Effects of early postnatal sibling deprivation on anxiety and vulnerability to cocaine in offspring rats.
BACKGROUND
Early-life experience has long-term consequences on affective behavior and drug abuse in adults. While many manipulations used to study these consequences alter mother-infant interactions, the effects of sibling interactions are less well characterized.


OBJECTIVE
To examine the long-term effects of early postnatal sibling deprivation (EPSD) on anxiety-like behavior, sucrose preference and behavioral responses to cocaine in adult rats.


METHODS
After EPSD manipulation, in which litters were culled to one pup on postnatal day 1 (PN1) or 7 (PN7), the dams' maternal behavior was observed. After the pups reached adulthood, we tested their behavioral responses in the elevated plus maze and sucrose consumption, and to cocaine conditioned place preference and cocaine sensitization.


RESULTS
The pups with EPSD on PN1 received more maternal licking/grooming during the first postnatal week. EPSD on PN1 but not PN7 enhanced locomotor activity in the open field test and exploration of open arms in the elevated plus maze in both female and male offspring. While EPSD had no effect on sucrose intake in adult rats, it decreased vulnerability to cocaine sensitization and cocaine conditioned place preference in male but not female rats.


CONCLUSIONS
Our findings that early postnatal sibling deprivation influences maternal licking/grooming behavior, as well as anxiety-like behavior and vulnerability to drugs in pups that have grown to adulthood, suggests that both sibling interaction and maternal behavior, play critical roles in individual development.
Li
Yan-Qin
YQ
National Institute on Drug Dependence, Peking University, 38 Xue Yuan Road, Haidian District, Beijing, China.
Wang
Xiao-Yi
XY
Zhai
Hai-Feng
HF
Zheng
Yong-Qiu
YQ
Zhang
Xiang Yang
XY
Kosten
Therese
T
Lu
Lin
L
D000818:Animals; D001007:Anxiety / Q000523:psychology*; D019970:Cocaine-Related Disorders / Q000523:psychology*; D003216:Conditioning, Operant / Q000187:drug effects; D005260:Female; D008297:Male; D008425:Maternal Behavior; D009043:Motor Activity / Q000502:physiology; D011247:Pregnancy; D051381:Rats; D012727:Sex Characteristics; D012931:Social Environment; D012934:Social Isolation / Q000523:psychology*; D013395:Sucrose; D015430:Weight Gain / Q000187:drug effects
D013395:Sucrose