Sex differences in the effect of acute fasting on excitatory and inhibitory synapses onto ventral tegmental area dopamine neurons
Bibliographic record
Abstract
KEY POINTS: Fasting can increase motivation for food and can energize reward-seeking. Ventral tegmental area (VTA) dopamine neurons respond to motivationally relevant information and fasting can influence mesolimbic dopamine concentration. An acute overnight fast differentially alters food approach behaviours and excitatory synaptic transmission onto VTA dopamine neurons of male or female mice. While inhibitory synapses onto VTA dopamine neurons are not altered by fasting in male or female mice, male mice had strengthened excitatory synapses whereas female mice had increased endocannabinoid-mediated short-term plasticity at excitatory synapses. These results help us understand how fasting differentially influences excitatory synaptic transmission onto dopamine neurons and may inform different strategies for fasting-induced food seeking by male and female mice. ABSTRACT: Dopamine neurons in the ventral tegmental area (VTA) are important for energizing goal-directed behaviour towards food and are sensitive to changes in metabolic states. Fasting increases the incentive motivation for food and the mobilization of energy stores and has sex-dependent effects. However, it is unknown how acute fasting alters excitatory or inhibitory synaptic transmission onto VTA dopamine neurons. An acute 16 h overnight fast induced increased food-seeking behaviour that was more predominant in male mice. Fasting increased miniature excitatory postsynaptic current frequency and amplitude in male, but not female, mice. This effect was not due to altered release probability as there was no change in the paired pulse ratio, nor was it due to an altered postsynaptic response as there was no change in the AMPA receptor/NMDA receptor ratio or response to glutamate uncaging. However, this effect was consistent with an increase in the number of release sites. In addition, depolarization-induced suppression of excitation, a measure of short-term endocannabinoid-mediated plasticity, was enhanced in female but not male fasted mice. There were no fasting-induced changes at inhibitory synapses onto dopamine neurons of male or female mice. Taken together, these results demonstrate that fasting influences excitatory synapses differentially in male and female mice, but preserves inhibitory synapses onto dopamine neurons, indicating that the mesolimbic circuits of male and female mice respond differently to acute energy deprivation.
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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 | 0.000 |
| 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".