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Microinjection of a 5-HT3 receptor agonist into the NTS of awake rats inhibits the bradycardic response to activation of the von Bezold-Jarisch reflex.
- Source :
-
Brain research bulletin [Brain Res Bull] 2001 Jan 01; Vol. 54 (1), pp. 7-11. - Publication Year :
- 2001
-
Abstract
- In the present study we investigated the effects of bilateral microinjection into the lateral commissural nucleus tractus solitarius (NTS) of 2-methyl-5-HT, a 5-HT3 receptor agonist, on the bradycardic response of the von Bezold-Jarisch reflex of awake rats. We evaluated mainly the bradycardic response because in previous studies we documented that the hypotensive response of the von-Bezold-Jarisch reflex in awake rats is secondary to the intense bradycardic response. The Bezold-Jarisch reflex was activated by intravenous injection of serotonin (8 microg/kg) in awake rats before and 1, 3, 10, 20 and 60 min after bilateral microinjection of 2-methyl-5-HT (5 nmol/50 nl, n = 8) into the NTS. Microinjections of 2-methyl-5-HT into the NTS produced a significant increase in basal mean arterial pressure [(MAP), 97 +/- 4 vs. 114 +/- 4 mmHg), no changes in basal heart rate and a significant reduction in bradycardic (-78 +/- 19; -94 +/- 24 and -107 +/- 21 bpm) and hypotensive (-16 +/- 4; -10 +/- 5 and -17 +/- 4 mmHg) responses to activation of the von Bezold-Jarisch reflex at 3, 10 and 20 min, respectively, when compared with the control value (-231 +/- 13 bpm and -43 +/- 4 mmHg). The data of the present study suggest that serotonin acting on 5-HT3 receptors in the NTS may play an important inhibitory neuromodulatory role in the bradycardic response to activation of the von Bezold-Jarisch reflex.
- Subjects :
- Analysis of Variance
Animals
Arousal
Blood Pressure drug effects
Bradycardia chemically induced
Heart Rate drug effects
Male
Microinjections
Nerve Fibers drug effects
Nerve Fibers physiology
Neural Inhibition drug effects
Parasympathetic Nervous System cytology
Parasympathetic Nervous System drug effects
Parasympathetic Nervous System physiology
Rats
Rats, Wistar
Receptors, Serotonin, 5-HT3
Serotonin analogs & derivatives
Solitary Nucleus cytology
Solitary Nucleus physiology
Sympathetic Nervous System cytology
Sympathetic Nervous System drug effects
Sympathetic Nervous System physiology
Synaptic Transmission drug effects
Bradycardia physiopathology
Receptors, Serotonin physiology
Reflex, Abnormal drug effects
Serotonin pharmacology
Serotonin Receptor Agonists pharmacology
Solitary Nucleus drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 0361-9230
- Volume :
- 54
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Brain research bulletin
- Publication Type :
- Academic Journal
- Accession number :
- 11226709
- Full Text :
- https://doi.org/10.1016/s0361-9230(00)00408-1