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 (M1), dopaminergic (D1 and D2) 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 1 h after treatment. The results have shown that pilocarpine administration and resulting SE produced a downregulation of M1 receptor in hippocampus (41%) and striatum (51%) and an increase in the dissociation constant (Kd) 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. D1 and D2 receptor densities in hippocampus and striatum remained unaltered meanwhile Kd values for D1 receptor declined significantly, 33% in hippocampus and 26% in striatum. Similarly, Kd values for D2 decreased 55% in hippocampus and 52% in striatum. From the preceding results, it is clear that there is a possible relation between alterations in muscarinic 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.