AJP - Endocrinology and Metabolism, Vol 253, Issue 4 E401-E409, Copyright © 1987 by American Physiological Society
Maternal-fetal communication of circadian phase in a precocious rodent, the spiny mouse
D. R. Weaver and S. M. Reppert
Children's Service, Massachusetts General Hospital, Boston.
The development of circadian rhythms was examined in a precocious rodent
species, the spiny mouse. Spiny mouse pups born and reared in constant
darkness expressed robust circadian rhythms in locomotor activity as early
as day 5 of life. Free-running activity rhythms of pups born and reared in
constant darkness were coordinated with the dam on the day of birth.
Postnatal maternal influences on pup rhythmicity are minimal in this
species, as pups fostered on the day of birth to dams whose circadian
phases were opposite to the pups' original dams were coordinated with their
original dams on the day of birth. Studies using 2-deoxy-D-[1-14C]-glucose
autoradiography showed that there were synchronous (coordinated) rhythms in
metabolic activity in the maternal and fetal suprachiasmatic nuclei,
directly demonstrating prenatal coordination of maternal and fetal
rhythmicity. Maternal-fetal coordination of circadian phase was not the
result of direct entrainment of the fetuses to the environmental light-dark
cycle. These results demonstrate that there is prenatal communication of
circadian phase in this precocious species, without demonstrable postnatal
maternal influences on pup circadian rhythmicity. Spiny mice therefore
represent an important animal model in which circadian rhythms in the
postnatal period can be used to precisely assess prenatal influences on
circadian phase.
