Vestibular diseases
| B6Ei.GL-Nox3het/J |
Homozygotes for the autosomal recessive head tilt (het) mutation have a subtle head tilt. They may also circle abnormally and be hyperactive. They are unable to sense orientation under water and therefore, cannot swim properly. If held by the tail, they retract rather than extend their limbs, and they flex ventrally rather than dorsally. When lowered quickly by the tail, they don’t extend their forelimbs. If dropped vertically from a short distance, they have difficulty righting themselves. They lack otoliths, and their saccules and utricles are misshapen. Their vestibular neurons don’t respond at all to pulsed linear acceleration. The mice are not deaf, have normal cochleas and middle ears, and normally functioning melanocytes. The het allele product is likely involved in forming the otoliths, perhaps through the regulation of calcium secretion by neuroepithelial cells.
References
Bergstrom RA, You Y, Erway LC, Lyon MF, Schimenti JC 1998. Deletion mapping of the head tilt (het) gene in mice: a vestibular mutation causing specific absence of otoliths. Genetics 150:815-22.
Harrod CG, Baker JF. 2003. The vestibulo ocular reflex (VOR) in otoconia deficient head tilt (het) mutant mice versus wild type C57BL/6 mice. Brain Res 972:75-83.
JAX® Mice for vestibular diseases research
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