Juvenile rats display rough-and-tumble playing with conspecifics (play fighting behavior) and produce 22 and 50 kHz ultrasonic vocalizations (USVs). The 22 kHz USV is considered to reflect negative emotionality such as anxiety, fear, and distress, whereas the 50 kHz USV is considered to reflect positive emotionality such as joy, happiness, and satisfaction. USV is a sensitive tool for measuring emotionality in socially interactive situations. However, effects of prenatal ethanol-exposure on the acoustic characteristics of play fighting-induced USVs have remained unclear. In Experiment I, we recorded USVs produced by prenatally ethanol-exposed rats during play fighting on postnatal days (PNDs) 40-42 and examined the acoustic characteristics of negative and positive emotion-induced USVs. In Experiment II, we examined the anxiety levels through elevated plus maze testing on PNDs 37-39 and frequencies of playful attacks on PNDs 43-45 in ethanol-exposed rats. Ethanol was administered to pregnant rats in three gradually increased concentrations between gestational days (GDs) 8 and 20. From GDs 14 to 20, ethanol-containing tap water at concentrations of 30% and 15% (v/v) was administered to the high- and low-ethanol groups, respectively. Tap water without added ethanol was given to the control group. On PNDs 40-42, three rats from the same sex and same ethanol concentration group but from different litters were placed together into a playing cage for play fighting. The high-ethanol male triads displayed elevations of 20-35 kHz USVs reflecting negative emotionality and reductions of 45-70 kHz USVs reflecting positive emotionality compared with both the low-ethanol and control male triads. The high-ethanol male triads had prominent elevations of 20-35 kHz USVs with durations longer than 200 ms, whereas the control male triads did not produce such 20-35 kHz USVs at all. There was no difference in USV acoustic characteristics among the female triads. In addition, the high-ethanol male rats exhibited greater anxiety levels and less frequencies of play fighting than the control male rats. Altogether, we conclude that prenatal exposure to ethanol enhances negative emotionality such as anxiety and, accordingly, 20-35 kHz USVs reflecting negative emotionality are produced with a marked decrease in play fighting, suggesting difficulties in social interactions with conspecifics.

中文翻译：

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产前乙醇暴露对幼年大鼠打架引起的超声发声的声学特性的影响。

幼鼠表现出粗暴地玩同种动物（玩斗行为），并产生22和50 kHz的超声波发声（USV）。22 kHz USV被认为反映了焦虑，恐惧和痛苦等负面情绪，而50 kHz USV被认为反映了喜悦，幸福和满意的正面情绪。USV是在社交互动情况下衡量情绪的敏感工具。但是，尚不清楚产前乙醇暴露对打架引起的USV声学特性的影响。在实验I中，我们记录了出生后暴露于酒精的大鼠在出生后40-42天的比赛中所产生的USV，并检查了由负情绪和正情绪诱发的USV的声学特性。在实验二中 我们通过对酒精暴露的大鼠进行PND 37-39升高和迷宫测试以及对PND 43-45进行嬉戏发作的频率来检查焦虑水平。在孕期（GDs）8至20之间以三种逐渐增加的浓度向怀孕大鼠施用乙醇。从GDs 14至20，以30％和15％（v / v）的浓度将含乙醇的自来水给予高剂量。 -和低乙醇基团。对照组不加乙醇的自来水。在PND 40-42上，将三只来自相同性别和相同乙醇浓度组但来自不同垫料的大鼠放在一起放在游戏笼中进行游戏战斗。与低乙醇男性黑社会和对照男性黑社会相比，高乙醇男性黑社会的身高升高20-35 kHz USV，反映出负面情绪，而降低45-70 kHz USV情绪反映出积极。高乙醇雄性三联体的突出高度为20-35 kHz USV，持续时间长于200 ms，而对照雄性三联体根本不产生这种20-35 kHz USV。在女性黑社会中，USV声学特性没有差异。另外，与对照雄性大鼠相比，高乙醇雄性大鼠表现出更大的焦虑水平和较少的打架频率。总而言之，我们得出的结论是，产前暴露于乙醇会增强诸如焦虑之类的负面情绪，因此，会产生20-35 kHz的反映负面情绪的USV，而打架明显减少，