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Repeated acute testing of anticonvulsant drugs in amygdala kindled rats: increase in anticonvulsant but decrease in
1Department of Pharmacology, Toxicology, and Pharmacy, School of Veterinary Medicine, Hannover, Germany. wloscher@pharma.tiho-hannover.de
Epilepsia
|May 10, 2000
Summary
Repeatedly testing anticonvulsant drugs (AEDs) in the same kindled rats alters their response, increasing potency and reducing side effects. This impacts the reliability of AED drug testing in epilepsy research.
Area of Science:
- Neuroscience
- Pharmacology
- Epilepsy Research
Background:
- Kindled rat models are crucial for evaluating anticonvulsant drugs (AEDs).
- Repeated use of the same animals or historical data is common due to cost and time.
- Potential confounding factors include repeated drug exposure and seasonal variations.
Purpose of the Study:
- To investigate the effects of repeated acute drug testing on anticonvulsant and adverse effects in amygdala-kindled rats.
- To assess the influence of seasonal variation on drug responses in this model.
- To examine the effects of carbamazepine (CBZ), phenobarbital (PB), and valproate (VPA) over 6-9 months.
Main Methods:
- Two groups of amygdala-kindled rats were tested monthly with CBZ, PB, or VPA.
- Anticonvulsant activity was measured by the focal seizure threshold (afterdischarge threshold; ADT).
- Plasma drug levels were monitored to rule out pharmacokinetic changes.
Main Results:
- Repeated testing significantly decreased ADT and potentiated AED effects.
- Ataxia, an adverse effect, was markedly reduced with repeated testing.
- Seasonal differences in PB and VPA potency were observed initially but were overshadowed by repeated testing effects.
Conclusions:
- Repeated acute drug testing in kindled rats alters their sensitivity to AEDs.
- Increased anticonvulsant potency and decreased adverse effects can lead to false-positive results for new compounds.
- Further research is needed to understand the mechanisms behind these altered drug responses.