Different neural circuits between physiological and psychological stress-induced PTSD like ＂nightmare＂ in rats： Insights from c-Fos mapping

Aim Posttraumatic nightmares are a core component of posttraumatic stress disorder （PTSD） and mechanistically linked to the development and maintenance of this disorder, but little is known about their mecha- nism. Methods We utilized a communication box to establish an animal model of physiological stress （foot-shock I FSI） and psychological stress （PS） to mimic the direct suffering and witnessing of traumatic events. Results Twenty-one days after traumatic stress, some of the experimental animals presented startled awakening （ i. e. , were startled awake by a supposed ＂nightmare＂） with different electroencephalographic spectra features. Our neuroan- atomical results showed that the secondary somatosensory cortex and primary auditory cortex may play an important role in remote traumatic memory retrieval in FS ＂nightmare＂ （FSN） rats, whereas the temporal association cortex may play an important role in PS ＂nightmare＂ （PSN） rats. The FSN and PSN groups possessed common emotion evocation circuits, including activation of the amygdala and inactivation of the infralimbic prefrontal cortex and ven- tral anterior cingulate cortex. The decreased activity of the granular and dysgranular insular cortex was only oh-served in PSN rats. Conclusion The present results imply that different types of stress may cause PTSD-like ＂nightmares＂ in rodents and identified the possible neurocircuitry of memory retrieval and emotion evocation.

抑制STAT3活化对GD2阳性乳腺癌干细胞自我更新能力的影响

目的:探讨选择性STAT3抑制剂Stattic对GD2^+乳腺癌干细胞自我更新能力的影响。方法:运用流式细胞仪从乳腺癌细胞系MDA-MB-231中分选GD2^+乳腺癌干细胞;采用CCK-8、乳腺球形成实验鉴定GD2^+乳腺癌干细胞的增殖、自我更新能力;Western-blot法检测GD2^+/GD2^-乳腺癌细胞中STAT3、pSTAT3蛋白表达;通过Stattic抑制实验,研究Stattic选择性抑制STAT3对GD2^+乳腺癌干细胞自我更新能力的影响作用。结果:接种1 000个细胞,GD2^+细胞乳腺球形成数目为(22.38±3.44)个,GD2^-细胞为(7.14±1.14)个,GD2^+细胞形成的乳腺球数目显著大于GD2^-细胞的乳腺球数目(P<0.05);GD2^+细胞形成乳腺球的大小为(148.47±41.34)μm,GD2^-细胞为(57.10±13.58)μm,2组比较差异有统计学意义(P<0.05);从第2天开始,GD2+乳腺癌干细胞增殖速度明显低于GD2^-细胞(P<0.05);p STAT3蛋白在GD2+乳腺癌细胞表达显著高于GD2^-乳腺癌细胞(P<0.05),但STAT3表达2组比较差异无统计学意义(P>0.05);选择性STAT3抑制剂Stattic干预GD2^+乳腺癌干细胞,其自我更新能力、增殖能力均显著降低(P<0.05)。结论:Stattic选择性抑制STAT3可以抑制GD2^+乳腺癌干细胞的自我更新能力。

Post-traumatic stress disorder risk and brain-derived neurotrophic factor Val66Met

Brain-derived neurotrophic factor(BDNF), which regulates neuronal survival, growth differentiation, and synapse formation, is known to be associated with depression and post-traumatic stress disorder(PTSD). However, the molecular mechanism for those mental disorders remains unknown. Studies have shown that BDNF is associated with PTSD risk and exaggerated startle reaction(a major arousal manifestation of PTSD) in United States military service members who were deployed during the wars in Iraq and Afghanistan. The frequency of the Met/Met in BDNF gene was greater among those with PTSD than those without PTSD. Among individuals who experienced fewer lifetime stressful events, the Met carriers have significantly higher total and startle scores on the PTSD Checklist than the Val/Val carriers. In addition, subjects with PTSD showed higher levels of BDNF in their peripheral blood plasma than the non-probable-PTSD controls. Increased BDNF levels and startle response were observed in both blood plasma and brain hippocampus by inescapable tail shock in rats. In this paper, we reviewed these data to discuss BDNF as a potential biomarker for PTSD risk and its possible roles in the onset of PTSD.

