Neurochemical Effects of Chronic Dietary and Repeated High-Level Acute Exposure to Chlorpyrifos in Rats
Bibliographic record
Abstract
Very little is known about the effects of chronic exposure to relatively low levels of anticholinesterase insecticides or how the effects of chronic exposure compare to those of higher, intermittent exposure. To that end, adult male rats were fed an anticholinesterase insecticide, chlorpyrifos (CPF), for 1 year at three levels of dietary exposure: 0, 1, or 5 mg/kg/day (0+oil, 1+oil, and 5+oil). In addition, half of each of these groups also received a bolus dosage of CPF in corn oil (“spiked” animals; 60 mg/kg initially and 45 mg/kg thereafter) every 2 months (0+CPF, 1+CPF, 5+CPF). Animals were analyzed after 6 or 12 months of dosing, and again 3 months after cessation of dosing (i.e., “recovery” animals—six experimental groups with n = 4–6/group/time point). Cholinesterase (ChE) activity was measured in retina, whole blood, plasma, red blood cells, diaphragm, and brain [pons, striatum, and the rest of the brain (referred to simply as “brain”)]. Muscarinic receptor density was assessed in retina, pons, and brain, whereas dopamine transporter density and the levels of dopamine and its metabolites were assessed in striatum. Cholinesterase activity at 6 and 12 months was not different in any of the tissues, indicating that a steady state had been reached prior to 6 months. The 1+oil group animals showed ChE inhibition only in the blood, whereas the 5+oil group exhibited ≥50% ChE inhibition in all tissues tested. One day after the bolus dose, all three groups (0+CPF, 1+CPF, 5+CPF) showed ≥70% ChE inhibition in all tissues. Muscarinic receptor density decreased only in the brain of the 5+oil and 5+CPF groups, whereas dopamine transporter density increased only at 6 months in all three spiked groups. Striatal dopamine or dopamine metabolite levels did not change at any time. Three months after CPF dosing ended, all end points had returned to control levels. These data indicate that, although chronic feeding with or without intermittent spiked dosages with CPF produces substantial biochemical changes in a dose- and tissue-related manner, there are no persistent biochemical changes.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".