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  • Author or Editor: Liverana Lauretti x
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Roberto Pallini, Eduardo Fernandez, Liverana Lauretti, Elisabetta Dell'Anna, Frank La Marca, Carlo Gangitano, Aurora Del Fà, Corrado Olivieri-Sangiacomo, Alessandro Sbriccoli and Gian Franco Rossi

✓ The superior cervical ganglion (SCG) has been grafted to the brain of adult rats in an attempt to reverse the parkinsonian syndrome that follows destruction of central dopamine systems. However, the main limitation to this approach is the massive cell death that occurs in the grafted SCG after direct transplantation into the brain.

In adult rats, 6-hydroxydopamine (6-OHDA) was stereotactically injected into the right substantia nigra (SN). One month later, dopamine denervation was assessed using the apomorphine-induced rotational test. In rats with a positive test, an autologous peripheral nerve (PN) graft was tunneled from the right cervical region to the ipsilateral parietal cortex. One end of the PN graft was sutured to the transected postganglionic branch of the SCG and the other end was inserted into a surgically created cortical cavity. The apomorphine test was repeated at 3 days and again at 1, 3, and 5 months after surgery. The brain, SCG, and PN graft were studied under light and electron microscopy and with the tyrosine hydroxylase immunohistochemical and horseradish peroxidase tracing methods.

Three days after grafting, there were no significant differences on the apomorphine test as compared to the preoperative test. Conversely, 1, 3, and 5 months after grafting, the number of rotations was reduced by 69% (± 20.2), 66.6% (± 17.1), and 72.5% (± 11.3), respectively. Control rats that received a free PN graft to the brain and underwent section of the postganglionic branch of the SCG did not show significant changes on the apomorphine test after surgery. Histological examination revealed that the PN graft was mostly reinnervated by amyelinic axons of small caliber. Approximately 40% of the SCG neuronal population that normally projects to the postganglionic branch survived axotomy and regenerated the transected axons into the PN graft. Axons arising from the SCG elongated the whole length of the graft, crossed the graft—brain interface and extended into brain regions adjacent to the denervated striatum up to 2037 µm from the graft insertion site.

This work shows that the ingrowth of catecholamine-regenerating axons from the SCG to dopamine-depleted brain parenchyma significantly reduces behavioral abnormalities in hemiparkinsonian rats. This effect cannot be ascribed either to the brain cavitation or to the PN tissue placement in the brain.

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Roberto Pallini, Eduardo Fernandez, Liverana Lauretti, Francesco Draicchio, Vito E. Pettorossi, Carlo Gangitano, Aurora Del Fà, Corrado Olivieri-Sangiacomo and Alessandro Sbriccoli

✓ In adult guinea pigs, the oculomotor nerve was sectioned proximally (at the tentorial edge) or more distally (at the orbital fissure) and immediately repaired by reapproximation. During a 24-week postoperative period, extrinsic eye motility was assessed by analyzing the vestibulo-ocular reflexes. The regenerated oculomotor nerve was studied morphometrically on semi-thin histological sections at 16 and 24 weeks postinjury. The selectivity of muscle reinnervation was investigated by injection of both single (horseradish peroxidase) and double (fluorescent dyes) retrograde axonal tracers into the eye muscles. Following proximal repair of the oculomotor nerve, the degree of recovery of extraocular motility varied among different animals and remained stable over long-term observations. In animals with poor recovery, aberrant eye movements were always found, and the somatotopic map of the reinnervated eye muscles was greatly altered. Distortions of the central representation were also seen in those animals in which a good level of functional recovery was seen. However, in animals with good recovery, a topographic bias was re-established by about 65% of the original neuronal population, as opposed to 26% in the animals with poor recovery. Neurons located contralateral to the axotomized nucleus sprouted intra-axially and projected their axons to denervated eye muscles. The number and diameter of the regenerated axons, the number and soma diameter of the axotomized neurons, and the ratio of distal axonal branches to proximal supporting neurons were all related to the degree of functional recovery.

Following repair of the oculomotor nerve at the orbital fissure, extraocular motility had recovered in all of the animals at 16 weeks without aberrant phenomena. Functional regeneration of the distally transected oculomotor nerve is thought to be the result of selective muscle reinnervation.

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Massimo Miscusi, Florian Ebner, Sabrina Ceccariglia, Marta Menegazzi, Sofia Mariotto, Luigi Berra, Aurora Del Fa, Carlo Gangitano, Liverana Lauretti, Paolo Missori, Roberto Delfini and Hisanori Suzuki

Object

Because of toxicity at high concentrations, nitric oxide (NO) contributes to spinal cord injury (SCI) secondary lesions. At low concentrations NO modulates nuclear factor–κB (NF-κB) activation. The authors investigated the activity of neuronal and endothelial NO synthase (nNOS and eNOS) to determine correlations with NF-κB activation and inducible NOS (iNOS) expression soon after SCI.

Methods

In 48 adult male Wistar rats clip-based (50 g/mm2/10 seconds) SCI was induced, and spinal cords were removed at different intervals for the following evaluations: 1) assaying specific activity of nNOS and eNOS; 2) electrophoresis mobility shift assay for activated NF-κB; 3) Northern blotting for iNOS; 4) immunohistochemistry for iNOS and NF-κB; and 5) immunofluorescence for iNOS and NF-κB.

At 15 minutes postinjury, eNOS activity decreased significantly (p < 0.001), as did nNOS activity at 1 hour compared with these levels in control animals and rats killed at 15 and 30 minutes after SCI (p < 0.001). Basal NF-κB levels were variable in controls and at 15 and 30 minutes after injury. One hour postinjury, NF-κB activation was diffuse. Inducible NOS messenger RNA localized diffusely, peaking 6 hours after injury and remaining stable until 24 hours postinjury. Immunohistochemical analysis showed diffuse iNOS and NF-κB staining, especially in neurons inside and around the lesion. Immunofluorescence demonstrated that injured neurons were a source of NF-κB and iNOS soon after injury.

Conclusions

Both nNOS and eNOS exhibited different regulation and roles soon after injury: nNOS correlated with NF-κB activation, whereas eNOS may have participated in vascular changes of the injured spinal cord. Neurons seemed to play a pivotal role in modulating and amplifying the inflammatory response in the injured spinal cord.