Sj. Murphy et al., THE EFFECT OF HYPOXIA AND CATECHOLAMINES ON REGIONAL EXPRESSION OF HEAT-SHOCK PROTEIN-72 MESSENGER-RNA IN NEONATAL PIGLET BRAIN, Brain research, 727(1-2), 1996, pp. 145-152
The present study has shown that hypoxia leads to expression of heat-s
hock protein in the brain of newborn piglets and this process is almos
t completely abolished by depletion of catecholamines prior to the hyp
oxic episode. The piglets were anesthetized and mechanically ventilate
d. One hour of hypoxia was generated by decreasing the oxygen fraction
in the inspired gas (FiO2) from 22% to 6%-10%. FiO2 was then returned
to the control value for a period of 2 h. Following the 2 h of reoxyg
enation, regional expression of the 72-kDa heat-shock protein (hsp72)
mRNA was determined using in situ hybridization and autoradiography. T
he hypoxic insult (cortical pO(2) = 3-10 mmHg) induced expression of h
sp72 mRNA in regions of both white and gray matter, with strong expres
sion occurring in the cerebral cortex of individual animals. Depleting
the brain of catecholamines prior to hypoxia, by treating the animals
with alpha-methyl-p-tyrosine (AMT), resulted in a major change in the
hsp72 mRNA expression. In the catecholamine depleted group of animals
, the intensity of hsp72 mRNA expression was greatly decreased or almo
st completely abolished relative to the nondepleted hypoxic group. The
se results suggest that the catecholamines play a significant role in
the expression of the hsp72 gene in response to hypoxic insult in neon
atal brain.