Maternal entrainment in the circadian activity rhythm of laboratory mouse (C57BL/6J)

Journal/Book: Physiol Behav. 1999; 68: the Boulevard Langford Lane, Kidlington, Oxford Ox5 1GB, England. Pergamon-Elsevier Science Ltd. 157-162.

Abstract: Maternal entrainment of circadian activity rhythm was studied in the laboratory mouse (C57BL/6J). Pregnant mice gave birth in constant dim light and the mother raised the pups until Postnatal Day 18 (weaning). The wheel running activity of these pups was individually monitored from Day 18. It was found that the phases of pups' activity on the day of weaning were similar to the phases of their mother's rhythm (p < 0.001), indicating that maternal entrainment occurs in the C57BL/6J pups. When the mother mouse was cyclically presented to the pups for 12 h of a day, thereby creating presence-absence (PA) cycles of 12:12 h, it was found that the pups' activity rhythm entrained to the imposed cycles. The onset of activity of the pups coincided with the beginning of the mother's 12-h absence period. It is proposed that the social contact between the mother and the pups is taken by the pups as subjective day (rest time) and absence of the mother as subjective night (activity time). This maternal (nonphotic) entrainment, however, does not continue beyond Postnatal Days 23-26, despite ongoing PA. Cycles. These results indicate that the PA cycles of the mother are a transient zeitgeber, and are effective in entraining the rhythm of pups only for about 4 weeks after birth.

Note: Article Viswanathan N, Northeastern Univ, Dept Biol, 414 Mugar Life Sci Bldg, Boston,MA 02115 USA

Keyword(s): circadian rhythm; Zeitgeber; inbred mouse; postnatal; mother-pup; development; presence-absence cycles; entrainment; nonphotic; HAMSTER PHODOPUS-SUNGORUS; SUPRACHIASMATIC NUCLEUS; PRENATAL INJECTIONS; AGONIST SKF-38393; MELATONIN; MOTHER; EXPRESSION; ONTOGENY; RECEPTOR; ABSENCE

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