Biparental care in C57BL/6J mice: effects on adolescent behavior and alcohol consumption.

RATIONALE

Social attachment plays an important role in offspring development. Different parenting experiences during lactation may shape offspring behavior and later alcohol use.

OBJECTIVES

We tested the hypothesis that differential rearing conditions (single mother, SM or biparental, BP) in the non-monogamous C57BL/6J mice may affect (1) parental behavior during lactation, (2) adolescent behavior, and (3) adolescent initiation of alcohol drinking.

METHODS

Mice were reared in SM or BP (cohabitation of father-mother since copulation) condition until weaning (postnatal day, PND, 21). Litters from both conditions were filmed during PNDs 6, 9, and 12 and an ethogram was made taking into account nest-, pup-, or self-directed behaviors. At PNDs, 28-29 adolescent animals were evaluated in a modified version of the concentric square field for measurement of behavioral patterns. Other groups of adolescents were tested in a 4-h daily, two-bottle choice alcohol consumption test (10% alcohol vs. water) during 3 weeks (4 days per week).

RESULTS

Single mothers spent less time in the nest, left unattended the nest more times, displayed more self-directed and less pup-directed behaviors than BP parents. SM-reared adolescents displayed more anxiogenic-like and less risk-associated behaviors than BP counterparts. The alcohol consumption test indicated a strong effect of rearing condition. Since the fifth day of test, SM adolescents consumed more quantities of alcohol than BP adolescents.

CONCLUSIONS

During single-mother parenting, pups are left unattended more often, and during adolescence, these organisms exhibited increased anxiety responses. This behavioral phenotype may act as a risk factor for alcohol initiation during adolescence.