近交系マウスの飼育条件の差異が母親行動とその仔の成熟後のopen-field行動に及ぼす効果

飽田 宜子

doi:10.4992/jjpsy.50.73

EFFECTS OF REARING CONDITIONS ON THE BEHAVIOR OF MOTHERS AND ON THE LATER OPEN-FIELD BEHAVIOR OF THE OFFSPRING IN THE MOUSE

TAKAKO AKUTA

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JOURNAL FREE ACCESS

1979 Volume 50 Issue 2 Pages 73-81

DOI https://doi.org/10.4992/jjpsy.50.73

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Published: July 20, 1979 Received: May 13, 1978 Available on J-STAGE: July 16, 2010 Accepted: - Advance online publication: - Revised: -
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Date of correction: July 16, 2010 Reason for correction: - Correction: ABSTRACT Details: Wrong : There is a complex mother-infant interaction in mammalian species, including the human being. The development of infants is closely related to the mother's behavior, while the mother changes her behavior in correspondence with the behavioral development of her offspring. The purpose of the present study was to investigate the mother-infant interaction in the mouse by observing the behavior of mothers rearing litters of two different sizes during the lactation period. The adult behavior of the offspring was also examined in an open field in order to assess the effects of pre-weaning litter size and post-weaning group size.
In Experiment I, the litter size of I20 mice was reduced to either two or eight on the day after parturition. The behavior of the mothers rearing these litters, were observed by using the time sampling technique. Maternal behaviors recorded were nursing, licking pups, and nest building; and non-maternal behaviors were eating, drinking, self-grooming, resting, and active state. Each observation period was 30min in duration, and there were three observation period at regular hours (10:00, 13:00 and 16:00) on every alternate day during the entire lactation period, beginning on Day 0-1 (the day of birth or the next day) until Day 18-19. There was no difference in maternal behavior between the mothers rearing large and small litters. In non-maternal behavior, there was a difference: The mothers of the small litters were less active and spent more time resting.
In Experiment II, the offspring used in Experiment I were re-grouped at weaning (21 days of age) into groups of either two or eight of the same sex. At nine weeks of age, each animal was placed in an open field for 5min a day for three consecutive days. Five measures were taken: ambulation, defecation, rearing, face-washing, and grooming. Both the pre-weaning litter size and the post-weaning group size produced significant differences in the open-field behavior. The animals that were raised in a small litters defecated less and showed smaller number of face-washing and grooming than those from a large litters. Compared with the animals housed in groups of eight those housed in pairs showed more defecation and a great number of more ambulation and rearing.
The results suggest that any difference in the behavior of mothers, not necessarily the one directed toward pups constitutes a change in early experience and affects their behavior at a later time. Also, the pre-weaning and post-weaning rearing conditions affect different aspects of the open-field behavior in the adulthood.
Right : The mother-infant interaction was studied in the mouse by changing the size of litters. Litter size was reduced to either two or eight on the day following parturition, and the behavior of the mothers was observed by the time-sampling technique during the entire lactation period. There was no significant difference in their maternal behavior, (nursing, licking pups, and nest bulding). The mothers of the small litters were less active and spent more time resting than the mothers of the large litters. The offspring were re-grouped at weaning (21 days of age) into groups of two or eight of the same sex, and tested in an open field at nine weeks of age. The pre-weaning litter size and the post-weaning group size affected different aspects of the open-fieldbehavior.

Abstract

The mother-infant interaction was studied in the mouse by changing the size of litters. Litter size was reduced to either two or eight on the day following parturition, and the behavior of the mothers was observed by the time-sampling technique during the entire lactation period. There was no significant difference in their maternal behavior, (nursing, licking pups, and nest bulding). The mothers of the small litters were less active and spent more time resting than the mothers of the large litters. The offspring were re-grouped at weaning (21 days of age) into groups of two or eight of the same sex, and tested in an open field at nine weeks of age. The pre-weaning litter size and the post-weaning group size affected different aspects of the open-fieldbehavior.

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