxidation, antioxidant activities and stress protein (HSP72/73, GRP94) expression in kidney and liver of rats under lithium treatment

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The present work was aimed at studying the effects of a subchronic lithium treatment on rat liver and kidneys, paying attention to the relationship between lithium toxicity, oxidative stress, and stress protein expression. Male rats were submitted to lithium treatment by adding 2 g of lithium carbonate/kg of food for different durations up to 1 month. This treatment led to serum concentrations ranging from 0.5 mM (day 7) to 1.34 mM (day 28) and renal insufficiency highlighted by an increase of blood creatinine and urea levels and a decrease of urea excretion. Lithium treatment was found to trigger an oxidative stress both in kidney and liver, leading to an increase of lipid peroxidation level (TBARS) and of superoxide dismutase and catalase activities. Conversely, glutathione peroxidase activity was reduced. Constitutive HSP73 (heat shock protein 73) expression was not modified by lithium treatment, whereas inducible HSP72 was down-regulated in kidney. GRP94 (glucose regulated protein 94) appeared as two isoforms of 92 and 98 kDa: the 98-kDa protein being overexpressed in kidney by lithium treatment whereas 92-kDa protein was underexpressed both in kidney and liver (AU)

Lipid peroxidation, antioxidant activities and stress protein (HSP72/73, GRP94) expression in kidney and liver of rats under lithium treatment.

The present work was aimed at studying the effects of a subchronic lithium treatment on rat liver and kidneys, paying attention to the relationship between lithium toxicity, oxidative stress, and stress protein expression. Male rats were submitted to lithium treatment by adding 2 g of lithium carbonate/kg of food for different durations up to 1 month. This treatment led to serum concentrations ranging from 0.5 mM (day 7) to 1.34 mM (day 28) and renal insufficiency highlighted by an increase of blood creatinine and urea levels and a decrease of urea excretion. Lithium treatment was found to trigger an oxidative stress both in kidney and liver, leading to an increase of lipid peroxidation level (TBARS) and of superoxide dismutase and catalase activities. Conversely, glutathione peroxidase activity was reduced. Constitutive HSP73 (heat shock protein 73) expression was not modified by lithium treatment, whereas inducible HSP72 was down-regulated in kidney. GRP94 (glucose regulated protein 94) appeared as two isoforms of 92 and 98 kDa: the 98-kDa protein being overexpressed in kidney by lithium treatment whereas 92-kDa protein was underexpressed both in kidney and liver.

Neuroprotective and neurotrophic effects of long term lithium treatment in mouse brain.

Since the worldwide approval of lithium therapy in 1970, lithium has been used for its anti-manic, antidepressant, and anti-suicidal effects. The last decade has witnessed the following discoveries about its neuroprotective and neurotrophic properties, yet the therapeutic mechanisms at the cellular level remain not-fully defined. We have undertaken the present study to determine if chronic lithium treatment, at therapeutically relevant concentrations, exerts neurotrophic/neuroprotective effects in the mouse brain in vivo. For this purpose, 10 months aged mice were fed for 3 months on food pellets contained 1 g (L1 group) or 2 g (L2 group) lithium carbonate/kg, resulting in serum concentrations of 0.4 and 0.8 mM, respectively. The evaluation of lipid peroxidation level and the activities of catalase, superoxide-dismutase and glutathione-peroxidase showed that chronic Li administration, at therapeutic doses doesn't induce oxidative stress in brain tissue. No changes in the expression levels of molecular chaperones, namely, the HSP70, and HSP90 heat shock proteins and the GRP94 glucose-regulated protein were detected. Moreover, this treatment has caused (1) an increase in the relative brain weight (2) a delay in the age induced cerebral glucose impairment (3) an enhancement of the neurogenesis in hippocampus and enthorinal cortex highlighted by silver impregnation. Under these experimental conditions, no modifications were observed in expression levels of GSK3 and of its downstream target ß-catenin proteins. These results suggested that chronic Li administration, at therapeutic doses, has a neuroprotective/neurotrophic properties and its therapeutic mechanism doesn't implicate GSK3 inactivation.

