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- Shepheard, S, et al.
(författare)
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Possible antimigraine mechanisms of action of the 5HT1F receptor agonist LY334370
- 1999
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Ingår i: Cephalalgia : an international journal of headache. - : SAGE Publications. - 0333-1024. ; 19:10, s. 851-858
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated whether the selective 5HT1F receptor agonist LY334370 has other possible antimigraine mechanisms in addition to the proposed inhibition of dural plasma extravasation. LY334370 (up to 10−5 M) had no vasoconstrictor effects on human cerebral arteries in vitro. It had no effect (up to 10 mg kg−1, iv) on neurogenic vasodilation of dural blood vessels produced by electrical stimulation of the dura mater in anesthetized rats. Nor had it any effect (at 3 mg kg−1, iv) on the hyperalgesia produced by injection of carrageenan into the paw of conscious rats or on nociceptive reflex responses in the spinalized, decerebrate rabbit (up to 3 mg kg−1, iv), indicating that it has no general analgesic properties. However, it significantly inhibited activation of second-order neurons in the trigeminal nucleus caudalis produced by electrical stimulation of the dura mater in anesthetised rats at 3 mg kg−1, iv. These results provide evidence to suggest that LY334370 has a central mechanism of action in blocking the transmission of nociceptive impulses within the trigeminal nucleus caudalis and that this may represent a mechanism through which it has its antimigraine effect.
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- Erlinge, David, et al.
(författare)
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Phenotype changes of the vascular smooth muscle cell regulate P2 receptor expression as measured by quantitative RT-PCR
- 1998
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Ingår i: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 248:3, s. 864-870
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Tidskriftsartikel (refereegranskat)abstract
- Studies using selective agonists have suggested that the contractile effect of extracellular nucleotides, such as ATP and UTP, in blood vessels is mediated mainly by P2X1 receptors with a smaller contribution of P2Y receptors while the mitogenic effect is mediated by P2Y (P2Y1, P2Y2, P2Y4, and P2Y6) receptors with no effect of P2X1 receptors. This indicates a difference in P2 receptor expression between the contractile and the synthetic phenotype of the SMC. To measure the expression of mRNA for these receptors a competitive RT-PCR assay was developed that utilised synthetic RNA-competitors allowing determination of the number of mRNA copies for each receptor in the samples. In the synthetic phenotype the mitogenic P2Y1 and P2Y2 receptor transcripts were upregulated by 342- and 8-fold, respectively, while the contractile P2X1 receptor is totally downregulated and the P2Y4 and P2Y6 receptors were unchanged. This plasticity of the receptor expression may be important in the transition from the contractile to the synthetic SMC phenotype.
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- Paech, K, et al.
(författare)
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Differential ligand activation of estrogen receptors ERalpha and ERbeta at AP1 sites
- 1997
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 277:5331, s. 1508-1510
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Tidskriftsartikel (refereegranskat)abstract
- The transactivation properties of the two estrogen receptors, ERα and ERβ, were examined with different ligands in the context of an estrogen response element and an AP1 element. ERα and ERβ were shown to signal in opposite ways when complexed with the natural hormone estradiol from an AP1 site: with ERα, 17β-estradiol activated transcription, whereas with ERβ, 17β-estradiol inhibited transcription. Moreover, the antiestrogens tamoxifen, raloxifene, and Imperial Chemical Industries 164384 were potent transcriptional activators with ERβ at an AP1 site. Thus, the two ERs signal in different ways depending on ligand and response element. This suggests that ERα and ERβ may play different roles in gene regulation.
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