Constitutive expression of heat shock protein HSP25 in the central nervous system of the developing and adult mouse.

Immunohistochemistry and in situ hybridization have been used to survey constitutive heat shock protein (HSP)25 expression in the brain and spinal cord of the developing and adult mouse. The data reveal both transient and sustained patterns of expression and demonstrate robust differences between mice and rats. During development, HSP25 is transiently expressed in neurons of the inferior colliculus, various thalamic subnuclei, and the majority of Purkinje cells in the cerebellum. Sustained expression into adulthood is seen in neurons of the cranial nerve nuclei, spinal cord motoneurons, median preoptic nucleus, and a subset of Purkinje cells. Differences in HSP25 expression between adult rats and mice include the somatic motor nuclei innervating the extraocular muscles, which are HSP25 immunoreactive only in the rat. Similar differences in HSP25 expression are seen during the development of the inferior colliculus, thalamus, and cerebellum, where expression is restricted to mice.