ABSTRACT
The maternal care received by rat pups malnourished by being rotated between lactating females and nonlactating foster mothers was examined. During the 1st 2 weeks after birth there were no differences in maternal care, but during the 3rd week females caring for pups fed only 8 hr daily nursed more and built better nests than females caring for pups fed 16 or 24 hr. These differences in maternal care may interact with and diminish any effects of nutritional deprivation in the pups.
Subject(s)
Maternal Behavior , Protein-Energy Malnutrition/psychology , Animals , Female , Lactation , Male , Nesting Behavior , Pregnancy , RatsABSTRACT
The effects of 2 methods of restricting food intake--large-litter rearing and rotation between lactating and nonlactating females--on sensory factors involved in homing to the nest by rat pups were examined. Homing was observed in the unaltered home cage, when olfactory cues were altered and when visual cues were altered. Stunted animals homed less in the unaltered cage than did well-nourished controls as a result of a maturational delay. Prior to eye opening, stunted animals showed greater disruption of homing when olfactory cues were altered and after eye opening they showed greater disruption when visual cues were altered. These effects could reflect decreased sensitivity, an inability to use alternate cues, or behavioral disruption by novel stimulation. Nonnutritional factors were also found to affect homing as the 2 well-nourished groups differed in their behaviors. These differences appeared to be due to animals reared in small litters maturing more slowly than animals rotated between females.
Subject(s)
Nesting Behavior/physiology , Sensory Receptor Cells/physiology , Animals , Female , Growth , Pregnancy , Rats , Smell/physiology , Vision, Ocular/physiologyABSTRACT
Visual discrimination at 3 months of age was examined by the Lashley jumping stand test to rats malnourished by one of the following techniques: intergenerational malnutrition over 14 to 18 generations; protein deficiency from birth on; rearing in large litters, and rotation among lactating and non-lactating females. All four treatments caused stunting during the litter period, but only the first two were associated with reduced weights at the time of testing. Deficits in visual discrimination were most severe in males and females with intergenerational malnutrition. Both large-litter rearing and protein deficiency for one generation impaired visual discrimination in males only, whereas rotation between lactating and non-lactating females did not reduce visual discrimination in either gender. It is possible that extranutritional factors associated with each type of malnutrition may serve either to enhance or diminish the impact of malnutrition on the nervous system.
Subject(s)
Nutrition Disorders/physiopathology , Protein Deficiency/physiopathology , Visual Perception/physiology , Animals , Animals, Suckling , Female , Food Deprivation , Lactation , Litter Size , Male , Nutrition Disorders/genetics , Pregnancy , Rats , Sex FactorsABSTRACT
Rat pups stunted by housing only 8 hr daily with lactating females and 16 hr with nonlactating foster mothers showed a delay in returning to their nest from other parts of the home cage. This delay was not due to changes in activity level or to lack of attraction to the nest, but appeared to be perceptual in nature. Both lactating and nonlactating females caring for stunted litters tended to be more maternal than those caring for control pups. After nutritional rehabilitation, the adult experimental animals showed no deficits in learning a series of visual discrimination problems in a modified version of the Lashley jumping stand procedure with a nonappetitive reinforcement. We compared the results with those obtained when other methods of stunting animals are employed and concluded that different methods of stunting may result in both common and divergent effects on behavior. Although many methods of stunting may produce similar behavioral deficits during the period of food deprivation, after rehabilitation behavioral deficits reported with other techniques of stunting may be due to extranutritional causes rather than to reduced food intake per se.
Subject(s)
Behavior, Animal , Food Deprivation , Lactation , Maternal Deprivation , Animals , Avoidance Learning , Body Weight , Discrimination Learning , Female , Male , Maternal Behavior , Orientation , Pregnancy , Rats , Visual PerceptionABSTRACT
As nurslings, rat pups reared in large litters showed reduced frequencies of returns to their nest from other parts of the home cage and reached maximum levels of nest returns at older ages than control animals from small litters. These differences were not due to differences in activity level or attraction to the nest but appeared to be perceptual in nature. As adults, animals from large litters showed deficits in learning the 1st 2 problems in a series of visual discriminations in a modified version of the Lashley jumping stand technique in which food reinforcement was not used. The deficits were confined to male animals only and were the result of stronger position habits in the early part of training, rather than an inability to make the discriminations. A comparison of these results with those obtained when other methods of stunting animals are employed revealed that different methods of stunting may result in both common and divergent effects on behavior. One long-term consequence of large litter rearing appears to be increased emotional response to noval situations.
