title: The spiny rat Proechimys guyannensis as model of resistance to epilepsy: chemical characterization of hippocampal cell populations and pilocarpine-induced changes.
abstract: At variance with pilocarpine-induced epilepsy in the laboratory rat, pilocarpine administration to the tropical rodent Proechimys guyannensis (casiragua) elicited an acute seizure that did not develop in long-lasting status epilepticus and was not followed by spontaneous seizures up to 30 days, when the hippocampus was investigated in treated and control animals. Nissl staining revealed in Proechimys a highly developed hippocampus, with thick hippocampal commissures and continuity of the rostral dentate gyri at the midline. Immunohistochemistry was used to study calbindin, parvalbumin, calretinin, GABA, glutamic acid decarboxylase, and nitric oxide synthase expression. The latter was also investigated with NADPH-diaphorase histochemistry. Cell counts and densitometric evaluation with image analysis were performed. Differences, such as low calbindin immunoreactivity confined to some pyramidal cells, were found in the normal Proechimys hippocampus compared to the laboratory rat. In pilocarpine-treated casiraguas, stereological cell counts in Nissl-stained sections did not reveal significant neuronal loss in hippocampal subfields, where the examined markers exhibited instead striking changes. Calbindin was induced in pyramidal and granule cells and interneuron subsets. The number of parvalbumin- or nitric oxide synthase-containing interneurons and their staining intensity were significantly increased. Glutamic acid decarboxylase(67)-immunoreactive interneurons increased markedly in the hilus and decreased in the CA1 pyramidal layer. The number and staining intensity of calretinin-immunoreactive pyramidal cells and interneurons were significantly reduced. These findings provide the first description of the Proechimys hippocampus and reveal marked long-term variations in protein expression after an epileptic insult, which could reflect adaptive changes in functional hippocampal circuits implicated in resistance to limbic epilepsy.
authors.affiliation: Department of Morphological and Biomedical Sciences, Faculty of Medicine, University of Verona, Strada Le Grazie 8, 37134 Verona, Italy.
authors.forename: P F
authors.initials: PF
authors.lastname: Fabene
authors.forename: L
authors.initials: L
authors.lastname: Correia
authors.forename: R A
authors.initials: RA
authors.lastname: Carvalho
authors.forename: E A
authors.initials: EA
authors.lastname: Cavalheiro
authors.forename: M
authors.initials: M
authors.lastname: Bentivoglio
mesh_terms: D000818:Animals; D064032:Calbindin 2; D064026:Calbindins; D002452:Cell Count; D004195:Disease Models, Animal; D004827:Epilepsy / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D007150:Immunohistochemistry; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009410:Nerve Degeneration / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D010862:Pilocarpine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar / Q000033:anatomy & histology / Q000378:metabolism; D012377:Rodentia / Q000033:anatomy & histology / Q000378:metabolism*; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects* / Q000502:physiology
chemical_list: C576512:Calb2 protein, rat; D064032:Calbindin 2; D064026:Calbindins; D018721:Muscarinic Agonists; D009419:Nerve Tissue Proteins; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G; D010862:Pilocarpine; D019001:Nitric Oxide Synthase; D009252:NADPH Dehydrogenase; D005968:Glutamate Decarboxylase