Progesterone and maternal aggressive behavior in rats

Area of Science:

• Neuroendocrinology
• Behavioral Neuroscience
• Reproductive Biology

Background:

• Maternal aggression is a key component of the maternal behavioral repertoire in many species.
• The role of specific hormones, particularly progesterone, in modulating this behavior during lactation is not fully understood.

Purpose of the Study:

• To investigate the influence of progesterone (P4) on maternal aggressive behavior in lactating rats.
• To explore the effects of progesterone receptor antagonism and allopregnanolone synthesis inhibition on maternal aggression.

Main Methods:

• Lactating rats were ovariectomized post-parturition, and aggressive behaviors against an intruder were recorded.
• The effects of RU 486 (progesterone receptor antagonist) and finasteride (allopregnanolone inhibitor) were analyzed in non-ovariectomized lactating rats.
• Plasma prolactin levels were measured.

Main Results:

• Ovariectomy reduced maternal aggressive behavior and licking frequency, while increasing plasma prolactin.
• Administration of RU 486 significantly increased the aggressiveness of lactating females.
• Finasteride administration did not alter aggressive behavior.

Conclusions:

• Gonadal hormones, including progesterone, appear necessary for the full expression of maternal aggressive behavior post-parturition.
• Elevated progesterone levels during the postpartum period may contribute to the natural decrease in maternal aggression observed in lactating rats.