Protective effect of cactus (Opuntia ficus indica) cladode extract upon nickel-induced toxicity in rats.

The purpose of this study carried out on male Wistar rats, was to evaluate the protective effects of regular ingestion of juice from the prickly pear cactus (Opuntia ficus indica) cladodes against nickel chloride toxicity. Rats were given either normal tap water or water containing 25% of cactus juice for one month. Then, rats of each group were injected daily, for 10 days, with either NiCl(2) solution (4mg (30micromol)/kg body weight) or with the same volume of saline solution (300mM NaCl). Significant increases of lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase activities and of cholesterol, triglycerides and glucose levels were observed in blood of nickel-treated rats. In the liver, nickel chloride was found to induce an oxidative stress evidenced by an increase in lipid peroxidation and changes in antioxidant enzymes activities. Superoxide-dismutase (SOD) activity was found to be increased whereas glutathione peroxidase and catalase activities were decreased. These changes did not occur in animals previously given cactus juice, demonstrating a protective effect of this vegetal extract.

[Effects of low doses of Li carbonate injected into mice. Functional changes in kidney seem to be related to the oxidative status]. / Effets chroniques de faibles doses de carbonate de lithium chez la souris. Relations entre statut oxydant et modifications fonctionnelles et structurales des reins et du cerveau.

Effects of daily injections of lithium carbonate (20, 40 or 80 mg/kg body weight) during 14 and 28 days were investigated in Wistar mice. Attention was paid (1) to changes in concentrations of lithium, creatinine and urea in serum, (2) to level of oxidative stress by measuring lipids peroxidation level and catalase, superoxide-dismutase and glutathione-peroxidase activities, and (3) to changes in the histological structure of brain. The first intraperitoneal injection was followed by a transitory peak of lithium in the blood, reaching 0.25 mM and 1.1 mM and disappearing 6 and 12 h later for the 20 and 80 mg/kg doses, respectively. From the first to the last day of treatment, lithium concentrations in the blood, measured 12 h after the injections, increased from 0 to 0.11 mM (20 mg/kg dose) or 0.25 mM (80 mg/kg dose). The 80 mg/kg treatment induced a renal insufficiency evidenced by an increase of blood creatinine and urea levels. Lithium treatment was found to trigger an oxidative stress in kidney, but not in brain. In kidney, the lipid peroxidation level (TBARS) and the superoxide dismutase and catalase activities were increased. No change in glutathione peroxidase activity was detected. Histology of the brain cortex revealed interesting modifications: thicker neuronal cells and a denser network of dendrites, as compared to controls.

High risk of temporary alteration of semen parameters after recent acute febrile illness.

OBJECTIVE: To report parameters in semen samples and sperm deoxyribonucleic acid integrity in a fertile volunteer presenting a 2-day fever of 39 degrees -40 degrees C. DESIGN: Case report. SETTING: University-affiliated teaching hospital. INTERVENTION(S): None. PATIENT(S): Semen samples from a fertile volunteer of proven fertility were obtained and analyzed before the febrile illness episode and at days 15, 37, 58, 79, and >180 after the fever. MAIN OUTCOME MEASURE(S): Semen parameters (total sperm count, motility a+b, and vitality), sperm protamination state, measured by sperm chromatin structure assay (SCSA) and apoptotic activities, measured by terminal uridine nick-end labeling (TUNEL) assay. RESULTS: Total sperm count significantly decreased at days 15, 37, and 58 after the fever and returned to normal by day 79 after the fever. The percentage of motility significantly decreased at days 15 and 37 after the fever and returned to normal by day 58. Vitality score also showed a slight, although not statistically significant, decrease after the fever. The DNA fragmentation index (DFI, a SCSA parameter), which defines abnormal chromatin structure, significantly increased by 24% and 36% at days 15 and 37 after the fever, respectively, and decreased to 15% and 8% when reaching days 58 and 79 after the fever. High DNA stainability (HDS, a SCSA parameter) also significantly increased at day 37 after the fever. On the other hand, sperm DNA fragmentation, as measured by TUNEL assay, increased up to 23% by day 15 after the fever but this was not statistically significant. CONCLUSION(S): This report demonstrates that a febrile episode can have marked effects on semen parameters and sperm DNA integrity. These results are particularly important for the counseling of infertile couples and in relation to assisted reproductive techniques (ART).

