The effect of chlorpromazine and tetracaine on the rapid axonal transport of neurosecretory material in the hypothalamo-neurohypophysial system of the rat. A biochemical and ultrastructural study

Observations on fast axoplasmic transport in peripheral nerve following repetitive electrical stimulation

In a series of 13 cats the effect of electrical stimulation of peripheral nerve on the mechanism of fast axoplasmic transport was studied. Electrical stimulation was used for varying time periods at parameters reported in the range of those used to produce electroanalgesia in man. Our results indicate that at these parameters, electrical stimulation produced no effect on this important aspect of nerve function, and, therefore, our work lends support to the safety of these devices in pain states.

In vitro effects of chlorpromazine on microtubules and the Golgi complex in embryonic chick spinal ganglion cells: an electron microscopic study

Spinal ganglia from 11-day-old chick embryos were incubated in media containing chlorpromazine (CPZ), lidocaine or D-amphetamine and subsequently examined by transmission electron microscopy. CPZ and lidocaine both caused a structural modification of the neuroblasts similar to that induced by the microtubular-disrupting drugs colchicine and vinblastine. That is, there was a partial disappearance of cytoplasmic microtubules with a concomitant increase in the number of microfilaments and the dictyosomes of the Golgi complex changed, with the number of narrow cisternae decreasing and the number of associated vacuoles increasing. Moreover, the dictyosomes were more distinctly separated from each other than in control ganglia. D-Amphetamine did not give rise to any clear changes in either the microtubular system or the Golgi complex and, furthermore, opposed the colchicine-like effects of CPZ. On the basis of these results it is suggested that the subcellular mechanism of action of CPZ involves the cytoplasmic microtubular system and thus secondarily leads to structural and functional alterations in the Golgi complex, viz., in the case of nerve cells, a disturbance in the production and packaging of material destined for the axon terminals.

Ultrastructural studies of the superior cervical trunk of the mouse: distribution, cytochemistry and stability of fibrous elements in preganglionic fibers

The ultrastructure of axons in the preganglionic cervical sympathetic trunk of the mouse is described with emphasis on the number, distribution and stability of fibrous elements in the axoplasm. Neurofilaments outnumbered microtubules in myelinated and non-myelinated axons of all sizes, and the ratio of neurofilaments to microtubules in non-myelinated axons at each point studied was fairly consistent and independent of axonal diameter. The density of neurofilaments and microtubules, however, was greater in axons of progressively smaller diameter. In non-myelinated axons and small myelinated axons neurofilaments were uniformly distributed throughout the axoplasm resulting in minimum and maximum interfilament distances of 300 angstrom and 500 angstrom respectively; the spacing of fibrous elements within any one axon was dependent upon its diameter and position with respect to the superior cervical ganglion in the preganglionic trunk. The maximum interfilament distance was also found in large myelinated axons where neurofilaments, occurring in fascicles, were separated by distances of approximately 500 angstroms. Cytochemical staining of axons with lanthanum hydroxide, ruthenium red or alkaline bismuth delineated the delicate filamentous matrix interconnecting microtubules, neurofilaments and other organelles in the axoplasm. Alkaline bismuth stain was most intense in myelinated axons where heaviest deposition of reaction product was associated with neurofilaments. Treatment in vitro of the cervical sympathetic trunk with 5 X 10(-5) M vinblastine sulfate dissociated microtubules and induced formation of crystalline arrays of "tubular" elements. A uniform center to center spacing of 250-300 angstrom was found for crystalloids in non-myelinted axons; however, in myelinated axons the center to center spacing was not uniform and varied in the range 300-600 angstrom. Neurofilaments and their surface projections were unaffected by vinblastine. Fixation in the presence of lanthanum enhanced delineation of crystalloid elements. Exposure of 0-4 degrees C for up to three hours had no consistent effect on microtubules or neurofilaments. In contrast, cold treatment disrupted the delicate axonal matrix and resulted in the formation of aggregates of coarse flocculent material in the axoplasm.

Neurophysin in the brain and pituitary gland of normal and scrapie-affected sheep—I

By use of an immunofluorescence histochemical technique with a cross-species reactive antiserum to porcine neurophysin-II the precise localization of neurophysin in the pituitary gland and the hypothalamic area of the brain of the sheep has been determined. Neurophysin was confined to neurosecretory pathways originating from the supraoptic and paraventricular hypothalamic nuclei. The major pathway terminates in the neurohypophysis but in addition a second neurophysin-containing pathway proceeds in the external infundibular zone of the median eminence-pituitary stalk and is associated with the presence of vasopressin. In sheep affected with the hereditary degenerative disease known as natural scrapie, this supraoptico-paraventriculo-infundibular pathway is preserved and hypertrophied, while the major pathway to the posterior lobe of the pituitary degenerates. The supraoptic and paraventricular nuclei in the sheep comprise at least two distinct but morphologically similar neuronal populations affected differently by the natural scrapie genome, one undergoing dissolution by middle-age and one surviving and becoming hyperactive. This premature ageing is probably associated with a primary biochemical lesion affecting the rate of the axonal flow of neurosecretory vesicles and of their discharge at synaptic terminals. Possible metabolic and circulatory bases for such an anomaly are considered. The presence of neurophysin in the rostral and caudal adenohypophysis supports the view that vasopressin is acting directly as a trophic-hormone releasing factor, possibly for the quick release of adrenocorticotropic hormone and of growth hormone. The relation of neurophysin-rich aggregations in the neurohypophysis to Herring bodies and the turnover of neurosecretory material are discussed.

Reversal of morphological differentiation of mouse neuroblastoma cells by mitosis-inhibitors and anesthetics

Differentiated mouse neuroblastoma cells (C 1300) were exposed to various mitosis-inhibitors (vinblastine, colchicine and griseofulvin) and substances with anesthetic action (lidocaine, tetracaine, chlorpromazine and sodium dodecyl sulphate). All the drugs caused rapid retraction of the neurites, which was reversible in all cases but for sodium dodecyl sulphate, and showed a sigmoid dose-response relationship. The two groups of substances caused morphologically similar effects in that the microtubules disappeared and the intracellular orientation was lost. The order of potency of the anesthetics corresponded to their efficiency to cause nerve-block and antihemolysis as reported by others. Colchicine, griseofulvin, lidocaine and chlorpromazine were tested for effects of agglutination of undiffentiated cells. They inhibited agglutination at doses that were only slightly higher than those causing neurite retraction. The possibility of a close relationship between the cell membrane and microtubule system will be considered.