5-HT1B receptor subtype and aging in rat resistance vessels.
The effects of 5-hydroxytryptamine (5-HT), 5-carboxamidotryptamine, and sumatriptan on rat caudal arteries were examined, with the goal of finding experimental conditions useful in enhancing the 'silent' 5-HT(1B) receptor subtype. It was shown that both reserpine treatment and K(+) depolarization increased the vasoconstriction by 5-HT receptor agonists. The role of the 5-HT(2A) receptor in vasoconstriction was examined using ritanserin (50 nmol/l), a selective 5-HT(2A) antagonist, whereas that of the 'silent' 5-HT(1B) receptor was examined using SB-224289 (0.2 micromol/l), a selective 5-HT(1B) receptor antagonist. The influence of age on the 'silent' 5-HT(1B) receptor subtype was also investigated; for this, the effect of sumatriptan, a selective 5-HT(1B/1D )agonist, was tested on arterial tissues of both young and old rats which had been either K(+) depolarized or reserpine treated or both. It was found that aging strongly shifted the concentration-vasoconstriction curve generated by sumatriptan to the left, also increasing the maximum contractile response, mainly in reserpine-treated tissues. RT-PCR was used to study the expression of 5-HT(1B) and 5-HT(2A) receptors in both young and old tissues. The results support the idea that reserpine-treated and K(+)-depolarized caudal arteries from old rats can be a pharmacological model which is useful in highlighting the 'silent' 5-HT(1B) receptor subtype.
Froldi
Guglielmina
G
Department of Pharmacology and Anaesthesiology, University of Padova, Padova, Italy. g.froldi@unipd.it
Montopoli
Monica
M
Zanetti
Miriam
M
Dorigo
Paola
P
Caparrotta
Laura
L
D000375:Aging / Q000378:metabolism*; D000818:Animals; D002536:Cerebral Arteries / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D044302:Receptor, Serotonin, 5-HT1B / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology; D058825:Serotonin 5-HT1 Receptor Agonists; D058829:Serotonin 5-HT1 Receptor Antagonists; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D018170:Sumatriptan / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects*; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D044302:Receptor, Serotonin, 5-HT1B; D058825:Serotonin 5-HT1 Receptor Agonists; D058829:Serotonin 5-HT1 Receptor Antagonists; D017366:Serotonin Receptor Agonists; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D012701:Serotonin; D018170:Sumatriptan; C047087:5-carboxamidotryptamine