AJP - Regulatory, Integrative and Comparative Physiology, Vol 267, Issue 2 596-R601, Copyright © 1994 by American Physiological Society
Day length affects immune cell numbers in deer mice: interactions with age, sex, and prenatal photoperiod
J. M. Blom, J. M. Gerber and R. J. Nelson
Department of Psychology, Johns Hopkins University, Baltimore, Maryland 21218.
The extent to which day length affects immune function was examined in the
present study. Three goals were pursued: 1) to confirm and extend the
observation that the immune systems of adult deer mice (Peromyscus
maniculatus) are responsive to changes in photoperiod, 2) to examine the
development of the photoperiod-associated changes in immune function, and
3) to discover whether photoperiodic information transmitted to the young
during gestation influences immune function. In experiment 1, adult mice
housed in short days had higher white blood cell and lymphocyte numbers
than their long-day cohorts. Red blood cell and differential cell counts
did not differ between long- and short-day animals. No sex differences were
observed in the pattern of immune responses to photoperiod. The effect of
photoperiod on immune cells in prepubertal animals was examined in
experiment 2; a similar pattern of results was obtained as that for
experiment 1, suggesting that the photoperiodic effect on the immune system
is not mediated by sex steroid hormones. Prenatal and postnatal
photoperiodic effects on immune cells were examined in experiment 3; pups
gestated in one day length were cross-fostered to mothers in the same day
length conditions or to mothers maintained in the alternative day length.
The results of experiment 3 suggested that photoperiodic information
transmitted from the mother to the young in utero subsequently affected
immune systems of the pups. Animals gestated in short day lengths displayed
higher immune status throughout life than mice gestated in long days. These
results are discussed from an adaptive functional perspective.
