Effects of feeding and light cycles on activity rhythms of maternally isolated rat pups
Motor activity of infant rat pups was measured continuously between days 3 and 18 of postnatal age. Mother-reared rats on a 12:12 LD cycle exhibited significant rhythmic activity in the circadian range as early as day 5 of postnatal age. Some of the pups reared in isolation from maternal and sibling...
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Veröffentlicht in: | Physiology & behavior 1987, Vol.39 (2), p.169-181 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Motor activity of infant rat pups was measured continuously between days 3 and 18 of postnatal age. Mother-reared rats on a 12:12 LD cycle exhibited significant rhythmic activity in the circadian range as early as day 5 of postnatal age. Some of the pups reared in isolation from maternal and sibling contact and kept on 12:12 LD cycles, feeding cycles, or combinations of feeding, temperature, and LD cycles also showed rhythmic activity but it was less persistent and of a lower amplitude than the rhythms of the mother-reared group. In the isolated rat pups nocturnal partitioning of activity was strengthened in the presence of both a light-dark cycle and a feeding cycle but only when the feeding resembled more natural nursing rhythms. In animals kept on constant light and a feeding cycle, activity occurred slightly more often during the 12-hr interval of decreased food intake. The addition of a temperature cycle—cooler nocturnal temperature—decreased the proportions of nocturnal motor activity. These results indicate that feeding and light-dark cycles may contribute to the synchronization of activity rhythms during the early postnatal period. |
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ISSN: | 0031-9384 1873-507X |
DOI: | 10.1016/0031-9384(87)90006-0 |