Abstract
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. The purpose of this study is to investigate the effects of DA receptor subtype-selective agonists on 22- and 50-kHz call rates. 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. 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. 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.
Highlights
Adult rat ultrasonic vocalizations (USVs) are commonly divided into two main categories: calls in the the 20–30-kHz range, termed 22-kHz USVs, and calls in the 35–90-kHz range, termed 50-kHz USVs (Portfors 2007)
During the initial amphetamine screen, the median 50-kHz call rate was 32 calls per minute with an interquartile range (IQR) of 5.5–61; with the low callers removed from each experiment, the median 50-kHz call rate was 54 calls per minute, IQR 40–77
The call rate was much lower under control conditions than after amphetamine administration
Summary
Adult rat ultrasonic vocalizations (USVs) are commonly divided into two main categories: calls in the the 20–30-kHz range, termed 22-kHz USVs, and calls in the 35–90-kHz range, termed 50-kHz USVs (Portfors 2007). These two categories have been proposed to indicate negative and positive affective states, respectively (Knutson et al 2002; Wöhr and Schwarting 2012). The association between USV categories and affective valence appears more complex; notably, male rats emit 22-kHz calls after ejaculation (Barfield and Geyer 1972) and emit 50-kHz calls as well as 22-kHz calls during intermale aggression (Sales 1972b; Thomas et al 1983)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.