Differential synaptic inhibition and serotonin 5-HT7 receptor-mediated modulation in identified dorsal horn neurons
Bibliographic record
Abstract
Serotonergic modulation of pain transmission in the spinal cord involves the activation of multiple receptor types, including 5-HT 7 receptors. Activation of spinal 5-HT 7 receptors appears to have a predominant antinociceptive effect in various animal models. Although the serotonergic modulation of dorsal horn circuits has been extensively investigated, information about the specific effects of serotonergic receptors on identified neuron types remains limited. To address this, we have employed transgenic mice expressing channelrhodopsin-2 (ChR2) in inhibitory neurons, under the control of the vesicular GABA transporter (VGAT) promoter. Postsynaptic inhibitory responses (oIPSCs) induced by optogenetic stimulation of spinal cord slices displayed distinct properties in superficial dorsal horn VGAT+ and VGAT- neurons (inhibitory and putative excitatory neurons, respectively). While oIPSCs recorded from VGAT+ neurons showed GABA- and glycine-mediated components of similar amplitudes, oIPSCs from VGAT- neurons were predominantly mediated by glycine. Consistently, immunofluorescence staining for the glycine transporter GlyT2 in mice expressing dTomato in GAD2 neurons revealed that GlyT2+ boutons primarily contact putative excitatory interneurons, which are negative for GAD2. Activation of 5-HT 7 receptors by the agonist LP-211 significantly enhanced both the frequency of spontaneous inhibitory currents and the amplitude of oIPSCs in VGAT- neurons. In minimal optical stimulation experiments, application of LP-211 reduced the number of synaptic failures and increased the quantal content of oIPSCs, indicating presynaptic modulation mediated by 5-HT 7 receptors. Our results suggest that enhanced synaptic inhibition of dorsal horn excitatory interneurons may contribute to the role of 5-HT 7 receptors in suppressing pain transmission at the spinal cord level.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".