间隙前抑制耳后肌反射应用于小型猪模型

目的 应用小型猪作为研究对象,分别应用耳后肌反射(Post-Auricular Muscle Response, PAMR)与眨眼反射(Eye-Blink Response, EBR)测量间隙前抑制惊跳反射(Gap-induced inhibition of the Acoustic Startle, GPIAS),从而确定PAMR可成为测量GPIAS的方法,为耳鸣模型验证提供更加敏感、客观的方法。方法 选取3只3月龄大小的雄性小猪,分别应用PAMR以及EBR进行5次耳鸣模型行为范式—GPIAS的检测。应用SPSS21.0软件进行统计分析。结果 每只小型猪PAMR在no-gap情况下幅值均大于给予gap时的情况;每只小型猪EBR“no-gap”幅值大于“gap”时,但多数无统计学意义,且出现了gap幅值大于no-gap幅值的情况;进行GN Ratio(gap/no-gap)的计算后比较发现PAMR的ratio值均稳定小于1,EBR的值波动较大且出现>1的情况。结论 PAMR可以稳定且客观地反映耳鸣行为学检测范式GPIAS,表明PAMR可以成为小型猪耳鸣动物模型检测的方法,为后续阐明耳鸣的机制奠定了基础。

Context Dependent Auditory Thresholds Determined by Brainstem Audiometry and Prepulse Inhibition in Mongolian Gerbils

Information on hearing thresholds is not always reliable as differences in these thresholds have been described even for the same species. This may partially be due to different methods used by different labs. A frequently used approach to obtain an estimate of hearing threshold is the electrophysiological recording of auditory brainstem responses (ABR). They are usually recorded under deep anesthesia and represent the auditory evoked far-field potentials at various levels in the central auditory pathway. Alternatively, several behavioral approaches are employed. These commonly use operant or classical conditioning to determine hearing thresholds. A potential disadvantage of these methods is that any sound conditioning may in principle alter auditory perception and therefore auditory thresholds. To exclude this type of methodological bias a prepulse inhibition (PPI) paradigm can be used where an audiogram can be determined without any kind of pre-training. Here we compare the threshold estimates obtained by two different ABR and PPI measurements where stimuli are presented in different contexts, either randomly or non-randomly, to test for a possible effect of auditory sensitization. In addition we test the effect of a frequency specific acoustic trauma on the audiograms obtained with both methods. In general we find behaviorally determined audiograms to be significantly lower in absolute thresh- old compared to ABR measurements. Furthermore non-randomized presentation context of the stimuli generally results in audiograms with 10 to 15 dB lower thresholds than pseudo-randomized presentation. Finally, the amount of threshold loss induced by acoustic trauma is similar for all methods tested.

ACOUSTIC STARTLE RESPONSE AFFECTED BY AGING AND CHOLINERGIC NEUROTRANSMITTERS

The acoustic startle response has been used to evaluate tinnitus and hyperacusis in animal models. Gap induced prepulse in- hibition of the acoustic startle reflex （gap-PPI） is affected by tinnitus and loudness changes. Since tinnitus and reduced sound tolerance are commonly seen in elderly, we measured gap-PPI in Fischer 344 rats, an aging related hearing loss model, at dif- ferent agcs： 3-5 months, 9-12 months, and 15-17 months. The startle response was induced by three different intensity of sound： 105, 95 and 85 dB SPL. Gap-PPI was induced by different duration of silent gaps from 1 to 100 ms. When thc startle was induced by 105 dB SPL sound intensity, the gap-PPI induced by 50 ms silent gap was significantly lower than those in- duced by 25 or 100 ms duration, showing a ＂notch＂ in the gap-PPI function. The ＂notch＂ disappeared with the reduction of startle sound, suggesting the ＂notch＂ may be related with hyper-sensitivity to loud sound. As the intensity of the stimulus de- creased, the appearance of the hyperacusis-like effect decreased more quickly for the youngest group of rats. We also tested scopolamine, a muscarinic acetylcholine receptor antagonist, and mecamylamine, a nicotinic acetylcholine receptor antago- nist, on the effect of gap-PPI. When scopolamine was administered, the results indicated no addition effect on the hyperacu- sis-like phenomenon in the two older groups. Mecamylamine, the nicotinic antagonist also showed effects on the appearance of hyperacusis on rats in different ages. The information derived from the study will be fundamental for the further research in determining the cause and treatment for hyperacusis.

