Alessandro Sbriccoli

Prenatal exposure to ethanol in rats: effects on liver energy level and antioxidant status in mothers, fetuses, and newborns.

The fetal alcohol syndrome is a clinical condition that affects newborns from alcoholic mothers. It is not clear, however, whether ethanol consumption during gestation can affect liver functions of fetuses and newborns. In this study, we aimed to assess the effects of ethanol administration on body weight, liver energy level, and antioxidant status of mothers, fetuses, and newborns. Pregnant rats were exposed to ethanol during the third week of gestation. Body weight, survival, and liver concentration of gluthatione (GSH) and adenosintriphosphate (ATP) were measured. No differences were observed in body weight or in liver ATP and GSH between mothers exposed to ethanol and control animals. Conversely, fetuses from rats exposed to ethanol showed a marked decrease in GSH, ATP, and body weight when compared to those from control rats. Newborns exposed prenatally to ethanol were no different from those born to control mothers. This study suggests that an amount of ethanol that is not sufficient to determine a significant effect on mothers can, nevertheless, cause a marked decrease in growth and in liver antioxidant and energy status in fetuses. These parameters, however, return to control value one week after ethanol discontinuation.

Effects of L-carnitine, L-acetylcarnitine and gangliosides on the regeneration of the transected sciatic nerve in rats

Three pharmacological agents, L-carnitine, L-acetylcarnitine and gangliosides, were tested for their ability to enhance the regeneration of the rat sciatic nerve following transection and microsurgical repair. The drugs were administered intraperitoneally at the dose of 50 mg/kg/d for 28 and 56 d postoperatively. At the end of treatment, the motor function recovery of the peroneal component of the sciatic nerve was assessed and the regenerated nerves were analysed morphometrically on histological semi-thin sections. Also, the reinnervated extensor digitorum longus (EDL) muscles were studied histochemically using the adenosine-triphosphatase (ATP-ase) technique 56 d after surgery. Motor function assessment at 56 d after nerve repair revealed that L-acetylcarnitine-treated animals recovered a clinical grade significantly higher (p less than 0.05) than the control animals. Twenty-eight days after nerve repair, the number of myelinated fibres was significantly higher (p less than 0.05) in L-acetylcarnitine and ganglioside-treated animals than in control animals. However, 56 d after nerve repair the number of regenerated fibres in all the drug-treated groups was not significantly different from that of the control group. The EDL muscles of the drug-treated animals did not show significant differences from those of control animals with respect to fibre composition and fibre diameter although the L-acetylcarnitine-treated animals exhibited a significantly lower (p less than 0.05) degree of muscle atrophy than did the control animals. The results of the present work seem to indicate that L-acetylcarnitine and to a lesser extent gangliosides exert some favourable effect on the regeneration of the transected sciatic nerve in rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Spatial analysis reveals alterations of parvalbumin- and calbindin-positive local circuit neurons in the cerebral cortex of mutant mdx mice

The aim of the present study was to investigate the spatial organization of selected populations of local circuit neurons in the cerebral cortex of the mutant mdx mouse, an acknowledged model of Duchenne Muscular Dystrophy. To this purpose, we quantified and compared the distribution of parvalbumin- and calbindin-positive neurons in the motor, somatosensory, visual, and anterior cingulate cortices of wild-type and mdx mice. The methodological approach was based on generation of two-dimensional Voronoi polygons from digital charts of the cell populations visualized immunohistochemically. Polygon areas were then analyzed and the derived coefficients of variation were statistically compared. Using this strategy, we were able to reveal, in mdx mice, changes involving both the above populations of interneurons. These changes were evident in the motor and anterior cingulate cortices but not in the somatosensory and visual cortices. In addition, the changes of coefficients of variation were area-specific in the cortex of mdx mice. The values increased in the motor cortex and decreased in the anterior cingulate cortex with respect to the corresponding values of wild-type animals. The present findings point out widespread alterations in the mdx cortex involving also areas not primarily related to sensorimotor integration. In addition, we demonstrate that cortical alterations of the local circuit machinery are characterized in mdx mice by individual regional differences.

Multifaceted alterations of the thalamo-cortico-thalamic loop in adult rats prenatally exposed to ethanol

The thalamo-cortico-thalamic loop was investigated in adult rats exposed to ethanol during the last week of fetal life. Animals underwent either cortical or thalamic injections of lectin-conjugated horseradish peroxidase. Results demonstrate that prenatal exposure to ethanol causes permanent changes in the thalamocortical circuits. Alterations of thalamo-cortical and cortico-thalamic projections are concentrated at the level of axon terminal fields. The most severe thalamic damage is observed in the anterior intralaminar and midline nuclei; crossed cortico-thalamic projections also appear to be severely impaired. In the cortex, the damage to thalamic terminals displays a medio-lateral gradient of increasing severity through sensori-motor areas, with the lateral fields more impaired. Cells of origin of thalamo-cortical and cortico-thalamic projections are less affected by prenatal ethanol exposure: in the thalamus and layer 5 of sensori-motor cortex labeled cells exhibit normal values of areal numeric density. Conversely, cortico-thalamic neurons of layer 6, especially in the lateral agranular sensori-motor field, display smaller values of areal density than those of normal animals. Possible mechanisms underlying the establishment of these abnormalities are discussed.

Reconstruction of peripheral nerves: the phenomenon of bilateral reinnervation of muscles originally innervated by unilateral motoneurons.

