Inhibition of 50-kHz ultrasonic vocalizations by dopamine receptor subtype-selective agonists and antagonists in adult rats

• Published in: Psychopharmacology 2013-04, Vol.226 (3), p.589-600
• Main Authors: Scardochio, Tina, Clarke, Paul B. S.
• Format: Article
• Language: English
• Subjects: Amphetamine - pharmacology; Animal communication; Animals; Biomedical and Life Sciences; Biomedicine; Brain stimulation; Dopamine - metabolism; Dopamine Agonists - pharmacology; Dopamine Antagonists - pharmacology; Dopamine D2 Receptor Antagonists; Dopamine receptors; Male; Neurosciences; Original Investigation; Pharmacology/Toxicology; Physiological aspects; Properties; Psychiatry; Psychopharmacology; Rats; Rats, Long-Evans; Receptors, Dopamine D1 - agonists; Receptors, Dopamine D1 - antagonists & inhibitors; Receptors, Dopamine D1 - metabolism; Receptors, Dopamine D2 - agonists; Receptors, Dopamine D2 - metabolism; Receptors, Dopamine D3 - agonists; Receptors, Dopamine D3 - antagonists & inhibitors; Receptors, Dopamine D3 - metabolism; Reward; Rodents; Ultrasonic waves; Ultrasonics; Vocalization, Animal - drug effects
• ISSN: 0033-3158; 1432-2072
• DOI: 10.1007/s00213-012-2931-6

Rationale Adult rats emit ultrasonic calls at around 22 and 50 kHz, which are often elicited by aversive and rewarding stimuli, respectively. Dopamine (DA) plays a role in aspects of both reward and aversion. Objective The purpose of this study is to investigate the effects of DA receptor subtype-selective agonists on 22- and 50-kHz call rates. Methods Ultrasonic calls were recorded in adult male rats that were initially screened with amphetamine to eliminate low 50-kHz callers. The remaining subjects were tested after acute intraperitoneal or subcutaneous injection of the following DA receptor-selective agonists and antagonists: A68930 (D1-like agonist), quinpirole (D2-like agonist), PD 128907 (D3 agonist), PD 168077 (D4 agonist), SCH 39166 (D1-like antagonist), L-741,626 (D2 antagonist), NGB 2904 (D3 antagonist), and L-745,870 (D4 antagonist). The indirect DA/noradrenaline agonist amphetamine served as a positive control. Results As expected, amphetamine strongly increased 50-kHz call rates. In contrast, D1-, D2-, and D3-selective DA receptor agonists, when given alone, inhibited calling; combinations of D1- and D2-like agonists also decreased call rate. Given alone, the D1-like and D3 antagonists significantly decreased call rate, with a similar trend for the D2 antagonist. Agonist–antagonist combinations also decreased calling. The D4 agonist and antagonist did not significantly affect 50-kHz call rates. Twenty-two-kilohertz calls occurred infrequently under all drug conditions. Conclusion Following systemic drug administration, tonic pharmacological activation of D1-like or D2-like DA receptors, either alone or in combination, does not appear sufficient to induce 50-kHz calls. Dopaminergic transmission through D1, D2, and D3 receptors appears necessary for spontaneous calling.