Annals of the New York Academy of Sciences, Vol 496, Issue 1 501-509, Copyright © 1987 by New York Academy of Sciences
Stress-behavior interactions in hamster tumor growth
L. Temoshok, H. V. Peeke, C. W. Mehard, K. Axelsson and D. M. Sweet
The aim of this study was to investigate the effects of a mechanical
stressor and individual behavior differences (separately and in
combination) on tumor development in the female Syrian hamster. Studies by
other investigators have documented the tumor-enhancing effects of such
mechanical stressors as rotational stress. Previous studies by our group
found that both size of tumor and time to tumor detection were
significantly related to a dimension we call "activation." Eighty 100-day
old female Syrian hamsters were placed in circular plexiglas environments
in groups of 10. Nineteen days after introduction to the cages, a stress
condition was imposed on half the animals (four cages). This consisted of
shaking each cage of animals three times a week for three 10-minute
intervals. Each group's behavior was videotaped in multiple samples to
document pre- and poststress behaviors. Twelve days after the stress
condition was initiated, each animal was injected subcutaneously midback
with one melanoma tumor fraction. Animals were palpated every three days to
determine time to detection of tumor. The videotaped behavior samples were
coded for behaviors associated with "activation," inactivity, and
interaction. Factor analysis resulted in basically the same first factor of
activation found in our previous studies. Hamsters in the nonstressed
groups had a significantly longer time to tumor development than those in
the stressed groups (22.5 days vs. 12.6 days, p less than 0.005). While no
prestress behaviors were associated significantly with time to tumor
detection, the poststress activation factor was significantly correlated
with longer time to tumor development in the stressed group (r = .61, p
less than 0.0001). These results suggest that while the stress condition is
more powerful than prestress individual behaviors in affecting the outcome
variable, stress appears to interact with the individual behaviors related
to "activation" to mitigate the negative effects of stress on tumor growth.
