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R Duffard

Publications and source records attributed to R Duffard.

26 records · Page 2Linked to original sources
PubMed1992

Effects of 2,4-dichlorophenoxyacetic acid on Rhizobium sp. membrane fluidity.

The effects of 1 mM 2,4-Dichlorophenoxyacetic acid on Rhizobium sp. in pure culture was studied. In a previous work it was demonstrated that this herbicide produces an alteration on the saturated to unsaturated phospholipid acyl chains ratio. In the present paper, it was found that this alteration produces a modification on the membrane fluidity in bacteria that had achieved the stationary phase. The same results were obtained when determinations were done in liposomes from sonicated lipids of treated bacteria, indicating that changes in phospholipid acyl chains may be the main cause of membrane fluidity alteration. In addition, it was determined that leucine transport as well as Ca(++)-ATPase activity (a membrane enzyme) was affected under the experimental conditions.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1990

Changes in brain serotonin and 5-hydroxyindolacetic acid levels induced by 2,4-dichlorophenoxyacetic butyl ester.

Brain concentrations of Serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) were determined in male, mother and virgin female adult rats after exposure to 69 mg/kg body weight/day of 2,4-dichlorophenoxyacetic butyl ester (2,4-Dbe) during 15 or 45 consecutive days. Both 5-HT and 5-HIAA concentrations were increased in the brain. These effects reverted to levels even lower than controls, when the animals were fed an untreated diet after the 2,4-Dbe treatment. High 5-HT and 5-HIAA brain concentrations were also observed in adult rats born from treated mothers (during pregnancy and lactancy) and fed with or without treated diet after weaning. Two different effects on serotoninergic system were detected: a transient effect if 2,4-Dbe was given to adult rats in a short period of time and a permanent effect if the herbicide was supplied during pre- and post birth period (rat brain development). However, in utero exposed but lactationally cross-fostered rat pups were not affected, suggesting that prenatal exposure did not have any influence on the postnatal status of the neurotransmitter(s).

2,4-Dichlorophenoxyacetic Acid↗
PubMed1990

Behavioral changes in rats fed a diet containing 2,4-dichlorophenoxyacetic butyl ester.

Oral administration of 2,4-dichlorophenoxyacetic butyl ester (2,4-Dbe) at a dose of 69 mg/kg/day to nulliparous females had no deleterious effects on either open field (OF) and rotarod performance. By contrast, dams treated with 2,4-Dbe during pregnancy exhibited impairments of OF activity, rotarod performance and improved active avoidance learning (AAL) retention. Administration of 2,4-Dbe to 90-day-old intact male rats depressed spontaneous OF activity, acquisition of conditioned avoidance responses (CARs) and rotarod endurance, but improved AAL performance. Castration itself impaired performance in the rotarod test, and improved AAL, but did not alter OF activity significantly. The effects of castration were reversed by exogenous testosterone. In gonadectomized rats, 2,4-Dbe prevented the reversal of the effect of testosterone on the influence of castration on behavior if given concomitantly with the testosterone. However, when the 2,4-Dbe treatment started seven days after testosterone, the 2,4-Dbe effects on OF, rotarod and AAL behaviors were reinstated. Thus, testosterone appears to be important for causing the toxic effects of 2,4-Dbe in rats.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1986

Changes in fatty acid composition in myelin lipids after 2,4-dichlorophenoxyacetic butyl ester treatment.

Previous studies have shown that 2,4-Dichlorophenoxyacetic butyl ester (2,4-D b.e.) causes hypomyelination in chicks born from eggs externally treated and alters the myelin chemical composition. In this paper the effect of 2,4-D b.e. on myelin phospholipid and fatty acid composition has been examined. The results of our investigations show significant variations in the phospholipid composition, with the phosphatidyl inositol content increased and sphingomyelin and phosphatidyl ethanolamine contents diminished. The fatty acid pattern of the individual myelin lipids is also significantly altered, with an important reduction of long chain fatty acids and an increase of saturated fatty acids. The observed changes in the chemical composition implicate alterations in the intrinsic properties of this membrane.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1982

Hatching and lipid composition of chicks brain from eggs treated with 2,4-dichlorophenoxyacetic butyl ester.

Fertilized hen's eggs were painted, before starting incubation, with solutions of commercial 2,4-dichlorophenoxyacetic butyl ester, (0.8 mg, 3.1 mg, 6.3 mg, 9.4 mg and 12.1 mg of pure drug) in ether. Hatchability studies suggest that the fetotoxic effects observed are related to the drug concentration. There are no statistically significant differences between control and treated groups in body weight, cerebral wet, and dry weights and water content. Protein and total lipid levels are dose dependently decreased. Phospholipids are significantly diminished in the 6.3 mg of 2,4-dichlorophenoxyacetic butyl ester group. Gangliosides are increased while cholesterol and glycolipids are diminished; their decrease is inverse to drug concentration. A decrease in glycolipids suggests an alteration of the normal process of myelination.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

Central nervous system myelin deficit in rats exposed to 2,4-dichlorophenoxyacetic acid throughout lactation.

Our results show that 2,4-dichlorophenoxyacetic acid (2,4-D) exposure through mother's milk during the period of rapid myelination (from the 15th to the 25th postnatal days) results in a myelin deficit in the pup's brain and demonstrates the vulnerability of the developing central nervous system (CNS) to 2,4-D. After 100 mg/kg 2,4-D administration to dams, brains of male and female rats show a significant diminution of myelin markers such as monohexosylceramide as well as phospholipids and free fatty acids (FFA) and an increase of cholesteryl esters. Histological studies revealed myelin deficit in some brain regions after 2,4-D treatment. These data indicate that 2,4-D, through the mother's milk, alters the myelination process during a specific postnatal period.

2,4-Dichlorophenoxyacetic Acid↗
PubMedDate not supplied

Detection of 2,4-dichlorophenoxyacetic acid (2,4-D) residues in neonates breast-fed by 2,4-D exposed dams.

Knowing early nutritional status have been shown to be an important factor in determining the activity level of rats later in life, we studied offspring of dams which had received 50, 70 or 700 mg/kg of 2,4-Dichlorophenoxyacetic acid (2,4-D) during nursing. Neonatal tissues and the stomach content (milk) were examined up to 16 post natal days to detect body and organs weight alterations and 2,4-D residues after 2,4-D maternal dosing every-other-day, from post natal day 1. We detected 2,4-D residues in stomach content, blood, brain and kidney of 4-day-old neonates breast-fed by 2,4-D exposed mothers and onward. 2,4-D residues were dose- and exposure-time-dependent. The highest dose impaired body growth, as well as low tissue weights and diminished stomach contents. Levels of 2,4-D residues in stomach content, blood, kidney and brain of post natal rats (age PD 4-PD 16) fed through lactation from dams treated with 2,4-D demonstrated that 2,4-D was transferred to the neonates and the diminished body and tissues weight during this developmental period could be due to a diminished milk intake or/and to the direct 2,4-D toxic effect. Besides, when the herbicide treatment (100 mg 2,4-D/kg) was withdrawn from the dams, 2,4-D residues remained in the stomach content of neonates for at least one week. This fact indicated that dams continued depurating the herbicide through their milk.

2,4-Dichlorophenoxyacetic Acid↗