Spinal subarachnoid injection of colchicine in rats

Beta IV tubulin is selectively expressed by oligodendrocytes in the central nervous system

Oligodendrocyte differentiation and myelination involve dramatic changes in cell signaling pathways, gene expression patterns, cell shape, and cytoskeletal organization. In a pilot study investigating CNS angiogenesis, oligodendrocytes were intensely labeled by antisera directed against the C-terminal of Tie-2, a 140-kDa transmembrane receptor for angiopoietin. Immunoprecipitation of rat brain proteins with Tie-2 C-terminal antisera, however, produced a single spot of approximately 55-kDa pI approximately 5 by two-dimensional (2D) electrophoresis, which was identified as beta-tubulin by mass spectrometry. Isotype-specific antibodies for beta(IV) tubulin selectively labeled oligodendrocytes. First detected in premyelinating oligodendrocytes, beta(IV) tubulin was abundant in myelinating oligodendrocyte perinuclear cytoplasm and processes extending to and along developing myelin internodes. Beta(IV) tubulin-positive MTs were diffusely distributed in oligodendrocyte perinuclear cytoplasm and not organized around the centrosome. Beta(IV) tubulin may play a role in establishing the oligodendrocyte MT network, which is essential for the transport of myelin proteins, lipids, and RNA during myelination.

Effect of colchicine on micturition reflex in rats

Intracerebral or intraspinal cord, but not intraperitoneal, injection of low doses of colchicine in rats induces specific toxic symptoms. This paper deals in particular with the effect of colchicine on micturition. After the injection of 5-25 micrograms/rat in cerebral ventricle or 2.5-20 micrograms/rat intraspinal cord, bladder content was markedly increased, due to a dramatic urine retention. Time of latency of vesical retention was related to the dose and to the route of colchicine administration. Cystometrographic analyses were performed in control and treated rats at various intervals of time after the injection: bladder tone, as expressed by the delta P/delta V ratio, monitored from 12 to 120 hr after colchicine injection, decreased more and more during time, suggesting that the observed vesical hypotonicity is an irreversible phenomenon.

Colchicine reduces myelin thickness and axoplasm volume

A Silastic cuff containing either colchicine (1% w/v) or no colchicine was placed around the lingual disorder tympani nerve of the Mongolian gerbil. After 3 days of exposure to colchicine, the mean period of the myelin sheaths was 23% less than the period observed in nerves treated with cuffs lacking colchicine, while the average number of lamellae was unaltered. At the same time colchicine reduced the volume of axoplasm by an average of 19%, an effect which was independent of fiber diameter.

50ppm MnBK subclinical neuropathy in rats

40 rats were subjected daily for 6 months to an atmosphere containing 50ppm MnBK. 32 of the rats presented with demyelination of the sciatic nerve and 2 of these with axonal hypertrophy.

Studies on the early changes in acute isoniazid neuropathy in the rat

Large single doses if isoniazid by mouth (1--2g/kg) have been shown to produce in rats Wallerian degeneration visible with the light microscope from the third day onwards. By contrast, changes in axons are seen from 24 h onwards by electron microscopy. The earliest ultrastructural changes are associated with vacuoles appearing between axon and Schwann cells. These are large and focal, and often compress the axon. The adjacent axon may show changes in smooth ER, and in microtubular arrangement. Alterations in smooth membranes and in mitochondria are visible in Schwann cell cytoplasm, not necessarily related to the vacuole formation and axonal features. It is suggested that INH neuropathy is essentially a multifocal axonal lesion.