5-HT2 receptors in the nucleus tractus solitarius: characterisation and role in cardiovascular regulation in the rat.
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.
Merahi
N
N
INSERM U288, Faculté de Médecine Pitié-Salpétrière, Paris, France.
Orer
H S
HS
Laguzzi
R
R
D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine / Q000031:analogs & derivatives / Q000494:pharmacology; D000662:Amphetamines / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D004357:Drug Synergism; D005728:Ganglia, Sympathetic / Q000502:physiology; D015171:Ganglionectomy; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008526:Medulla Oblongata / Q000737:chemistry*; D008845:Microinjections; D016202:N-Methylaspartate / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000032:analysis* / Q000187:drug effects / Q000502:physiology; D012016:Reference Values; D012701:Serotonin / Q000494:pharmacology
D000662:Amphetamines; D011985:Receptors, Serotonin; C076285:2,5-dimethoxy-3-nitroamphetamine; D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine; C003943:2,5-dimethoxy-4-bromoamphetamine; D012701:Serotonin; D016202:N-Methylaspartate