| 1. |
|
|
| 2. |
|
|
| 3. |
- Larsson, Max, et al.
(författare)
-
Quantitative analysis of immunogold labeling indicates low levels and non-vesicular localization of L-aspartate in rat primary afferent terminals.
- 2001
-
Ingår i: Journal of Comparative Neurology. - : John Wiley & Sons. - 0021-9967 .- 1096-9861. ; 430:2, s. 147-159
-
Tidskriftsartikel (refereegranskat)abstract
- The role of L-aspartate as an excitatory neurotransmitter in primary afferent synapses in the spinal cord dorsal horn is disputed. To further investigate this issue, we examined the presence of aspartate-like immunoreactivity in primary afferent nerve terminals and other tissue components of the dorsal horn. We also examined the relationship between aspartate and glutamate immunogold labeling density and the density of synaptic vesicles in primary afferent terminals and presumed inhibitory terminals forming symmetric synapses. Weak aspartate immunosignals, similar to or lower than those displayed by presumed inhibitory terminals, were detected in both C-fiber primary afferent terminals in lamina II (dense sinusoid axon terminals, identified by morphological criteria) and in A-fiber primary afferent terminals in laminae III-IV (identified with anterograde transport of choleragenoid-horseradish peroxidase conjugate). The aspartate immunogold signal in primary afferent terminals was only about one-fourth of that in deep dorsal horn neuronal cell bodies. Further, whereas significant positive correlations were evident between synaptic vesicle density and glutamate immunogold labeling density in both A- and C-fiber primary afferent terminals, none of the examined terminal populations displayed a significant correlation between synaptic vesicle density and aspartate immunogold labeling density. Thus, our results indicate relatively low levels and a non-vesicular localization of aspartate in primary afferent terminals. It is therefore suggested that aspartate, rather than being a primary afferent neurotransmitter, serves a role in the intermediary metabolism in primary afferent terminals.
|
|
| 4. |
- 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.
|
|
| 5. |
- Fundin, Bengt T., et al.
(författare)
-
A comprehensive immunofluorescence and lectin binding analysis of intervibrissal fur innervation in the mystacial pad of the rat
- 1997
-
Ingår i: Journal of Comparative Neurology. - 0021-9967 .- 1096-9861. ; 385:2, s. 185-206
-
Tidskriftsartikel (refereegranskat)abstract
- The innervation of the intervibrissal fur in the mystacial pad of the rat and mouse wasexamined by immunofluorescence with a wide variety of antibodies for neuronal relatedstructural proteins, enzymes, and peptides as well as for lectin binding histofluorescence with Griffonia simplicifolia (GSA). Anti-protein gene product 9.5 (PGP) immunofluorescencelabeled all sets of axons and endings. The innervation in the upper dermis and epidermis wasdistributed through a four tiered dermal plexus. From deep to superficial, the second tier wasthe source of all apparent myelinated mechanorceptors, the third tier of nearly all thepeptidergic and GSA binding innervation, and the fourth tier of nonpeptidergic GSA negativeinnervation (peptide-/GSA-). Three types of mechanoreceptors—Merkel, transverse lanceolate,and longitudinal lanceolate endings—innervated guard hair follicles. All had similarlabeling characteristics for 160 kDa and 200 kDa neurofilament subunits, peripherin,carbonic anhydrase, synaptophysin, and S100. Palisades of longitudinal lanceolate endingswere part of piloneural complexes along circumferentially oriented sets of transverselanceolate endings, peptidergic free nerve endings (FNEs), and peptide-/GSA- FNEs. Thelongitudinal lanceolate endings were the only mechanoreceptors in the mystacial pad that haddetectable calcitonin gene-related peptide. The epidermis contained four types of unmyelinatedendings: simple free nerve endings (FNEs), penicillate endings, cluster endings and bushendings. Only the simple FNEs were clearly peptidergic. Virtually all others were peptide-/GSA-. Each bush ending was actually an intermingled cluster of endings formed by severalunmyelinated axons and occasionally anAd axon. In contrast to the other unmyelinated innervationto the epidermis, bush endings labeled with an antibody against the Schwann cell protein S100. Thenecks and mouths of follicles, as well as superficial vasculature, were innervated by a mixture of unmyelinated peptidergic and/or GSA labeled sensory and sympathetic axons. Small presumptivesweat glands were innervated by three sets of peptidergic axons of which one was immunoreactivefor somatostatin. Potential functions of the various sets of innervation are discussed.
|
|
| 6. |
- Hallbeck, Martin, 1970-, et al.
