Maternal care received by rat pups treated with 6-hydroxydopamine

Selective depletion on CNS dopamine in neonatal rats, by intracisternal injection of 6-hydroxydopamine on the fifth day of life, is associated with hyperactivity, learning disturbances, and growth retardation. To assess the degree to which pup behavioral deficits result from, or influence, alterations in maternal care, mother-pup interaction was investigated during the first 13 days of pup life in 3 groups of litters: 6-OHDA-treated, sham treated, and normal control. Measures of maternal behaviors included nursing, nest-building, retrieval, and locomotor activity; biological measures of pup maturation included weight, length, and righting time. These indices of mother-pup interaction revealed 4 stable dimensions and significant developmental patterns. 6-OHDA-treated pups were significantly lighter and shorter, and somewhat retarded in righting time. Although pup 6-OHDA treatment did not disrupt the organization or sequence of mothering, treated pups were increasingly distinguished from controls by the promptness with which they were retrieved. The profound and enduring behavioral deficits of dopamine depletion in the newborn period appear to occur in the presence of adequate, and perhaps enhanced, maternal care.