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Prenatal cocaine but not prenatal malnutrition affects foster mother-pup interactions in rats
J Tonkiss1, J S Shumsky, P L Shultz
1Center for Behavioral Development and Mental Retardation, Boston University School of Medicine, MA 02118, USA.
Insights
Prenatal cocaine exposure and malnutrition in rats independently impacted pup development and mother-pup interactions. Cocaine primarily affected physical milestones, while malnutrition and cocaine together altered nursing behaviors.
Area of Science:
- Neuroscience
- Developmental Psychology
- Toxicology
Background:
- Prenatal exposure to substances like cocaine can have detrimental effects on offspring development.
- Maternal malnutrition during pregnancy is also a significant risk factor for developmental abnormalities.
- Understanding the combined impact of these exposures is crucial for public health and intervention strategies.
Purpose of the Study:
- To investigate the independent and combined effects of prenatal cocaine exposure and malnutrition on mother-pup interactions in rats.
- To assess the impact of these exposures on pup development, including birth weight and milestone attainment.
- To analyze maternal behaviors such as contact and nursing in response to exposed pups.
Main Methods:
- Sprague-Dawley rat dams were assigned to low-protein (malnourished), control, or chow diets.
- Within each diet group, dams received either cocaine or saline injections during critical prenatal periods.
- Litters were cross-fostered to control mothers to isolate the effects of prenatal exposure on mother-pup interactions and pup development.
Main Results:
- Prenatal cocaine and malnutrition independently impaired birth weight and reflexive milestones.
- Physical milestone attainment was solely affected by prenatal cocaine exposure.
- Maternal behavior showed nuanced changes: control-diet mothers increased contact with cocaine-exposed pups initially, while malnourished pups elicited more passive nursing.
Conclusions:
- Prenatal cocaine and malnutrition act independently on pup development and maternal interactions, with no additive effects observed.
- Prenatal cocaine exposure has a more pronounced effect on physical development compared to malnutrition.
- Specific maternal care behaviors, like nursing, are sensitive to combined prenatal insults.
Abstract:
The separate and combined effects of prenatal cocaine exposure and malnutrition on mother-pup interactions in rats were assessed daily from postnatal day 2 to day 21. Sprague-Dawley dams were fed a diet of low protein content (6% casein), an isocaloric diet of adequate protein content (25% casein, control), or a laboratory chow diet prior to mating and throughout pregnancy. Within each diet group, rats received either cocaine injections (30 mg/kg IP two times per week prior to mating and then 30 mg/kg SC daily from days 3 to 18 of pregnancy) or saline injections. Litters were fostered on the day of birth to control mothers (i.e., nondrug-exposed dams fed the control or chow diet). Foster mothers fed the 25% casein diet showed increased contact with cocaine-exposed pups compared with nondrug-exposed pups in the second postnatal week but lower levels as the pups approached weaning. Passive nursing was increased in dams caring for prenatally malnourished, cocaine-exposed pups compared with those caring for similar pups with no drug exposure. Chow-fed mothers did not differ in their behavior towards pups with or without prenatal cocaine treatment. Prenatal cocaine and malnutrition independently compromised birth weight and various reflexive milestones but the attainment of physical milestones was affected only by prenatal cocaine. There were no additive effects of the two prenatal insults on any measure of mother-pup interaction or pup development.