Sex dimorphism in an animal model of multiple sclerosis: Focus on pregnenolone synthesis

Neuroactive steroids, molecules produced from cholesterol in steroidogenic cells (i.e., peripheral glands and nervous system) are physiological modulators and protective agents of nervous function. A possible role for neuroactive steroids in the sex-dimorphic clinical manifestation, onset and progression of Multiple Sclerosis (MS) has been recently suggested. To explore this possibility, we assessed the synthesis of the first steroidogenic product (pregnenolone; PREG) in the spinal cord of experimental autoimmune encephalomyelitis rats, a MS model. Data obtained indicate that the synthesis of PREG in the spinal cord is altered by the pathology in a sex-dimorphic way and depending on the pathological progression. Indeed, in male spinal cord the synthesis was already decreased at the acute phase of the disease (i.e., 14 days post induction - dpi) and maintained low during the chronic phase (i.e., 45 dpi), while in females this effect was observed only at the chronic phase. Substrate availability had also a role in the sex-dimorphic kinetics. Indeed, at the chronic phase, male animals showed a reduction in the levels of free cholesterol coupled to alteration of cholesterol metabolism into oxysterols; these effects were not observed in female animals. These findings suggest that the comprehension of the neurosteroidogenic processes could be relevant to better understand the sexual dimorphism of MS and to possibly design sex-oriented therapeutic strategies based on neuroactive steroids.

Size and specimen-dependent strategy for x-ray micro-ct and tem correlative analysis of nervous system samples

Correlative approaches are a powerful tool in the investigation of biological samples, but require specific preparation procedures to maintain the strength of the employed methods. Here we report the optimization of the embedding protocol of nervous system samples for a correlative synchrotron X-ray computed microtomography (micro-CT) and transmission electron microscopy (TEM) approach. We demonstrate that it is possible to locate, with the micrometric resolution of micro-CT, specific volumes of interest for a further ultrastructural characterization to be performed with TEM. This approach can be applied to samples of different size and morphology up to several cm. Our optimized method represents an invaluable tool for investigating those pathologies in which microscopic alterations are localized in few confined regions, rather than diffused in entire tissues, organs or systems. We present a proof of concept of our method in a mouse model of Globoid Cells Leukodistrophy.

Neuroprotective effects of progesterone in chronic experimental autoimmune encephalomyelitis

Observations so far obtained in experimental autoimmune encephalomyelitis (EAE) have revealed the promising neuroprotective effects exerted by progesterone (PROG). The findings suggest that this neuroactive steroid may potentially represent a therapeutic tool for multiple sclerosis (MS). However, up to now, the efficacy of PROG has been only tested in the acute phase of the disease, whereas it is well known that MS expresses different features depending on the phase of the disease. Accordingly, we have evaluated the effect of PROG treatment in EAE induced in Dark Agouti rats (i.e. an experimental model showing a protracted relapsing EAE). Data obtained 45 days after EAE induction show that PROG treatment exerts a beneficial effect on clinical score, confirming surrogate parameters of spinal cord damage in chronic EAE (i.e. reactive microglia, cytokine levels, activity of the Na(+) ,K(+) -ATPase pump and myelin basic protein expression). An increase of the levels of dihydroprogesterone and isopregnanolone (i.e. two PROG metabolites) was also observed in the spinal cord after PROG treatment. Taken together, these results indicate that PROG is effective in reducing the severity of chronic EAE and, consequently, may have potential with respect to MS treatment.

Neuropathological changes in the peripheral nervous system and spinal cord in a transgenic mouse model of Niemann-Pick disease type A

OBJECTIVE

Type A Niemann-Pick is a severe neurological disease, caused by a mutation of the gene of acid sphingomyelinase (ASM) and reduced enzyme activity. Some studies reported neuropathological changes occurring in the central nervous system of ASM deficient transgenic (ASMKO) mice, while a detailed study on the peripheral nervous system (PNS) at different ages is currently lacking. The aim of our study was to examine the pathological changes occurring in the PNS and in the spinal cord in an AMSKO model of Niemann-Pick disease (NPD) Type A.

MATERIAL AND METHOD

Dorsal root ganglia (DRG), peripheral nerves and spinal cord specimens were obtained from ASMKO mice and age-matched wild type animals (age range = 1-7 months). They were observed at the light and electron microscope. Behavioral testing was performed to assess motor coordination and reactivity. Fluoro-Jade B was used as a high affinity fluorescent marker for degenerating neurons.

RESULTS

Typical NPD cytoplasmic inclusions were observed in DRG neurons and satellite cells, in peripheral nerve Schwann cells, in spinal cord neurons and in endothelial cells. All these inclusions were present from the age of 1 month and increased with aging. By Fluoro-Jade B staining we demonstrated the occurrence of neuronal degeneration starting from 5 months of age.

CONCLUSION

Despite the fact that a definite diagnosis of NPD Type A depends on enzymatic assays and/or molecular analysis, morphological investigation remains an important diagnostic procedure. Well-defined and complete neuropathological information about the ASMKO mouse model, inclusive of PNS examination, may be crucial in the pre-clinical evaluation of new therapies.

