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Published on: April 9, 2019
Neuronal circuits underlying acute morphine action on dopamine neurons
Marion Jalabert1, Romain Bourdy, Julien Courtin
1Université de Bordeaux, F-33076 Bordeaux, France.
Summary
Morphine increases dopamine neuron firing by targeting the rostromedial tegmental nucleus (RMTg) via opioid receptors. This action is dependent on ventral tegmental area (VTA) glutamatergic input, revealing a key circuit for morphine
Area of Science:
- Neuroscience
- Pharmacology
- Addiction Research
Background:
- Dopamine neurons in the ventral tegmental area (VTA) are crucial for drug addiction.
- The precise neural circuits mediating morphine's effects on VTA dopamine neurons remain unclear.
Purpose of the Study:
- To elucidate the neural circuit through which morphine acutely affects dopamine neurons in rats.
- To define the anatomical and functional roles of specific brain regions in morphine's action.
Main Methods:
- In vivo electrophysiology
- Tract-tracing experiments
- Targeted neuronal inactivation in rats
Main Results:
- Morphine activates VTA μ opioid receptors on rostromedial tegmental nucleus (RMTg) efferents, increasing dopamine neuron firing.
- This effect is dependent on glutamatergic input from the VTA.
- The GABAergic RMTg is identified as a critical target for acute morphine action.
Conclusions:
- A specific neural circuit for acute morphine action on VTA dopamine neurons has been defined.
- The RMTg plays a key role in mediating morphine's effects on dopamine system activity.
- Understanding this circuit provides insight into the neurobiology of opioid analgesia and addiction.
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