Acoustic trauma-induced auditory cortex enhancement and tinnitus

There is growing evidence suggests that noise-induced cochlear damage may lead to hyperexcitability in the central auditory system(CAS)which may give rise to tinnitus.However,the correlation between the onset of the neurophysiological changes in the CAS and the onset of tinnitus has not been well studied.To investigate this relationship,chronic electrodes were implanted into the auditory cortex(AC) and sound evoked activities were measured from awake rats before and after noise exposure.The auditory brainstem response(ABR) was used to assess the degree of noise-induced hearing loss.Tinnitus was evaluated by measuring gap-induced prepulse inhibition(gap-PPI).Rats were exposed monaurally to a high-intensity narrowband noise centered at 12 kHz at a level of 120 dB SPL for 1 h.After the noise exposure,all the rats developed either permanent(>2 weeks) or temporary(<3 days) hearing loss in the exposed ear(s).The AC amplitudes increased significantly 4 h after the noise exposure.Most of the exposed rats also showed decreased gap-PPI.The post-exposure AC enhancement showed a positive correlation with the amount of hearing loss.The onset of tinnitus-like behavior was happened after the onset of AC enhancement.

Acoustic startle reflex and pre-pulse inhibition in tinnitus patients

Gap induced pie-pulse inhibition(Gap-PPI) of acoustic startle reflex has been used as a measurement of tinnitus in animal models.However,whether this test is sensitive to detect tinnitus in humans is still unclear.Based on the testing procedure used in animal studies,a human subject testing method was formulated and conducted to investigate if a similar result could be found in tinnitus patients.Audiologic and tinnitus assessments and acoustic startle reflex measurements were performed on seven tinnitus subjects and nine age matched subjects without tinnitus.There was no significant difference found between the control and tinnitus group on the Gap-PPl across the frequencies evaluated.The amplitude of the startle response in the tinnitus group with normal hearing thresholds was significantly higher than the control group and those with tinnitus and hearing loss.This preliminary result suggests that hyperexcitability in the central auditory system may be involved in tinnitus.There was no correlation between hearing thresholds and the increased amplitude of startle response.

A Method for Quantifying the Emotional Intensity and Duration of a Startle Reaction with Customized Fractal Dimensions of EEG Signals

The assessment of emotions with fractal dimensions of EEG signals has been attempted before, but the quantification of the intensity and duration of sudden and short emotions remains a challenge. This paper suggests a method for this purpose, by using a new fractal dimension algorithm and by adjusting the amplitude of the EEG signal in order to obtain maximal separation of high and low fractal dimensions. The emotion was induced by embedding a scary image at 20 seconds in landscape videos of 60 seconds length. The new method did not only detect the onset of the emotion correctly, but also revealed its duration and intensity. The intensity is based on the magnitude and impulse of the fractal dimension signal. It is also shown that Higuchi’s method does not always detect emotion spikes correctly;on the contrary, the region of the expected emotional response can be represented by fractal dimensions smaller than the rest of the signal, whereas the new method directly reveals distinct spikes. The duration of these spikes was 10 - 11 seconds. The magnitude of these spikes varied across the EEG channels. The build-up and cool-down of the emotions can occur with steep and flat gradients.

