Cre recombinase-mediated restoration of nigrostriatal dopamine in dopamine-deficient mice reverses hypophagia and bradykinesia.
Level 5 - mechanism / opinion, no new human data
Animal model and mechanistic laboratory study
PubMed 16723393 · doi:10.1073/pnas.0603081103
What was done
Researchers developed a dopamine-deficient floxed-stop (DDfs) mouse line with an inactivated Tyrosine hydroxylase (Th) gene, causing trace brain dopamine levels, severe hypoactivity, and aphagia. To selectively rescue dopamine signaling in the nigrostriatal pathway, they bilaterally injected a retrogradely transported canine adenovirus (CAV-2) expressing Cre recombinase into the central caudate putamen to reactivate Th expression in projecting midbrain neurons. Feeding behavior was assessed using lickometer cages, and locomotion, coordination, and thigmotaxis were compared between virally rescued DDfs mice and controls.
What was found
The abstract reports no numerical values. Viral restoration of dopamine in the central caudate putamen reversed lethal aphagia and normalized baseline locomotion. However, compared with controls, rescued mice exhibited hyperphagia, altered meal structure, nighttime hyperactivity, impaired motor coordination, and increased thigmotaxis.
Why it matters
This study demonstrates that dorsal striatal dopamine signaling is sufficient to sustain essential feeding and basic locomotion, but highlights that other dopaminergic circuits are necessary for fine-tuned coordination and normal behavioral patterning.
Limits
The study was conducted entirely in mice, limiting direct translation to human neurological conditions. The abstract provides no sample sizes, effect sizes, or quantitative variance measures. The approach evaluated a single regional rescue and did not isolate the contributions of other distinct dopaminergic subcircuits.
Cited by
- supports Rats genetically engineered to lack dopamine will consume food placed directly in their mouth, but will starve to death if food is placed even a body length away.