Biomedical subjects

R Cuppini

Publications and source records attributed to R Cuppini.

At least 37 records · Page 2Linked to original sources

PubMed1993

Nodal and terminal sprouting by regenerating nerve in vitamin E-deficient rats.

The increased number of poly-innervated cells in normal and reinnervated extensor digitorum longus (edl) muscle of vitamin E-deficient rats suggests enhanced sprouting by motor neurons in conditions of decreased protection against lipid peroxidation. End-plates and terminal axons were observed by a combined technique that shows both end-plate acetylcholinesterase area and axons. Quantitative observations of nodal and terminal sprouting in normally innervated and reinnervated edl muscles of vitamin E-deficient rats were carried out. Branch points of nerve terminal within end-plates were also observed. Three main results were obtained. First, a notable increase of both terminal and nodal sprouting was found in reinnervated muscles of normal and vitamin E-deficient rats; moreover, a relative increase in the number of nodal sprouts occurs in the long run. Second, in muscles of uninjured, vitamin E-deficient rats, nodal and terminal sprouting and branching within end-plate was greater than in controls. Third, nodal sprouting by regenerating axons was more affected by vitamin E-deficiency than terminal sprouting and branching within end-plates.

Acetylcholinesterase↗

PubMed1993

Regeneration of motor nerves in bilobalide-treated rats.

Bilobalide, a terpene extracted from the leaves of the Ginkgo biloba tree, has been proposed to exert trophic and protective effects on neurons and on Schwann's cells in various neuropathies. The reinnervation of the extensor digitorum longus muscle following traumatic nerve damage was investigated in rats by using electrophysiological and histological techniques. Evaluation parameters included the membrane resting potential of muscle cells, the spontaneous quantal release of acetylcholine, and the percentage of muscle cells receiving multiple innervation. The percentage of muscle cells receiving multiple innervation reached a peak more rapidly in treated animals and declined subsequently to values lower than those found in controls. These data suggest that the rearrangement of regenerated innervation occurs more rapidly in bilobalide-treated animals.

Animals↗

PubMed1993

Increased number of dorsal root ganglion neurons in vitamin-E-deficient rats.

Quantitative and morphometric observations were carried out on neurons of L3-L6 dorsal root ganglia (DRGs) in control and vitamin-E-deficient rats at different ages. Controls were fed a standard diet and sacrificed at 1 or at 5 months of age; deficient rats were fed a diet without vitamin E from 1 to 5 months of age and then sacrificed. No significant difference in total number of neurons was found, but an increase in neuron sizes, a decrease in nucleus-cytoplasm ratio, and a more circular neuron shape were found in controls with increasing age (from 1 to 5 months). In L3-L6 DRGs of vitamin-E-deficient rats (5 months of age), a higher number of neurons was found than in those of either young or adult controls. Moreover, some morphometric characteristics of neurons in the deficient rats were similar to those of neurons in 1-month-old controls. The findings suggest that vitamin E deficiency can trigger events resulting in appearance of new neurons, possibly anticipating phenomena that normally occur in aging.

Age Factors↗

PubMed1992

[Muscle reinnervation in rats treated with vitamin E].

During muscle reinnervation, a transitory phase of polyinnervation occurs. In reinnervated muscles of vitamin E deficient rats, sprouting and polyinnervation are increased with respect to reinnervated controls. In this work, polyinnervation was observed in reinnervated extensor digitorum longus (edl) muscle of rats treated with pharmacological doses of vitamin E. Sciatic nerve was crushed and edl muscle was examined electrophysiologically at 30, 40 and 60 days after denervation. The percentage of polyinnervated cells in controls peaked at 30 days and thus it decreased. In muscles of vitamin E treated rats, the time course of percentage of polyinnervated muscle cells was qualitatively the same, but it was decreased at all times.

Animals↗

PubMed1991

Glucose-6-phosphate dehydrogenase activity in dorsal root ganglia of vitamin E-deficient rats.

The effect of dietary vitamin E on the activity of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD) was studied in the dorsal root ganglia of rat. One-month-old male Sprague-Dawley rats were randomly assigned to two dietary treatment groups for 2 months. The first received a standard diet supplemented with vitamin E, the second was fed a basal vitamin E-deficient diet. The activity of G6PD was markedly decreased in ganglia of the deficient animals with respect to the controls. On the other hand, the activity of the 6PGD was not significantly altered in the deficient animals. In the red cells the two enzyme activities presented a similar situation and the level of the reduced glutathione in the red cells was not significantly altered by the status of dietary vitamin E. Kinetic analysis with crude extracts of ganglia or partially purified G6PD demonstrated that there was no direct modulatory effect of the vitamin on the enzyme activity. Moreover, nondenaturing gel electrophoresis performed in this study revealed that none of the three G6PD activity bands which appeared on the acrylamide gel were significantly altered in the deficient animals. At present, the mechanism linking the G6PD activity with the status of dietary vitamin E remains unknown. Our results suggest, however, that a reduced NADPH generation produced by a decay of G6PD activity may limit the glutathione peroxidase, a very active enzyme in detoxifying peroxides, and may predispose the nervous tissue to oxidant injury.

