Distinct influence of the group III metabotropic glutamate receptor agonist ( R, S)-4-phosphonophenylglycine [( R, S)-PPG] on different forms of neuronal damage

• Published in: Neuropharmacology 2000-04, Vol.39 (5), p.911-917
• Main Authors: Henrich-Noack, P, Flor, P.J, Sabelhaus, C.F, Prass, K, Dirnagl, U, Gasparini, F, Sauter, A, Rudin, M, Reymann, K.G
• Format: Article
• Language: English
• Subjects: ( R, S)-PPG; Action Potentials - drug effects; Action Potentials - physiology; Animals; Brain Diseases - drug therapy; Brain Diseases - pathology; Brain Diseases - physiopathology; Brain Ischemia - drug therapy; Brain Ischemia - pathology; Cell Hypoxia - drug effects; Corpus Striatum - drug effects; Corpus Striatum - pathology; Cytoprotection - drug effects; Disease Models, Animal; Excitotoxicity; Gerbillinae; Glycine - analogs & derivatives; Glycine - pharmacology; Hippocampus - cytology; Hippocampus - drug effects; Hippocampus - physiopathology; In Vitro Techniques; Ischaemia; Male; Metabotropic glutamate receptors; Mice; Mice, Inbred C57BL; Neurons - drug effects; Neuroprotection; Neuroprotective Agents - pharmacology; Quinolinic Acid - pharmacology; Rats; Rats, Sprague-Dawley; Rats, Wistar; Receptors, Metabotropic Glutamate - agonists; Receptors, Metabotropic Glutamate - antagonists & inhibitors; Rodentia
• ISSN: 0028-3908; 1873-7064
• DOI: 10.1016/S0028-3908(99)00256-7

With this study we evaluated the influence of ( R, S)-4-phosphonophenylglycine [( R, S)-PPG], a selective group III metabotropic glutamate receptor agonist, on excitotoxic, hypoxic/hypoglycaemic and ischaemic cerebral damage in rodents. Consistent with previous data showing neuroprotective and anticonvulsive effects (Gasparini, F., Bruno, V., Battaglia, G., Lukic, S., Leonhardt, T., Inderbitzin, W., et al., 1999. ( R, S)-4-Phosphonophenylglycine, a potent and selective group III metabotropic glutamate receptor agonist, is anticonvulsive and neuroprotective in vivo. Journal of Pharmacology and Experimental Therapeutics 290, 1678–1687), we found pronounced neuroprotective effects with ( R, S)-PPG (300 nmol) in a model of excitotoxicity, i.e. quinolinic acid-induced striatal lesions in rats. However, neither in focal cerebral ischaemia in mice nor in global cerebral ischaemia in gerbils or rats did ( R, S)-PPG have any significant influence on the extent of neuronal damage. In a model of hypoxia/hypoglycaemia in acutely isolated hippocampal slices, however, ( R, S)-PPG led to an improved recovery of population spike amplitude. As acutely isolated hippocampal slices are only viable for a few hours, these electrophysiological recordings can only be performed in a limited time window after the challenge—when most probably excitotoxicity is still the predominant influence in hypoxic pathophysiology. From this we conclude that group III mGluR agonists might be promising drugs against damage mediated mainly by excitotoxicity, but less likely against development of neuronal death due to ischaemia.