Effects of dopamine agonists on calling behavior in the green tree frog, Hyla cinerea

Dopamine (DA) is an important neurotransmitter involved in social behaviors, such as courtship and pair-bonding. In the green tree frog (Hyla cinerea), calling behavior is the primary social behavior used for mate attraction, and is critical for the reproductive success of the species. Our study examined how DA influences advertisement calling behavior of the green tree frog. In a field environment, calling males were treated with either a DA receptor-specific agonist (SKF-38393 or quinpirole), a non-specific DA agonist (apomorphine), or a control Ringer's solution, and vocalizations were recorded after a 20 min post-injection period. Behavioral analyses focused on if and when the frogs called (call latency), and the number of calls produced during post-injection recordings (call rate). There were significant differences in all measurements that varied with treatment and/or dose. The results demonstrate that activation of D2-like receptors has an inhibitory effect on vocalization in the green tree frog, while the D1-like and non-specific DA agonists do not affect calling behavior. These findings coincide with behavioral data from other taxa, and support the function of D2-like receptors in the inhibition of certain social behaviors. Overall, the results suggest conservation for DA in social behaviors across vertebrates.