Effects of intraperitoneal injection of Rofecoxib in a mouse model of ALS

There is increasing evidence that inflammatory mechanisms are involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). Inhibition of a key mediator of inflammation, cyclooxygenase 2 (COX-2), represents a promising therapeutic approach in ALS. Here we tested the in vivo effects of a specific COX-2 inhibitor, Rofecoxib, administered by intraperitoneal injection, in the SOD1(G93A G1H) mouse model of the familial form of ALS (fALS). Rofecoxib administration commenced at postnatal day 60 (P60), since the hallmarks of inflammation in the spinal cord were found to occur beyond this time-point in this mouse model of fALS. We found a significant but small delay in the onset of locomotor impairment in mice treated with Rofecoxib at the dose of 10 mg/kg of weight. However, survival was not effected by treatment. As prostaglandin E2 levels in spinal cord or in plasma were not reduced by Rofecoxib treatment, these results may suggest lack of sufficient bioavailability as the reason for the modest clinical changes observed.

Chemotherapy Delays Progression of Motor Neuron Disease in the SOD1 G93A Transgenic Mouse

BACKGROUND

A significant proliferation of glial cells occurs in the spinal cord and brainstem of SOD1 G93A transgenic mice with familial amyotrophic lateral sclerosis (ALS). Since activated glia may contribute to motor neuron degeneration, we tested whether inhibition of gliosis using low-dose chemotherapy is beneficial in this mouse model.

METHODS

Mice were administered fortnightly intraperitoneal injections of 0.1 mg/kg vincristine (VIN) or saline commencing at postnatal day 68 before disease onset. Mice were sacrificed at end-stage disease, and spinal cords were examined for histology.

RESULTS

Survival of VIN-treated mice was significantly increased at 132.0 +/- 4.1 days compared to control animals at 117.8 +/- 2.1 days (p < 0.05). Furthermore, analysis of microglia and astrocyte populations suggests a reduction in the former following VIN therapy.

CONCLUSION

This study suggests that chemotherapy may offer an alternative therapy or co-therapy for ALS.

The serotonin precursor 5-hydroxytryptophan delays neuromuscular disease in murine familial amyotrophic lateral sclerosis

INTRODUCTION

Reduction in the levels of whole-blood serotonin is a common feature of Down syndrome (DS) individuals and transgenic mice overexpressing wild-type SOD1. Administration of the metabolic precursor 5-hydroxytryptophan (5-HTP) leads to reversal of both serotonin deficits and hypotonia in humans. The effect of 5-HTP treatment on the progression of motor neuron disease in mutant SOD1 mice was examined.

METHODS

Pre-disease transgenic SOD1 G93A mice and wild-type littermates were systemically administered 5-HTP thrice weekly (0, 5 or 50 mg/kg). Animal weights, locomotor function and survival were recorded weekly. Plasma serotonin levels were measured post-mortem.

RESULTS

Treatment with 5-HTP significantly delayed hindlimb weakness and mortality in SOD1 G93A mice in a dose-dependent manner. Wild-type mice were not adversely affected by 5-HTP administration. Baseline serotonin levels did not differ between wild-type and ALS mice. Blood platelet serotonin levels increased proportionally with dose.

CONCLUSIONS

Increased blood serotonin by administration of 5-HTP in SOD1 G93A mice led to improved locomotor function and survival. A role for serotonin metabolism in mice with elevated SOD1 expression and motor neuron disease is suggested by these studies.

Opposing effects of low and high-dose clozapine on survival of transgenic amyotrophic lateral sclerosis mice

