| 1. |
- Edström, Anders, et al.
(författare)
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The use of the regenerating frog sciatic nerve for pharmacological studies of orthograde and retrograde axonal transport
- 1987
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 401:1, s. 34-42
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Tidskriftsartikel (refereegranskat)abstract
- The outgrowth region of the regenerating frog sciatic nerve shows an increased permeability for various drugs, which has been utilized for pharmacological studies of axonal transport. Six days after a bilateral crush lesion, the nerves, including the spinal ganglia, were incubated in a compartmented chamber. Orthograde transport was assessed from the proximodistal distribution and the accumulation of labelled proteins in the nerve growth region. Retrograde transport was examined by allowing orthogradely transported materials to reverse at the regenerating region and then to accumulate at a ligature during a second incubation period. The distribution of radioactivity along the nerve was assayed by fluorography of whole-mount nerve preparations or by scintillation counting. Fluorography made it possible to increase the spatial resolution and to demonstrate effects in the elongating part of the regenerating nerve. Colchicine at low concentrations (10-100 μM) only inhibited axonal transport in the outgrowth region (6 mm long at 6 days after crush) and along some mm of the nerve proximal to the crush. Compound 48/80 (50 μg/ml), the most specific calmodulin inhibitor so far described, inhibited the transport along the same part of the nerve. Cytochalasin B (10 μg/ml) inhibited transport by effects limited to the outgrowth region. Both orthograde and retrograde transport showed sensitivity to these and some other drugs. The regenerating frog sciatic nerve seems to have significant advantages for pharmacological studies of axonal transport.
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| 2. |
- Ekström, Per A R, et al.
(författare)
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Nerve regeneration and serum levels of insulin-like growth factor-I in rats with streptozotocin-induced insulin deficiency
- 1989
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 496:1-2, s. 141-147
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Tidskriftsartikel (refereegranskat)abstract
- Peripheral nerve regeneration was studied in female Sprague-Dawley rats with streptozotocin-induced insulin deficiency. Nerve regeneration was provoked by a crush lesion on the sciatic nerve 21 days after the streptozotocin injection. The regeneration was assessed by a pinch test at different time-points after injury. The rate ofregeneration in insulin-deficient animals, 2.5 mm/day, was significantly lower than in control animals, 2.9 mm/day(P < 0.05). There was no difference in the initial delay, i.e. the period before regeneration attains a constant velocity. One group of insulin-deficient rats was treated with insulin during the regeneration period by means of implanted osmotic mini-pumps. This treatment prevented the decrease in regenerationsw. After 6 days the sciatic nerves of insulin-deficient rats had regenerated 12.3 ±0.3 mm (mean ±S.E.M.), while the corresponding value for insulin-treated rats was 15.7 ±0.6 mm (P > 0.01). The streptozotocin-treated rats were found to have a 39% reduction in the serum level of insulin-like 1 growth factor-I (IGF-I)_compared to control rats (0.33 ± 0.22 μg/ml and 0.54 ± ml respectively, (P < 0.001). Insulin treatment 1830 1732 during the regeneration period completely restored the IGF-I level back to normal.
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| 3. |
- Ekström, Per, et al.
(författare)
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Calmodulin‐Binding Proteins Within the Slow Phase of Axonal Transport in the Rabbit Vagus Nerve Per Ekstrom and Martin Kanje
- 1987
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042 .- 1471-4159. ; 49:1, s. 146-151
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: : Calmodulin‐binding proteins (CBPs) in the rabbit vagus nerve were studied by means of calmodulin‐Sepha‐rose affinity chromatography and polyacrylamide gel electrophoresis. The soluble fraction (105g supernatant) of a nerve homogenate contained four CBPs with molecular weights of 44, 55, 91, and 93 kD, respectively. Slowly transported proteins were recovered in the vagus 3 days after injection of [35S]methionine into the nodose ganglion. Four labelled CBPs with molecular weights of 44, 55, 69, and 83 kD, respectively were found. The nodose ganglion con tained two labelled CBPs, 44 and 55 kD. The 55‐kD CBP was identified as tubulin after immunoblotting. In separate experiments it was also shown that bovine brain tubulin bound to the calmodulin column.
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| 4. |
- Ekström, Per, et al.
