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Published on: July 4, 2013
Neural sensitivity to sex steroids predicts individual differences in aggression: implications for behavioural
K A Rosvall1, C M Bergeon Burns, J Barske
1Department of Biology, Indiana University, Bloomington, IN 47405, USA. krosvall@indiana.edu
Proceedings. Biological Sciences
|June 8, 2012
Summary
Aggressiveness in dark-eyed juncos is linked to neural sensitivity to steroids, not just testosterone levels. Gene expression for steroid-processing molecules predicted aggression in both males and females.
Area of Science:
- Behavioral endocrinology
- Neuroscience
- Evolutionary biology
Background:
- Testosterone (T) influences traits like aggression, but individual differences in behavior don't always correlate with circulating T levels.
- This suggests neural sensitivity to steroids may play a key role in behavioral variation, an unresolved issue.
Purpose of the Study:
- To investigate the relative importance of circulating testosterone and neural steroid sensitivity in predicting aggressive behavior.
- To examine sex differences in the relationship between behavior and endocrine parameters in wild dark-eyed juncos.
Main Methods:
- Measured aggressiveness in male and female dark-eyed juncos during staged intrusions.
- Assessed plasma T levels and quantified mRNA abundance for androgen receptor (AR), aromatase (AROM), and oestrogen receptor alpha (ORα) in brain regions.
- Analyzed covariation between behavior and endocrine/neural parameters, comparing sexes.
Main Results:
- Circulating testosterone levels correlated with aggressiveness only in males.
- Gene expression of ORα, AR, and AROM in specific brain areas covaried with individual differences in aggressiveness in both sexes.
- Neural gene expression patterns predicted aggressiveness across sexes, independent of circulating T levels.
Conclusions:
- Individual variation in aggressiveness is associated with neural gene expression for steroid-processing molecules in both male and female juncos.
- These findings highlight the role of neural sensitivity to steroids in shaping aggressive behavior, with implications for understanding its evolution.
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