Resveratrol interference with the cell cycle protects human neuroblastoma SH-SY5Y cell from paclitaxel-induced apoptosis

In previous studies we demonstrated that resveratrol acts in an antiapoptotic manner on the paclitaxel-treated human neuroblastoma (HN) SH-SY5Y cell line inhibiting the apoptotic pathways induced by the antineoplastic drug. In the present study we evaluated the antiapoptotic effect of resveratrol, studying its activity on cell cycle progression. We determined the mitotic index of cultures exposed to resveratrol and paclitaxel alone or in combination, the cell cycle distribution by flow cytometric analysis (FACS), and the modulation of some relevant cell cycle regulatory proteins. Resveratrol is able to induce S-phase cell arrest and this interference with the cell cycle is associated with an increase of cyclin E and cyclin A, a downregulation of cyclin D1, and no alteration in cyclin B1 and cdk 1 activation. The resveratrol-induced S-phase block prevents SH-SY5Y from entering into mitosis, the phase of the cell cycle in which paclitaxel exerts its activity, explaining the antiapoptotic effect of resveratrol.

Pixantrone (BBR2778) reduces the severity of experimental allergic encephalomyelitis

Pixantrone is less cardiotoxic and is similarly effective to mitoxantrone (MTX) as an antineoplastic drug. In our study, pixantrone reduced the severity of acute and decreased the relapse rate of chronic relapsing experimental allergic encephalomyelitis (EAE) in rats. A marked and long-lasting decrease in CD3+, CD4+, CD8+ and CD45RA+ blood cells and reduced anti-MBP titers were observed with both pixantrone and MTX. In vitro mitogen- and antigen-induced T-cell proliferation tests of human and rodents cells evidenced that pixantrone was effective at concentrations which can be effectively obtained after i.v. administration in humans. Cardiotoxicity was present only in MTX-treated rats. The effectiveness and the favorable safety profile makes pixantrone a most promising immunosuppressant agent for clinical use in multiple sclerosis (MS).

Effect of trans-resveratrol on signal transduction pathways involved in paclitaxel-induced apoptosis in human neuroblastoma SH-SY5Y cells

trans-Resveratrol (3,4',5-trihydroxystilbene) is able to significantly reduce paclitaxel-induced apoptosis in the human neuroblastoma (HN) SH-SY5Y cell line, acting on several cellular signaling pathways that are involved in paclitaxel-induced apoptosis. trans-Resveratrol reverses phosphorylation of Bcl-2 induced by paclitaxel and concomitantly blocks Raf-1 phosphorylation, also observed after paclitaxel exposure, thus suggesting that Bcl-2 inactivation may be dependent on the activation of the Raf/Ras cascade. trans-Resveratrol also reverses the sustained phosphorylation of JNK/SAPK, which specifically occurs after paclitaxel exposure.Overall, our observations demonstrate that (a) the toxic action of paclitaxel on neuronal-like cells is not only related to the effect of the drug on tubulin, but also to its capacity to activate several intracellular pathways leading to inactivation of Bcl-2, thus causing cells to die by apoptosis, (b) trans-resveratrol significantly reduces paclitaxel-induced apoptosis by modulating the cellular signaling pathways which commit the cell to apoptosis.

Circulating nerve growth factor level changes during oxaliplatin treatment-induced neurotoxicity in the rat

BACKGROUND

Oxaliplatin neurotoxicity represents a clinically-relevant problem and its etio-pathogenesis is still unknown. We explored the possible role of some neuronal growth factors ("neurotrophins") during the course of oxaliplatin sensory neuronopathy.

MATERIALS AND METHODS

In our rat model two different doses of oxaliplatin were used (2 and 3 mg/kg i.v. twice weekly for 9 times). The neurotoxicity of the treatment was assessed with neurophysiological and pathological methods and serum neurotrophin levels were measured by ELISA.

RESULTS

Both oxaliplatin-treated groups showed the neurophysiological and neuropathological changes which mimic the chronic effects of oxaliplatin administration in humans, e.g. reversible sensory impairment due to dorsal root ganglia neuron damage. These changes were associated with a significant and dose-dependent reduction only in the circulating level of nerve growth factor (NGF), which returned to normal values after neurophysiological and pathological recovery.

CONCLUSION

This specific association between neurological impairment and NGF modulation indicates that NGF impairment has a role in the neurotoxicity of oxaliplatin.

Anti-apoptotic effect of trans-resveratrol on paclitaxel-induced apoptosis in the human neuroblastoma SH-SY5Y cell line

Paclitaxel, an anticancer drug, induces apoptosis in human neuroblastoma cell line SH-SY5Y. The addition of trans-resveratrol, a natural antioxidant present in grapes and red wine, to SH-SY5Y cultures exposed to paclitaxel significantly reduces cellular death. The neuroprotective action of trans-resveratrol is due neither to its antioxidant capacity nor to interference with the polymerization of tubulin induced by paclitaxel. However, trans-resveratrol is able to inhibit the activation of caspase 7 and degradation of poly-(ADP-ribose)-polymerase which occur in SH-SY5Y exposed to paclitaxel. Resveratrol, therefore, exerts its anti-apoptotic effect by modulating the signal pathways that commit these neuronal-like cells to apoptosis.

