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Offspring open field performance following maternal lead exposure: a question of dosage and nutritional status
Insights
Maternal lead (Pb) exposure in rats caused hyperactivity in offspring only when it also reduced pup size. These behavioral differences disappeared by adulthood, suggesting weight changes, not lead itself, influenced early behavior.
Area of Science:
- Neuroscience
- Developmental Toxicology
- Behavioral Science
Background:
- Maternal lead (Pb) exposure is linked to offspring hyperactivity.
- Reduced pup size is a consistent correlate of Pb exposure.
- Previous studies haven't fully disentangled the effects of Pb exposure from weight differences.
Purpose of the Study:
- To investigate the impact of varying lead acetate dosages on offspring exploratory behavior.
- To compare Pb-exposed and control offspring, accounting for potential weight differences.
- To determine if observed behavioral changes persist into adulthood.
Main Methods:
- Female rats received lead acetate (0, 400, 750, or 1000 mg/kg) from pre-mating through nursing.
- Offspring underwent open field testing at postnatal days 22-31.
- Offspring were retested at 120 days of age.
Main Results:
- Offspring from the 750 and 1000 mg/kg groups showed significantly different exploratory patterns compared to controls.
- These behavioral differences were observed only when offspring also exhibited reduced birth and/or weaning weights.
- Behavioral differences were absent upon retesting at 120 days of age.
Conclusions:
- Reduced offspring weight, a consequence of high-dose lead exposure, appears to be the primary driver of altered exploratory behavior.
- The observed behavioral changes are transient and not indicative of long-term neurodevelopmental deficits solely due to lead exposure.
- Weight normalization in adulthood mitigates the behavioral effects associated with developmental lead exposure.
Abstract:
Although a number of experiments has revealed offspring hyperactivity following maternal lead (Pb) exposure, a consistent correlate has been reduced pup size. The present study was designed to measure exploratory behavior employing a range of Pb dosages that allowed for the comparison between Pb and control offspring both in the presence and the absence of weight differences. Female rats were exposed to one of four dosages (0, 400, 750 or 1000 mg/kg) of Pb acetate from 21--90 days of age, mated and then continued on treatment throughout gestation and nursing. Treatment was administered via a restricted water schedule. Open field testing began on Day 22 with the pups receiving 3 min trials for 10 consecutive nights. At 120 days of age, all pups were retested. Analysis indicated that only in the presence of reduced birth and/or weaning weights (Groups 750 and 1000) did offspring exhibit exploratory patterns that were significantly different from controls. These differences were absent at retest.