Effects of an adenosine analogue administration on the striatal NMDA receptors in an experimental model of epilepsy

Specific [H-3]-MK801 binding to rat NMDA receptors following the administration of the convulsant drug 3-mercaptopropionic acid (MP) and the adenosine analogue cyclopentyladenosine (CPA) was studied in striatal membrane fractions. MP administration (150 mg/kg, i.p.) caused an increase of 53% and 52% in [H-3]-MK801 binding during seizure and the postseizure period respectively. Administration of CPA (2 mg/kg, i.p.) raised [H-3]-MK801 binding by 72%. When CPA was administered 30 min before MP and rats sacrificed at seizure (CPA + MPc), an increase of 64%, was observed. Saturation results indicate that receptor sites increased their maximal binding capacity (B-max) in all treatments while the apparent dissociation constant (K-d) remained unchanged. MP administration brought about an increase of 52% and 42% in [H-3]-MK801 binding sites during seizure and postseizure respectively. Administration of CPA raised receptor density by 75%. When CPA was administered 30 min before MP and rats sacrificed at seizure (CPA + MPc), an increase of 62%, was observed. These results show that striatal NMDA receptors have a selective role in seizure activity in the basal ganglia and that the adenosine analogue administration may modify [H-3]-MK801 binding in a way similar to that of the convulsant drug. (C) 2000 Elsevier Science Ltd. All rights reserved.