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Pontine GABAergic pathways: role and plasticity in the hypoxic ventilatory response
Yee-Hsee Hsieh1, Ruth E Siegel, Thomas E Dick
1Department of Pharmacology, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4965, USA.
Respiratory Physiology & Neurobiology
|November 3, 2004
Summary
The hypoxic ventilatory response (HVR) is shaped by pontine GABAergic pathways. Blocking these pathways alters breathing during hypoxia, and chronic hypoxia induces molecular changes in the pons, reducing HVR.
Area of Science:
- Neuroscience
- Respiratory Physiology
- Molecular Biology
Background:
- The hypoxic ventilatory response (HVR) is crucial for oxygen homeostasis.
- GABAergic pathways in the ventrolateral (vl) pons play a role in regulating breathing.
- Adaptation to chronic hypoxia involves neural plasticity.
Purpose of the Study:
- To investigate the role of pontine GABA(A) receptors in HVR.
- To examine the effects of chronic sustained hypoxia (CSH) on HVR.
- To identify molecular changes associated with HVR plasticity.
Main Methods:
- HVR was assessed by recording phrenic nerve activity (PNA) in response to acute hypoxia.
- GABA(A) receptors in the vl pons were blocked using bicuculline injections.
- Animals were conditioned to CSH using a hypobaric chamber.
- GABA(A) receptor subunit mRNA expression in the pons and medulla was analyzed.
Main Results:
- Blocking vl pontine GABA(A) receptors prolonged expiratory duration during hypoxia.
- CSH attenuated the HVR compared to naive animals.
- CSH induced alpha6 and delta GABA(A) receptor subunit mRNAs in the pons.
Conclusions:
- Pontine GABAergic pathways are critical for modulating the HVR.
- CSH induces plasticity in the HVR, involving changes in GABA(A) receptor subunits in the pons.
- These findings highlight the importance of pontine GABAergic signaling in hypoxic adaptation.