Gabapentin Increases a Tonic Inhibitory Conductance in Hippocampal Pyramidal Neurons
Bibliographic record
Abstract
BACKGROUND: The mechanisms underlying the therapeutic actions of gabapentin remain poorly understood. The chemical structure and behavioral properties of gabapentin strongly suggest actions on inhibitory neurotransmission mediated by gamma-aminobutyric acid (GABA); however, gabapentin does not directly modulate GABAA or GABAB receptors. Two distinct forms of GABAergic inhibition occur in the brain: postsynaptic conductance and a persistent tonic inhibitory conductance primarily generated by extrasynaptic GABAA receptors. The aim of this study was to determine whether gabapentin increased the tonic conductance in hippocampal neurons in vitro. As a positive control, the effects of vigabatrin, which irreversibly inhibits GABA transaminase, were also examined. METHODS: GABAA receptors in hippocampal neurons from embryonic mice were studied using whole cell patch clamp recordings. Miniature inhibitory postsynaptic currents and the tonic current were recorded from cultured neurons that were treated for 36-48 h with gabapentin, vigabatrin, or gabapentin and vigabatrin. To determine whether gabapentin increased the expression of GABAA receptors, Western blots were stained with antibodies selective for alpha1, alpha2, and alpha5 subunits. RESULTS: GABAA receptors were insensitive to the acute application of gabapentin, whereas chronic treatment increased the amplitude of the tonic current threefold (EC50 = 209 microm) but did not influence miniature inhibitory postsynaptic currents. Vigabatrin increased the tonic conductance, and the maximally effective concentration did not occlude the actions of gabapentin, which suggests that these compounds act by different mechanisms. Neither gabapentin nor vigabatrin increased the expression of GABAA receptors in the neurons. CONCLUSIONS: Gabapentin increases a tonic inhibitory conductance in mammalian neurons. High-affinity GABAA receptors that generate the tonic conductance may detect small increases in the ambient concentration of neurotransmitter caused by gabapentin.
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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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".