The preferential mGlu2/3 receptor antagonist, LY341495, reduces the frequency of spike-wave discharges in the WAG/Rij rat model of absence epilepsy.
We examined the expression and function of group-II metabotropic glutamate (mGlu) receptors in an animal model of absence seizures using genetically epileptic WAG/Rij rats, which develop spontaneous non-convulsive seizures after 2-3 months of age. Six-month-old WAG/Rij rats showed an increased expression of mGlu2/3 receptors in the ventrolateral regions of the somatosensory cortex, ventrobasal thalamic nuclei, and hippocampus, but not in the reticular thalamic nucleus and in the corpus striatum, as assessed by immunohistochemistry and Western blotting. In contrast, mGlu2/3 receptor signalling was reduced in slices prepared from the somatosensory cortex of 6-month-old WAG/Rij rats, as assessed by the ability of the agonist, LY379268, to inhibit forskolin-stimulated cAMP formation. None of these changes was found in "pre-symptomatic" 2-month-old WAG/Rij rats. To examine whether pharmacological activation or inhibition of mGlu2/3 receptors affects absence seizures, we recorded spontaneous spike-wave discharges (SWDs) in 6-month-old WAG/Rij rats systemically injected with saline, the mGlu2/3 receptor agonist LY379268 (0.33 or 1 mg/kg, i.p.), or with the preferential mGlu2/3 receptor antagonist, LY341495 (0.33, 1 or 5 mg/kg, i.p.). Injection of 1mg/kg of LY379268 (1 mg/kg, i.p.) increased the number of SWDs during 3-7 h post-treatment, whereas injection with LY341495 reduced the number of seizures in a dose-dependent manner. It can be concluded that mGlu2/3 receptors are involved in the generation of SWDs and that an upregulation of these receptors in the somatosensory cortex might be involved in the pathogenesis of absence epilepsy.
Ngomba
R T
RT
I.N.M. Neuromed, 86077 Pozzilli, Italy.
Biagioni
F
F
Casciato
S
S
Willems-van Bree
E
E
Battaglia
G
G
Bruno
V
V
Nicoletti
F
F
van Luijtelaar
E L J M
EL
D000367:Age Factors; D000596:Amino Acids / Q000494:pharmacology* / Q000627:therapeutic use; D000704:Analysis of Variance; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D001522:Behavior, Animal; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000378:metabolism / Q000473:pathology; D001931:Brain Mapping; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism; D004195:Disease Models, Animal; D004569:Electroencephalography / Q000379:methods; D004832:Epilepsy, Absence / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology* / Q000627:therapeutic use; D018755:GABA Agonists / Q000494:pharmacology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D007211:Indoles; D008297:Male; D017551:Microdialysis / Q000379:methods; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism; D014966:Xanthenes / Q000494:pharmacology* / Q000627:therapeutic use
D000596:Amino Acids; D018691:Excitatory Amino Acid Antagonists; D018755:GABA Agonists; D005904:Glial Fibrillary Acidic Protein; D007211:Indoles; C114624:LY 341495; D018094:Receptors, Metabotropic Glutamate; D014966:Xanthenes; C108822:metabotropic glutamate receptor 2; C102718:metabotropic glutamate receptor 3; C007293:DAPI; D000242:Cyclic AMP; D001418:Baclofen