Basal expression of stress-inducible hsp70 mRNA detected in hippocampal and cortical neurons of normal rabbit brain

In response to stresses, such as elevated temperature, cells increase synthesis of a group of highly conserved proteins known as heat shock proteins (hsps). Here, we report detection of basal expression of the stress-inducible hsp70 mRNA species in neurons of the normal rabbit brain. By regional Northern blot analysis, basal levels of hsp70 mRNA were observed in control hippocampus, cortical layers, thalamus, and kidney. Using radioactive in situ hybridization, similar patterns of expression were noted for constitutive hsc70 mRNA and hsp70 mRNA in the unstressed rabbit forebrain. Non-radioactive (DIG) in situ hybridization allowed localization of both heat shock mRNA species to hippocampal neurons. In addition, a dual in situ hybridization protocol, which allowed colocalization of two mRNAs to a single cell, demonstrated that hsp70 and hsc70 mRNAs are expressed in the same hippocampal and cortical neurons.