Early weaning decreases play-fighting behavior during the postweaning developmental period of Wistar rats.
We examined the influence of early weaning on the development of play-fighting behaviors and anxiety status in Wistar rats. Pups were divided into two groups, those weaned at postnatal day (PD) 16 (early-weaned group) and those weaned at PD30 (normally weaned group), and were housed in pairs of the same sex. Playful interactions were measured for each pair once a week from 4 to 7 weeks of age. Thereafter, during early adulthood, all the rats were subjected to the elevated plus-maze test. The frequencies of pinning and playful attack were less in the early-weaned group than in the normally weaned group. In the elevated plus-maze test, rat pups in the early-weaned group had higher anxiety levels. The results showed that deprivation of mother-pup interactions during the preweaning period decreases affiliative interactions between cage mates, including play-fighting behaviors during the postweaning developmental period, and increases anxiety levels during early adulthood.
Shimozuru
Michito
M
Laboratory of Veterinary Ethology, University of Tokyo, Tokyo 113-8657, Japan.
Kodama
Yuka
Y
Iwasa
Takashi
T
Kikusui
Takefumi
T
Takeuchi
Yukari
Y
Mori
Yuji
Y
D000374:Aggression / Q000523:psychology*; D000375:Aging / Q000523:psychology*; D000818:Animals; D005239:Fear; D005260:Female; D008297:Male; D008426:Maternal Deprivation; D010988:Play and Playthings; D051381:Rats; D017208:Rats, Wistar / Q000523:psychology*; D012727:Sex Characteristics; D012931:Social Environment; D014886:Weaning