Regional distribution of Hsp70 in the CNS of young and old food-restricted rats following hyperthermia.
We examined the effect of aging on the capacity of the brain to produce heat shock protein (Hsp70) in response to heat stress, using high-powered microwaves (HPM, 2.06 GHz, 2.2 W/cm(2)) to induce hyperthermia for periods so brief that thermoregulatory factors were functionally eliminated as confounding variables. Unanesthetized young (6 months) and old (25 months) male, food-restricted Sprague-Dawley rats were exposed to HPM to induce a mean peak tympanic temperature (T(ty)) of 42.2 degrees C within 30 s. T(ty) returned to <40.0 degrees C within 6 min post-exposure in both age groups. Rats were euthanized 6 or 24 h later for immunohistochemical determination of Hsp70 accumulation in 10 brain regions. HPM exposure induced significant increases in 7 of the 10 regions. There were no significant differences observed in the pattern or density of Hsp70 accumulation between the young and old rats at 6 h post-HPM exposure, with the exception of the medial vestibular nucleus, which demonstrated significantly greater Hsp70 accumulation in the old rats. There were significant differences between the age groups at 24 h post-exposure, however, there was no general pattern; i.e., depending on the brain region, aged rats displayed significantly greater, lesser, or similar increases in Hsp70 expression compared with young. Taken together, these results demonstrate that the brain of aged, food-restricted rats does not display a loss of capacity to accumulate Hsp70 in response to heat stress.
Walters
T J
TJ
Air Force Research Laboratory, Directed Energy Bioeffects Division, Radio Frequency Radiation Branch, Brooks Air Force Base, TX, USA. thomas.walters@AMEDD.army.mil
Ryan
K L
KL
Mason
P A
PA
D000375:Aging / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism*; D005334:Fever / Q000378:metabolism*; D005508:Food Deprivation / Q000502:physiology*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008872:Microwaves; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
D018840:HSP70 Heat-Shock Proteins