Activation of male-typical aggression by testosterone but not its metabolites in C57BL/6J female mice
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1Department of Psychology, Lehigh University, Bethlehem, PA 18015.
Abstract:
Ovariectomized adult C57BL/6J mice were exposed to androgens, estrogens, or combined androgen-estrogen treatments and tested for the display of male-typical aggressive behavior toward olfactory bulbectomized stimulus males. Among the androgenic treatments (testosterone, dihydrotestosterone, or methyltrienolone) only testosterone, which, in contrast to the other androgens, can be aromatized, activated fighting behavior. In the second experiment, estradiol benzoate (EB) was totally ineffective as an aggression-promoting compound. Lastly, combined EB+dihydrotestosterone also did not induce male-like aggression. These data suggest that T itself may be capable of promoting aggression without undergoing aromatization or 5 alpha-reduction.
Insights
Testosterone directly promotes male aggressive behavior in mice, independent of its conversion into other hormones. This finding clarifies the hormonal basis of aggression in male mice.
Area of Science:
- Neuroendocrinology
- Behavioral Neuroscience
- Animal Models
Background:
- Hormonal influences on aggression are complex, involving androgens and estrogens.
- The specific roles of testosterone metabolites in promoting male-typical aggressive behavior require further elucidation.
Purpose of the Study:
- To investigate the direct effects of testosterone and its metabolites on male aggressive behavior in ovariectomized mice.
- To determine whether aromatization or 5 alpha-reduction of testosterone is necessary for its pro-aggressive effects.
Main Methods:
- Ovariectomized C57BL/6J mice were administered testosterone, dihydrotestosterone, methyltrienolone, estradiol benzoate, or combined treatments.
- Aggressive behavior was assessed by testing experimental mice against olfactory bulbectomized stimulus males.
Main Results:
- Only testosterone administration activated fighting behavior; dihydrotestosterone and methyltrienolone did not.
- Estradiol benzoate alone or in combination with dihydrotestosterone was ineffective in promoting aggression.
- These results indicate testosterone's potential to directly promote aggression without metabolic conversion.
Conclusions:
- Testosterone itself, not its metabolites, appears to be the primary driver of male-typical aggressive behavior in this model.
- The findings suggest that aromatization and 5 alpha-reduction pathways may not be essential for testosterone's pro-aggressive effects.