| 1. |
- Berglöf, Elisabet, et al.
(författare)
-
Beneficial effects of antioxidant-enriched diet for tyrosine hydroxylase-positive neurons in ventral mesencephalic tissue in oculo grafts
- 2009
-
Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 515:1, s. 72-82
-
Tidskriftsartikel (refereegranskat)abstract
- Supplementation of antioxidants to the diet has been proved to be beneficial in aging and after brain injury. Furthermore, it has been postulated that the locus coeruleus promotes survival of dopamine neurons. Thus, this study was performed to elucidate the effects of a blueberry-enriched diet on fetal ventral mesencephalic tissue in the presence or absence of locus coeruleus utilizing the in oculo grafting method. Sprague-Dawley rats were given control diet or diet supplemented with 2% blueberries, and solid tissue pieces of fetal locus coeruleus and ventral mesencephalon were implanted as single and co-grafts. The results revealed that the presence of locus coeruleus tissue or the addition of blueberries enhanced the survival of ventral mesencephalic tyrosine hydroxylase (TH)-positive neurons, whereas no additive effects were observed for the two treatments. The density of TH-positive nerve fibers in ventral mesencephalic tissue was significantly elevated when it was attached to the locus coeruleus or by blueberry treatment, whereas the innervation of dopamine-beta-hydroxylase-positive nerve fibers was not altered. The presence of locus coeruleus tissue or bluberry supplementation reduced the number of Iba-1-positive microglia in the ventral mesencephalic portion of single and co-grafts, respectively, whereas almost no OX6 immunoreactivity was found. Furthermore, neither the attachment of ventral mesencephalic tissue nor the addition of blueberries improved the survival of TH-positive neurons in the locus coerulean grafts. To conclude, locus coeruleus and blueberries are beneficial for the survival of fetal ventral mesencephalic tissue, findings that could be useful when grafting tissue in Parkinson's disease.
|
|
| 2. |
- Berglöf, Elisabet, et al.
(författare)
-
Glial influence on nerve fiber formation from rat ventral mesencephalic organotypic tissue cultures.
- 2007
-
Ingår i: Journal of Comparative Neurology. - 0021-9967. ; 501:3, s. 431-42
-
Tidskriftsartikel (refereegranskat)abstract
- Rat fetal ventral mesencephalic organotypic cultures have demonstrated two morphologically different dopamine nerve fiber growth patterns, in which the initial nerve fibers are formed in the absence of astrocytes and the second wave is guided by astrocytes. In this study, the presence of subpopulations of dopamine neurons, other neuronal populations, and glial cells was determined. We used "roller-drum" organotypic cultures, and the results revealed that beta-tubulin-positive/tyrosine hydroxylase (TH)-negative nerve fibers were present as early as 1 day in vitro (DIV). A similar growth pattern produced by TH-positive neurons was present from 2 DIV. These neurites grew to reach distances over 4 mm and over time appeared to be degenerating. Thin, vimentin-positive processes were found among these nerve fibers. As the first growth was retracted, a second outgrowth was initiated and formed on migrating astrocytes. TH- and aldehyde dehydrogenase-1 (ALDH1)-positive nerve fibers formed both the nonglia-associated and the glia-associated outgrowth. In cultures with membrane inserts, only the glia-associated outgrowth was found. Vimentin-positive cells preceded migration of NG2-positive oligodendrocytes and Iba-1-positive microglia. Oligodendrocytes appeared not to be involved in guiding neuritic growth, but microglia was absent over areas dense with TH-positive neurons. In conclusion, in "roller-drum" cultures, nerve fibers are generally formed in two sequences. The early-formed nerve fibers grow in the presence of thin, vimentin-positive processes. The second nerve fiber outgrowth is formed on astroglia, with no correlation to the presence of oligodendrocytes or microglia. ALDH1-positive nerve fibers, presumably derived from A9 dopamine neurons, participate in formation of both sequences of outgrowth.
|
|
| 3. |
- Novikova, Liudmila N, et al.
