TY - JOUR
T1 - The gigantocellular depressor area revisited
AU - Aicher, Sue A.
N1 - Funding Information:
The experiments described in this paper were conducted at Cornell University Medical College, so long ago that the name had not yet been changed. The work was supported by the Program Project Grant directed by Donald J. Reis (HL18974) and by HL56301 (SAA) and an Established Investigator Award from the American Heart Association (SAA). I would like to thank Dr Shaun Morrison for helpful discussions of these data, Ms Jennifer Mitchell for proofreading the paper, Ms Sarita Sharma for histological assistance, and Ms Kristin Swanson for her assistance with the photomicrographs.
PY - 2003/10
Y1 - 2003/10
N2 - 1. In studies conducted with Dr Donald Reis we described a functionally distinct region of the rat medullary reticular formation that we called the Gigantocellular Depressor Area (GiDA). The GiDA was defined as a region from which vasodepressor and sympathoinhibitory responses were evoked by nanoinjections of glutamate. We later showed that cells in the GiDA project to autonomic nuclei in the medulla, brainstem, and spinal cord, including the intermediolateral cell column. We also showed that kainic acid lesions of the GiDA induce hypertension and block the baroreceptor reflex evoked by electrical stimulation of the aortic depressor nerve. The present studies describe the effects of muscimol nanoinjections into the GiDA 2. Nanoinjections of muscimol were made in the GiDA of anesthetized rats and changes in arterial pressure, heart rate, and responses to aortic depressor nerve stimulation were measured. 3. Bilateral nanoinjections of muscimol into the GiDA evoke an increase in arterial pressure and lead to fulminating hypertension. Unilateral injections of muscimol into the GiDA block the baroreflex response evoked by electrical stimulation of the ipsilateral aortic depressor nerve, However, these unilateral injections of muscimol into the GiDA evoked profound falls in arterial pressure to nearly spinal levels. In spite of this fall in blood pressure, heart rate also decreased significantly and there was not a compensatory tachycardia, Both the arterial pressure and baroreceptor responses required several hours to recover following the muscimol injections. 4. Although these data are consistent with the proposal that the GiDA is critical for the baroreflex, the opposing effects on blood pressure of unilateral and bilateral injections of muscimol are difficult to reconcile with our current models of central sympathetic regulation.
AB - 1. In studies conducted with Dr Donald Reis we described a functionally distinct region of the rat medullary reticular formation that we called the Gigantocellular Depressor Area (GiDA). The GiDA was defined as a region from which vasodepressor and sympathoinhibitory responses were evoked by nanoinjections of glutamate. We later showed that cells in the GiDA project to autonomic nuclei in the medulla, brainstem, and spinal cord, including the intermediolateral cell column. We also showed that kainic acid lesions of the GiDA induce hypertension and block the baroreceptor reflex evoked by electrical stimulation of the aortic depressor nerve. The present studies describe the effects of muscimol nanoinjections into the GiDA 2. Nanoinjections of muscimol were made in the GiDA of anesthetized rats and changes in arterial pressure, heart rate, and responses to aortic depressor nerve stimulation were measured. 3. Bilateral nanoinjections of muscimol into the GiDA evoke an increase in arterial pressure and lead to fulminating hypertension. Unilateral injections of muscimol into the GiDA block the baroreflex response evoked by electrical stimulation of the ipsilateral aortic depressor nerve, However, these unilateral injections of muscimol into the GiDA evoked profound falls in arterial pressure to nearly spinal levels. In spite of this fall in blood pressure, heart rate also decreased significantly and there was not a compensatory tachycardia, Both the arterial pressure and baroreceptor responses required several hours to recover following the muscimol injections. 4. Although these data are consistent with the proposal that the GiDA is critical for the baroreflex, the opposing effects on blood pressure of unilateral and bilateral injections of muscimol are difficult to reconcile with our current models of central sympathetic regulation.
KW - Arterial blood pressure
KW - Baroreceptor reflex
KW - Gigantocellular reticular formation
KW - Muscimol
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U2 - 10.1023/A:1025011827220
DO - 10.1023/A:1025011827220
M3 - Article
C2 - 14514009
AN - SCOPUS:0042317213
SN - 0272-4340
VL - 23
SP - 479
EP - 490
JO - Cellular and Molecular Neurobiology
JF - Cellular and Molecular Neurobiology
IS - 4-5
ER -