Peripheral Injections of Dopamine (Dl) and Dopamine 2 (D2) Agonists and Antagonists Do Not Affect Sexual and Aggressive Behaviors in Male Green Anoles

Abstract

Social behaviors are modulated by neurotransmitters, including dopamine. Dopamine is a conserved neurotransmitter among vertebrates. Dopaminergic receptors of the 01 and 02 subtype are also conserved among taxa, and are involved in many different kinds of social behaviors, such as sexual and aggressive behaviors in mammals and birds. However, the functions of the receptors vary across taxa. In reptiles there have only been two studies examining the relationship between the receptors and behaviors. This study examined the effects of 01 and 02 agonists and antagonists on sexual and aggressive behaviors in the male green anole lizard (Anolis carolinensis). For the 01 agonist, the following doses were tested: 0.005 11g/kg, 0.05 jlgjkg, 0.001 mgjkg, 0.01 mgjkg, 0.1 mgjkg, 1.0 mgjkg, and 10.0 mgjkg. For the 02 agonist only the 1.0 and 10.0 mgjkg doses were tested. Both the 01 and 02 antagonists were tested at 0.1 and 1 mgjkg. Neither the agonists nor antagonists affected social behaviors. These findings differ from previous research, which demonstrated an effect of 01 and 02 agonists and antagonists on social behaviors in mammals and birds. One potential reason for the lack of significance is that the drug may be binding to receptors in various regions in the brain that could be causing counteracting effects. Future studies should look at individually administering the drugs directly into brain regions known to regulate sexual and aggressive behaviors.