AJP - Regulatory, Integrative and Comparative Physiology, Vol 245, Issue 4 600-R605, Copyright © 1983 by American Physiological Society
Genetic variation, chronic stress, and the central and peripheral noradrenergic systems
D. A. Blizard, L. S. Freedman and B. Liang
Male rats from two inbred strains genetically selected for variation in
response to stress were exposed for 9 consecutive days to 50 min of
intermittent foot shock and killed 24 h after the last stress session.
Maudsley Nonreactive (MNRA/Har) rats, genetically selected for decreased
reactivity to stress, exhibited a significantly greater elevation (114%
above control levels) in tyrosine hydroxylase activity in the locus
ceruleus after chronic stress than Maudsley Reactive (MR/Har) animals (63%
above control levels), genetically selected for heightened reactivity to
stress. In the peripheral noradrenergic system, chronic stress produced an
increase in norepinephrine (NE) content of small intestine and submaxillary
gland of MNRA/Har rats, whereas chronic stress had no effect on NE content
of these same tissues in MR/Har animals. These results are consistent with
the proposition that genetic selection for variation in susceptibility to
stress has altered the capacity of the central and peripheral noradrenergic
system to adapt to chronic stress.
