Cocaine sensitivity in Borna disease virus-infected rats.

Borna disease virus (BDV) is a neurotropic RNA virus that infects warm-blooded animals to cause disturbances of movement and behavior. Studies in infected rats have demonstrated behavioral sensitivity to direct and indirect dopamine (DA) agonists; however, behavioral responses to an indirect DA agonist with a pure presynaptic effect have not been analyzed. Rats infected with BDV had an enhanced response to the locomotor, behavioral, and convulsant effects of cocaine at intraperitoneal doses of 7.5, 15, and 30 mg/kg. The basis for this sensitivity was examined by striatal DA uptake site and D1 and D2 receptor autoradiography. DA uptake sites, labeled with [3H] mazindol, were reduced in medial caudate-putamen (CP), and binding of [3H] raclopride to D2 sites was reduced in medial and ventral striatal areas. The topography of DA uptake and D2 site loss corresponds to the distribution of BDV viral nucleic acids in CP and overlays the medial striatal areas that function in conditioned reward. The BDV-infected rat provides a model of cocaine sensitivity based on viral central nervous system infection and may have relevance for studies of cocaine abuse in the context of other viral encephalopathies, such as those associated with HIV infection.