(författare)
-
Distribution of preprovasopressin mRNA in the rat central nervous system
- 1999
-
Ingår i: Journal of Comparative Neurology. - 0021-9967 .- 1096-9861. ; 411:2, s. 181-200
-
Tidskriftsartikel (refereegranskat)abstract
- Vasopressin released in the central nervous system has been shown to be involved both in homeostatic mechanisms (e.g., water balance, thermoregulation, cardiovascular regulation, metabolism, and antinociception) and in higher brain functions (e.g., social recognition and communication, and learning and memory). Many nuclear groups have been proposed to synthesize vasopressin, but available data are conflicting. We have used a sensitive in situ hybridization technique to identify the distribution of the neurons that may be the origin of the vasopressin in the central nervous system of the male Sprague-Dawley rat. Vasopressin mRNA-expressing neurons were most abundant in the hypothalamus (e.g., the paraventricular, supraoptic, and suprachiasmatic nuclei) but were also seen in the medial amygdaloid nucleus, the bed nucleus of stria terminalis, and the nucleus of the horizontal diagonal band. Previously unreported vasopressinergic neurons were seen in the entorhinal and piriform cortices, the ventral lateral portion of the parabrachial nucleus, the pedunculopontine nucleus, and the rostral part of the ventral periaqueductal gray matter and the adjacent portion of the mesencephalic reticular nucleus. Vasopressin mRNA expression suggestive of neuronal labeling was seen in the pyramidal layer of the CA1–3 fields and the dentate gyrus of the hippocampus. In addition, vasopressin mRNA expression, probably representing axonal mRNA, was detected over the hypothalamopituitary tract. No or insignificant preprovasopressin mRNA expression was present in the cerebellum, locus coeruleus, subcoeruleus, or the spinal cord. These findings provide novel information on the distribution of vasopressin neurons that are important for our understanding of how vasopressin acts in the brain.
|
|
| 7. |
- Hallbeck, Martin, 1970-, et al.
(författare)
-
Spinal cord-projecting vasopressinergic neurons in the rat paraventricular hypothalamus
- 1999
-
Ingår i: Journal of Comparative Neurology. - 0021-9967 .- 1096-9861. ; 411:2, s. 201-211
-
Tidskriftsartikel (refereegranskat)abstract
- The paraventricular hypothalamic nucleus (PVH) is a key structure for the maintenance of homeostasis. Homeostatic regulation includes modulation of signaling in the spinal cord. This may be exerted by neurons in the PVH with spinal projections. However, the PVH is not a homogeneous structure, but consists of anatomically and functionally distinct subdivisions. In this study, we have analyzed the distribution of spinal cord-projecting PVH neurons that express vasopressin, an important neuropeptide in autonomic regulation. Vasopressinergic neurons were identified with a radiolabeled riboprobe complementary to vasopressin mRNA combined with immunohistochemical labeling of retrogradely transported cholera toxin subunit b in spinally projecting neurons. More than 40% of the spinally projecting neurons in the PVH of naive Sprague-Dawley rats were found to express vasopressin mRNA. The lateral parvocellular subdivision and the ventral part of the medial parvocellular subdivision contained the densest distribution of spinal cord-projecting vasopressin mRNA-expressing neurons. The magnocellular subdivisions displayed large numbers of vasopressin mRNA-expressing neurons, but very few of those projected to the spinal cord. The dorsal parvocellular subdivision contained a large number of spinally projecting neurons, but very few of those expressed vasopressin mRNA. These findings show that the PVH gives rise to a major vasopressinergic projection to the spinal cord and that the spinal cord-projecting vasopressinergic neurons are parceled into anatomically distinct cell groups. This provides an anatomical basis for a selective activation of functionally different groups in the PVH as part of a behaviorally adaptive response, including modulation of autonomic activity and pain processing at the spinal level.
|
|
| 8. |
- Hallböök, Finn, et al.
(författare)
-
Expression of neurotrophins and trk receptors in the avian retina
- 1996
-
Ingår i: Journal of Comparative Neurology. - 0021-9967 .- 1096-9861. ; 364:4, s. 664-676
-
Tidskriftsartikel (refereegranskat)abstract
- Using the RNase protection assay, we have found that nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3) are expressed in the avian retina during development. The expression peaks around embryonic days 12-15, with decreasing levels at later stages of development. Abundant levels of NGF and BDNF but low levels of NT-3 mRNA were found in the adult retina. We also found that light/darkness regulated the levels of NGF and BDNF mRNAs but not the levels of NT-3 mRNA in the 5-day-old chicken retina. It was demonstrated that NGF and BDNF mRNA levels were up-regulated by light exposure. The cellular localization of mRNA expression for the neurotrophins and neurotrophin receptors TrkA, TrkB, and TrkC in the retina was studied using in situ hybridization. The patterns of NGF and trkA mRNA expression were very similar and were localized to the external part of the inner nuclear layer on the border with the outer plexiform layer and corresponded to the localization of horizontal cells. NT-3 labeling was also found over the external part of the inner nuclear layer, whereas trkC mRNA was found over all layers in the retina. BDNF labeling was found over all layers in the retina, whereas TrkB labeling was intense over cells in the ganglion cell layer, which is in agreement with the response of ganglion cells to BDNF stimulation. Functional neurotrophin receptors were suggested by the response of retinal explants to neurotrophin stimulation. These data indicate that the neurotrophins play local roles in the retina that involve interactions between specific neuronal populations, which were identified by the localization of the Trk receptor expression. The data also suggest that NGF and BDNF expression is regulated by normal neuron usage in the retina.
|
|
| 9. |
- Karlsson, Miriam, et al.