(författare)
-
BDNF abolishes the survival effect of NT-3 in axotomized Clarke neurons of adult rats
- 2000
-
Ingår i: Journal of Comparative Neurology. - : Wiley-Liss, Inc.. - 0021-9967 .- 1096-9861. ; 428:4, s. 671-680
-
Tidskriftsartikel (refereegranskat)abstract
- Neurotrophin-3 (NT-3) and brain-derived neurotrophic factor (BDNF) have previously been shown to support survival and axonal regeneration in various types of neurons. Also, synergistic neuroprotective effects of these neurotrophins have been reported in descending rubrospinal neurons after cervical spinal cord injury (Novikova et al., [2000] Eur. J. Neurosci. 12:776-780). The present study investigates the effects of intrathecally delivered NT-3 and BDNF on the survival and atrophy of ascending spinocerebellar neurons of Clarke nucleus (CN) after cervical spinal cord injury in adult rats. At 8 weeks after cervical spinal cord hemisection, 40% of the axotomized CN neurons had been lost, and the remaining cells exhibited marked atrophy. Microglial activity was significantly increased in CN of the operated side. Intrathecal infusion of NT-3 for 8 weeks postoperatively resulted in 91% cell survival and a reduction in cell atrophy, but did not reduce microglial activity. In spite of the fact that the CN neurons expressed both TrkC and TrkB receptors, only NT-3 had a neuroprotective effect, whereas BDNF was ineffective. Furthermore, when a combination of BDNF and NT-3 was administered, the neuroprotective effect of NT-3 was lost. The present results indicate a therapeutic potential for NT-3 in the treatment of spinal cord injury, but also demonstrate that in certain neuronal populations the neuroprotection obtained by a combination of neurotrophic factors may be less than that of a single neurotrophin.
|
|
| 4. |
- Novikova, Liudmila N, et al.
(författare)
-
Differential effects of neurotrophins on neuronal survival and axonal regeneration after spinal cord injury in adult rats.
- 2002
-
Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 452:3, s. 255-63
-
Tidskriftsartikel (refereegranskat)abstract
- Spinal cord injury (SCI) induces retrograde cell death in descending pathways, which can be prevented by long-term intrathecal infusion of neurotrophins (Novikova et al. [2000] Eur J Neurosci 12:776-780). The present study investigates whether the same treatment also leads to improved regeneration of the injured tracts. After cervical SCI in adult rats, a peripheral nerve graft was attached to the rostral wall of the lesion cavity. The animals were treated by local application into the cavity of Gelfoam soaked in (1) phosphate buffered saline (untreated controls) or (2) a mixture of the neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) (local treatment), or by intrathecal infusion of BDNF + NT-3 for (3) 2 weeks (short-term treatment) or (4) 5-8 weeks (long-term treatment). Despite a very strong survival effect, long-term treatment failed to stimulate ingrowth of descending tracts into the nerve graft. In comparison with untreated controls, the latter treatment also caused 35% reduction in axonal sprouting of descending pathways rostral to the lesion site and 72% reduction in the number of spinal cord neurons extending axons into the nerve graft. Local and short-term treatments neither prevented retrograde cell death nor enhanced regeneration of descending tracts, but induced robust regeneration of spinal cord neurons into the nerve graft. These results indicate that the signal pathways promoting neuronal survival and axonal regeneration, respectively, in descending tracts after SCI respond differently to neurotrophic stimuli and that efficient rescue of axotomized tract neurons is not a sufficient prerequisite for regeneration.
|
|
| 5. |
- Vedin, Viktoria, 1975-, et al.
(författare)
-
Regional differences in olfactory epithelial homeostasis in the adult mouse
- 2009
-
Ingår i: Journal of Comparative Neurology. - : Wiley. - 0021-9967 .- 1096-9861. ; 513:4, s. 375-384
-
Tidskriftsartikel (refereegranskat)abstract
- The olfactory sensory neurons in the nasal cavity of the adult mouse are organized into a few regions that differ in their molecular properties, as several classes of genes show regional expression. Most renowned is the fact that expression of each of hundreds of different odorant receptor genes is limited to one such region, or zone, of the olfactory neuroepithelial sheet. Zone differences are in place at birth, as exemplified here by the expression of neuronal progenitor marker Foxg1. We herein describe that an adult pattern showing regional differences in neurogenesis develops during the first few weeks of postnatal life which, e.g., is reflected in the temporal and regional regulation of the neuronal progenitor marker Ascl1. The most dorsomedial zone shows significantly fewer cells in S-phase in the adult but not in newborn mice by two different measures. Moreover, we show that there are regional differences in the relative differentiation, cell survival, and thickness of the olfactory epithelium. These findings are compatible with the view that zones are inherently distinct and that such differences contribute to generate regional differences in cellular homeostasis that in turn may modulate the capacity of a region to adjust to extrinsic influence.
|
|
| 6. |
- Warrington, Rachael E., et al.
