5-HT2 receptors in the nucleus tractus solitarius: characterisation and role in cardiovascular regulation in the rat.

Abstract

The effects of the local application of drugs acting on 5-HT2 receptors in the nucleus tractus solitarius (NTS) on the heart rate and blood pressure were investigated in normal and nodose ganglionectomized anaesthetized rats. The unilateral micro-injection of an agonist such as 2,5-dimethoxy-3-bromo-amphetamine (DOB) (0.1-0.5 pmol) or 2,5-dimethoxy-3-nitroamphetamine (DON) (0.1-0.5 pmol) produced a dose-dependent hypotension and bradycardia in both intact and ganglionectomized animals. These cardiovascular effects were similar to those observed after the unilateral micro-injection of low doses (pmol) of 5-HT, and could be prevented by the prior micro-injections of the 5-HT2 antagonists ketanserin, ritanserin and piremperone. These findings support the hypothesis that 5-HT2 receptors within the NTS play a role in the reflex regulation of blood pressure. In addition, it was also observed that the micro-injection of subthreshold doses of 5-HT or DOB significantly enhanced the hypotension and bradycardia produced by the unilateral micro-injection of N-methyl-D-aspartate (NMDA). The potentiation of NMDA depressor effects by 5-HT or DOB could be totally prevented by ketanserin or piremperone, suggesting that 5-HT acting upon 5-HT2 receptors in the NTS may intervene in the reflex control of blood pressure by modulating the glutamatergic transmission.

• Authors: N Merahi, H S Orer, R Laguzzi
• Journal: Brain research (Brain Res) Vol. 575 Issue 1 Pg. 74-8 (Mar 13 1992) ISSN: 0006-8993 [Print] Netherlands
• PMID: 1504784 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amphetamines
• Receptors, Serotonin
• 2,5-dimethoxy-3-nitroamphetamine
• 2,5-Dimethoxy-4-Methylamphetamine
• 2,5-dimethoxy-4-bromoamphetamine
• Serotonin
• N-Methylaspartate

Topics

• 2,5-Dimethoxy-4-Methylamphetamine (analogs & derivatives, pharmacology)
• Amphetamines (pharmacology)
• Animals
• Blood Pressure (drug effects, physiology)
• Drug Synergism
• Ganglia, Sympathetic (physiology)
• Ganglionectomy
• Heart Rate (drug effects, physiology)
• Male
• Medulla Oblongata (chemistry)
• Microinjections
• N-Methylaspartate (pharmacology)
• Rats
• Rats, Inbred Strains
• Receptors, Serotonin (analysis, drug effects, physiology)
• Reference Values
• Serotonin (pharmacology)