Decrease in mesencephalic dopamine autoreceptors in experimental herpes simplex encephalitis.

Brain dopamine receptors were determined in experimental herpes encephalitis using an animal model, where herpes simplex virus type 1 was inoculated onto the cornea of rabbits. The animals exhibit an asymmetric posture and circling to the side of inoculation, which appears to be connected to the altered dopamine transmission in the mesostriatal system. In this study striatal and mesencephalic D-1 and D-2 dopamine receptors were measured by radioligand techniques using 3H-SCH 23390 and 3H-spiroperidol as ligands. In the striatal D-1 and D-2 receptors there were no significant differences between HSV-inoculated and control rabbits. In the substantia nigra-ventral tegmental area there was a significant decrease in the D-2 receptors (Bmax) on the side contralateral to the primary virus inoculation and the direction of the rotational behaviour, without any changes in the D-1 receptors. Thus experimental herpes simplex virus infection seems to affect the mesencephalic dopamine autoreceptors, leading to unilateral activation of the mesostriatal dopamine system and rotational behaviour.