| 1. |
- Dock, Hua, et al.
(författare)
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DNA Methylation Inhibitor Zebularine Confers Stroke Protection in Ischemic Rats
- 2015
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Ingår i: TRANSLATIONAL STROKE RESEARCH. - : Springer Verlag (Germany). - 1868-4483 .- 1868-601X. ; 6:4, s. 296-300
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Tidskriftsartikel (refereegranskat)abstract
- 5-Aza-deoxycytidine (5-aza-dC) confers neuroprotection in ischemic mice by inhibiting DNA methylation. Zebularine is another DNA methylation inhibitor, less toxic and more stable in aqueous solutions and, therefore more biologically suitable. We investigated Zebularines effects on brain ischemia in a rat middle cerebral artery occlusion (MCAo) model in order to elucidate its therapeutic potential. Male Wistar wild-type (WT) rats were randomly allocated to three treatment groups, vehicle, Zebularine 100 mu g, and Zebularine 500 mu g. Saline (10 mu L) or Zebularine (10 mu L) was administered intracerebroventricularly 20 min before 45-min occlusion of the middle cerebral artery. Reperfusion was allowed after 45-min occlusion, and the rats were sacrificed at 24-h reperfusion. The brains were removed, sliced, and stained with 2 % 2,3,5-triphenyltetrazolium chloride (TTC) before measuring infarct size. Zebularine (500 mu g) reduced infarct volumes significantly (p less than 0.05) by 61 % from 20.7 +/- 4.2 % in the vehicle treated to 8.1 +/- 1.6 % in the Zebularine treated. Zebularine (100 mu g) also reduced infarct volumes dramatically by 55 to 9.4 +/- 1.2 %. The mechanisms behind this neuroprotection is not yet known, but the results agree with previous studies and support the notion that Zebularine-induced inhibition of DNA methyltransferase ameliorates ischemic brain injury in rats.
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| 2. |
- Hilke, Susanne, et al.
(författare)
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Estrogen induces a rapid increase in galanin levels in female rat hippocampal formation : possibly a nongenomic/indirect effect
- 2005
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Ingår i: European Journal of Neuroscience. - : Wiley. - 0953-816X .- 1460-9568. ; 21:8, s. 2089-2099
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Tidskriftsartikel (refereegranskat)abstract
- Administration of 17β-estradiol to ovariectomized rats increased the concentrations of galanin-like immunoreactivity (LI) in the hippocampal formation by 215% (P < 0.001) within 1 h. An increase of 125% (P < 0.05) was observed in the same brain region in the proestrous phase of a normal estrous cycle. Tamoxifen® did not block the 17β-estradiol-induced increase in the concentration of galanin-LI but resulted in a 62% decrease in the hypothalamus within 1 h. In vivo microdialysis in the dorsal hippocampal formation showed a decrease of extracellular galanin-LI (P < 0.001) 1−2 h after treatment with 17β-estradiol, indicating a decreased release of galanin. For comparision, we studied the concentrations of neuropeptide Y, which were not influenced significantly in any of the regions studied. Taken together our results suggest that 17β-estradiol inhibits galanin release, presumably from noradrenergic nerve terminals, and primarily via a nongenomic/indirect action, not necessarily involving the classical nuclear receptors ER-α or ER-β. These rapid estrogen-induced changes in galanin release could influence transmitter signalling and plasticity in the hippocampal formation.
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| 3. |
- Hilke, Susanne, et al.
(författare)
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Galanin in the hippocampal formation of female rats : effects of 17beta estradiol
- 2005
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Ingår i: Neuropeptides. - : Elsevier BV. - 0143-4179. ; 39:3, s. 253-257
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Tidskriftsartikel (refereegranskat)abstract
- 17β-Estradiol induced an increase in tissue concentrations of galanin in the hippocampal formation of ovariectomized rats. This increase was dose- and time dependent, and occurred already 60 min after steroid administration and was not blocked by Tamoxifen®. There was also an increase in galanin in the pro-estrous phase in regularly cycling rats. The estrogen-induced rapid increase may at least in part be due to decreased release of galanin as demonstrated by in vivo microdialysis studies. Thus, sex steroid hormones may influence signalling molecules in brain areas of importance for cognitive functions.
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| 4. |
- Holm, Lovisa, et al.