Oxidative stress induced by fluoride in adult mice and their suckling pups.

To assess renal and liver damages in pregnant and lactating mice as well as in their suckling pups, Wistar female mice were given 500 ppm NaF (226 ppm F-) in drinking water from the 15th day of pregnancy until day 14 after delivery. All mice were sacrificed on day 14 after parturition. In the present work, we evaluated the effects of sodium fluoride on histopathological aspects of kidney, antioxidant status, lipid peroxidation levels and on the expression of four stress proteins (namely, the cytosolic heat shock proteins: HSP72, 73, 90 and the reticulum-associated GRP94). Histological studies have shown many abnormalities in mothers and their pups. Biochemical results showed that lipid peroxidation increased in NaF-treated mice, as evidenced by high kidney and liver thiobarbituric acid reactive substance (TBARS) levels. Alteration of the antioxidant system was confirmed by the significant decline of serum total antioxidant status and of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in red blood cells. Besides, fluoride treatment induced a decrease in serum levels of non-enzymatic antioxidants such as uric acid and of some oligoelements: zinc and copper, known to be cofactors of superoxide dismutase (SOD-Cu-Zn). Compared to control group, the 72kDa protein was found to be overexpressed in kidney of 14-day-old mice only. HSP90 expression in liver appeared moderately inhibited in mothers, but decreased significantly in their pups. No significant changes were detected in the expression of 94kDa protein in both liver and kidney. Results showed that fluoride given to dams led to an oxidative stress in mothers as well as in offspring able to induce enhanced lipid peroxidation levels and protein conformational changes, as suggested by stress protein (HSP, GRP) expression changes.

[Impact of green tea on oxidative stress induced by ammonium metavanadate exposure in male rats]. / Impact du thé vert sur l'effet oxydatif du métavanadate d'ammonium chez le rat male pubère.

Transitional metals, as vanadium, are known to exert noxious effects by generating oxidative stress. Addition of antioxidants in the diet could decrease the cytotoxic effect related to the oxidative stress. The present study, carried out in Wistar rats, is a contribution to the evaluation of protective effects of green tea Camellia sinensis, which is known to be rich in antioxidant compounds (polyphenols...). Rats were divided into four groups: (C) was control, (V) was given ammonium metavanadate (AMV), (TH) was given herbal tea as drink (66 g/l) and TH + V was given tea and metavanadate. Group (TH) was given herbal tea one month before vanadium treatment. Metavanadate was daily i.p. injected (5 mg NH4VO3/kg body weight) for 10 days. (C) and (TH) groups received i.p. injections of 0.9% NaCl during the same period. Changes in lipid peroxidation levels (TBARS) in kidney, liver and testes, serum concentrations of vitamins E and A and superoxidismutase (SOD) and catalase (CAT) activities in blood cells were determined. One month pre-treatment with green tea, followed by 10 days of treatment (TH) did not change TBARS in liver and testes as compared to controls, but induced a clear decrease of TBARS in kidneys. Intraperitoneal administration of AMV to rats (V) induced a time-dependant increase of TBARS in kidney, liver and testes that was lowered in rats (V + TH) drinking tea. Vitamin E concentrations were found to be drastically decreased from day 1 to 10 in rats (V). Vitamin A concentration was decreased at day 10 only. Drinking tea lowered AMV inhibitory effects in rats (V + TH), and conversely an increase of vitamins A and E concentrations were found at day 10. SOD and catalase activities were found increased in the blood cells from day 1 to day 5 and conversely decreased at day 10. In contrast, associated to green tea, AMV did not affect SOD and catalase activities compared to controls.

