In vivo synthesis of a stress protein (SP71) in response to hyperthermia was examined in brain and several other tissues from rats ranging in age from 1 day to 25 weeks old. The synthesis of SP71 was increased dramatically by hyperthermia at all ages in all tissues examined except brain. We were unable to detect any increase in SP71 synthesis in brain due to hyperthermia until the rats were more than 2 weeks old. SP71 synthesized by the cerebral microvasculature in response to the trauma of tissue slicing has previously been reported to show a similar requirement for postnatal development. The onset of the increase in synthesis of SP71 in response to either mild hyperthermia or mechanical trauma correlates with the structural and functional maturation of the cerebral microvasculature and the blood-brain barrier.
Age Factors Animals