AJP - Endocrinology and Metabolism, Vol 243, Issue 6 443-E449, Copyright © 1982 by American Physiological Society
Foster mother rat entrains circadian adrenocortical rhythm in blinded pups
K. Takahashi, C. Hayafuji and N. Murakami
Free-running patterns of blood corticosterone rhythm were examined between
the fourth and eighth postnatal week in blinded pups optically enucleated
on day 1. When blinded pups were raised by intact natural mothers, the peak
time of corticosterone rhythm appeared near the time of light-dark (LD)
transition, which was close to that of mothers, and then free-ran. This
phase relation between mothers and pups showed that mothers entrained pups'
corticosterone rhythm. When blinded pups born of LD (or DL) mothers were
raised by DL (or LD) foster mothers, the corticosterone rhythm in blinded
pups was close to that of foster mothers at 4 wk of age, indicating that a
foster mother plays a predominant role in entraining the pups' rhythm. When
blinded pups were raised by blinded mothers whose rhythm was out of phase
of the lighting cycle, pups' rhythm was in phase with that of mothers,
showing that lighting cycle did not affect the pups' rhythm. These facts
indicate that the mother nursing pups acts as the most predominant
entrainer of corticosterone rhythm of the blinded pups.
