Prenatal malnutrition alters diazepam-mediated suppression of ultrasonic vocalizations in an age dependent manner

Area of Science:

• Neuroscience
• Developmental Biology
• Pharmacology

Background:

• Prenatal malnutrition can impact neurodevelopment and behavior.
• Benzodiazepines, like diazepam, affect the GABAergic system and can suppress ultrasonic vocalizations (USVs) in pups.

Purpose of the Study:

• To investigate how prenatal malnutrition affects the sensitivity of rat pups to the USV suppressant effects of diazepam.
• To determine if developmental stage influences these effects.

Main Methods:

• Male rat pups from dams fed either a protein-deficient (6% casein) or adequate (25% casein) diet were used.
• Pups were injected with diazepam (0.03–3 mg/kg) or vehicle at postnatal days 7 or 11, followed by cooling stress.
• Ultrasonic vocalizations (USVs) were quantified to measure diazepam's suppressant effect.

Main Results:

• Diazepam dose-dependently suppressed USVs in both groups at both ages.
• No difference in diazepam sensitivity was observed at postnatal day 7.
• At postnatal day 11, prenatally malnourished rats showed significantly greater USV suppression by low doses of diazepam compared to controls.

Conclusions:

• Prenatal malnutrition leads to a differential sensitivity to benzodiazepine receptor agonists in the second postnatal week.
• This altered sensitivity may reflect changes in the developing GABAergic system due to malnutrition.
• The findings suggest adaptive or compensatory changes in the GABAergic system in response to developmental disturbances.