Mice: postpartum aggression is elevated following prenatal progesterone exposure

Area of Science:

• Neuroendocrinology
• Developmental Psychology
• Behavioral Neuroscience

Background:

• Prenatal hormone exposure influences offspring behavior.
• Progesterone's role in fetal development is complex and not fully understood.
• Masculinization of behavior by prenatal androgens is well-documented.

Purpose of the Study:

• To investigate the effects of prenatal progesterone exposure on adult female offspring behavior.
• To examine if prenatal progesterone exposure influences masculinization of behavior in mice.
• To assess the impact of progesterone on anogenital distance and reproductive performance.

Main Methods:

• Pregnant Rockland-Swiss mice were administered sesame oil or varying doses of progesterone (250 or 500 micrograms) during a critical gestational period (Days 12-16).
• Postpartum aggressive behavior of female offspring was assessed in adulthood by introducing a male intruder.
• Relative anogenital distance, body weight, and reproductive performance were also measured.

Main Results:

• Both doses of progesterone significantly increased the intensity of aggression (number of attacks) in adult female offspring.
• A low dose of progesterone also led to a significant increase in relative anogenital distance.
• No significant effects on birth weight, adult body weight, or reproductive performance were observed.

Conclusions:

• Prenatal progesterone exposure can lead to masculinization of behavior, specifically increased aggression, in female offspring.
• These findings support the hypothesis that prenatal hormone exposure can alter brain differentiation and subsequent behavior.
• Progesterone's influence extends beyond reproductive functions, impacting behavioral patterns in offspring.