Dopaminergic neurotransmission in chronic herpes simplex virus brain infection in rabbits.

In this study we have examined brain concentrations of monoamine neurotransmitters and striatal and mesencephalic D-2 receptors in a chronic model of herpes simplex virus (HSV) encephalitis. The HSV-inoculated rabbits were killed two months after inoculation. Dopamine (DA), noradrenaline, serotonin and their metabolites were determined in the substantia nigra, caudate nucleus, putamen, nucleus accumbens, and olfactory tubercles using HPLC with electrochemical detection. The Bmax and Kd values of D-2 receptors were studied in the striatum and in the mesencephalon using 3H-spiroperidol as ligand. The animals showed rotational behaviour, consisting of posture tilting to the inoculated side and circling in the same direction during the first week, then slowly subsiding. Compared with controls, the concentration of homovanillic acid (HVA) was reduced in the ascending DA system on both sides. Neither in the number nor affinity of D-2 receptors were there any differences between the HSV-inoculated and control rabbits. The decreased HVA concentrations suggest that dopaminergic hypofunction can develop as a consequence of previously experienced acute HSV brain infection.