(författare)
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Changes in galanin and GalR1 gene expression in discrete brain regions after transient occlusion of the middle cerebral artery in female rats
- 2012
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Ingår i: Neuropeptides. - : Elsevier. - 0143-4179 .- 1532-2785. ; 46:1, s. 19-27
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Tidskriftsartikel (refereegranskat)abstract
- Injury to neurons results in upregulation of galanin in some central and peripheral systems, and it has been suggested that this neuropeptide may play a protective and trophic role, primarily mediated by galanin receptor 2 (GalR2). The objective of the present study was to investigate galanin, GalR1, GalR2 and GalR3 gene expression in the female rat brain seven days after a 60-min unilateral occlusion of the middle cerebral artery followed by reperfusion. Quantitative real-time PCR was employed in punch-biopsies from the locus coeruleus, somatosensory cortex and dorsal hippocampal formation including sham-operated rats as controls. Galanin gene expression showed a ~2.5-fold increase and GalR1 a ~1.5-fold increase in the locus coeruleus of the ischemic hemisphere compared to the control side. Furthermore, the GalR1 mRNA levels decreased by 35% in the cortex of the ischemic hemisphere. The present results indicate that a stroke-induced forebrain lesion upregulates synthesis of galanin and GalR1 in the locus coeruleus, a noradrenergic cell group projecting to many forebrain areas, including cortex and the hippocampal formation. These results support the notion that galanin may play a role in the response of the central nervous system to injury and have trophic eff ects.
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| 5. |
- Holm, Lovisa, et al.
(författare)
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Effects of intracerebroventricular galanin or a galanin receptor 2/3 agonist on the lesion induced by transient occlusion of the middle cerebral artery in female rats
- 2011
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Ingår i: Neuropeptides. - : Elsevier Science B.V., Amsterdam. - 0143-4179 .- 1532-2785. ; 45:1, s. 17-23
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have shown that injury to the central and peripheral nervous system can increase expression of galanin, a 29 amino acid neuropeptide. Moreover, there is evidence that galanin, especially through its galanin receptor 2 (GalR2) receptor, plays a neuroprotective role in different injury models. However, direct studies of a possible neuroprotective effect of galanin in experimental stroke models are lacking. Galanin, a GalR2/3 agonist or artificial CSF was continuously infused intracerebroventricularly (i.c.v.) in naive female rats after a 60 min transient and focal occlusion of the middle cerebral artery. The animals were sacrificed, and the ischemic lesion was visualized using 2,3,5-triphenyltetrazolium hydrochloride (TTC) staining. The lesion was 98% larger after i.c.v, administration of the GalR2/3 agonist (2.4 nmol/day) seven days after occlusion compared to artificial CSF (p = 0.023). No statistically significant differences were found after seven days in the groups treated with galanin in three different concentrations (0.24, 2.4 and 24 nmol/day; p = 0.939, 0.715 and 0.977, respectively). There was no difference in the size of the ischemic lesions measured after three days in the galanin-treated group (2.4 nmol/d) compared to artificial CSF (p = 0.925). The present results show, surprisingly, that a GalR2/3 agonist doubled the size of the ischemic lesion. Whether this effect primarily reflects the properties of the current model, species, gender and/or the mode of galanin administration, e.g. causing desensitization, or whether galanin indeed lacks neuroprotective effect of its own, remains to be corroborated.
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| 6. |
- Ingberg, Edvin, 1988-, et al.
(författare)
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Effect of laser Doppler flowmetry and occlusion time on outcome variability and mortality in rat middle cerebral artery occlusion : inconclusive results
- 2018
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Ingår i: BMC Neuroscience. - London : BioMed Central. - 1471-2202. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Stroke is among the leading causes of death and disability. Although intense research efforts have provided promising treatment options in animals, most clinical trials in humans have failed and the therapeutic options are few. Several factors have been suggested to explain this translational difficulty, particularly concerning methodology and study design. Consistent infarcts and low mortality might be desirable in some, but not all, studies. Here, we aimed to investigate whether the use of laser Doppler flowmetry (LDF) and the occlusion time (60 vs. 45 min) affected outcome variability and mortality in a rat stroke model. Eighty ovariectomized female Wistar rats were subjected to ischemic stroke using intraluminal filament middle cerebral artery occlusion with or without LDF and with occlusion times of 45 or 60 min. Outcome was evaluated by triphenyl tetrazolium chloride staining of brain slices to measure infarct size and a modified sticky tape test.RESULTS: Neither LDF nor occlusion times of 45 versus 60 min significantly affected mortality, outcome variability or outcome severity.CONCLUSIONS: Due to the unexpectedly high mortality and variability the statistical power was very low and thus the results were inconclusive.
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| 7. |
- Ingberg, Edvin, et al.