(författare)
-
Nerve growth factor receptor TrkA is expressed by horizontal and amacrine cells during chicken retinal development
- 1998
-
Ingår i: J. Comp. Neurol.. ; 400:3, s. 408-416
-
Tidskriftsartikel (refereegranskat)abstract
- Nerve growth factor is known to stimulate neurite outgrowth and support neuronal survival during embryonic development. We have studied the expression of the nerve growth factor receptor, TrkA, at both mRNA and protein levels during the course of chicken retinal development. Furthermore, we have compared the expression of trkA mRNA with that of the 75-kD low-affinity neurotrophin receptor (p75NTR). RNase protection assay identified peak-levels of trkA mRNA in the late embryonic retina. Using in situ hybridization and immunohistochemistry, we found cells expressing TrkA in both the internal and the external part of the inner nuclear layer, corresponding to amacrine and horizontal cells, respectively. The TrkA-expressing amacrine cell has a unistratified dendritic arborization in the second sublamina of the inner plexiform layer, and may represent the stellate amacrine cell described by Cajal. The horizontal cells, possessing arciform dendrite processes in the outer plexiform layer, showed strong TrkA immunoreactivity in both dendrites and cell bodies. During the course of retinal development, the TrkA-expressing amacrine cells decreased in number, whereas the TrkA-expressing horizontal cells persisted. Because nerve growth factor was expressed where the horizontal cells, but not where the amacrine cells were located, these findings raise the question of whether nerve growth factor could locally support the survival of TrkA-expressing interneurons during retinal development.
|
|
| 10. |
- Nässel, Dick R, et al.
(författare)
-
Proline-specific dipeptidyl peptidase activity in the cockroach brain and intestine : Partial characterization, distribution, and inactivation of tachykinin-related peptides
- 2000
-
Ingår i: Journal of Comparative Neurology. - 0021-9967 .- 1096-9861. ; 418:1, s. 81-92
-
Tidskriftsartikel (refereegranskat)abstract
- Proline-specific dipeptidyl peptidase (DPP TV) is an established enzyme known to degrade neuropeptides and peptide hormones in vertebrate tissues. DPP TV cleaves peptides at the Pro(2) residue. Because several neuropeptides of the cockroach Leucophaea maderae, such as LemTRP-1 (APSGFLGVRamide), are potential substrates for this peptidase, we investigated the occurrence of proline-specific DPP activity in cockroach tissues. Partly purified DPP activity was characterized from the brain and midgut of L. maderae by using Gly-Pro-4-nitroanilide as a substrate. The highest activity was obtained from the membrane fraction of intestine; about 10 times less activity (per milligram protein) was obtained from brain membranes. A smaller amount of soluble DPP activity could also be identified in both tissues. Gel chromatography of the solubilized intestinal DPP activity revealed a molecular mass of about 75 kDa. The enzyme had a pH optimum of 8.5. Diprotin A (Ile-Pro-Ile) was an efficient competitive inhibitor of the cockroach DPP, whereas other known DPP inhibitors were found to be less potent. When incubated with human and cockroach DPP IV, the cleavage products of LemTRP-1 were AP and SGFLGVRamide (des-AP-LemTRP-1) as determined by mass spectrometry of high-performance liquid chromatography (HPLC)-purified peptide fragments. The AP fragment was biologically inactive and the des-AP fragment had a drastically reduced myostimulatory activity on the hindgut of L. maderae. The blowfly TRP callitachykinin-I (CavTK-I; APTAFYGVRamide) was cleaved in two steps to des-AP-CavTK-I and desAPTA-CavTK-I, showing that cockroach DPP does not only liberate Xaa-Pro, but also Xaa-Ala dipeptides. The fragment desAPTA-CavTK-I was completely inactive on the cockroach hindgut. To compare, LemTRP-3 and CavTK-II, which lack a Pro(2), were not cleaved by DPP IV. Enzyme histochemistry for DPP IV was performed on cryostat sections of brain and intestine with Gly-Pro-4-methoxy-2-naphthylamide as the substrate and Fast Blue B as the chromogen. Strong histochemical labeling was seen in specific neuropils of the brain such as the calyces of the mushroom bodies, the antennal glomeruli, and the central body. Also, the inner lining of the midgut (the peritrophic membrane) and the malpighian tubules were strongly labeled by reaction product. In both the brain and intestine, the enzyme-histochemical reaction was inhibited by diprotin A.
|
|
