Related Experiment Video
Updated: Jun 27, 2026
Peering into the Dynamics of Social Interactions: Measuring Play Fighting in Rats
Published on: January 18, 2013
Maternal separation enhances offensive play-fighting, basal corticosterone and hypothalamic vasopressin mRNA
Alexa H Veenema1, Inga D Neumann
1Department of Behavioral Neuroendocrinology, Institute of Zoology, University of Regensburg, Regensburg, Germany.
Insights
Early life stress from maternal separation (MS) in rats significantly increased aggressive play-fighting in juveniles. This early-life stress also led to neuroendocrine changes, impacting social behavior throughout life.
Area of Science:
- Neuroscience
- Behavioral Biology
- Endocrinology
Background:
- Early life stress is a known risk factor for altered adult emotionality, including aggression.
- Maternal separation (MS) in rats has been previously shown to increase adult intermale aggression.
Purpose of the Study:
- To investigate if maternal separation (MS) in early life alters juvenile play-fighting behavior in Wistar rats.
- To examine the neuroendocrine correlates of these behavioral changes.
Main Methods:
- Wistar rats underwent daily maternal separation (3h) from postnatal day 1-14.
- Juvenile play-fighting behaviors were assessed.
- Plasma corticosterone levels and vasopressin mRNA expression in specific brain regions were measured.
Main Results:
- MS significantly increased offensive play-fighting behaviors, including nape attacks and offensive biting/pulling.
- MS rats exhibited fewer submissive play behaviors.
- Elevated plasma corticosterone and increased vasopressin mRNA in the paraventricular nucleus and bed nucleus of the stria terminalis were observed in MS rats.
Conclusions:
- Maternal separation enhances aggressive play-fighting in juvenile rats.
- These behavioral changes are associated with alterations in neuroendocrine parameters, specifically corticosterone and vasopressin.
- Early life stress impacts social conflict coping mechanisms across the lifespan.
Abstract:
Early life stress is a risk factor for altered adult emotionality including impaired social behavior, enhanced aggression and violence. These behavioral deficits most likely have an earlier onset in life. We recently demonstrated that maternal separation (MS, 3h daily on postnatal day 1-14) increased intermale aggression in adult Wistar rats. Here, we investigated whether MS induced alterations in juvenile play-fighting, which is a precursor of aggression. MS increased offensive play-fighting behaviors in juvenile male rats, as indicated by a twofold increase in the number of nape attacks, a higher frequency of offensive pulling and biting, and a lower frequency of submissive play behaviors. Furthermore, MS rats showed higher plasma corticosterone levels and higher vasopressin mRNA expression in the paraventricular nucleus and the bed nucleus of the stria terminalis compared with control rats during the early dark phase. Thus, MS enhanced aggressive play-fighting accompanied by changes in several relevant neuroendocrine parameters. Taken together with previous findings, the increase in aggressive behaviors both at juvenile and adult age illustrates that exposure to MS alters the way rats cope with social conflict situations throughout life.
