Department of Psychology, Brock University, St. Catharines, ON L2S 3A1, Canada.
Department of Psychology, Brock University, St. Catharines, ON L2S 3A1, Canada.
Pharmacol Biochem Behav. 2019 Jan;176:23-32. doi: 10.1016/j.pbb.2018.11.006. Epub 2018 Nov 13.
Systemic pharmacological manipulation of dopamine (DA) signaling has been central to many investigations of 50 kHz ultrasonic vocalizations (USVs) in the rat. In particular, the indirect DA releaser d-amphetamine (AMPH) has been used extensively in many such investigations. The possible unique character of the native transmitter relative to DA-stimulating drugs such as AMPH in inducing and modulating emission of 50 kHz USVs has not been investigated. Adult male Long Evans rats were tested with intracerebral application of DA into the nucleus accumbens shell at several doses (3.75 μg-120 μg) to determine its capacity to induce 50 kHz USV emission. Additionally, the call profile characteristics of intracerebral DA injections were compared with those of intracerebral application of AMPH. Results indicated that local increases in DA signaling within the nucleus accumbens shell are sufficient to increase 50 kHz call rate, reduce latency to call, and increase the degree of frequency modulation of emitted USVs. However, our results found that microinjections of DA were not as efficacious in either inducing 50 kHz USVs or increasing frequency modulation without antagonism of the dopamine reuptake transporter when compared with AMPH. In summary, these results support the notion that the native transmitter DA is driving the increase in frequency modulation seen after administration of DA stimulating drugs. These results also suggest that drugs affecting dopamine may be altering the 50 kHz call profile in a distinct manner from the native transmitter and thus caution should be used in interpreting their effects.
多巴胺（DA）信号的系统药理学操纵一直是大鼠 50 kHz 超声发声（USVs）许多研究的核心。特别是，间接 DA 释放剂 d-苯丙胺（AMPH）在许多此类研究中被广泛使用。与 AMPH 等刺激 DA 的药物相比，内源性递质在诱导和调节 50 kHz USVs 发射方面可能具有独特的特征，这一点尚未得到研究。使用几种剂量（3.75 μg-120 μg）的脑内立体定位给予 DA 到伏隔核壳内，对成年雄性 Long Evans 大鼠进行测试，以确定其诱导 50 kHz USV 发射的能力。此外，还比较了脑内 DA 注射与脑内 AMPH 应用的叫声特征。结果表明，伏隔核壳内 DA 信号的局部增加足以增加 50 kHz 叫声率、减少叫声潜伏期并增加发出的 USVs 的频率调制程度。然而，我们的结果发现，与 AMPH 相比，当多巴胺再摄取转运体的拮抗作用不存在时，DA 微注射在诱导 50 kHz USVs 或增加频率调制方面的效果并不如 AMPH 那么有效。总之，这些结果支持这样的观点，即内源性递质 DA 正在驱动 DA 刺激药物给药后频率调制的增加。这些结果还表明，影响多巴胺的药物可能以与内源性递质不同的方式改变 50 kHz 叫声特征，因此在解释它们的影响时应谨慎使用。
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