Brain research bulletin
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Brain research bulletin · Jul 2000
Vestibular-induced behaviour of rats born and raised in hypergravity.
One group of rats were bred and kept under hypergravity (HG) conditions (2.5 g) in a centrifuge. Another group were bred and kept under normal gravity conditions (1 g). Rats from both groups were dropped from a supine position into a water basin under infrared illumination leaving only gravity (1 g for both groups) for orientation. ⋯ Surfacing of young HG rats is less successful (36% at age 6 weeks) and requires more time. On average, surfacing of adult rats of both groups is about the same. Apparently, the repeated stay of centrifuge-bred rats at 1 g for experiments and daily care suffices to recalibrate and improve their orientation, which is essential for surfacing.
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Brain research bulletin · Feb 2000
Clinical Trial Controlled Clinical TrialCholinergic enhancement improves performance on working memory by modulating the functional activity in distinct brain regions: a positron emission tomography regional cerebral blood flow study in healthy humans.
Previously, we have shown that physostigmine, an acetylcholinesterase inhibitor, improved performance on a working memory for faces task, as reflected by reduced reaction time (RT), and reduced task-specific regional cerebral blood flow (rCBF) in right prefrontal cortex and, further, that these reductions in RT and right frontal rCBF were significantly correlated. Here we investigated the relation between the effects of physostigmine on task performance and task-specific functional brain response throughout the cortex by examining correlations between physostigmine-related changes in rCBF in all brain areas and changes in RT. ⋯ In subjects who received a placebo infusion of saline, no significant correlations between changes in RT and cortical rCBF were observed. The results show that cholinergically induced improvements in working memory performance are related to alterations in neural activity in multiple cortical regions, including increased neural activity in regions associated with early perceptual processing and decreased neural activity in regions associated with attention, memory encoding, and memory maintenance.
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Brain research bulletin · Oct 1999
The neuroprotective and hypothermic effect of GYKI-52466, a non-competitive alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-antagonist on histological and behavioural variables in the gerbil global ischemia model.
The neuroprotective activity of the non-competitive alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) antagonist GYKI-52466 (1-[4-aminophenyl]-4-methyl-7,8-methylene-dioxy-5H-2,3-benzodia zep ine HCI; EGIS-8159) was studied in the gerbil bilateral carotid occlusion (BCO) model of global ischemia. Drug effect on hippocampal CA1 neuronal loss, hypermotility, and cognitive deficit (decrease in spontaneous alternation (SA) behaviour in the Y-maze) induced by 5-min or 3-min BCO were measured. GYKI-52466 was administered at 4 x 15 mg/kg intraperitoneal (i.p.) doses 30, 45, 60, and 75 min following surgery. ⋯ Administration of 4 x 10 mg/kg i.p. chlorpromazine to gerbils 15 min before and 0, 15, and 30 min after 3-min BCO resulted in considerable hypothermia (5.5 degrees C peak effect, 8 h duration), but no protective action of the compound on CA1 cell loss and hypermotility was observed. However, chlorpromazine inhibited the ischemia-induced cognitive impairment. The results suggest that drug-induced hypothermia may differentially influence the histological and the behavioural outcomes of ischemic intervention.
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Brain research bulletin · Aug 1999
The effect of perineural colchicine on nerve injury-induced spinal glial activation and neuropathic pain behavior.
Factors transported centrally from the site of a peripheral nerve injury are known to provide cellular activation signals to the dorsal root ganglion and spinal cord. Yamamoto and Yaksh [35] were able to use colchicine disruption of axonal transport to abolish thermal hyperalgesia after sciatic chronic constriction in the rat. The current study set out to ascertain whether this observation could be reproduced by applying the same pharmacologic paradigm to a complete, segmentally specific, spinal nerve tight ligation (SPTL) and assessing the impact of this treatment on mechanical allodynia and central, spinal glial activation. ⋯ Neuronal tracer injected into the sciatic nerve could not be found at the L5 spinal level following perineural colchicine treatment or tight ligation of the L5 spinal nerve, however, tracer was present at the unobstructed L4 spinal level. These results suggest that central astrocytic and microglial responses may be triggered by disruption of transported signals from the periphery, because they are induced by either colchicine or tight ligation. Conversely, axonally transported factors, either from the site of nerve injury or from the periphery, do not appear to be critical for the development of mechanical allodynia.