DISTRIBUTION OF CONSTITUTIVE-INDUCIBLE AND HYPERTHERMIA-INDUCIBLE HEAT-SHOCK MESSENGER-RNA SPECIES (HSP70) IN THE PURKINJE LAYER OF THE RABBIT CEREBELLUM

In previous studies we have analyzed the effect of hyperthermia on the expression of hsp70 genes in the rabbit cerebellum using an hsp70 riboprobe which hybridized to both constitutively expressed and stress-inducible transcripts (1-3). These studies have now been extended utilizing riboprobes which are able to discriminate hyperthermia-inducible hsp70 mRNA of size 2.7 kb and constitutively expressed mRNA of size 2.5 kb. In situ hybridization with the inducible specific riboprobe revealed a prominent induction of the 2.7 kb species 1 hr after a 2-3-degrees-C increase in body temperature in the following cerebellar cell types i) Bergmann glial cells in the Purkinje layer, ii) glial cells in deep white matter fiber tracts and iii) granule neurons. The inducible transcript was not detected in the cerebellum of control animals. The constitutive specific riboprobe detected the 2.5 kb transcript in several neuronal cell types of the cerebellum such as Purkinje and granule neurons with little increase in signal in hyperthermic animals compared to controls.