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Medullary ventral surface GABA receptors affect respiratory and cardiovascular function
Brain Research
|September 23, 1982
Summary
Gamma-aminobutyric acid (GABA) and muscimol applied to Schlaefke's area in cats caused respiratory depression and cardiovascular changes. These findings suggest GABA receptors in this brainstem region modulate vital functions.
Area of Science:
- Neuroscience
- Respiratory Physiology
- Cardiovascular Physiology
Background:
- Previous studies showed GABA and muscimol in cerebrospinal fluid spaces caused cardiorespiratory depression.
- The precise location of action for these effects remained undetermined.
Purpose of the Study:
- To localize the specific brainstem area responsible for the cardiorespiratory effects of GABA and muscimol.
- To investigate the role of GABA receptors in respiratory and cardiovascular control.
Main Methods:
- GABA and muscimol were applied topically to specific areas on the ventral surface of the medulla in anesthetized cats.
- Ventilation, respiratory rate, tidal volume, and arterial blood pressure were monitored.
- Bicuculline, a GABA antagonist, was used to test the specificity of the GABAergic effects.
Main Results:
- Application of muscimol and GABA to Schlaefke's area significantly reduced minute ventilation and tidal volume, causing hypotension and bradycardia.
- These effects were specific to Schlaefke's area, as application to Loeschcke's or Mitchell's areas yielded no significant changes.
- Bicuculline application to Schlaefke's area reversed the depressant effects of muscimol and GABA.
Conclusions:
- GABA receptors are present in Schlaefke's area on the ventral medulla.
- Activation of these GABA receptors leads to respiratory depression, hypotension, and bradycardia.
- GABA likely functions as a key inhibitory neurotransmitter in the central regulation of respiratory and cardiovascular systems.