Replacement of the quinoline system in 2-phenyl-4-quinolinecarboxamide NK-3 receptor antagonists

Results from a medicinal chemistry approach aimed at replacing the quinoline ring system in the potent and selective human neurokinin-3 (hNK-3) receptor antagonists 1-4 of general formula I are discussed. The data give further insight upon the potential NK-3 pharmacophore. In particular, it is highlighted that both the benzene-condensed ring and the quinoline nitrogen are crucial determinants for optimal binding affinity to the hNK-3 receptor. Some novel compounds maintained part of the binding affinity to the receptor (5, 6, 10 and 13) and compound 5, featuring the naphthalene ring system, appears to be suitable for further modifications; it offers the option to introduce electron-withdrawing groups at position 2 and 4, conferring on the ring an overall electron-deficiency similar to that of the quinoline.

Discovery of a novel class of selective non-peptide antagonists for the human neurokinin-3 receptor. 2. Identification of (S)-N-(1-phenylpropyl)-3-hydroxy-2-phenylquinoline-4-carboxamide (SB 223412)

Optimization of the previously reported 2-phenyl-4-quinolinecarboxamide NK-3 receptor antagonist 14, with regard to potential metabolic instability of the ester moiety and affinity and selectivity for the human neurokinin-3 (hNK-3) receptor, is described. The ester functionality could be successfully replaced by the ketone (31) or by lower alkyl groups (Et, 21, or n-Pr, 24). Investigation of the substitution pattern of the quinoline ring resulted in the identification of position 3 as a key position to enhance hNK-3 binding affinity and selectivity for the hNK-3 versus the hNK-2 receptor. All of the chemical groups introduced at this position, with the exception of halogens, increased the hNK-3 binding affinity, and compounds 53 (3-OH, SB 223412, hNK-3-CHO binding Ki = 1.4 nM) and 55 (3-NH2, hNK-3-CHO binding Ki = 1.2 nM) were the most potent compounds of this series. Selectivity studies versus the other neurokinin receptors (hNK-2-CHO and hNK-1-CHO) revealed that 53 is about 100-fold selective for the hNK-3 versus hNK-2 receptor, with no affinity for the hNK-1 at concentrations up to 100 microM. In vitro studies demonstrated that 53 is a potent functional antagonist of the hNK-3 receptor (reversal of senktide-induced contractions in rabbit isolated iris sphincter muscles and reversal of NKB-induced Ca2+ mobilization in CHO cells stably expressing the hNK-3 receptor), while in vivo this compound showed oral and intravenous activity in NK-3 receptor-driven models (senktide-induced behavioral responses in mice and senktide-induced miosis in rabbits). Overall, the biological data indicate that (S)-N-(1-phenylpropyl)-3-hydroxy-2-phenylquinoline-4-carboxamide (53, SB 223412) may serve as a pharmacological tool in animal models of disease to assess the functional and pathophysiological role of the NK-3 receptor and to establish therapeutic indications for non-peptide NK-3 receptor antagonists.

Discovery of a novel class of selective non-peptide antagonists for the human neurokinin-3 receptor. 1. Identification of the 4-quinolinecarboxamide framework

A novel class of potent and selective non-peptide neurokinin-3 (NK-3) receptor antagonists, featuring the 4-quinolinecarboxamide framework, has been designed based upon chemically diverse NK-1 receptor antagonists. The novel compounds 33-76, prompted by chemical modifications of the prototype 4, have been characterized by binding analysis using a membrane preparation of chinese hamster ovary (CHO) cells expressing the human neurokinin-3 receptors (hNK-3-CHO), and clear structure-activity relationships (SARs) have been established. From SARs, (R)-N-[alpha-(methoxycarbonyl)benzyl]-2-phenylquinoline-4-carboxamide (65, SB 218795, hNK-3-CHO binding Ki = 13 nM) emerged as one of the most potent compounds of this novel class. Selectivity studies versus the other neurokinin receptors (hNK-2-CHO and hNK-1-CHO) revealed that 65 is about 90-fold selective for hNK-3 versus hNK-2 receptors (hNK-2-CHO binding Ki = 1221 nM) and over 7000-fold selective versus hNK-1 receptors (hNK-1-CHO binding Ki = > 100 microM). In vitro functional studies in rabbit isolated iris sphincter muscle preparation demonstrated that 65 is a competitive antagonist of the contractile response induced by the potent and selective NK-3 receptor agonist senktide with a Kb = 43 nM. Overall, the data indicate that 65 is a potent and selective hNK-3 receptor antagonist and a useful lead for further chemical optimization.