Collar‐induced elevation of mRNA and functional activity of 5‐HT_1B receptor in the rabbit carotid artery

Abstract

1 Hypersensitivity to serotonin (5-HT) develops in rabbit collared carotid arteries. Previous data demonstrated the involvement of 5-HT 1 -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-HT 1 -like receptors. Furthermore, the expression of messenger RNA (mRNA) and protein of 5-HT 1B , 5-HT 1D and 5-HT 2A receptors was addressed. 2 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. 3 In sham and collared rings concentration-response curves (CRC's) to 5-HT were monophasic. Only in collared segments the presence of a 5-HT 2A antagonist (spiperone or ketanserin, 0.1 mM) revealed a biphasic CRC which was even more pronounced when a moderate tone was induced by KCl pointing to functional 5-HT 1 -like receptors. 4 The rabbit carotid artery constitutively expressed 5-HT 1B and 5-HT 2A mRNA, not 5-HT 1D mRNA. Manipulation of the carotid artery increased the 5-HT 1B mRNA level. Collar placement raised it even further. The 5-HT 2A mRNA level remained unchanged. All the anti-5-HT receptor antibodies tested resulted in variable, non speci®c patterns with multiple bands. 5 In conclusion, collar placement elevates mRNA expression and activity of the 5-HT 1B receptor in the rabbit carotid artery.

Amplification of sumatriptan-induced contractions with phenylephrine, histamine and KCl in the isolated human mesenteric artery: in-vitro evidence for sumatriptan-induced mesenteric ischaemia

“…Intriguingly, in one of these two patients, in a small branch of artery which was collared but not occluded by surrounding fibrotic connective tissue, the sensitivity to and E max for sumatriptan were much higher than those in the uncollared normal small branch of the same patient. This observation is in accordance with the study of Geerts et al (2000) that placement of a collar on the rabbit carotid artery raised the amount of 5-HT 1B mRNA and receptor density, resulting in increased sensitivity to 5-HT. Pretension in our study was about 15 mN just before the start of the experiments, as opposed to 2 mN in the study of Nilsson et al (1997) in which no contraction to sumatriptan was detected.…”

The role of endothelin receptor antagonism in collar-induced intimal thickening and vascular reactivity changes in rabbits

“…In accordance with the findings of previous studies (Ü stu¨nes et al 1996; Kerry et al 1999), collaring increased the pD 2 values of 5-HT in arteries, a characteristic feature of the collar model (De Meyer et al 1990Hickey et al 1996). As stated before, the 5-HT 1B receptor subtype has been found to be responsible for the development of hypersensitivity to 5-HT in the collar model (Geerts et al 1999(Geerts et al , 2000. With regard to the effect of TAK-044 on 5-HT-induced contractions, chronic treatment with TAK-044 (21 days) seems to enhance the E max values of 5-HT without affecting pD 2 values in both collared and sham arteries.…”

“…In 1999, in this model, Geerts et al demonstrated that the serotonergic receptor involved in the hypersensitivity to 5-HT of rabbit collared carotid artery is a 5HT 1B receptor subtype (Geerts et al 1999). Morover, Geerts et al (2000) further reported that collar placement elevates mRNA expression and activity of the 5HT 1B receptor in the rabbit carotid artery. In our study, consistent with previous results (De Meyer et al 1994;Ü stu¨nes et al 1996;Kerry et al 1999;Yasa et al 1999), the collar placement suppressed 120 mM KCl-induced contractions in collared rabbit carotid arteries.…”

Characterization of the human basilar artery contractile response to 5‐HT and triptans

“…Then the lysates were clarified by centrifugation (10 000 g, for 10 min at 4°C). The protein content of the supernatant was determined by the standard method of the bicinchoninic acid (BCA) [24]. Samples (60 lg protein) were boiled for 5 min in a denaturizing solution (200 mM Tris- [30][31][32][33][34][35][36][37][38][39][40] min, in 100 mM Tris-base, 100 mM bicine, 0.1% (w/v) SDS buffer], and electroblotted onto a polyvinyl difluoride (PVDF) membrane (Roche) in 96 mM glycine, 12.5 mM Tris-base and 20% (v/v) methanol cooled transfer buffer (overnight at 40 V and 10°C).…”