p-Chloroamphetamine-induced ejaculation and the 22-kHz vocalization of the male rat

It is well known that the male rats paired with receptive females emit the 22-kHz vocalization after ejaculation. The question addressed is whether after ejaculation injected with PCA without receptive females the 22-kHz call would be emitted. Emission of the 22-kHz call in males injected by PCA was not observed after ejaculation.     

Relationship between 22-kHz calls and testosterone in male rats

Ultrasonic calls in rats induced by the presence of a predator, referred to as “22-kHz calls,” are mainly emitted by socially dominant male rats. Testosterone levels are closely related to social dominance in male rats. In the present study, we investigated the relationship between the emission of stress-induced 22-kHz calls and circulating testosterone levels in male rats, using a combination of surgery (castration or sham operation) and chronic steroid administration (testosterone or cholesterol) to modify circulating testosterone levels. We also assessed the effects of androgen and/or estrogen receptor antagonists on the emission of 22-kHz calls in male rats. An air puff stimulus, known to reliably induce 22-kHz calls in rats, was used as a stressor. Castrated rats with cholesterol implants exhibited significantly fewer 22-kHz calls than rats that had received a sham operation and cholesterol implants, and there was no significant difference between castrated rats with testosterone implants and rats that had received a sham operation and cholesterol implants. Only male rats pretreated with a binary mixture of androgen and estrogen antagonists exhibited significantly fewer 22-kHz calls than controls. These results show that testosterone in male rats has a positive effect on the emission of stress-induced 22-kHz calls, and the calls may be regulated by the activation of both androgen and estrogen receptors.     

Effect of anxiolytic drugs on air-puff-elicited ultrasonic vocalization in adult rats.

Ultrasonic vocalization (USV) responses elicited by air-puff stimuli were compared in regard to both quality and quantity with those elicited by electric foot-shock(s) in adult rats. Frequency pattern, duration, repetition rate and interpulse interval of air-puff-elicited USV were comparable to those observed on foot-shock-elicited USV. Diazepam (0.25-1.0 mg/kg, s.c.) and buspirone (0.1-1.0 mg/kg, s.c.) attenuated equally and dose-dependently the USV responses elicited by both aversive stimuli. Air-puff-elicited USV was specifically attenuated in a dose-dependent manner by the anxiolytic properties of several psychotropic agents: diazepam (1.0-10.0 mg/kg, p.o.), buspirone (10.0-100.0 mg/kg, p.o.), 8-OH-DPAT (0.01-0.5 mg/kg, s.c.). Haloperidol (0.2-1.0 mg/kg, s.c.) weakly attenuated the USV response. Imipramine (0.2-1.0 mg/kg, s.c.) which has no anxiolytic property had no effect. Consequently, air-puff-elicited USV as well as foot-shock-elicited USV may provide a reliable tool for the study of anxiety.     

杏仁核内的GABA介质传递及其在恐惧消退中的作用

动物的恐惧体验是一种防御性情绪过程,具有重要的适应意义.然而,缺乏对恐惧情绪的有效抑制机制会导致恐惧情绪过度表达以及焦虑障碍的发生.恐惧消退是最简单的一种恐惧抑制(fear inhibition)范式.而γ-氨基丁酸(gamma-aminobutyric acid,GABA)是中枢神经系统最主要的抑制性神经介质.杏仁核内部大量GABA介质突触传递在恐惧情绪表达、恐惧消退记忆(memory of fear extinction)的获得、存贮和提取过程中发挥了不可或缺的作用.     

Quantitative analysis of the ultrasonic vocalization responses elicited in adjuvant-induced arthritic rats for screening analgesic drugs

Adjuvant-induced arthritic (AIA) rats have been developed as a chronic pain model to evaluate the effects of analgesic drugs. The purpose of the present study was to examine whether there is dose-dependent inhibition of the emission of ultrasonic vocalization (USV) responses by analgesic drugs in AIA rats. It was demonstrated that morphine (1.25-5.0 mg/kg, s.c.) and ketoprofen (2.5-10.0 mg/kg, s.c.) dose-dependently inhibit USV responses. These results suggest that the USV responses elicited in AIA rats are useful for the quantitative evaluation of analgesic drugs.     