It is well known that after reconstruction of sectioned peripheral nerves in adult mammals, denervated muscles are reinnervated by the axotomized motoneurons lying in the original motonucleus. It is less well known that these muscles can also be reinnervated by uninjured motoneurons lying in the homologous contralateral motonucleus. Therefore, after nerve reconstruction, bilateral motoneuron reinnervation of muscles can occur. Contralateral motoneurons sprout axons that cross the midline, grow in the reconstructed nerve, and reach muscle targets. This phenomenon was observed after reconstruction of several different peripheral nerves in adult mammals, including the oculomotor nerve in guinea pigs and the facial and sciatic nerves in rats. The retrograde axonal transport of horseradish peroxidase was used for the study of the organization of the brainstem and spinal cord motonuclei. Horseradish peroxidase was injected into the medial rectus muscle, the stylohyoid muscle, and the trunk of the sciatic nerve. The distance between the homologous motonuclei of both sides influenced the occurrence of this phenomenon. In fact, bilateral reinnervation of muscles after nerve reconstruction was found in 36% (sciatic nerve), 50% (facial nerve), and 100% (oculomotor nerve) of the operated animals. The total number of contralateral motoneurons found were 14% (oculomotor nerve), 8% (facial nerve), and 5% (sciatic nerve). Bilateral reinnervation of muscles was evoked by both immediate and delayed peripheral nerve repair and was a stable phenomenon, seen between 3 and 21 months after facial nerve reconstruction.

Cortical and brainstem neurons containing calcium‐binding proteins in a murine model of Duchenne's muscular dystrophy: Selective changes in the sensorimotor cortex

In the muscular dystrophic (mdx) mouse, which is characterized by deficient dystrophin expression and provides a model of Duchennes muscular dystrophy, we previously demonstrated marked central nervous system alterations and in particular a quantitative reduction of corticospinal and rubrospinal neurons and pathologic changes of these cells. Prompted by these findings and in view of the relations between calcium ions and dystrophin, we analyzed with immunohistochemistry the neurons containing the calcium‐binding proteins parvalbumin, calbindin D28k, and calretinin in cortical areas and brainstem nuclei of mdx mice. In the sensorimotor cortex, parvalbumin‐positive and calbindin‐positive neurons, which represent a subset of cortical interneurons, were significantly more numerous in mdx mice than in wild‐type ones. In addition, the laminar distribution of parvalbumin‐positive neurons in the motor and somatosensory cortical areas of mdx mice was altered with respect to wild‐type animals. No alterations in the number and distribution were found in the parvalbumin‐ or calbindin‐expressing cell populations of the visual and anterior cingulate cortices of mdx mice. The pattern of calretinin immunoreactivity was normal in all investigated cortical areas. The cell populations containing either calcium‐binding protein were similar in brainstem nuclei of mdx and wild‐type mice. The present findings demonstrated selective changes of subsets of interneurons in the motor and somatosensory cortical areas of mdx mice. Therefore, the data showed that, in the cortices of these mutant animals, the previously demonstrated pathologic changes of corticospinal cell populations are accompanied by marked alterations in the local circuitry. J. Comp. Neurol. 456:48–59, 2003.

The organisation of spinal projecting brainstem neurons in an animal model of muscular dystrophy: A retrograde tracing study on mdx mutant mice

Previous studies we performed on the mdx mouse demonstrated marked central nervous system alterations in this model of human Duchenne muscular dystrophy, such as reduction in number and pathological changes of cortico-spinal neurons. Prompted by these findings we extended the survey of the mdx brain to the major brainstem-descending pathways: the rubro-, vestibulo-, reticulo-, and raphe-spinal projections. Horseradish peroxidase microinjections were performed in the cervical spinal cord of mdx and control mice. The rubro-spinal neurons were found to be significantly reduced in mutants compared to controls. The vestibulo-spinal, reticulo-spinal, and raphe-spinal cell populations, though less numerous in mdx than in control mice, were instead substantially spared. Our data further unveil the selective nature of mdx brain damage indicating a marked and selective involvement of the highest centers for motor control.

Crossed thalamo-cortical and cortico-thalamic projections in adult mice

The crossed thalamo-cortical and cortico-thalamic connections of the mouse are drawn using the tracer wheat germ agglutinin-horseradish peroxidase. After injections in the frontal cortex of the right hemisphere cells labeled retrogradely and axons labeled anterogradely are observed in the thalamus ipsilateral and contralateral to the cortical injections. The retrograde and anterograde labeling in the contralateral thalamus is less intense than ipsilaterally and involves the mediodorsal, ventral medial, central medial, and paracentral nuclei. Crossed fronto-thalamic axons reach more lateral regions than those containing contralateral thalamo-frontal neurons. Our results demonstrate that the thalamo-cortical system of mice has a bilateral component. The functional significance of this pathway and analogies with crossed thalamo-cortical connections in other species are discussed.

Modifications of thalamo-cortical circuitry in rats prenatally exposed to ethanol.

THE present study aimed to investigate the organization of thalamo-cortical connections in adult rats exposed to ethanol during the last week of foetal life. Animals underwent thalamic injections of lectin-conjugated HRP. Results demonstrate that the thalamic-recipient zone of sensorimotor cortex is significantly thinner in ethanol- exposed than in control cases. Animals exposed to ethanol also display aberrant thalamo-cortical terminations in layer 5a. Neurones of origin of cortico-thalamic projections are normally located in layers 5 and 6; they appear quantitatively comparable in control and ethanolexposed cases. Developmental alterations underlying the establishment of anomalous thalamo-cortical relationships are discussed.

Changes in the central representation of the extraocular muscles in the rat oculomotor nucleus after section and repair of the third cranial nerve

The anatomical location of motoneurons controlling the extraocular muscles within the oculomotor nucleus was investigated by injecting retrograde horseradish peroxidase (HRP) into individual eye muscles in control rats and in rats submitted to intracranial section and repair of the oculomotor nerve 6 months previously. Compared to the controls, the operated animals showed marked changes in the somatotopic organization of the oculomotor subnuclei. The possible nature of this re-arrangement is discussed.