Late direct and transneuronal effects in mice with targeted expression of a toxin gene to D1 dopamine receptor neurons.

Detailed analysis of a novel transgenic model of basal ganglia disease has been undertaken. In this model the expression of an attenuated form of the diphtheria toxin gene was tightly controlled by D1 dopamine receptor regulatory domains. The behavioral and both direct toxin-mediated and transneuronal effects observed in pups in the first postnatal week have been described.

Early direct and transneuronal effects in mice with targeted expression of a toxin gene to D1 dopamine receptor neurons.

The neurochemical profile was examined at postnatal day 3-4 in mutant mice generated by in vivo Cre mediated activation of an attenuated diphtheria toxin gene inserted into the D1 dopamine receptor gene locus. An earlier study of this model had shown that D1 dopamine receptor, substance P and dynorphin were not expressed in the striatum. Quantitative in situ hybridization analysis showed an increase in D2 dopamine receptor and enkephalin messenger RNA expression.

Targeted expression of a toxin gene to D1 dopamine receptor neurons by cre-mediated site-specific recombination.

Idiopathic Parkinson's disease involves the loss of midbrain dopaminergic neurons, resulting in the presynaptic breakdown of dopaminergic transmission in the striatum. Huntington's disease and some neurodegenerative diseases with Parkinsonian features have postsynaptic defects caused by striatal cell death. Mice were generated in which an attenuated form of the diphtheria toxin gene (tox-176) was expressed exclusively in D1 dopamine receptor (D1R)-positive cells with the aim of determining the effect of this mutation on development of the basal ganglia and on the locomotor phenotype.

Dopamine receptors and dopamine transporter in brain function and addictive behaviors: insights from targeted mouse mutants.

Recent advances in molecular biology have resulted in a number of genetically manipulated mice with defined changes at dopamine receptor and the dopamine transporter (DAT) loci. Mice with targeted mutations at the D1 receptor (D1R) are growth-retarded and show downregulated expression of dynorphin and substance P. Behavioral assessment indicates that mutants have deficiencies in spatial learning and initiating movement, as well as in responding to novel stimuli.