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The protective effect of 2-chloroadenosine against the development of amygdala kindling and on amygdala-kindled
A S Abdul-Ghani1, P J Attwell, H F Bradford
1Department of Biology and Biochemistry, Birzeit University, West-Bank, Israel.
Abstract:
The influence of 2-chloroadenosine, a non-metabolizable adenosine A1 receptor agonist, was tested on the development of electrically kindled amygdala and on the seizure responses of fully kindled rats. Focal intra-amygdaloid injection of 2-chloroadenosine (1-10 nmol/0.5 microl) 20 min before applying the daily kindling stimulus prevented the development of the kindling process. The behavioural seizure score and the afterdischarge duration were reduced below their initial values. The antiepileptogenic effects of 1 and 10 nmol of 2-chloroadenosine were reversible 8-10 days after withdrawal of the drug. When 2-chloroadenosine was tested on fully developed stage 5 amygdala-kindled seizures, it increased the generalised seizure threshold in a dose-dependent manner. A maximum efficiency of 125% (P < 0.001) was achieved with 5 nmol and the median effective dose was 0.55 nmol. Higher doses resulted in the reduced anticonvulsant effect (P < 0.05). With the same daily stimulation, 2-chloroadenosine 5 nmol in 0.5 microl vehicle, significantly reduced the maximum seizure score by 90%, the afterdischarge duration by 88% and completely blocked the generalised seizure duration. The antiseizure activity of the drug lasted for 3 days. In conclusion, 2-chloroadenosine not only acts as an anticonvulsant against electrically induced kindled seizures as described here, and against audiogenic seizures, electroshock and a variety of chemical convulsants as described by others, it prevents the development of the epileptic state by kindling-stimulation, i.e., it is antiepileptogenic. We theorise here that this is due to its blockade of presynaptic glutamate release.
Insights
2-chloroadenosine, an adenosine A1 receptor agonist, prevents epilepsy development and acts as an anticonvulsant in kindled rats. This drug shows potential for treating seizure disorders by blocking glutamate release.
Area of Science:
- Neuroscience
- Pharmacology
- Epilepsy Research
Background:
- Adenosine A1 receptors play a crucial role in regulating neuronal excitability.
- Epilepsy is a chronic neurological disorder characterized by recurrent seizures.
- Electrical kindling is a widely used animal model to study epileptogenesis.
Purpose of the Study:
- To investigate the effects of 2-chloroadenosine on the development of amygdala kindling.
- To evaluate the anticonvulsant properties of 2-chloroadenosine against established kindled seizures.
- To explore the potential of 2-chloroadenosine as an antiepileptogenic agent.
Main Methods:
- Focal intra-amygdaloid injections of 2-chloroadenosine in rats.
- Electrical stimulation to induce and maintain amygdala kindling.
- Behavioral seizure scoring and measurement of afterdischarge duration.
- Dose-response assessments for anticonvulsant and antiepileptogenic effects.
Main Results:
- 2-chloroadenosine prevented the development of electrical kindling, reducing seizure scores and afterdischarge durations.
- The antiepileptogenic effects were reversible within 8-10 days.
- 2-chloroadenosine increased the generalized seizure threshold in a dose-dependent manner, acting as an anticonvulsant.
- Anticonvulsant activity persisted for up to 3 days.
Conclusions:
- 2-chloroadenosine exhibits both anticonvulsant and antiepileptogenic properties.
- The drug effectively suppresses seizure development and reduces seizure severity in an amygdala kindling model.
- These findings suggest 2-chloroadenosine's potential therapeutic value in epilepsy, possibly via presynaptic glutamate release blockade.