Synaptic connections between GABAergic elements and serotonergic terminals or projecting neurons in the ventrolateral
Fu-Quan Huo1, Tao Chen, Bo-Chang Lv
1Department of Physiology and Pathophysiology, Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University School of Medicine, Xi'an 710061, PR China.
Cerebral Cortex (New York, N.Y. : 1991)
|November 5, 2008
Summary
Researchers found that GABAergic interneurons and serotonin play a key role in the ventrolateral orbital cortex (VLO) pain-relief pathway. This study reveals a local circuit in the VLO that modulates pain perception.
Area of Science:
- Neuroscience
- Pain Research
- Neuroanatomy
Background:
- The ventrolateral orbital cortex (VLO) is implicated in the brain's natural pain-relief system.
- This system involves a complex loop connecting the spinal cord, thalamus, VLO, and periaqueductal gray (PAG).
Purpose of the Study:
- To investigate the intricate connections of GABAergic neurons and serotonergic terminals within the VLO.
- To explore the relationship between GABAergic terminals and VLO neurons that project to the PAG.
- To provide morphological evidence for the role of GABAergic modulation in pain relief mediated by 5-HT(1A) receptors.
Main Methods:
- Utilized anterograde and retrograde tracing techniques.
- Combined tracing with immunofluorescence, immunohistochemistry, and electron microscopy.
- Examined GABAergic neurons, serotonergic terminals from the dorsal raphe nucleus (DR), and their synaptic connections.
Main Results:
- A significant majority (93%) of GABAergic neurons in the VLO express the 5-HT(1A) receptor.
- Serotonergic terminals from the DR form symmetrical synapses with GABAergic neuronal cell bodies and dendrites in the VLO.
- GABAergic terminals form symmetrical synapses with GABA(A) receptor-expressing neurons that project to the PAG.
Conclusions:
- A local neuronal circuit involving 5-HTergic terminals, GABAergic interneurons, and projection neurons exists within the VLO.
- Morphological evidence supports the hypothesis that GABAergic modulation is crucial for pain relief induced by 5-HT(1A) receptor activation.
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