Time Course of Hippocampal Glucose Utilization and Persistence of Parvalbumin Immunoreactive Neurons after Ibotenic Acid—Induced Lesions of the Rat Dentate Area

Abstract

Summary:The effects of ibotenic acid induced lesions of the dentate gyrus on hippocampal glucose utilization and parvalbumin-positive neurons were evaluated in male Wistar rats. Ibotenic acid was injected in the right dorsal dentate gyrus. Quantification of glucose utilization was performed 3 days, 3 weeks, or 3 months after the lesion using the 14C-2-deoxyglucose method. Nissl-stained sec tions and sections stained for acetylcholinesterase were used as references for anatomical delineation of the hip pocampal cytoarchitecture. Additional sections were stained for parvalbumin. The results revealed widespread reductions of glucose utilization in all layers and sectors of the hippocampus in the ipsilateral lesioned hemisphere and also in the nonlesioned contralateral hemisphere. The reductions occurred as early as 3 days after the lesion and persisted up to 3 months. In neither hippocampal struc-The hippocampal circuitry has attracted major at tention in neurobiological research for its well defined intrinsic organization and because afferent and efferent fibers can be attributed to distinct lay ers and sections of this cortical structure. The prev alent hippocampal pathway is the trisynaptic path, which originates in the entorhinal cortex and enters the hippocampus as the perforant path fibers via the molecular layer of the dentate gyrus. The dentate granule cells in turn give rise to the mossy fibers that project to the hilus and CA3 pyramidal cells. The CA3 pyramidal cells project to the CAl ipsilat erally as Schaffer collaterals and contralaterally as

Learning behaviour and cerebral protein kinase C, antioxidant status, lipid composition in senescence-accelerated mouse: influence of a phosphatidylcholine–vitamin B12diet

“…This result is in contrast to results showing an improvement of learning behaviour in rats with ibotenic acid-induced lesions that received a PC+vitamin B 12 (Masuda et al 1998;Hung et al 2000). This discrepancy may result from the nature of the brain lesions, since ibotenic acid-induced brain lesions can be reversible (Wree et al 1993), but the impairment of the neural system in aged SAMP8 is not reversible.…”

Brain Lactate Metabolism: The Discoveries and the Controversies

“…Where stated, lactate (Lac) concentration is divided by 2 to obtain glucose (Glc) equivalents of lactate. c Glucose utilization rate is the average of mean values from four subregions of the dentate gyrus of conscious rats from the study of Wree et al, 1993. Glucose delivery to the resting brain is equal to glucose utilization rate at steady state; glucose delivered during a 12-second interval is (0.66 mmol/g per min)(0.2 minutes) = 0.13 mmol/g.…”

Functional Cerebral Activity during Regeneration from Entorhinal Lesions in the Rat

“…Moreover, anal ysis of the field potentials after stimulation of the molecular layer of the dentate gyrus in slices of en torhinal lesioned rats suggests that even 55-65 days after the lesion, sprouting fibers have not restored normal electrophysiological properties in that area, but, rather, have produced an imbalance between excitation and inhibition (Clusmann et al , 1994), favoring the concept of a permanently altered cir cuitry. In a broader context, based on previous data from our laboratory, we are inclined to believe that lack of functional recovery after such hippocampal lesions may, possibly, be more the rule than the exception (Beck et al, 1990a,b;Wree et al , 1993). Lesions of the dentate gyrus by ibotenic acid injec tions led to profoundly reduced LCGV in all major hippocampal areas up to 3 months postlesion, the only difference being that the contralateral hemi sphere was as heavily affected as the ipsilateral (Wree et al , 1993).…”

“…In a broader context, based on previous data from our laboratory, we are inclined to believe that lack of functional recovery after such hippocampal lesions may, possibly, be more the rule than the exception (Beck et al, 1990a,b;Wree et al , 1993). Lesions of the dentate gyrus by ibotenic acid injec tions led to profoundly reduced LCGV in all major hippocampal areas up to 3 months postlesion, the only difference being that the contralateral hemi sphere was as heavily affected as the ipsilateral (Wree et al , 1993). Previous work points to the involvement of the contralateral hemisphere also af ter entorhinal lesions.…”