Behavioral changes in Anolis carolinensis following injection with fluoxetine

Area of Science:

• Neuroethology
• Behavioral Endocrinology
• Reptile Behavior

Background:

• Aggression and skin color changes are key communication signals in Anolis carolinensis.
• Serotonergic systems are known to modulate aggression in various species.

Purpose of the Study:

• To investigate the role of serotonin in regulating aggression and skin coloration in male Anolis carolinensis.
• To determine if fluoxetine dissociates the control of aggressive behavior from eyespot darkening.

Main Methods:

• Adult male Anolis carolinensis were subjected to daily male-male pairings to elicit aggression.
• Baseline aggressive responses and skin color changes were recorded.
• Animals received injections of fluoxetine or vehicle controls in a cross-over design.
• Aggression and skin color were measured during post-injection trials.

Main Results:

• Fluoxetine administration significantly decreased aggressive responding in male lizards.
• Fluoxetine treatment led to a significant darkening of the postorbital eyespot.
• Increased aggressivity and skin-color reactivity were observed after drug trials, though attribution to fluoxetine is uncertain.

Conclusions:

• Central serotonergic systems tonically regulate aggression in Anolis carolinensis, consistent with findings in other species.
• Serotonin appears to play a role in both aggression and eyespot darkening, but these phenomena can be pharmacologically dissociated.
• This study implicates serotonin in the regulation of both aggressive behavior and visual signaling in lizards.