ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract: Transient ischemia is known to lead to a long-lastingdepression of cerebral metabolic rate and blood flow and to an attenuatedmetabolic and circulatory response to physiological stimuli. However, thecorresponding responses to induced seizures are retained, demonstratingpreserved metabolic and circulatory capacity. The objective of the presentstudy was to explore how a preceding period of ischemia (15 min) alters therelease of free fatty acids (FFAs) and diacylglycerides (DAGs), the formationof cyclic nucleotides, and the influx/efflux of Ca2+, followingintense neuronal stimulation. For that purpose, seizure activity was inducedwith bicuculline for 30 s or 5 min at 6 h after the ischemia. ExtracellularCa2+ concentration (Ca2+e) was recorded, andthe tissue was frozen in situ for measurements of levels of FFAs, DAGs, andcyclic nucleotides. Six hours after ischemia, the FFA concentrations werenormalized, but there was a lowering of the content of 20:4 in the DAGfraction. Cyclic AMP levels returned to normal values, but cyclic GMP contentwas reduced. Seizures induced in postischemic animals showed similar changesin Ca2+e, as well as in levels of FFAs, DAGs, and cyclicnucleotides, as did seizures induced in nonischemic control animals, with theexception of an attenuated rise in 20:4 content in the DAG fraction. Weconclude that, at least in the neocortex, seizure-induced phospholipidhydrolysis and cyclic cAMP/cyclic GMP formation are not altered by a precedingperiod of ischemia, nor is there a change in the influx/efflux ofCa2+ during seizure discharge or in associated spreadingdepression.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1471-4159.2000.0752521.x
Permalink
