Presented at the Experimental Biology Symposium Neurotransmitters and Cardiovascular Regulation, Orlando, Florida, USA, March/April 2001.
The Baroreflex And Beyond: Control Of Sympathetic Vasomotor Tone By Gabaergic Neurons In The Ventrolateral Medulla
Article first published online: 10 DEC 2003
Clinical and Experimental Pharmacology and Physiology
Volume 29, Issue 5-6, pages 514–521, May/June 2002
How to Cite
Schreihofer, A. M. and Guyenet, P. G. (2002), The Baroreflex And Beyond: Control Of Sympathetic Vasomotor Tone By Gabaergic Neurons In The Ventrolateral Medulla. Clinical and Experimental Pharmacology and Physiology, 29: 514–521. doi: 10.1046/j.1440-1681.2002.03665.x
- Issue published online: 10 DEC 2003
- Article first published online: 10 DEC 2003
- baroreceptor reflex;
- blood pressure regulation;
- brain stem;
- C1 cell group;
- sympathetic vasomotor tone
1. Barosensitive, bulbospinal neurons in the rostral ventrolateral medulla (RVLM), which provide the major tonic excitatory drive to sympathetic vasomotor neurons, are prominently inhibited by GABA.
2. A major source of the GABAergic inhibition to presympathetic RVLM neurons arises from an area immediately caudal to the RVLM, known as the caudal ventrolateral medulla (CVLM).
3. Arterial baroreceptor afferents projecting to the nucleus tractus solitarius (NTS) provide a major tonic excitatory input to GABAergic CVLM neurons. These CVLM cells are a critical component for baroreflex-mediated changes in presympathetic RVLM neuronal activity, sympathetic nerve activity (SNA) and arterial pressure (AP).
4. Some GABAergic CVLM neurons are tonically activated by inputs independent of arterial baroreceptors or the NTS, providing a GABAergic-mediated inhibition of the presympathetic RVLM neurons that is autonomous of baroreceptor inputs.
5. GABAergic CVLM neurons appear to play two distinct, yet important, roles in the regulation of sympathetic vasomotor tone and AP. They dampen immediate changes in AP via the baroreflex and tonically inhibit the activity of the presympathetic RVLM neurons by baroreceptor-independent mechanisms. This baroreceptor-independent, GABAergic inhibition of presympathetic RVLM neurons may play an important role in determining the long-term level of sympathetic vasomotor tone and AP.