Lipid peroxidation and HSP72/73 expression in rat following cadmium chloride administration: interactions of magnesium supplementation.

OBJECTIVE: to determine whether magnesium (Mg) supplementation could have a protective effect against the cadmium (Cd)-induced oxidative stress in liver, kidneys and testes of adult male rats. Stress was evaluated by measuring lipid peroxidation by thiobarbituric acid reactive substances (TBARS) and the heat shock protein (HSP) 72/73 expression. CdCl2 injections (2.5mg/day/kg body weight) for 10 days resulted in a time dependent increase of Cd accumulation in liver, kidney and testes, the highest levels being found in liver (400 microg/g dried tissue). At the same time, an increase of lipid peroxidation was observed. The effect was maximal at day 1 of Cd treatment in liver and testes, and later (day 5) in kidney. Then, Cd-induced lipid peroxidation decreased, suggesting the activation of antioxidant defense mechanisms. Injections of Mg SO4 (300-600 mg/day/kg body weight) reduced in a dose-dependent manner Cd-induced lipid peroxidation in liver and kidney as well as the accumulation of Cd in liver, kidney and testes. In testes, a protective effect of Mg was found only during the early phase of Cd-poisoning. On days 5 and 10, lipid peroxidation was even increased as compared to controls. In liver and testes only the constitutive HSP73 was detected whereas in kidney both HSP73 and the inducible HSP72 were expressed. HSP72/73 expression was not significantly increased by Cd and HSP73 was even lowered in kidney, probably due to the strong dose used. These results were not modified by Mg injections. CONCLUSION: Mg supplementation can reduce Cd accumulation in organs and lipid peroxidation related to Cd administration.

Relationship between toxicity of selected insecticides and expression of stress proteins (HSP, GRP) in cultured human cells: effects of commercial formulations versus pure active molecules.

Three carbamate (formetanate, methomyl, pyrimicarb) and one pyrethroid (bifenthrin) insecticides were investigated both as pure chemicals and as commercial formulations in order to unveil possible toxic effects of additives and solvents present in the commercial formulations and to evaluate the cellular stress response as a defense mechanism. Toxic effects were evaluated on A549 cells, derived from a human lung carcinoma, by measuring (1) threshold concentrations leading to a decrease of the growth rate (LOEC), (2) sublethal concentrations (SC) which arrested growth without killing the cells, and (3) expression levels of several stress proteins, i.e., HSP27, HSP72/73, HSP90, GRP78, and GRP94. As compared to the pure active molecule, LOEC appeared at lower concentrations when using the commercial formulations, i.e., Dicarzol (formetanate), Lannate20 (methomyl) and Talstar or Kiros EV (bifenthrin). Propylene glycol and propylene glycol monomethyl ether, respectively, present in Talstar and kiros, do not account for the high toxicity of these commercial formulations and do not potentiate the toxicity of bifenthrin. Additive but not synergistic adverse effects were observed when cells are exposed to a mixture of 4 different commercial formulations. Our results show that the concentrations of active molecules recommended in flori-cultural general use or for spray preparations are much higher than SC concentrations, as determined on A549 pulmonary cells. GRP78 was up-regulated by all the insecticides, commercial preparations being more efficient to trigger the stress reaction. This suggests that insecticides and additives present in commercial formulations disrupt ER functions. Conversely, HSP72/73 was found to be down-regulated by all the insecticides. This seems to be related with a decrease of protein synthesis in the cytosol, as a result of the ER unfolded protein response. Indeed, tunicamycin, known to inhibit N-linked glycosylation in the ER, was found to induce a similar inverse correlation between GRP78 overexpression and HSP72/73 under-expression. Expression of GRP94 was found to be increased and HSP27 lowered by the highest concentrations of bifenthrin commercial formulations. Methomyl and Lannate20 only induced an under-expression of HSP90.

[Side effects of low serum lithium concentrations on renal, thyroid, and sexual functions in male and female rats]. / Effets secondaires de faibles concentrations de lithium sur les fonctions rénales, thyroïdiennes et sexuelles chez des rats matures mâles et femelles.

