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Neonatal handling increases fear and aggression in lactating rats
Marcia Giovenardi1, Marcia S de Azevedo, Simone P da Silva
1Laboratório de Neurociências, Universidade do Vale do Rio dos Sinos, São Leopoldo, Brazil.
Physiology & Behavior
|August 16, 2005
Summary
Neonatal handling in rats increases maternal aggression but not fear, challenging the link between these behaviors. Early life stimulation
Area of Science:
- Neuroscience
- Behavioral Biology
- Animal Behavior
Background:
- Neonatal handling influences adult behavior, affecting fear and aggression.
- Maternal aggression and fear responses in lactating rats vary across postpartum days.
Purpose of the Study:
- To investigate the long-term effects of neonatal handling on maternal aggression and fear in lactating rats.
- To analyze these effects on postpartum days 8 (high aggression) and 18 (low aggression).
Main Methods:
- Rats were divided into handled and nonhandled groups during the neonatal period.
- Adult females were tested for aggressive behavior towards an intruder and activity in an open field with a predator.
Main Results:
- Handled females exhibited higher aggression on postpartum day 8, with no difference on day 18.
- Handled females showed reduced locomotion and increased freezing in the open field on day 8.
- Neonatal handling disrupted the typical inverse relationship between aggression and fear.
Conclusions:
- Increased maternal aggression due to neonatal handling is independent of reduced fear.
- Early life stimulation's long-term effects are dynamic and context-dependent.
- The relationship between aggression and fear is more complex than previously assumed.