(författare)
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The effects of trifluoperazine on fast and slow axonal transport in the rabbit vagus nerve
- 1987
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Ingår i: Journal of Neurobiology. - : Wiley. - 0022-3034. ; 18:3, s. 283-293
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Tidskriftsartikel (refereegranskat)abstract
- The effects of trifluoperazine (TFP) on fast and slow axonal transport (AXT) of labeled proteins were examined in the rabbit vagus nerve. Cuffs soaked in a 10 mM, but not 0.1 mM or 1 mM, concentration of TFP applied locally around the vagus nerve in vivo blocked both fast and slow AXT, as measured by the accumulation of 3H‐labeled proteins. In vitro, fast AXT was affected by 0.1 mM TFP. The TFP cuff treatment caused a reduction in the number of axonal microtubules (MT) whereas cuffs soaked in saline had no effect. The levels of ATP, ADP, and AMP were not significantly lowered by the TFP treatment. The results suggest that both fast and slow AXT are sensitive to TFP treatment, and that the axonal MT‐system may be the main target of the drug.
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| 5. |
- Kanje, Martin, et al.
(författare)
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Ca2+-activated protease activity in frog sciatic nerve : Characterization and effect on rapidly transported axonal proteins
- 1985
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 327:1-2, s. 29-36
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Tidskriftsartikel (refereegranskat)abstract
- Protease activity was studied in the frog sciatic nerve. The activity was measured as the release of TCA-soluble radioactivity from either 3H-labelled proteins transported by rapid axonal transport (AXT) or 3H-labelled ganglionic proteins. In nerve homogenates containing transported substrates, protease activity exhibited two peaks, one around pH 5 and one around pH 8. Ca2+ at 100 μM or higher concentrations only stimulated the latter, which was inhibited by 1 mM parachloromercuric benzoate, a sulphydryl reagent, but unaffected by ATP (1 mM). The proteolytic activity was recovered in the 105 g supernatant of the homogenate. In desheathed nerves containing 3H-labelled transported proteins, the protease activity could be activated by exposing the nerve to a Ca2+-ionophore, X-537 A, or to an elevated Ca2+-concentration (50 mM). These conditions were also shown to increase the influx and efflux of 45Ca2+ in the nerves. The results indicate the presence within axons of a Ca2+-activated soluble protease, which degrades rapidly transported proteins. The finding that the protease degraded ganglionic soluble proteins to about the same extent suggests a broad substrate specificity. The present system should be useful for further characterization of protease activity during various physiological conditions.
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| 6. |
- Kanje, Martin, et al.
(författare)
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Effect of Estramustine Phosphate on the Assembly of Isolated Bovine Brain Microtubules and Fast Axonal Transport in the Frog Sciatic Nerve
- 1985
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Ingår i: Cancer Research. - 0008-5472. ; 45:5, s. 2234-2239
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Tidskriftsartikel (refereegranskat)abstract
- Estramustine phosphate (0.01 to 0.5 nriM), an estradiol mustard derivative used in the therapy of prostatic carcinoma, inhibited the assembly of brain microtubule proteins in vitro and disassembled preformed microtubules. In the presence of estramustine phosphate, the minimum microtubule-protein concentration sufficient for the assembly of microtubules was increased. Low concentrations of taxoi (20 μM) completely reversed the inhibition of assembly by estramustine phosphate. The effects were specific to estramustine phosphate since neither estradiol 170-phosphate, the hormonal moiety of the drug, nor nornitrogen mustard, the alkylating moiety, had any effect on assembly. Estramustine phosphate (0.1 to 0.5 HIM) was also found to reversibly inhibit fast axonal transport in the frog sciatic nerve. The nerve content of adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate was not significantly affected by estramustine phosphate. Our results suggest that the cytotoxic action of estramustine phosphate could be dependent partially on an interaction with microtubules, probably via the microtubule-associated proteins.
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| 7. |
- Kanje, Martin, et al.
(författare)
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The effect of gossypol on fast axonal transport and microtubule assembly
- 1986
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier BV. - 0005-2736. ; 856:3, s. 437-442
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Tidskriftsartikel (refereegranskat)abstract
- Gossypol at micromolar concentrations (2 μM) was found to inhibit axonal transport and a microsomal ATPase activity in the frog sciatic nerve, although axonal microtubules and the neuronal content of AMP, ADP and ATP were not affected. At slightly higher concentrations (30-40 μM), gossypol also inhibited microtubule assembly and neuronal energy metabolism. Gossypol accumulated in the nerve and the results indicate that gossypol may act as a potent neurotoxin.
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