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Peripheral neuropathy, either inherited or acquired, represents a very common disorder for which effective clinical treatments are not available yet. Observations here summarized indicate that neuroactive steroids, such as progesterone, testosterone and their reduced metabolites, might represent a promising therapeutic option. Peripheral nerves are able to synthesize and metabolize neuroactive steroids and are a target for these molecules, since they express classical and non-classical steroid receptors. Neuroactive steroids modulate the expression of key transcription factors for Schwann cell function, regulate Schwann cell proliferation and promote the expression of myelin proteins involved in the maintenance of myelin multilamellar structure, such as myelin protein zero and peripheral myelin protein 22. These actions may result in the protection and regeneration of peripheral nerves affected by different forms of pathological alterations. Indeed, neuroactive steroids are able to counteract biochemical, morphological and functional alterations of peripheral nerves in different experimental models of neuropathy, including the alterations caused by aging, diabetic neuropathy and physical injury. Therefore, neuroactive steroids, pharmacological agents able to increase their local synthesis and synthetic ligands for their receptors have a promising potential for the treatment of different forms of peripheral neuropathy.

Anti-sulfatide IgM antibodies have been recently associated with neuropathy but the clinical and electrophysiological correlations of this reactivity remains unclear. We reviewed the clinical and electrophysiological features of patients with high anti-sulfatide titers detected in our laboratory from 1991 to 1998. Of the 564 patients with different neurological diagnosis tested by enzyme-linked immunosorbent assay (ELISA), 11 had high anti-sulfatide IgM titers (>1/8000), 26 had titers of 1/8000 while 78 had titers of 1/4000. All patients with high anti-sulfatide IgM titers had a chronic, dysimmune, mostly sensorimotor neuropathy that in seven was associated with IgM monoclonal gammopathy. In most of these patients electrophysiological and morphological studies were consistent with a predominantly demyelinating neuropathy frequently associated with prominent axonal loss. Antibody titers of 1/8000, though always associated with neuropathy, did not correlate with a particular form or cause of neuropathy, while lower titers were equally distributed in patients with different neurological disorders. Our study indicate that high anti-sulfatide IgM titers (>1/8000) are highly predictive for a chronic, dysimmune, mostly demyelinating neuropathy often associated with IgM monoclonal gammopathy, and may therefore have potential diagnostic relevance.

In the present study, we investigated the peripheral nervous system (PNS) (both in terms of its ultrastructure and in terms of its function) of rats made cobalamin (Cbl)-deficient either through total gastrectomy or through prolonged feeding on a Cbl-deficient diet. In both these types of Cbl-deficient neuropathies we found: (a) ultrastructurally, intramyelin and endoneural edema, with no or minimal axonal damage in the PNS, in dorsal root ganglia, and the ventral and dorsal rootlets of the spinal cord; (b) electrophysiologically, a significant reduction in the nerve conduction velocity, consistent with that reported in (a); (c) morphometrically, a significant reduction in the density of myelinated fibers both in the sciatic nerve and in the peroneal nerve. All these pathological changes were reversed by chronic postoperative administration of Cbl into totally gastrectomized (TGX)-rats, hinting at the specificity of the damage itself in relation to the permanent Cbl-deficient status of the TGX-rats. No signs of segmental demyelination or remyelination were found. We also observed a turning of type I fibers into type II fibers in the soleus muscle of all our Cbl-deficient rats, however the Cbl deficiency had been induced. This muscular change was still present in TGX- and Cbl-treated rats, and it cannot be related to a malnutrition status, since it has been observed also in rats fed a Cbl-deficient diet. All these results demonstrate that Cbl deficiency strongly affects rat PNS within different parameters

Different attempts have been made to minimize the neurotoxicity of cisplatin (DDP) and the use of "neuroprotective" drugs seems to be a promising strategy. In rats we compared the effects on the dorsal root ganglia neurons and peripheral nerves of the administration of DDP alone or in combination with glutathione (GSH), a putative "neuroprotective" drug

So far various drugs have been used in an attempt to prevent or reduce cisplatin (CDDP)-induced peripheral neuropathy. Of those tried reduced glutathione (GSH) is one of the most promising. Its effectiveness has already been demonstrated by means of morphological methods in CDDP-treated rats in which high doses of GSH (up to 1200 mg/kg) were given. In the current study neurophysiological and morphological methods were used to evaluate the effect of low doses (150-300 mg/kg) of GSH i.p. on the peripheral nervous system of the rat. Four groups of 8 female Wistar rats were treated as follows: (A) CDDP 2 mg/kg i.p. weekly for 9 courses; (B) same as (A) plus GSH 150 mg/kg i.p. weekly; (C) same as (A) plus GSH 300 mg/kg i.p. weekly; (D) same as (A) plus GSH 150 mg/kg i.p. on the day of DDP injection followed by 150 mg/kg/day over the next 2 days. Eleven age-matched untreated rats were used as controls. Sensory conduction velocity was recorded in the tail nerve and morphologic and morphometric examinations were performed on the dorsal root ganglia neurons (L4-L6) in each animal. The results demonstrated that the neurophysiological and pathological changes induced by CDDP administration were less severe in rats co-treated with GSH. No significant differences could be related to the 3 different regimens of GSH co-treatments. This experiment confirms that GSH is able to reduce the neurotoxicity of CDDP and that it is effective even at doses as low as those used in the present study

The sural nerves of 6 patients with different signs of alcoholic neuropathy were studied qualitatively and quantitatively by electron microscopy. Myelinated and unmyelinated fibres showed degenerative changes of the Wallerian type. Concomitant involvement of the myelin appears to be secondary to axonal lesions. Regenerative processes, although frequently observed, did not balance the destruction of fibres in the degenerative phase. Quantitative studies indicated a reduced number of myelinated fibres and decreased percentage of the area covered in cross-section by myelinated and unmyelinated axons. The histograms of myelinated fibres showed a shift to the left of the peak of large and small fibres and an increased number of small-sized fibres. Similarly the histograms of unmyelinated fibres showed a shift to the left and a bimodal distribution with an increased number of small-sized fibres. Imbalance in degenerative and regenerative processes seems to be the basis of the chronic partial denervation observed in the nerves of alcoholic patients in this study