(författare)
-
Visual opsin expression and morphological characterization of retinal photoreceptors in the pouched lamprey (Geotria australis, Gray)
- 2021
-
Ingår i: Journal of Comparative Neurology. - : John Wiley & Sons. - 0021-9967 .- 1096-9861. ; 529:9, s. 2265-2282
-
Tidskriftsartikel (refereegranskat)abstract
- Lampreys are extant members of the agnathan (jawless) vertebrates that diverged ~500 million years ago, during a critical stage of vertebrate evolution when image‐forming eyes first emerged. Among lamprey species assessed thus far, the retina of the southern hemisphere pouched lamprey, Geotria australis, is unique, in that it possesses morphologically distinct photoreceptors and expresses five visual photopigments. This study focused on determining the number of different photoreceptors present in the retina of G. australis and whether each cell type expresses a single opsin class. Five photoreceptor subtypes were identified based on ultrastructure and differential expression of one of each of the five different visual opsin classes (lws, sws1, sws2, rh1, and rh2) known to be expressed in the retina. This suggests, therefore, that the retina of G. australis possesses five spectrally and morphologically distinct photoreceptors, with the potential for complex color vision. Each photoreceptor subtype was shown to have a specific spatial distribution in the retina, which is potentially associated with changes in spectral radiance across different lines of sight. These results suggest that there have been strong selection pressures for G. australis to maintain broad spectral sensitivity for the brightly lit surface waters that this species inhabits during its marine phase. These findings provide important insights into the functional anatomy of the early vertebrate retina and the selection pressures that may have led to the evolution of complex color vision.
|
|
| 7. |
- Wheaton, Benjamin J., et al.
(författare)
-
Identification of regenerative processes in neonatal spinal cord injury in the opossum (Monodelphis domestica) : A transcriptomic study
- 2021
-
Ingår i: Journal of Comparative Neurology. - : John Wiley & Sons. - 0021-9967 .- 1096-9861. ; 529:5, s. 969-986
-
Tidskriftsartikel (refereegranskat)abstract
- This study investigates the response to spinal cord injury in the gray short‐tailed opossum (Monodelphis domestica). In opossums spinal injury early in development results in spontaneous axon growth through the injury, but this regenerative potential diminishes with maturity until it is lost entirely. The mechanisms underlying this regeneration remain unknown. RNA sequencing was used to identify differential gene expression in regenerating (SCI at postnatal Day 7, P7SCI) and nonregenerating (SCI at Day 28, P28SCI) cords +1d, +3d, and +7d after complete spinal transection, compared to age‐matched controls. Genes showing significant differential expression (log2FC ≥ 1, Padj ≤ 0.05) were used for downstream analysis. Across all time‐points 233 genes altered expression after P7SCI, and 472 genes altered expression after P28SCI. One hundred and forty‐seven genes altered expression in both injury ages (63% of P7SCI data set). The majority of changes were gene upregulations. Gene ontology overrepresentation analysis in P7SCI gene‐sets showed significant overrepresentations only in immune‐associated categories, while P28SCI gene‐sets showed overrepresentations in these same immune categories, along with other categories such as “cell proliferation,” “cell adhesion,” and “apoptosis.” Cell‐type–association analysis suggested that, regardless of injury age, injury‐associated gene transcripts were most strongly associated with microglia and endothelial cells, with strikingly fewer astrocyte, oligodendrocyte and neuron‐related genes, the notable exception being a cluster of mostly downregulated oligodendrocyte‐associated genes in the P7SCI + 7d gene‐set. Our findings demonstrate a more complex transcriptomic response in nonregenerating cords, suggesting a strong influence of non‐neuronal cells in the outcome after injury and providing the largest survey yet of the transcriptomic changes occurring after SCI in this model.
|
|