Social buffering ameliorates conditioned fear responses in female rats

The stress experienced by an animal is ameliorated when the animal is exposed to distressing stimuli along with a conspecific animal(s). This is known as social buffering. Previously, we found that the presence of an unfamiliar male rat induced social buffering and ameliorated conditioned fear responses of a male rat subjected to an auditory conditioned stimulus (CS). However, because our knowledge of social buffering is highly biased towards findings in male subjects, analyses using female subjects are crucial for comprehensively understanding the social buffering phenomenon. In the present studies, we assessed social buffering of conditioned fear responses in female rats. We found that the estrus cycle did not affect the intensity of the rats' fear responses to the CS or their degree of vigilance due to the presence of a conspecific animal. Based on these findings, we then assessed whether social buffering ameliorated conditioned fear responses in female rats without taking into account their estrus cycles. When fear conditioned female rats were exposed to the CS without the presence of a conspecific, they exhibited behavioral responses, including freezing, and elevated corticosterone levels. By contrast, the presence of an unfamiliar female rat suppressed these responses. Based on these findings, we conclude that social buffering can ameliorate conditioned fear responses in female rats.     

A comparative study of isolation-induced ultrasonic vocalization in rodent pups.

The purpose of this study was to determine whether species differences in neonatal vocalizations of rodent pups could be observed. Ultrasonic vocalizations of pups of 5 rodent species, mouse (ICR), vole (Microtus arvalis), Syrian hamster, rat (Wistar-Imamichi), and Mongolian gerbil were recorded from 3 to 15 or 21 days of age. Recordings were made under conditions of separation from mothers and litter mates in a cooled chamber (approximately 10 degrees C). The major species differences observed were age specific and species specific frequencies. The Mongolian gerbil displayed a different frequency change with age. Namely, the day on which ultrasonic vocalizations ceased was delayed in Mongolian gerbil compared with the other rodents. The modal peak frequencies of ultrasound emitted from pups at 3 days of age were low (around 35 kHz) in the vole and the Syrian hamster, medium (around 45 kHz) in the rat and the Mongolian gerbil, and high (around 55 kHz) in the mouse.     

ChAT::Cre transgenic rats show sex-dependent altered fear behaviors,ultrasonic vocalizations and cholinergic marker expression

The cholinergic system is a critical regulator of Pavlovian fear learning and extinction. As such, we have begun investigating the cholinergic system's involvement in individual differences in cued fear extinction using a transgenic ChAT::Cre rat model. The current study extends behavioral phenotyping of a transgenic ChAT::Cre rat line by examining both freezing behavior and ultrasonic vocalizations (USVs) during a Pavlovian cued fear learning and extinction paradigm. Freezing, 22 kHz USVs, and 50 kHz USVs were compared between male and female transgenic ChAT::Cre+ rats and their wildtype (Cre-) littermates during fear learning, contextual and cue-conditioned fear recall, cued fear extinction, and generalization to a novel tone. During contextual and cued fear recall ChAT::Cre+ rats froze slightly more than their Cre- littermates, and displayed significant sex differences in contextual and cue-conditioned freezing, 22 kHz USVs, and 50 kHz USVs. Females showed more freezing than males in fear recall trials, but fewer 22 kHz distress calls during fear learning and recall. Females also produced more 50 kHz USVs during exposure to the testing chambers prior to tone (or shock) presentation compared with males, but this effect was blunted in ChAT::Cre+ females. Corroborating previous studies, ChAT::Cre+ transgenic rats overexpressed vesicular acetylcholine transporter immunolabeling in basal forebrain, striatum, basolateral amygdala, and hippocampus, but had similar levels of acetylcholinesterase and numbers of ChAT+ neurons as Cre- rats. This study suggests that variance in behavior between ChAT::Cre+ and wildtype rats is sex dependent and advances theories that distinct neural circuits and processes regulate sexually divergent fear responses.     

