Selective vulnerability of hippocampal NAAGergic neurons in experimental temporal lobe epilepsy.
The dipeptide N-acetylaspartylglutamate (NAAG) has been recently implicated in numerous neurological disorders. NAAG binds and stimulates group II metabotropic glutamate receptors producing a down-modulation of synaptic glutamate release. In the present immunohistochemical study, we compare the distribution of NAAG-containing (NAAGergic) neurons between the hippocampus of control and chronic epileptic rats obtained with the pilocarpine model of temporal lobe epilepsy. In the hippocampal formation, NAAGergic neurons comprise a subpopulation of GABAergic neurons. Examination by light microscopy revealed a significant reduction of NAAG-immunoreactive neurons in CA3 stratum oriens (35.8%) and CA1 stratum oriens (78.87%), stratum pyramidale (40%), and stratum radiatum (56.6%). Similar loss of NAAGergic neurons was observed in the subiculum characterized by 71.82% and 77.53% reduction in the stratum oriens and radiatum, respectively, when compared with controls. NAAGergic neurons in CA2 and dentate gyrus were apparently resistant to seizure-related cell loss but appeared more complex and exhibited numerous NAAG-positive puncta. Our findings indicate a selective vulnerability of NAAGergic neurons in temporal lobe epilepsy.
Pacheco Otalora
Luis F
LF
Department of Biological Sciences at the University of Texas at Brownsville/Texas Southmost College, 80 Fort Brown, Brownsville, TX 78520, USA.
Moffett
John R
JR
Garrido-Sanabria
Emilio R
ER
D000818:Animals; D002452:Cell Count / Q000379:methods; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004151:Dipeptides / Q000378:metabolism*; D004195:Disease Models, Animal; D004833:Epilepsy, Temporal Lobe / Q000139:chemically induced / Q000473:pathology*; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006624:Hippocampus / Q000473:pathology*; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000378:metabolism* / Q000473:pathology*; D010862:Pilocarpine; D051381:Rats; D017207:Rats, Sprague-Dawley; D050598:Vesicular Glutamate Transport Protein 1 / Q000378:metabolism
D004151:Dipeptides; D007527:Isoenzymes; D050598:Vesicular Glutamate Transport Protein 1; D010862:Pilocarpine; C027172:isospaglumic acid; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1