The present study, carried out in rats, is a contribution to explore physiological mechanisms underlying lithium toxicity. Male and female mature rats were divided into three groups and fed on commercial pellets: group (C) was control, group (Li1) was given 2000 mg lithium carbonate/kg of food, and group (Li2) was given 4000 mg lithium carbonate/kg of food. If we take into account the BW of the rats and the quantity of food they eat every day, we can estimate that the quantities of lithium carbonate ingested per day and kilogram of BW are, respectively, for the groups Li1 and Li2, of 212 mg (5,738 mmol Li) and 323 mg (8,742 mmol Li) for the males, and about 190 mg (5,142 mmol Li) and 289 mg (7,822 mmol Li) for the females. After 7, 14, 21 and 28 days, serum concentrations of lithium, creatinine, free triiodothyronine (FT3) and thyroxine (FT4), testosterone and estradiol were measured. Attention was also paid to growth rate and a histological examination of testes or vaginal mucosa was carried out. In treated rats, a dose-dependent loss of appetite and a decrease in growth rate were observed together with polydipsia, polyuria, and diarrhoea. Lithium serum concentrations were found to increase from 0.44 mM (day 7) to 1.34 mM (day 28) in Li1 rats and from 0.66 to 1.45 mM (day 14) in Li2 rats. Treatment was stopped at day 14 in Li2 rats because of a high mortality. The significant increase of creatinine that appeared, respectively, at day 7 and 14 in Li2 and Li1 rats shows that serum lithium concentrations ranging from 0.62 to 0.75 mM were able to induce renal insufficiency, secondarily leading to a time-dependent rise in lithium serum concentrations. A significant decrease of serum thyroxine (FT4) and triiodothyronine (FT3) levels was observed for lithium concentrations ranging from: 0.66 to 0.75 mmol l(-1) (Li2 rats) to 1.27 mmol l(-1) (Li1 rats). This effect was more pronounced for FT3, suggesting a defect of FT4/FT3 conversion. Under lithium treatment, the testosterone level decreased and spermatogenesis was stopped. By contrast, in treated female rats, estradiol level was found to be increased in a dose-dependent manner and animals were blocked in the diestrus phase at day 28. These results show that lithium can rapidly induce toxic effects in the rat at concentrations used for the treatment of bipolar disorders in human.

[Interaction of intermittent fasting on the cytotoxic effects of nickel in rats at puberty]. / Interaction du jeûne intermittent sur les effets cytotoxiques rénaux du nickel chez le rat pubère.

This study has been undertaken with the aim of determining if intermittent fasting can be considered as a malnutrition that amplifies, according to numerous authors, the cytotoxic effects of environmental pollutants. We have used 200 male and female rats of 'Wistar' descent (BW approximately 180 g). These rats are distributed into two groups: some nourished daily (N) and others nourished one day over two (J) during a month. By the end of this month, each group is itself split into two subgroups, the first one receiving tap water as drinkable water (group NO and JO); the other one receiving the water enriched by the chloride of nickel at the rate of 100 mg NiCl2 per litre (groups NNi and JNi). Intermittent fasting goes on parallel to treatment during 2, 4, 10, 16, 30 and 60 days. For the exploration of the protein of stress (HSP) and of the metallothioneines (MT), the nickel is administered by injection at the rate of 4 mg NiCl2 per kg during 1 and 5 days. Our results show that the mineral seric and renal balance does not vary in conditions of intermittent fasting compared with conditions of normal nutrition. Our study show than that nickel induced a renal deficiency by decreasing the creatinemia and uraemia rate, which is confirmed by the histological study, and induced a decrease in the induction of the HSP73 and in the synthesis of the (MT). The association of nickel with intermittent fasting would inhibit these effects. In conclusion, intermittent fasting does not manifest itself as a malnutrition that amplifies the nickel's effects. Nevertheless, it seems that the calorific lack provoked by intermittent fasting is beneficial to the body by increasing its performances against the cytotoxic effects induced by nickel.

