Genetic analysis of the role of protein kinase C signaling pathways in behaviors by direct gene transfer with HSV-1 vectors.

A genetic intervention strategy is described to elucidate the specific biochemical pathways in identified types of neurons that underlie behavioral adaptations. This strategy contains three parts: A Herpes simplex virus (HSV-1) vector is used to obtain localized gene transfer, a cell type-specific promoter is used to target expression to a particular type of neuron, and a constitutively active signal transduction enzyme is expressed to alter neuronal physiology. To enable this approach, a constitutively active protein kinase C (PKC) was developed which causes a long-lasting, activation-dependent increase in neurotransmitter release from cultured sympathetic neurons. This genetic intervention strategy was tested using the nigrostriatal system: Microinjection of HSV-1 vectors that contain the tyrosine hydroxylase promoter targeted expression to dopaminergic nigrostriatal neurons. Expression of the constitutively active PKC in a small percentage of nigrostriatal neurons (approximately 0.1-2%) produced a long-term (> or = 1 month) change in apomorphine-induced rotational behavior, the amount of rotational behavior correlated with the number of affected nigrostriatal neurons, and D2-like dopamine receptor levels were elevated in the striatal regions innervated by the affected nigrostriatal neurons. The strengths and limitations of this genetic intervention strategy are discussed.