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Effects of perinatal diazepam administration on two sexually dimorphic nonreproductive behaviors
A Guillamón1, J M Calés, M Rodriguez-Zafra
1Departamento de Psicobiología, Universidad Nacional de Educación a Distancia, Madrid, Spain.
Insights
Prenatal and early postnatal diazepam (DZ) exposure in rats reduced activity in both sexes. Only early postnatal DZ altered sex differences in lever-pressing behavior, impacting male rats more significantly.
Area of Science:
- Neuroscience
- Developmental Psychology
- Pharmacology
Background:
- Prenatal and early life exposures can impact neurodevelopment.
- Diazepam (DZ) is a commonly used anxiolytic medication with potential developmental effects.
- Sexual dimorphisms in behavior emerge during development and can be influenced by hormonal factors.
Purpose of the Study:
- To investigate the long-term effects of prenatal and/or early postnatal diazepam (DZ) exposure on behavioral outcomes in rats.
- To examine potential alterations in open field activity and operant conditioning (lever-pressing) due to developmental DZ exposure.
- To explore the interaction between DZ exposure and sexual differentiation of behavior.
Main Methods:
- Rat pups were exposed daily to 2.5 mg/kg diazepam (DZ) during the last week of gestation and/or from birth to day 16.
- Open field activity was assessed in 60-day-old rats over five days.
- Continuously reinforced lever-pressing response was measured in 90-day-old rats over four days.
Main Results:
- All DZ exposure groups exhibited decreased open field activity in both sexes, without altering the natural female hyperactivity compared to males.
- Males showed higher lever-pressing rates than females at 90 days.
- Early postnatal DZ exposure specifically reduced male lever-pressing rates, diminishing the observed sex difference, while female rates remained unaffected.
Conclusions:
- Developmental diazepam exposure can lead to lasting reductions in general activity.
- Early postnatal diazepam exposure selectively impacts the development of sex-specific behaviors, particularly in males.
- These findings suggest a potential interaction between diazepam and hormonal influences during critical periods of sexual differentiation.
Abstract:
The effects of prenatal and/or early postnatal diazepam (DZ) administration on open field activity and continuously reinforced lever-pressing response were studied. Rat pups of both sexes were prenatally (during the last week of pregnancy) and/or postnatally (from the day of birth to day 16) daily exposed to a 2.5 mg/kg dose of DZ. At the age of 60 days all groups were tested in the open field for 5 consecutive days and thirty days later they were studied in a continuously reinforced lever-pressing situation during four consecutive days. In the open field test, females showed greater activity than males and prenatal and/or early postnatal DZ treatments did not alter this sexual dimorphism, although all treatments decreased the open field activity in both male and female 60-day-old rats. In the Skinner box, 90-day-old males presented higher rates of lever-pressing response than females, and only the early postnatal DZ treatment was effective in altering this sexual dimorphism, by decreasing the male's but not female's rates of response. These results are discussed in regard to the possible interaction between DZ and gonadal hormones during the early sexual differentiation period.