Animals↗

PubMed1991

[Analysis of miniature potentials in reinnervated rat muscle].

Miniature endplate potentials (MEPPs) are regarded as the expression of release of a single quantum of acetylcholine by motor nerve endings in the muscle. Mepp frequency is dependent on the presynaptic mechanism, but MEPP amplitudes and time courses are the result of the characteristics of pre- and postsynaptic structures and of the interaction between them. After post-traumatic reinnervation of skeletal muscles, MEPP frequency increases, reaching slowly normal values. Two groups of male, Sprague Dawley rats were used: in the first group left sciatic nerve was crushed and nerve fibres were allowed to regenerate, whereas the others were regarded as controls. MEPPs were intracellularly recorded in end plates of normal and reinnervated left extensor digitorum longus muscle. MEPPs were sampled and recorded on a personal computer, and, subsequently, amplitude, rise time and half decay time were computed. At early stage after reinnervation, MEPPs showed rise times and decay times longer than normal. Afterwards, we did not find differences between mepp time courses by normal and reinnervated end plates. The possible relationships between the results and changes in acetylcholine receptor number and type, and in acetylcholinesterase activity occurring during denervation and reinnervation are discussed.

Acetylcholine↗

PubMed1991

[Progression of multiple innervation of reinnervated rat muscle treated with bilobalide].

During motor nerve regeneration a transitory polyinnervation of muscle cells occurs, which represents a phase of rearrangement of the recovered innervation. Bilobalide, a terpene extrated from Ginkgo biloba leaves, was proposed to affect some aspects of nervous system development and regeneration. In this work, influence of bilobalide on polyinnervation in reinnervated extensor digitorum longus muscle was studied, through electrophysiological and histological techniques. The muscle was denervated crushing the sciatic nerve and it was examined at 1 or 2 months after denervation. The polyinnervated muscle cells in controls reached 24% at 1 month and thus the percentage decreased. In muscles of bilobalide treated rats the number of polyinnervated cells was decreased at both times.

Action Potentials↗

PubMed1990

Time course of sprouting during muscle reinnervation in vitamin E-deficient rats.

A typical aspect of motoneuron plasticity is the sprouting which occurs during muscle reinnervation, resulting in a transitory multiple innervation of the muscle cells. In order to verify the effect of a decreased protection from free radical attack on the sprouting, the multiple innervation in the extensor digitorum longus muscle, following sciatic nerve crush and regeneration, was studied in vitamin E-deficient rats. Thus, the innervated end-plates and the end-plates with multiple innervation were studied with histochemical and electrophysiological techniques. The percentage of innervated end-plates was similar in both groups at 30 as well as at 60 days after nerve crush. Nevertheless, multiple innervation was found in a larger part of the muscle and it lasted longer in the deficient rats. This finding is discussed in relation to some of the major hypotheses of sprouting; it may be relevant in the treatment of some lesions of peripheral nerve.

Action Potentials↗

PubMed1990

Maturation of the spontaneous transmitter release by regenerated nerve endings in vitamin E-deficient rats.

In order to verify the importance of the protection against lipid peroxidation in presynaptic differentiation and maturation, the reappearance and maturation of the spontaneous transmitter release during the extensor digitorum longus muscle reinnervation following a lesion of the sciatic nerve were studied in normal and vitamin E-deficient rats. The study was carried out by intracellular recordings in order to observe the miniature end plate potentials in the reinnervated end plates. In control and vitamin E-deficient rats the first signs of muscle innervation reappeared simultaneously, but in the latter the spontaneous transmitter release mechanism matured more slowly; furthermore, in the long-term, very low mepp frequencies continued to occur. The data suggest a slowing of the transmitter release mechanism maturation and a protracted rearrangement of innervation in the deficient rats.

Animals↗

PubMed1989

Effect of ethanol on the maturation of the spontaneous transmitter release by regenerated nerve endings.

The cellular mechanisms involved in the theratogentic action of ethanol are not well known, but neuron outgrowth and synaptogenesis are regarded as the periods in which ethanol causes its major damage in the nervous system. The effects of chronic treatment with ethanol on the maturation of the spontaneous transmitter release by regenerated nerve endings in the rat were studied. The sciatic nerve was crushed and miniature end plate potentials (mepps) were recorded intracellularly in the re-innervated extensor digitorum longus muscle at different points in time after denervation; end plate potentials (epps) were also recorded. Two main effects were observed in the re-innervated muscles of ethanol-treated rats: (1) the appearance of spontaneous and evoked transmitter release was delayed and (2) the subsequent increase in frequency of mepps is faster. The possible mechanisms involved in these effects are discussed.

Animals↗

PubMed1988