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Brain creatine kinase reaction rates and reactant concentrations during seizures in developing rats
D Holtzman1, R Meyers, I Khait
1Department of Neurology, Children's Hospital, Boston, MA, USA.
Epilepsy Research
|April 1, 1997
Summary
Brain creatine kinase (CK) activity increases with age in rats. During seizures, CK activity rises in older rats but not younger ones, impacting brain energy reserves.
Area of Science:
- Neuroscience
- Biochemistry
- Physiology
Background:
- Brain creatine kinase (CK) plays a crucial role in cellular energy buffering by catalyzing the reversible transfer of a phosphate group between phosphocreatine (PCr) and adenosine triphosphate (ATP).
- Understanding the developmental changes and seizure-induced alterations in CK activity is vital for comprehending brain energy metabolism under physiological and pathological conditions.
Purpose of the Study:
- To investigate the developmental differences in brain CK catalyzed phosphorus fluxes in young (7-day-old) and older (21-day-old) rats.
- To determine the impact of pentylenetetrazole (PTZ)-induced seizures on brain CK activity and energy metabolites (PCr, ATP) in rats of different ages.
Main Methods:
- Utilized phosphorus-31 nuclear magnetic resonance spectroscopy ([31P]NMR) to measure in vivo brain CK rate constants and concentrations of PCr and ATP.
- Induced seizures using pentylenetetrazole (PTZ) and monitored metabolic changes before and during seizure activity in both age groups.
Main Results:
- CK rate constants were approximately three times higher in 21-day-old rats compared to 7-day-old rats prior to seizures, indicating age-dependent maturation of this enzyme system.
- During PTZ-induced seizures, CK rate constants increased by about 60% in older rats, while they remained unchanged or decreased in younger rats.
- Minor decreases in PCr were observed during seizures in both age groups, with a small decrease in ATP noted only in the 7-day-old rats.
Conclusions:
- Brain CK activity matures significantly between 7 and 21 days of age in rats.
- Older rats exhibit a more robust increase in CK activity during seizures, suggesting a greater capacity to maintain ATP homeostasis compared to younger rats.
- The observed changes in PCr and ATP highlight age-dependent differences in brain energy metabolism during acute seizure events.