The effect of morphine dependance and withdrawel on morphine reward efficacy as evaluated by the intra-cranial self-stimulation rate-frequency function
Bibliographic record
Abstract
An important issue in the drug dependence literature is the extent to which dependence and withdrawal contribute to the motivational forces driving drug taking. One theory asserts that dependent individuals re-administer opiates primarily to remove the negative effects of withdrawal; a second theory predicts that administration of increasing doses is due to motivational desensitization to the acute rewarding effects of opiates. Studies of drug reward utilizing self-administration rates are hard to interpret because of the complex effects of tolerance and drug kinetics on response rate. Since rewards summate, the efficacy of drug rewards can be assessed by their effects on the rewarding effect of electrical brain stimulation. We examined the influence of morphine dependence on the function relating response rate to the pulse frequency of brain stimulation. The M50 index of this function assesses changes in reward efficacy independent of a drugs effect on performance. Rats were randomly assigned to one of 3 groups. A dependent (D) group that received a nightly subcutaneous dose of morphine of 30 mg/kg, a non-dependent (ND) group that received a nightly saline injection or a food deprivation (FD) group that also received nightly saline but food consumption was controlled to match the loss of body weight in the D group. Rats were tested to determine the M50 1-h and 3-h after doses of morphine, and 18+ hr after nightly injections - a time point during which dependent animals are in withdrawal. Doses tested in ascending order were 0mg/kg, 1 mg/kg, 3 mg/kg, 10 mg/kg and 30 mg/kg morphine s.c. administered once a day for three successive days. Morphine decreased the M50 to a dose ceiling after which higher doses caused less facilitation. Morphine 1 mg/kg and 3 mg/kg caused equivalent decrease in M50 in D, ND and FD rats but for D rats the ceiling was shifted up to 10mg/kg. The morphine dose-response curve was otherwise the same in D, ND and FD rats. Additionally, with
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".