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- Blixt, Frank W., et al.
(författare)
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MEK/ERK/1/2 sensitive vascular changes coincide with retinal functional deficit, following transient ophthalmic artery occlusion
- 2019
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835. ; 179, s. 142-149
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Tidskriftsartikel (refereegranskat)abstract
- Retinal ischemia remains a major cause of blindness in the world with few acute treatments available. Recent emphasis on retinal vasculature and the ophthalmic artery's vascular properties after ischemia has shown an increase in vasoconstrictive functionality, as previously observed in cerebral arteries following stroke. Specifically, endothelin-1 (ET-1) receptor-mediated vasoconstriction regulated by the MEK/ERK1/2 pathway. In this study, the ophthalmic artery of rats was occluded for 2 h with the middle cerebral artery occlusion model. MEK/ERK1/2 inhibitor U0126 was administered at 0, 6, and 24 h following reperfusion and the functional properties of the ophthalmic artery were evaluated at 48 h post reperfusion. Additionally, retinal function was evaluated at day 1, 4, and 7 after reperfusion. Occlusion of the ophthalmic artery led to a significant increase of endothelin-1 mediated vasoconstriction which can be attenuated by U0126 treatment, most evident at higher ET-1 concentrations of 10−7 M (Emax151.0 ± 22.0% of 60 mM K+), vs non-treated ischemic arteries Emax 212.1 ± 14.7% of 60 mM K+). Retinal function also deteriorated following ischemia and was improved with treatment with a-wave amplitudes of 725 ± 36 μV in control, 560 ± 21 μV in non-treated, and 668 ± 73 μV in U0126 treated at 2 log cd*s/m2 luminance in the acute stages (1 days post-ischemia). Full spontaneous retinal recovery was observed at day 7 regardless of treatment. In conclusion, this is the first study to show a beneficial in vivo effect of U0126 on vascular contractility following ischemia in the ophthalmic artery. Coupled with the knowledge obtained from cerebral vasculature, these results point towards a novel therapeutic approach following ischemia-related injuries to the eye.
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| 2. |
- Frederiksen, Simona Denise, et al.
(författare)
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Expression of Pituitary Adenylate Cyclase-activating Peptide, Calcitonin Gene-related Peptide and Headache Targets in the Trigeminal Ganglia of Rats and Humans
- 2018
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522. ; 393, s. 319-332
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Tidskriftsartikel (refereegranskat)abstract
- Neurotransmitter and headache target localization in the trigeminal ganglia (TG) might increase the understanding of sites of action, and mechanisms related to headache therapy. The overall aim of the study was to investigate the presence of migraine targets in the TG with particular emphasis on pituitary adenylate cyclase-activating peptide (PACAP) and calcitonin gene-related peptide (CGRP), known to be involved in cranial pain processing, and selected headache targets. Rat- and human TG were processed for immunohistochemistry. PACAP-38, CGRP and the headache targets were expressed in rat and human TG. PACAP receptors were confined to neurons and satellite glial cells (SGCs), however with variability between the receptor subtypes PACAP type I receptor (PAC1) and vasoactive intestinal peptide/PACAP receptors 1/2 (VPAC1/2). 5-Hydroxytryptamine (5-HT) receptors were expressed in neuronal somas in rat and human TG (human TG frequency: 5-HT1D > 5-HT1B/1F). Synaptosomal-associated protein 25 kDa (SNAP25) was primarily expressed in SGCs in humans, and neurons in rats, while synaptic vesicle glycoprotein 2A (SV2-A) was confined to SGCs and some neurons in rats and humans. Occasionally, PACAP-38-positive cells also expressed VPAC1, SNAP25 and SV2-A. VPAC1 was generally detected in SGCs enveloping PACAP-38-positive and -negative neuronal somas. Our study revealed potential sites of actions for anti-headache drugs such as PACAP receptor antagonists, Lasmiditan (5-HT1F agonist) and Botox (blocks exocytosis through SV2-A/SNAP25) in rat and human TG and considerable overlap between species in expression to specific cell types, except for VPAC1 and SNAP25.
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| 3. |
- W Blixt, Frank, et al.
(författare)
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Increased endothelin-1-mediated vasoconstriction after organ culture in rat and pig ocular arteries can be suppressed with MEK/ERK1/2 inhibitors
- 2018
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-3768 .- 1755-375X. ; 96:5, s. 619-625
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Even though retinal vascular changes following ischaemia have been poorly understood, the upregulation of vasoconstrictive endothelin-1 (ET-1) receptors (ETA/ETB) following global cerebral ischaemia has been described. The aim of this study was to investigate whether or not the MEK/ERK1/2 pathway is involved in the observed upregulation and whether specific MEK/ERK1/2 inhibitors U0126 and trametinib can prevent it.METHODS: The aim was also to localize ETAand ETBreceptors using immunohistochemistry in both fresh rat ophthalmic arteries and after 24-hr organ culture and study the receptors functionally using myography. Pig retinal arteries also underwent 24-hr organ culture to validate similar responses across species and the retinal vasculature.RESULTS: Results showed that following organ culture there is a significant increase in ET-1-mediated vasoconstriction, in particular via the ETBreceptor. Furthermore, immunohistochemistry revealed a clear increase in pERK in the smooth muscle cells of rat ophthalmic artery. U0126 and trametinib were successful in attenuating the functional vasoconstriction in both rat and pig, as well as restoring immunofluorescence of pERK to fresh levels and counteracting ETBexpression in the smooth muscle cells of the rat ophthalmic artery.CONCLUSION: This is the first study to show that the MEK/ERK1/2 pathway in responsible for the increase in functional vasoconstriction via ET-1 receptor in rat ophthalmic and pig retinal arteries. Furthermore, this study is the first to suggest a way of inhibiting and preventing such an increase. With these results, we suggest a novel approach in retinal ischaemia therapy.
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