Affective neuroscience: amygdala's role in experiencing fear

A new neuropsychological study of a rare patient provides novel evidence that amygdala lesions can virtually abolish the experience of fear, illuminating neurobiological mechanisms of fear experience.     

Social modulation of fear: Facilitation vs buffering

Social behaviors largely constitute mutual exchanges of social cues and the responses to them. The adaptive response also requires proper interpretation of the current context. In fear behaviors, social signals have bidirectional effects—some cues elicit or enhance fear whereas other suppress or buffer it. Studies on the social facilitation and social buffering of fear provide evidence of competition between social cues of opposing meanings. Co‐expression of opposing cues by the same animal may explain the contradicting outcomes from the interaction between naive and frightened conspecifics, which reflect the fine balance between fear facilitation and buffering. The neuronal mechanisms that determine that balance provide an exciting target for future studies to probe the brain circuits underlying social modulation of emotional behaviors.     

The peep vocalization in group reared chicks (Gallus domesticus): Its relation to fear

The relation of fear and arousal to peeping in socially-reared chicks was investigated in a series of four experiments. Pre-test exposure to loud noise or shock resulted in decreased peeping in chicks tested in isolation, while in the presence of a mirror, pre-test exposure to loud noise reduced peeping, but pre-test shock had no effect. It was also shown that neither transquilizer (Pacitran) ingestion nor experimenter proximity had any significant influence on peeping. An inverse relationship between peeping and activity latency was also revealed in these experiments, and peeping was usually found to precede the initiation of activity. The relationship between fear and the peep vocalization of sociallyreared chicks is discussed.     

Ultrasonic vocalization in response to unavoidable aversive stimuli in rats: effects of benzodiazepines

The effects of two benzodiazepine derivatives (diazepam, 0.5-1 mg/kg; alprazolam, 1.25-2.5 mg/kg) on ultrasonic calling elicited in adult rats by unavoidable aversive stimuli (footshocks) were investigated. The results show that either diazepam or alprazolam affected the duration of ultrasonic calls. In particular, a significant decrease in the length of ultrasounds was found in the group of animals treated with these benzodiazepines. The effects of diazepam were counteracted by the benzodiazepine-antagonist Ro 15-1788. On the other hand, neither a neuroleptic agent, such as haloperidol (0.5-1 mg/kg), nor an antidepressant, such as desipramine (5-10 mg/kg) influenced the parameters of ultrasonic emission in this experimental situation. The present results suggest that ultrasonic vocalization in response to unavoidable aversive stimuli could be considered as a potential new tool for studying drugs with antianxiety properties.     

Age-related impairment of ultrasonic vocalization in Tau.P301L mice: possible implication for progressive language disorders

Background

Tauopathies, including Alzheimer''s Disease, are the most frequent neurodegenerative diseases in elderly people and cause various cognitive, behavioural and motor defects, but also progressive language disorders. For communication and social interactions, mice produce ultrasonic vocalization (USV) via expiratory airflow through the larynx. We examined USV of Tau.P301L mice, a mouse model for tauopathy expressing human mutant tau protein and developing cognitive, motor and upper airway defects.

Methodology/Principal Findings

At age 4–5 months, Tau.P301L mice had normal USV, normal expiratory airflow and no brainstem tauopathy. At age 8–10 months, Tau.P301L mice presented impaired USV, reduced expiratory airflow and severe tauopathy in the periaqueductal gray, Kolliker-Fuse and retroambiguus nuclei. Tauopathy in these nuclei that control upper airway function and vocalization correlates well with the USV impairment of old Tau.P301L mice.

Conclusions

In a mouse model for tauopathy, we report for the first time an age-related impairment of USV that correlates with tauopathy in midbrain and brainstem areas controlling vocalization. The vocalization disorder of old Tau.P301L mice could be, at least in part, reminiscent of language disorders of elderly suffering tauopathy.