Neuropathological Studies of Rats Following Multiple Exposure to Tri-Ortho-Tolyl Phosphate, Chlorpyrifos and Stress
| Autor: | Jonathan Hinckley, Marion Ehrich, Laird Williams, Lisa Flory, Lynn Tobias, Lesley Colby, Sandra Hancock, Bernard S. Jortner |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Male
Insecticides Degeneration (medical) Toxicology Hippocampus Nerve Fibers Myelinated 030226 pharmacology & pharmacy 0403 veterinary science chemistry.chemical_compound 0302 clinical medicine Plasticizers Corticosterone Chronic stress Toxicity Tests Chronic 04 agricultural and veterinary sciences Tritolyl Phosphates Drug Combinations medicine.anatomical_structure Spinal Cord Chlorpyrifos Neurotoxicity Syndromes Glucocorticoid medicine.drug medicine.medical_specialty Dose 040301 veterinary sciences Injections Subcutaneous Drinking Pathology and Forensic Medicine Gracile fasciculus 03 medical and health sciences Stress Physiological Internal medicine medicine Animals Rats Long-Evans Molecular Biology Dose-Response Relationship Drug business.industry Cell Biology Spinal cord Axons Rats Endocrinology chemistry Nerve Degeneration business Carboxylic Ester Hydrolases |
| Zdroj: | Toxicologic Pathology. 33:378-385 |
| ISSN: | 1533-1601 0192-6233 |
| DOI: | 10.1080/01926230590930254 |
| Popis: | Adult male Long-Evans rats were exposed to 2 neurotoxic organophosphates in a setting of chronic stress, over a 63-day period. The organophosphates were tri- ortho-tolyl phosphate (TOTP) administered in 14 gavage doses of 75, 150 or 300 mg/kg, and chlorpyrifos, given in two 60 mg/kg subcutaneous exposures. Corticosterone was added to the drinking water at 400 μg/ml, to model aspects of chronic stress. These compounds/dosages were administered individually and in combination, with appropriate controls, giving rise to 16 experimental groups. The major neuropathologic change was the presence of axonal degeneration progressing to myelinated fiber degeneration, mainly in distal regions of selected fiber tracts and peripheral nerve, seen in animals sacrificed on experimental day 63. The cervical spinal cord and medullary levels of the sensory gracile fasciculus were most prominently affected. This axonopathy/fiber degeneration was TOTP dose-related at the 300 and 150 mg/kg levels. There was association of this lesion with inhibition of the enzyme neurotoxic esterase in hippocampal tissue from TOTP-treated rats. Such an association categorizes this disease process as organophosphate ester-induced delayed neuropathy. Neither chlorpyrifos nor corticosterone appeared to contribute to the neuropathic events or the enzyme inhibition. A cohort of rats was maintained on the corticosterone dosing, but without additional exposure to TOTP or chlorpyrifos, for an additional 27 days. When these rats were examined on day 90, the nerve fiber degeneration had progressed in all experimental groups administered the 300 mg/kg dose of TOTP (lower doses were not studied at the 90-day interval), although hippocampal neurotoxic esterase had returned to control values. |
| Databáze: | OpenAIRE |
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