J Neurosci 2002 Apr 1;22(7):2660-8
Metabotropic glutamate receptor 5 upregulation in A-fibers after spinal nerve injury: 2-methyl-6-(phenylethynyl)-pyridine (MPEP) reverses the induced thermal hyperalgesia.
Hudson LJ, Bevan S, McNair K, Gentry C, Fox A, Kuhn R, Winter J.
Oxford GlycoSciences Ltd., Abingdon, OX14 4RY, United Kingdom.
Metabotropic glutamate receptor 5 (mGluR5) protein increased after sciatic nerve section in ipsilateral L4 and L5 DRG neuronal profiles, with most of the increase occurring in myelinated A-fiber somata. mGluR5 also increased in lamina II of the ipsilateral spinal cord and the proximal sciatic nerve stump in this model. After L5 spinal nerve ligation, mGluR5 immunoreactivity increased dramatically not only in damaged L5 but also in the neighboring undamaged L4. Interestingly, after partial sciatic nerve section, mGluR5 expression did not change in either L4 or L5 DRG neuronal profiles. Both spinal nerve ligation and sciatic nerve partial section produced significant mechanical and thermal hyperalgesia and tactile allodynia. After partial sciatic nerve section, the mGluR5-specific antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP) had no effect on any of these behaviors. However, after L5 spinal nerve ligation, although MPEP failed to alter the induced tactile allodynia or mechanical hyperalgesia, it dose dependently reversed the developed thermal hyperalgesia. Therefore, reversal of thermal hyperalgesia by MPEP correlates with increased mGluR5 in lumbar DRG A-fiber somata after nerve injury. Furthermore, A-fibers in the uninjured L4 DRG after L5 spinal nerve ligation that have increased mGluR5 are the same A-fibers that newly express vanilloid receptor 1 after such injury. Together, these results suggest that, after L5 spinal nerve injury, mGluR5 expression on A-fibers is essential to the development of thermal hyperalgesia. After partial nerve section, however, it is unlikely that thermal responses are mediated through mGluR5 because no such increase in mGluR5 is detected in this model and MPEP is ineffective.
Curr Opin Mol Ther 2002 Jun;4(3):251-8
Proteomic approaches to central nervous system disorders.
Rohlff C, Southan C.
Oxford GlycoSciences, Abingdon, UK.
The discovery, design and evaluation of new medicines is critically dependent on the elucidation of protein mechanisms involved in human diseases. Since the proteome of a cell or tissue is not a simple reflection of its transcriptome, direct protein-based analysis is needed. Advances in proteomic technologies are improving the analysis of membrane proteins and signaling complexes with increased speed and molecular detail. Changes in protein isoforms due to post-translational modifications, such as phosphorylation induced by cell signaling events and alternative splice forms of receptors, may be mapped to an altered protein expression pattern in clinically relevant cell populations with a causative or diagnostic disease link. A CNS proteome database derived from primary human tissues may avoid ambiguities of experimental models. It will also accelerate the development of more specific diagnostic and prognostic disease markers as well as new selective therapeutics. Proteomics is also being applied to resolve in silico gene prediction uncertainties by direct open reading frame verification. These advances hold great promise for improvements in the understanding, diagnosis and therapy of central nervous system disorders. |
