Levels of somatostatin and cholecystokinin in the brain of ataxic mutant mice

ROR alpha in genetic control of cerebellum development: 50 staggering years

The staggerer mutation was first identified at the Jackson Laboratory in 1955. In the ensuing half-century, studies of staggerer mice have provided new insights into developmental neurobiology, gene regulatory networks, and circadian behavior. Recent work has expanded the role of RORalpha, the transcription factor mutated in staggerer, to peripheral tissues, including cholesterol and lipid metabolism, immune function, and bone development. This review focuses on the role of RORalpha in neural development and behavior revealed by the staggerer mutation and subsequent molecular studies.

RORalpha coordinates reciprocal signaling in cerebellar development through sonic hedgehog and calcium-dependent pathways

The cerebellum provides an excellent system for understanding how afferent and target neurons coordinate sequential intercellular signals and cell-autonomous genetic programs in development. Mutations in the orphan nuclear receptor RORalpha block Purkinje cell differentiation with a secondary loss of afferent granule cells. We show that early transcriptional targets of RORalpha include both mitogenic signals for afferent progenitors and signal transduction genes required to process their subsequent synaptic input. RORalpha acts through recruitment of gene-specific sets of transcriptional cofactors, including beta-catenin, p300, and Tip60, but appears independent of CBP. One target promoter is Sonic hedgehog, and recombinant Sonic hedgehog restores granule precursor proliferation in RORalpha-deficient cerebellum. Our results suggest a link between RORalpha and beta-catenin pathways, confirm that a nuclear receptor employs distinct coactivator complexes at different target genes, and provide a logic for early RORalpha expression in coordinating expression of genes required for reciprocal signals in cerebellar development.

Balance control and posture differences in the anxious BALB/cByJ mice compared to the non anxious C57BL/6J mice

A relation between anxiety disorders and balance control dysfunctions has been observed in many studies in humans. A mismatch in the integration of sensory inputs could trigger these disturbances. Very few experimental animal procedures have been designed to study the functional link between anxiety and balance control. A task was therefore developed, challenging the visual, vestibular and somesthesic sensory systems in mice. The test, called the 'rotating beam', gave an accurate assessment of balance control and the posture, using sensitive measures (number of falls and imbalances, position of tail and trunk). Striking differences were observed between the two inbred strains of mice known to have radically different anxiety-related behaviour. The highly anxious strain, BALB/cByJ, performed poorly compared to the non anxious strain, C57BL/6J. Balance control and postural abilities of anxious mice were improved by acute anxiolytic diazepam treatment. Lower behavioural performance level was registered in non anxious mice given anxiogenic beta-CCM treatment. The findings account for a strong relationship between anxiety and balance control in mice. Finally, the highly sensitive procedure proved to be well suited to the study of functional links between anxiety and sensorimotor processes.