Article date: December 2000
By: Inge S Geerts, Guido R Y De Meyer, Hidde Bult in Volume 131, Issue 8, pages 1723-1731
Hypersensitivity to serotonin (5‐HT) develops in rabbit collared carotid arteries. Previous data demonstrated the involvement of 5‐HT1‐like receptors which are not active in normal carotid arteries. This study investigated the interaction in the rabbit carotid artery between 5‐HT and a moderate tone as this can uncover functional 5‐HT1‐like receptors. Furthermore, the expression of messenger RNA (mRNA) and protein of 5‐HT1B, 5‐HT1D and 5‐HT2A receptors was addressed.
Silicone collars were placed around the carotid arteries of male New Zealand White rabbits for 1 week. Rings from inside (=collar) and outside (=sham) the collar were either mounted in isolated organ baths for isometric force measurements or frozen in liquid nitrogen to isolate total RNA or proteins which were subsequently analysed by respectively reverse transcriptase‐polymerase chain reaction and Western blot analysis.
In sham and collared rings concentration‐response curves (CRC's) to 5‐HT were monophasic. Only in collared segments the presence of a 5‐HT2A antagonist (spiperone or ketanserin, 0.1 μM) revealed a biphasic CRC which was even more pronounced when a moderate tone was induced by KCl pointing to functional 5‐HT1‐like receptors.
The rabbit carotid artery constitutively expressed 5‐HT1B and 5‐HT2A mRNA, not 5‐HT1D mRNA. Manipulation of the carotid artery increased the 5‐HT1B mRNA level. Collar placement raised it even further. The 5‐HT2A mRNA level remained unchanged. All the anti‐5‐HT receptor antibodies tested resulted in variable, non specific patterns with multiple bands.
In conclusion, collar placement elevates mRNA expression and activity of the 5‐HT1B receptor in the rabbit carotid artery.
Hypersensitivity to serotonin (5‐HT) develops in rabbit collared carotid arteries. Previous data demonstrated the involvement of 5‐HT1‐like receptors which are not active in normal carotid arteries. This study investigated the interaction in the rabbit carotid artery between 5‐HT and a moderate tone as this can uncover functional 5‐HT1‐like receptors. Furthermore, the expression of messenger RNA (mRNA) and protein of 5‐HT1B, 5‐HT1D and 5‐HT2A receptors was addressed.
Silicone collars were placed around the carotid arteries of male New Zealand White rabbits for 1 week. Rings from inside (=collar) and outside (=sham) the collar were either mounted in isolated organ baths for isometric force measurements or frozen in liquid nitrogen to isolate total RNA or proteins which were subsequently analysed by respectively reverse transcriptase‐polymerase chain reaction and Western blot analysis.
In sham and collared rings concentration‐response curves (CRC's) to 5‐HT were monophasic. Only in collared segments the presence of a 5‐HT2A antagonist (spiperone or ketanserin, 0.1 μM) revealed a biphasic CRC which was even more pronounced when a moderate tone was induced by KCl pointing to functional 5‐HT1‐like receptors.
The rabbit carotid artery constitutively expressed 5‐HT1B and 5‐HT2A mRNA, not 5‐HT1D mRNA. Manipulation of the carotid artery increased the 5‐HT1B mRNA level. Collar placement raised it even further. The 5‐HT2A mRNA level remained unchanged. All the anti‐5‐HT receptor antibodies tested resulted in variable, non specific patterns with multiple bands.
In conclusion, collar placement elevates mRNA expression and activity of the 5‐HT1B receptor in the rabbit carotid artery.
British Journal of Pharmacology (2000) 131, 1723–1731; doi:10.1038/sj.bjp.0703732
DOI: 10.1038/sj.bjp.0703732
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