Inhibition of calcium ATPase activity in rat brain and muscle by chlordecone

Proteomic response of Macrobrachium rosenbergii hepatopancreas exposed to chlordecone: Identification of endocrine disruption biomarkers?

The present work is the first study investigating the impacts of chlordecone, an organochlorine insecticide, on the proteome of the decapod crustacean Macrobrachium rosenbergii, by gel-free proteomic analysis. The hepatopancreas protein expression variations were analysed in organisms exposed to three environmental relevant concentrations of chlordecone (i.e. 0.2, 2 and 20µg/L). Results revealed that 62 proteins were significantly up- or down-regulated in exposed prawns compared to controls. Most of these proteins are involved in important physiological processes such as ion transport, defense mechanisms and immune system, cytoskeleton dynamics, or protein synthesis and degradation. Moreover, it appears that 6% of the deregulated protein are involved in the endocrine system and in the hormonal control of reproduction or development processes of M. rosenbergii (e.g. vitellogenin, farnesoic acid o-methyltransferase). These results indicate that chlordecone is potentially an endocrine disruptor compound for decapods, as already observed in vertebrates. These protein modifications could lead to disruptions of M. rosenbergii growth and reproduction, and therefore of the fitness population on the long-term. Besides, these disrupted proteins could be suggested as biomarkers of exposure for endocrine disruptions in invertebrates. However, further investigations are needed to complete understanding of action mechanisms of chlordecone on proteome and endocrine system of crustaceans.

ATSDR evaluation of health effects of chemicals. II. Mirex and chlordecone: health effects, toxicokinetics, human exposure, and environmental fate

This document provides public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective of the toxicology of mirex and chlordecone. It contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health. Additional substances will be profiled in a series of manuscripts to follow.

Effects of chlordecone and malnutrition on immune response in rats

Effect of Chlordecone (Cd) and malnutrition on total body and spleen weights, and plaque forming cells (PFC) were studied. Rats were fed on normal, calcium (Ca-D), protein (P-D) or Ca+P-deficient diets containing 0, 10 or 100 ppm of Cd for 2 or 4 weeks. High (95-100%) mortality was observed in malnourished rats treated with 100 ppm of Cd for 4 weeks. A slight decrease in body weight and an increase in spleen weight was observed in normal but not malnourished rats treated with 10 ppm of Cd for 4 weeks. PFC were significantly increased in both malnourished and Cd-treated rats. Similar increase in PFC was observed in rats fed on Ca-D but not P-D diet containing 10 or 100 ppm of Cd. Whereas, rats fed on Ca+P-D diet containing 100 ppm of Cd exhibited a significant decrease in PFC.

Inhibition of calmodulin-activated Ca2(-)-ATPase by endosulfan in rat brain

Endosulfan stereoisomer I (E-I) inhibited the activity of calmodulin-dependent Ca2+-ATPase to an extent of 15-55% in a concentration range of 1-20 microM under in vitro conditions without significantly affecting the basal enzyme activity. The less toxic isomer E-II produced no significant inhibition of Ca2+-ATPase activity up to a concentration of 40 microM. The inhibition of Ca2+-ATPase by E-I was noncompetitive with respect to substrate, free from the influence of calcium, and competitively inhibited calmodulin activation kinetics. Reconstitution with the exogenous addition of calmodulin (5 and 20 micrograms) restored the inhibited enzyme activity, indicating nonspecific binding of E-I with calmodulin. Both calmodulin-activated and basal enzyme activity was inhibited significantly in rats fed E-I (3 mg/kg body weight) for 15 d. These data suggest that endosulfan may modulate calmodulin-related events in neurons and result in its neurotoxicity.

Effects of chlordecone and chlordecone alcohol on isolated ovine erythrocytes

Chlordecone (CHLO, 14-30 microM) and chlordecone alcohol (CHLO ALC, 10-23 microM) altered the permeability of isolated ovine erythrocytes as evidenced by a concentration- and time-dependent induction of K+ efflux and hemolysis. Hemolysis, but not K+ efflux, was markedly delayed when the erythrocytes were suspended in isotonic sucrose. CHLO-induced and CHLO ALC-induced hemolysis and K+ efflux were dependent on the pH of the external media. Raising the pH from 6.5 to 9.4 inhibited CHLO-induced K+ efflux and hemolysis, whereas CHLO ALC-induced K+ efflux and hemolysis were increased. Low concentrations of both compounds (1-4 microM) protected erythrocytes against hypotonic hemolysis. Neither CHLO (30 microM) nor CHLO ALC (23 microM) induced the release of trapped K+ from KSCN-loaded unilamellar liposomes made from erythrocyte lipids. It is postulated that CHLO and CHLO ALC interact with membrane proteins and increase the permeability of the membrane to cations. This interaction leads to colloid-osmotic hemolysis.

Chlordecone inhibition of calmodulin activated calcium ATPase in rat brain synaptosomes

The effect of chlordecone on Ca2+-ATPase of rat brain synaptosomes in the absence and presence of calmodulin was determined in vitro and in vivo. A 50% activation of Ca2+-ATPase was obtained at 5 micrograms calmodulin per 1.5 ml reaction mixture containing 50 micrograms synaptosomal protein. Chlordecone inhibited Ca2+-ATPase in the absence of calmodulin with an IC50 of 10 microM, whereas chlordecone at 1.0 microM, which had no effect on the basal enzyme activity, completely inhibited the calmodulin activated Ca2+-ATPase. Chlordecone-treated rats showed a significant reduction in calmodulin levels in brain P2 fraction. Brain synaptosomal Ca2+-ATPase in chlordecone-treated rats showed a 50% reduction, which was restored by exogenously added calmodulin. These results suggest that chlordecone may be altering calmodulin-regulated synaptic processes in the brain.