Lipid metabolism, cerebral metabolic rate, and some related enzyme activities after brain infarction in rats.

Abstract

Multiple infarcts were produced in cerebral hemispheres of rats by injecting calibrated 50-/u.m microspheres into the left internal carotid artery, and alterations in lipid and energy metabolism were evaluated 24 hours later in the embolized hemisphere. Total phospholipid content was decreased by 26%, but the different classes of phospholipids were not equally affected. Phosphatidylinositol and phosphatidylserine levels were decreased by about 40% and phosphatidylcholine and phosphatidylethanolamine by 25%, while sphingomyelin level remained unchanged. There was a 3.2-fold increase in total free fatty acid content with a relatively larger rise in polyunsaturated free fatty acids 20:4 and 22:6 (20-fold increase). Determination of enzyme activities showed decreases in Na + ,K + -ATPase ( -21 %) and hexokinase (-14%) but no changes in phosphofructokinase and pyruvate kinase. Study of energy metabolism using the closed system method of Lowry et al showed a significant depression (-36%) of the cerebral metabolic rate. Taken together, these data suggest a relation between lipid alterations and dysfunction of energy metabolism. Phospholipid degradation with subsequent free fatty acid release and alteration in membrane-bound enzymes may have a direct effect on metabolic machinery and may slow cerebral metabolic rate. (Stroke 1987;18:418-425) I SCHEMIA initiates a progression of biochemical events that can lead to irreversible damage and cell death. The metabolic changes that occur after induction of a generalized brain ischemia and the recovery following a period of transient ischemia have been extensively studied.1 In focal and multifocal ischemia, the situation is more complex, resulting from the juxtaposition of ischemic and nonischemic regions. Alterations and disruption of cells within the ischemic focus may release a wide variety of compounds causing vascular and metabolic effects in the surrounding regions. Among the biochemical events occurring during ischemia, membrane alterations may have important consequences on the metabolism and function of the brain. Membranes and membranebound enzymes, especially Na + ,K + -ATPase, play a crucial role in energy metabolism, the transport of Na + and K + ions accounting for about half of the brain energy consumption.2 Free fatty acids (FFA), which are liberated from membrane phospholipids (PL) during ischemia, 3 are known to impair mitochondrial function 4 and to inhibit the Na + ,K + -ATPase activity. Received April 29, 1986; accepted October 14, 1986. er, most data about the effects of ischemia on PL, FFA, or energy metabolism have been obtained separately using various experimental models. The purpose of this study was to observe the simultaneous changes in PL, FFA, and energy metabolism that occur 24 hours after induction of brain infarction. Multifocal infarction was induced in rat cerebral hemispheres by intracarotid injection of calibrated microspheres," and the metabolic state of the embolized hemisphere was evaluated by quantifying PL and FFA, by measuring t...

Beneficial effect of 1,3-butanediol on cerebral energy metabolism and edema following brain embolization in rats.

“…Though we did not precisely measure infarct volume, it was estimated to be approximately 20% of the hemispheric volume. This estimation agrees with data from biochemical studies showing that a 20-30% depletion of cellular constituents such as high-energy phosphates, phospholipids, 13 and catecholamines 15 occurs in the embolized hemisphere 24 hours after microsphere injection.…”

Circulating and Brain BDNF Levels in Stroke Rats. Relevance to Clinical Studies

“…In the present study, embolic stroke was induced by the injection into the left carotid circulation of 50 µm-calibrated microspheres, a model that results in severe ischemia of the left hemisphere and formation of multiple infarcts that primarily affects the parieto-temporal cortex, the hippocampus and the thalamostriate areas [21], [22]. This model is unique because it allows inducing a large but controlled distribution of degrees of stroke severity by changing the number of injected microspheres.…”

Serum Ferritin in Stroke: A Marker of Increased Body Iron Stores or Stroke Severity?

“…Rats that did not lose consciousness during 4-VO were excluded. The histologic outcomes from these models as well as detailed protocols were previously reported by our laboratory (Bralet et al (1987) and Demougeot et al (2001) for brain embolization; Demougeot et al (2001Demougeot et al ( , 2003 for photothrombotic occlusion and Marie et al (1994) for 4-VO).…”