THE ONTOGENY OF P-GLYCOPROTEIN IN THE DEVELOPING HUMAN BLOOD BRAIN BARRIER: IMPLICATION FOR OPIOID TOXICITY IN NEONATES
Bibliographic record
Abstract
Neonates have been shown to have a heightened sensitivity to the central depressive effects of opioids compared to older infants and adults. The limited development of P-glycoprotein (P-gp), located on the luminal membrane of the brain endothelial cells, may limit the ability of the neonate to efflux morphine from the brain back to the systemic circulation. Presently, little is known about blood brain barrier P-gp expression during human development. The objective of the study was to determine the ontogeny of P-gp in the human BBB. Postmortem cortex samples from gestational age (GA) 20–26 weeks, GA 36–40 weeks, postnatal age (PNA) 0–3 months, PNA 3–6 months, and adults were immunostained for P-gp. Analysis was carried out by spinning disc confocal microscopy. The intensity of P-gp staining in adults was significantly higher compared to at GA 20–26 weeks (p=0.0002), GA 36–40 weeks (p=0.0002), and PNA 0–3 months (p=0.0044). P-gp intensity at GA 20–26 weeks (p=0.0011), GA 36–40 weeks (p=0.0013), and PNA 0–3 months (p=0.0173) was significantly lower compared to at PNA 3–6 months. P-gp expression in the BBB is limited at birth, increases with postnatal maturation, and reaches adult levels at approximately 3–6 months of age. Given the immaturity of BBB P-gp after birth, morphine may concentrate in the brain. This provides mechanistic support to life threatening opioid toxicity seen with maternal codeine use during breastfeeding.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".