Ventromedial medullary pathway mediating cardiac responses evoked from periaqueductal gray
| Autor: | Patrícia Maria Ferreira, G.C.A. Moraes, Marco Antônio Peliky Fontes, Carlos Henrique Xavier, D. Graziani, Gustavo Rodrigues Pedrino, Mauro Cunha Xavier Pinto, Onésia Cristina Oliveira-Lima, Michelle Mendanha Mendonça, Aline A. Mourão |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Agonist
Cardiac function curve Male medicine.medical_specialty Sympathetic Nervous System medicine.drug_class Blood Pressure Periaqueductal gray 03 medical and health sciences Cellular and Molecular Neuroscience chemistry.chemical_compound 0302 clinical medicine Afterload Internal medicine Neural Pathways medicine Animals Periaqueductal Gray GABA-A Receptor Agonists GABA-A Receptor Antagonists Rats Wistar Raphe Endocrine and Autonomic Systems GABAA receptor Chloralose business.industry Heart Endocrinology nervous system chemistry Muscimol Nucleus Raphe Pallidus Neurology (clinical) business 030217 neurology & neurosurgery |
| Zdroj: | Autonomic neuroscience : basicclinical. 228 |
| ISSN: | 1872-7484 |
| Popis: | Periaqueductal gray (PAG) is a midbrain region that projects to areas controlling behavioral and autonomic outputs and is involved in the behavioral and physiological components of defense reactions. Since Raphe Pallidus (RPa) is a medial medullary region comprising sympathetic premotor neurons governing heart function, it is worth considering the PAG-RPa path. We assessed: i) whether PAG projects to RPa; ii) the amplitude of cardiac responses evoked from PAG; iii) whether cardiovascular responses evoked from PAG rely on RPa. Experiments conducted in Wistar rats (±300 g) were approved by Ethics Committee CEUA-UFG (092/18). Firstly, (n = 3), monosynaptic retrograde tracer Retrobeads was injected into RPa; PAG slices were analyzed. Other two groups (n = 6 each) were anesthetized with urethane (1.4 g/kg) and chloralose (120 mg/kg) and underwent craniotomy, tracheostomy, catheterization of femoral artery and vein and of cardiac left ventricle. In one group, we injected the GABAA receptor antagonist, bicuculline methiodide (BMI – 40 pmol/100 nL) into lateral/dorsolateral (l/dl) PAG. Another group was injected (100nL) with the GABAA receptor agonist muscimol (20 mM) into RPa, 20 min before BMI into PAG. The results were: i) retrogradely labelled neurons were found in PAG; ii) PAG activation by BMI caused positive chronotropism and inotropism, which were accompanied by afterload increases; iii) RPa inhibition with Muscimol reduced heart rate, arterial and ventricular pressures; iv) the subsequent PAG activation still increased arterial pressure, cardiac chronotropy and inotropy, but these responses were significantly attenuated. In conclusion, PAG activation increases cardiac chronotropy and inotropy, and these responses seem to rely on a direct pathway reaching ventromedial medullary RPa neurons. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect