Modifications in muscarinic, dopaminergic and serotonergic receptors concentrations in the hippocampus and striatum of epileptic rats

The present study was undertaken in order to investigate the muscarinic (M-1), dopaminergic (D-1 and D-2) and serotonergic (5-HT2) receptors densities in hippocampus and striatum of Wistar rats after status epilepticus (SE) induced by pilocarpine. The control group was treated with 0.9% saline. An other group of rats received pilocarpine (400 mg/kg, s.c.) and both groups were sacrificed I h after treatment. The results have shown that pilocarpine administration and resulting SE produced a downregulation of M-1 receptor in hippocampus (4 1 %) and striatum (5 1 %) and an increase in the dissociation constant (K-d) values in striatum (42%) alone. In both areas the 5-HT2 receptor density remained unaltered, but a reduction (50%) and an increase (15%) in the Kd Values were detected in striatum and hippocampus, respectively D, and D2 receptor densities in hippocampus and striatum remained unaltered meanwhile Kd values for D, receptor declined significantly, 33% in hippocampus and 26% in striatum. Similarly, K-d values for D-2 decreased 55% in hippocampus and 52% in striatum. From the preceding results, it is clear that there is a possible relation between alterations in muscarimic receptor density and others systems studied as well as they suggest that changes in dissociation constant can be responsible for the establishment of pilocarpine-induced SE by altering the affinity of neurotransmitters such as acetylcholine, dopamine and serotonine. (c) 2005 Elsevier Inc. All rights reserved.