Clozapine is a potent atypical neuroleptic or antipsychotic agent used to relieve symptoms of early-diagnosed schizophrenia. Aside from well-described dopamine and serotonin receptor blockade effects, clozapine may also be neuroprotective through its modulation of the p75 neurotrophin receptor (p75(NTR)) and superoxide dismutase 1 (SOD1) expression. The death-signalling activities of both p75(NTR) and mutant SOD1 are implicated in motor neuron degeneration in humans and transgenic mice with amyotrophic lateral sclerosis (ALS). We therefore investigated the effects of clozapine in cell culture and mouse models of ALS. Clozapine dose-dependently inhibited full-length and cleaved p75(NTR) but not SOD1 protein expression in the motor neuron-like (NSC-34) cell line. Furthermore, low concentrations of clozapine protected NSC-34 cells from paraquat-mediated superoxide toxicity, nerve growth factor (NGF)-induced death signalling, and serum deprivation, whereas high concentrations potentiated death. Systemic thrice-weekly administration of low and high-dose clozapine to mutant superoxide dismutase 1 (SOD1(G93A)) mice produced differential effects on disease onset and survival. Low-dose treatment was associated with delayed locomotor impairment and death, compared to high-dose clozapine, which accelerated paralysis and mortality (P < 0.05). Increased death was not attributable to toxicity, as clozapine-induced agranulocytosis was not detected from blood analysis. High-dose clozapine, however, produced extrapyramidal symptoms in mice manifest by hindlimb rigidity, despite reducing spinal cord p75(NTR) levels overall. These results suggest that although clozapine may exert p75(NTR)-mediated neuroprotective activity in vitro, its profound antagonistic effects on dopaminergic and serotonergic systems in vivo at high doses may exacerbate the phenotype of transgenic ALS mice.

Leukemia inhibitory factor by systemic administration rescues spinal motor neurons in the SOD1 G93A murine model of familial amyotrophic lateral sclerosis

Leukemia inhibitory factor (LIF) is a survival factor for motoneurons. In this study we investigated whether intense systemic LIF therapy prevents the loss of lumbar motoneurons in the transgenic SOD1 G93A mouse model of familial amyotrophic lateral sclerosis. Treatment involved daily 25 microg/kg intraperitoneal injection for a period of 6 weeks starting at 70 days of age. Using the unbiased optical dissector technique, significant rescue of motoneurons in the LIF-treated group (3809+/-455) was found compared to the vehicle group (1085+/-140).

Chromosome studies of murine T-cell lymphoid leukemia and derived cell lines

Several cell lines were previously established from a spontaneous murine T-cell leukemia (LB). The aim of this study was to analyze the G- and C-banded karyotypes of the parental LB tumor cells and the derived cell lines. A sensitive cell line (LBL) from which two sublines originated, as well as Vincristine (LBR-V160) and Doxorubicin (LBR-D160) resistant cell lines, were used. Our results showed that LB cells had a pseudo-diploid karyotype with 40 acrocentric chromosomes in which trisomy of chromosome 14 was the most relevant alteration. The sensitive cell line showed this alteration in all metaphases studied; no changes in karyotypes were observed in either subline, despite their dissimilar morphology and growth patterns. In contrast, both resistant lines displayed a more heterogeneous karyotype with no common markers, except for the finding that chromosome 5 was involved in a trisomy in LBR-V160 and in a translocation with chromosome 12 in LBR-D160. Taking into account that the mdr genes are located in chromosome 5, these results suggest a possible association between such alterations and the acquisition of drug resistance.

A potential role for the p75 low-affinity neurotrophin receptor in spinal motor neuron degeneration in murine and human amyotrophic lateral sclerosis

INTRODUCTION

The p75 neurotrophin receptor has been recognized as a death-signalling molecule under certain circumstances. Its role in motor neuron degeneration in amyotrophic lateral sclerosis (ALS) was analysed in SOD1-G93A transgenic mice and in spinal cords from human amyotrophic lateral sclerosis.

METHOD

The precise loss of motor neurons in SOD1-G93A transgenic mice from birth to adulthood was established using the unbiased fractionator/optical dissector neuronal counting technique.

RESULTS

This study showed an early trend in the loss of lumbar motor neurons in SOD1-G93A mice, beginning at birth and progressing to a massive 80% reduction by 4 months of age, when the disease is severe. This study also found that the p75 neurotrophin receptor was expressed in lumbar motor neurons in symptomatic SOD1-G93A mice and in motor neurons in the cervical spinal cords of patients with ALS.

CONCLUSIONS

The murine and human ALS data suggest that the p75 neurotrophin receptor may play a death-signalling role in the pathogenesis of motor neuron degeneration. The precise mechanism by which this receptor drives the apoptotic process, both in murine SOD1-G93A motor neuron degeneration and in human amyotrophic lateral sclerosis, remains to be determined.

Leukaemia inhibitory factor abrogates Paclitaxel-induced axonal atrophy in the Wistar rat

A prominent side effect of Paclitaxel chemotherapy is sensorimotor peripheral neuropathy. Leukaemia inhibitory factor (LIF) supports the survival and regrowth of axotomised sensory and motor neurons and we therefore investigated if systemically administered LIF abrogated Paclitaxel-induced neuropathy. We found that whereas animals administered Paclitaxel alone exhibited a significant decrease in the percentage of large myelinated axons, this reduction was prevented by the co-administration of LIF.

