1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced dopamine D2 receptor hypersensitivity in the mouse is transient.

Adult C57 B1 mice were injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) using two dosage regimens. Following a 20 mg/kg/hour X 4 schedule, the number of dopamine D2 receptors labeled by 3H-spiperone was significantly increased at 2 days following the last injection of MPTP (124 +/- 8.0% of control values; p less than 0.025). Scatchard analysis revealed an increase in the number of 3H-spiperone binding sites. No significant difference between the control and MPTP treated animals could be detected in 3H-spiperone binding at 4 and 6 days following the short term MPTP treatment. Similarly, a regimen of 30 mg/kg/day X 10 MPTP caused a transient increase in 3H-spiperone binding to dopamine D2 receptors (1 day: 143 +/- 12%, p less than 0.01; 10 days: 101 +/- 3.7%, p greater than 0.05). These results suggest that MPTP does not produce permanent supersensitivity of dopamine D2 receptors in the mouse.