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Updated: May 3, 2026
A Method of Nodose Ganglia Injection in Sprague-Dawley Rat
Published on: November 25, 2014
[Ventrolateral periaqueductal gray metabotropic glutamate receptor subtypes 7 and 8 mediate opposite effects on
Na Sun1, Lingheng Kong, Ligang Niu
1Department of Basic Medicine, Xi'an Medical University, Xi'an 710021, China.
Objective:
To investigate the role of ventrolateral periaqueductal gray (VL-PAG) metabotropic glutamate receptors subtype 7 and 8 (mGluR 7/8) in descending modulation of cardiosomatic motor reflex (CMR) in rats.
Methods:
AMN082 (agonist of mGluR 7) and DCPG (agonist of mGluR 8) were injected into the VL-PAG of a rat model of CMR to observe their effects in modulating CMR. The raphe magnus nucleus (NRM) or the gigantocellular reticular nucleus (Gi) was then damaged, and the changes in VL-PAG descending modulation were observed.
Results:
Selective activation of mGluR 7 of the VL-PAG by AMN082 obviously facilitated capsaicin (CAP)-induced CMR (P<0.05), which was suppressed by DCPG-induced mGluR 8 activation (P<0.05). These facilitatory or inhibitory effects were completely reversed by group III mGluR antagonist MSOP. Damaging the NRM of VL-PAG main relay nucleus did not significantly affect the facilitatory effect produced by AMN082 microinjection (P>0.05), but partially attenuated the inhibitory effect of DCPG microinjection (P<0.05). Both the facilitatory effect of AMN082 and the inhibitory effect of DCPG were reduced obviously after bilateral Gi damage (P<0.05).
Conclusion:
VL-PAG mGluR 7 and mGluR 8 mediate biphasic regulation of CMR in rats probably through activation of different sub-nuclei and different neurons in the rostroventral medulla.
Insights
Metabotropic glutamate receptors 7 and 8 in the ventrolateral periaqueductal gray (VL-PAG) play a dual role in modulating the cardiosomatic motor reflex (CMR). Activation of mGluR 7 facilitates CMR, while mGluR 8 activation inhibits it.
Area of Science:
- Neuroscience
- Neuropharmacology
- Cardiovascular Physiology
Context:
- The cardiosomatic motor reflex (CMR) is a crucial physiological response.
- Descending pathways from the brainstem modulate autonomic and somatic functions.
- Metabotropic glutamate receptors (mGluRs) are implicated in various neural processes.
Purpose:
- To investigate the specific roles of ventrolateral periaqueductal gray (VL-PAG) metabotropic glutamate receptors subtype 7 and 8 (mGluR 7/8) in the descending modulation of the capsaicin-induced cardiosomatic motor reflex (CMR) in rats.
- To elucidate the downstream pathways involved in this modulation.
Summary:
- Selective activation of VL-PAG mGluR 7 by AMN082 facilitated CMR, while mGluR 8 activation by DCPG suppressed it.
- These effects were reversed by a group III mGluR antagonist.
- Modulation involved distinct pathways, with the gigantocellular reticular nucleus (Gi) being crucial for both facilitatory and inhibitory effects, while the raphe magnus nucleus (NRM) was primarily involved in the inhibitory pathway.
Impact:
- This study reveals a biphasic regulatory mechanism of CMR by VL-PAG mGluR 7 and mGluR 8.
- Findings suggest differential involvement of sub-nuclei within the rostroventral medulla.
- Provides insights into the neurobiological underpinnings of autonomic and somatic reflex control.
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