Combining functional magnetic resonance imaging with mouse genomics: new options in pain research.

This functional magnetic imaging study investigated the functional implications of genetic modification and pharmacological intervention on cerebral processing of heat-induced nociception in mice. Comparing dynorphin-overexpressing dream(-/-) with wild-type mice, smaller activated cortical and limbic brain structure sizes could be observed. Moreover, significantly reduced blood oxygenation level-dependent signal amplitudes were found in pain-related brain structures: sensory input, thalamic regions, sensory cortex, limbic system, basal ganglia, hypothalamus and periaqueductal grey. Administration of the specific kappa-opioid-receptor antagonist nor-binaltorphimine to dream(-/-) mice reversed this reduction to wild-type level in the same brain structures. These results show that blood oxygenation level-dependent functional magnetic imaging in the pain system of (transgenic) mice is feasible. Genetic modifications and pharmacological interventions modify brain responses in a structure-specific manner.