Correlation between decreased apoptosis and multidrug resistance (MDR) in murine leukemic T cell lines

Cancer cells may frequently develop cross-resistance to structurally dissimilar chemotherapeutic agents. However, the molecular mechanisms for sensitivity and resistance of tumor cells towards chemotherapy are still partially understood. Antineoplasic drugs have been shown to induce apoptosis in chemosensitive leukemias and solid tumors. In this work, cross-resistance among vincristine (VCR), doxorubicin (DOX) and other antineoplasic agents commonly used in the treatment of leukemia such as etoposide (VP-16), methotrexate (MTX), cyclophosphamide (CTX), dexamethasone (DEX), cytarabine (Ara-C) and L-asparaginase on vincristine resistant (LBR-V160), doxorubicin resistant (LBR-D160) and sensitive (LBR-) murine leukemic T cell lines, was determined. The effect of antineoplasic agents was assayed by tritiated thymidine incorporation. Our results showed that VCR exhibited cross-resistance with DOX, VP-16, DEX and MTX, while DOX demonstrated cross-resistance with VCR, VP-16 and MTX. Ara-C failed to present cross-resistance with any cell line. Apoptosis induced by the above drugs on the same cell lines was analyzed by acridine orange and ethidium bromide staining, DNA hypoploidy (flow cytometry) and oligonucleosomal fragmentation of nuclear DNA showing that therapeutic concentrations of these chemotherapeutic agents induced apoptosis in the LBR- cell line. Our results demonstrated that, except for DEX, none of the drugs presenting cross-resistance were able to induce cell death on LBR-V 160 or LBR-D 160 cell lines.

Induction of apoptosis in murine lymphoma cells by cyclosporin A

The aim of this study was to investigate if CsA could induce apoptosis in the murine T-lymphoma cell line LBC, whose growth is inhibited by this immunosuppressive drug. CsA induced programmed cell death in LBC cells with typical features of apoptosis demonstrated by exposure of phosphatidyl serine residues on the cell membrane, the decrease of cell DNA content, chromatin condensation, and nuclear fragmentation. Apoptosis was evident within 12 h after CsA incubation, with a maximal effect at 48 h, in a time and dose-dependent fashion. In addition, the role of apoptosis inhibitors (Bcl-2 and Bcl-x) and the apoptosis inducer (Bax) in CsA induced-apoptosis was evaluated. The expression of Bcl-2 and Bax proteins were high in LBC cells and following CsA treatment the expression of these proteins as well as Bcl-XL decreased. In this work we demonstrated that cell growth inhibition following CsA treatment in LBC was paralleled by the induction of apoptosis thus providing an interesting animal model to identify the mechanism participating in the regulation of apoptotic genes by CsA in T-cell neoplasms and to assess preclinical in vivo trials of T-cell lymphoma-related disorders.

Modulator activity of PSC 833 and cyclosporin-A in vincristine and doxorubicin-selected multidrug resistant murine leukemic cells

Multidrug resistance (MDR) lines from a murine T-cell leukemia were selected in increasing vincristine (VCR) or doxorubicin (DOX) concentrations. Daunorubicin (DNR) efflux was evidenced after 25 additional passages with constant 160 ng ml(-1) of either VCR or DOX, an effect that was inhibited by verapamil, cyclosporin-A (CsA) and PSC 833. The expression of Pgp was not evidenced in the resistant cell lines using anti-human Pgp antibodies. Cell proliferation assay showed that cell lines resistant to VCR (LBR-V160) or DOX (LBR-D160) required higher doses of either drug to produce GI50 compared with control cell line obtained after culture in the absence of VCR or DOX. When resistant cell lines were maintained during 60 days in the absence of either VCR or DOX, MDR phenotype reversal was obtained in LBR-D160 while LBR-V160 remained resistant to the drug, as shown by cell proliferation assays and by drug efflux pump functionality. When VCR or DOX were used together with either CsA or PSC 833, the latter was more effective to produce reversal of resistance than the former, whereas CsA presented greater cytotoxic effect than PSC 833 for sensitive and resistant cells. Cross-resistance was found between VCR, DOX and other antineoplasic agents on murine leukemic cell line. VCR was more effective to induce MDR since the resistant cell lines were more stable to the MDR phenotype.