Low-dose cisplatin protects human neuroblastoma SH-SY5Y cells from paclitaxel-induced apoptosis

Expression, distribution and glutamate uptake activity of high affinity-excitatory aminoacid transporters in in vitro cultures of embryonic rat dorsal root ganglia

Glutamate is the major mediator of excitatory signalling in the mammalian central nervous system, but it has recently been shown to play a role in the transduction of sensory input at the periphery and in peripheral neuropathies. New advances in research have demonstrated that rat peripheral sensory terminals and dorsal root ganglia (DRG) express molecules involved in glutamate signalling, including high-affinity membrane-bound glutamate transporters (GLAST [glutamate aspartate transporter], GLT1 [glutamate transporter 1], EAAC1 [excitatory aminoacid transporter 1]) and that alterations in their expression and/or functionality can be implicated in several models of peripheral neuropathy, neuropathic pain and hyperalgesia. Here we describe, through immunoblotting, immunofluorescence assays and β-counter analysis of [(3)H] l-glutamate uptake, the expression, distribution and activity of the glutamate transporters in in vitro cultures of embryonic dorsal root ganglia sensory neurons, sensory neurons+satellite cells and satellite cells. In this work we demonstrated that glutamate transporters are expressed in all cultures with a peculiar pattern of distribution. Even if GLAST is strongly detected in satellite cells, it is slightly expressed also in sensory neurons. GLT1 immunostaining is very weak in DRG neurons, but it was evident in the satellite cells. Finally, EAAC1 is localized in the soma and in the neuritis of sensory neurons, while it is not detectable in satellite cells. Moreover, all the cell cultures showed a strong sodium-energy-dependent glutamate uptake activity and it is more marked in neurons alone or in co-culture with satellite cells compared to satellite cells alone. Finally, we show that the complete or partial pharmacological inhibition of glutamate transporters virtually completely or partially abolish glutamate uptake in all cell culture. These results, that demonstrate that functionally active glutamate transporters can be studied in dorsal root ganglia cell cultures, provide further evidence for a role of glutamatergic transport in the peripheral nervous system and will be useful for testing whether any changes occur in in vitro models of peripheral nervous system damage.

Effect of the chronic combined administration of cisplatin and paclitaxel in a rat model of peripheral neurotoxicity

We have characterised for the first time the general and neurological side effects experienced when using a series of chronic non-lethal cisplatin + paclitaxel schedules in Wistar rats, selected according to our previous experience and the animals' maximum tolerated dose. At the pathological level, the use of combination schedules was definitely more toxic at the kidney and sternal bone marrow level than the single-agent schedules. At the neurophysiological examination based on the assessment of the nerve conduction velocity measurement in the tail nerve, we identified only one combination schedule that was more neurotoxic than the similar schedules based on single-agent administration. This observation was confirmed by the neuropathological examination performed on the sciatic nerve, dorsal root ganglia, ventral and dorsal roots. Our study supports the hypothesis that the general and, to a lesser extent, neurological effects of a combination of cisplatin and paclitaxel are different from those of the administration of both drugs as single agents. We believe that these models may be useful for testing neuroprotective strategies.

Improved proteome coverage by using iTRAQ labelling and peptide OFFGEL fractionation

Background

The development of mass spectrometric techniques and fractionation methods now allows the investigation of very complex protein mixtures ranging from subcellular structures to tissues. Nevertheless, this work is particularly difficult due to the wide dynamic range of protein concentration in eukaryotic tissues. In this paper, we present a shotgun method whereby the peptides are fractionated using OFFGEL electrophoresis after iTRAQ labelling.

Results

We demonstrated that iTRAQ peptide labelling enhances MALDI ionisation and that the OFFGEL fractionation of the labelled peptides introduces a supplementary criterion (pI) useful for validation and identification of proteins. We showed that iTRAQ samples allowed lower-concentrated proteins identification in comparison with free-labelled samples.

Conclusion

The combined use of iTRAQ labelling and OFFGEL fractionation allows a considerable increase in proteome coverage of very complex samples prepared from total cell extracts and supports the low-concentrated protein identification.