(författare)
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Effects of high and low 17 beta-estradiol doses on focal cerebral ischemia in rats
- 2016
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 6:20228
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Tidskriftsartikel (refereegranskat)abstract
- The majority of the numerous animal studies of the effects of estrogens on cerebral ischemia have reported neuroprotective results, but a few have shown increased damage. Differences in hormone administration methods, resulting in highly different 17 beta-estradiol levels, may explain the discrepancies in previously reported effects. The objective of the present study was to test the hypothesis that it is the delivered dose per se, and not the route and method of administration, that determines the effect, and that high doses are damaging while lower doses are protective. One hundred and twenty ovariectomized female Wistar rats (n = 40 per group) were randomized into three groups, subcutaneously administered different doses of 17 beta-estradiol and subjected to transient middle cerebral artery occlusion. The modified sticky tape test was performed after 24 h and the rats were subsequently sacrificed for infarct size measurements. In contrast to our hypothesis, a significant negative correlation between 17 beta-estradiol dose and infarct size was found (p = 0.018). Thus, no support was found for the hypothesis that 17 beta-estradiol can be both neuroprotective and neurotoxic merely depending on dose. In fact, on the contrary, the findings indicate that the higher the dose of 17 beta-estradiol, the smaller the infarct.
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| 8. |
- Ingberg, Edvin, 1988-, et al.
(författare)
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Effects of high and low 17β-estradiol doses on focal cerebral ischemia in rats
- 2016
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Ingår i: Scientific Reports. - London, United Kingdom : Nature Publishing Group. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The majority of the numerous animal studies of the effects of estrogens on cerebral ischemia have reported neuroprotective results, but a few have shown increased damage. Differences in hormone administration methods, resulting in highly different 17β-estradiol levels, may explain the discrepancies in previously reported effects. The objective of the present study was to test the hypothesis that it is the delivered dose per se, and not the route and method of administration, that determines the effect, and that high doses are damaging while lower doses are protective. One hundred and twenty ovariectomized female Wistar rats (n = 40 per group) were randomized into three groups, subcutaneously administered different doses of 17β-estradiol and subjected to transient middle cerebral artery occlusion. The modified sticky tape test was performed after 24 h and the rats were subsequently sacrificed for infarct size measurements. In contrast to our hypothesis, a significant negative correlation between 17β-estradiol dose and infarct size was found (p = 0.018). Thus, no support was found for the hypothesis that 17β-estradiol can be both neuroprotective and neurotoxic merely depending on dose. In fact, on the contrary, the findings indicate that the higher the dose of 17β-estradiol, the smaller the infarct.
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| 9. |
- Ingberg, Edvin, 1988-, et al.
(författare)
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Elevated body swing test after focal cerebral ischemia in rodents : methodological considerations
- 2015
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Ingår i: BMC Neuroscience. - : Springer Science and Business Media LLC. - 1471-2202. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: The elevated body swing test (EBST) is a behavioral test used to evaluate experimental stroke in rodents. The basic idea is that when the animal is suspended vertically by the tail, it will swing its head laterally to the left or right depending on lesion side. In a previous study from our lab using the EBST after middle cerebral artery occlusion (MCAo), rats swung contralateral to the infarct day 1 post-MCAo, but ipsilateral day 3 post-MCAo. This shift was unexpected and prompted us to perform the present study. First, the literature was systematically reviewed to elucidate whether a similar shift had been noticed before, and if consensus existed regarding swing direction. Secondly, an experiment was conducted to systematically investigate the suggested behavior. Eighty-three adult male and female Sprague-Dawley rats were subjected to MCAo or sham surgery and the EBST was performed up to 7 days after the lesion.Results: Both experimentally and through systematic literature review, the present study shows that the direction of biased swing activity in the EBST for rodents after cerebral ischemia can differ and even shift over time in some situations. The EBST curve for females was significantly different from that of males after the same occlusion time (p = 0.023).Conclusions: This study highlights the importance of adequate reporting of behavioral tests for lateralization and it is concluded that the EBST cannot be recommended as a test for motor asymmetry after MCAo in rats.
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| 10. |
- Ingberg, Edvin, 1988-, et al.
(författare)
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Method parameters' impact on mortality and variability in mouse stroke experiments : a meta-analysis
- 2016
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Ingår i: Scientific Reports. - London, England : Nature Publishing Group. - 2045-2322. ; 11:SUPP 3, s. 108-108
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Tidskriftsartikel (refereegranskat)abstract
- Although hundreds of promising substances have been tested in clinical trials, thrombolysis currently remains the only specific pharmacological treatment for ischemic stroke. Poor quality, e.g. low statistical power, in the preclinical studies has been suggested to play an important role in these failures. Therefore, it would be attractive to use animal models optimized to minimize unnecessary mortality and outcome variability, or at least to be able to power studies more exactly by predicting variability and mortality given a certain experimental setup. The possible combinations of methodological parameters are innumerous, and an experimental comparison of them all is therefore not feasible. As an alternative approach, we extracted data from 334 experimental mouse stroke articles and, using a hypothesis-driven meta-analysis, investigated the method parameters' impact on infarct size variability and mortality. The use of Swiss and C57BL6 mice as well as permanent occlusion of the middle cerebral artery rendered the lowest variability of the infarct size while the emboli methods increased variability. The use of Swiss mice increased mortality. Our study offers guidance for researchers striving to optimize mouse stroke models.
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