Expression of stress-related genes in a cadmium-resistant A549 human cell line.

This study was designed to explain the basis for Cd-acquired tolerance of A549 cells cultured in the presence of Cd. Thirty-day exposure of cultured human pneumocytes (A549 cell line) to 10 microM Cd was previously found to induce an acquired resistance persisting over several weeks of culture. Moreover, these Cd-resistant cells (R-cells) were found to proliferate faster than controls. No difference was found between R-cells and control cells (S-cells) concerning the basal and Cd-induced level of metallothioneins expression. However, after exposure to Cd, cell glutathione levels were unchanged in R-cells while they were either increased (at 10 microM Cd) or decreased (at 25 microM Cd) in S-cells. cDNA array analysis showed that genes encoding for (GPx1) glutathione peroxidase, glutathione reductase, catalase, and superoxide dismutase were similarly expressed in R- and S-cells, whereas the gene of (GPx2) glutathione peroxidase was overexpressed in R-cells. Most genes encoding stress proteins were similarly expressed, except for HSP27 and GRP94 genes, which were respectively under- (ratio 0.5 +/- 0.1) and over- (1.8 +/- 0.5) expressed in R-cells. Acute exposure to Cd was found to trigger the upregulation of genes encoding the chaperone proteins HSP90A, HSP27, HSP40, GRP78, HSP72, and HO-1 in S-cells. In R-cells, only HO-1 and HSP72 were overexpressed but at a lower level. This suggests that the Cd-related adverse conditions, leading to protein misfolding, are lowered in R-cells. It is likely that the upregulation of GPx2 in R-cells leads to a higher antioxidant defense in these cells.

[Cytotoxic effects of lead on the endocrine and exocrine sexual function of pubescent male and female rats. Demonstration of apoptotic activity]. / Exploration des effets cytotoxiques du plomb sur la fonction sexuelle endocrine et exocrine chez le rat pubère mâle et femelle. Mise en évidence d'une action apoptotique.

This study deals with the impact of chronic exposure to lead on male and female fertility in rats. Male and female rats (3 months old) were fed on commercial tablets (SICO, Sfax). For drinking, some rats were given distilled water (T = controls), the other ones were given distilled water enriched with lead acetate, either 3 (P1 group) or 6 mg ml-1 (P2 group), for 15, 30, 45, 60 or 90 days. In male rats, absolute and relative weights of testis, epididymis, prostate and seminal vesicles were found to significantly decrease at day 15 in the P2 group and at day 45 in the P1 group. However, at day 60, these absolute and relative weights returned to control values. Lead-induced pathological changes in spermatogenesis were observed at day 15 by histological study: arrest of cell germ maturation, changes in the Sertoli cells, and presence of apoptotic cells revealed by borated toluidine blue in the testis. Presence of lead deposits was observed after histochemical staining using sodium rhodizonate. Serum testosterone level was found to be lowered at day 15 in both (P1) and (P2) groups, to display a peak at day 60, then to return to controls values, in spite of the continuation of the treatment. In female rats, absolute and relative weights of ovary and uterus were found unchanged. The vaginal smears practiced in females revealed the oestrus phase in all groups. Exposed females were mated with control males, and fecundity was assessed 15 days later by counting the number of pregnancies and the number of concepti per pregnancy. Fertility was found to be reduced in females of P1 and P2 groups as compared to control females (T group). Lead level in blood was found to be poorly correlated with the level of poisoning, whereas lead accumulation in tail was found to be dose-dependent. Therefore, lead accumulation in tail appears as a more reliable biomarker of exposure to lead. In summary, our study shows that chronic exposure to lead causes a double sexual disorder in rats: first, disorder deals with the hormonal function, which is affected at the early stages of poisoning, but is rapidly corrected; second, disorder deals with the genital tract, affecting the testis and the ovary, resulting in a reduced fertility in both P1 and P2 females, in spite of the presence of a normal oestrus. The cytotoxic effect of lead in males seems to be related to an apoptotic process.