Prepulse inhibition (PPI) of tactile startle response in recombinant congenic strains of mice:QTL mapping and comparison with acoustic PPI

Prepulse inhibition （PPI） of the startle response is a psychophysiological measure of sensorimotor gating believed to be cross-modal between different sensory systems. We analyzed the tactile startle response （TSR） and PPI of TSR （tPPI）, using light as a prepulse stimulus, in the mouse strains A/J and C57BL/6J and 36 recombinant congenic strains derived from them. Parental strains were significantly different for TSR, but were comparable for tPPI. Among the congenic strains, variation for TSR was significant in both genetic backgrounds, but that of tPPI was significant only for the C57BL/6J background. Provisional mapping for loci modulating TSR and tPPI was carried out. Using mapping data from our previous study on acoustic startle responses （ASR） and PPI of ASR （aPPI）, no common markers for aPPI and tPPI were identified. However, some markers were significantly associated with both ASR and TSR, at least in one genetic background. These results indicate cross-modal genetic regulation for the startle response but not for PPI, in these mouse strains.

Roles of 5-HT2 receptors in effects of DOM,ketamine and methamphetamine on prepulse inhibition in Sprague Dawley rats

OBJECTIVE Prepulse inhibition(PPI)of the acoustic startle response provides a measure of sensorimotor gating system mecha⁃nisms,which is known to be impaired in schizo⁃phrenia patients.We assessed the effects of the 5-HT2A/2C receptor agonist(±)2,5-dimethoxy-4-methylamphetamine(DOM),the NMDA receptor antagonist ketamine,the dopamine receptor ago⁃nist methamphetamine(Meth)on PPI and the startle magnitude in SD rats.METHODS AND RESULTS Systemic administration of the three compounds all dose-dependently reduced PPI.However,as far as startle magnitude,only DOM at the doses of 3 mg·kg-1 reduced that,while both ketamine and Meth did not change the startle magnitudes.Furthermore,to determine whether 5-HT2A receptor mediate this effect,the non-spe⁃cific 5-HT2 receptor antagonist cyproheptadine,specific 5-HT2A receptor antagonist ketanserin and specific 5-HT2C receptor antagonist SB242084 were tested.Cyproheptadine,ketan⁃serin and SB242084 did not alter startle ampli⁃tude by themselves in SD rats and only ketanserin slightly increased PPI at higher dose(3 mg·kg-1).PPI impairment induced by DOM was restored by pretreatment of cyproheptadine(1 mg·kg-1)and ketanserin(1 mg·kg-1),while not by pretreat⁃ment of SB242084(1 mg·kg-1).Damage of PPI induced by ketamine and Meth was not reversed by cyproheptadine(1 and 5 mg·kg-1).CONCLU⁃SION The receptor mechanisms underlying the disruption of PPI caused by DOM,ketamine and Meth were different from each other,at least 5-HT2A receptor was not the junction receptor for which the three chemicals acted.

ANIMAL BEHAVIORAL MODELS OF TINNITUS

The pathophysiology of tinnitus is poorly understood and treatments are often unsuccessful. A number of animal models have been developed in order to gain a better understanding of tinnitus. A great deal has been learned from these models re- garding the electrophysiological and neuroanatomical correlates of tinnitus following exposure to noise or ototoxic drugs. Re- liable behavioral data is important for determining whether such electrophysiological or neuroanatomical changes are indeed related to tinnitus. Of the many documented tinnitus animal behavioral paradigms, the acoustic startle reflex had been pro- posed as a simple method to identify the presence or absence of tinnitus. Several behavioral models based on conditioned re- sponse suppression paradigms have also been developed. In addition to determining the presence or absence of tinnitus, some of the behavioral paradigms have provided signs of the onset, frequency, and intensity of tinnitus in animals. Although none of these behavioral models have been proved to be a perfect model, these studies provide useful information on understanding the neural mechanisms underlying tinnitus.

Startling Dream in A World of Ganghood—Heaven Gaia·Xiong Ying

On March 31,a Chinese high-end women’s clothing brand Heaven Gaia was showcased in the Golden Hall of the Beijing Hotel. The 2019 autumn and winter series were released under the theme of'startling dream'. The whole release consisted of four sections,'Dancing Warblers and Butterflies in Spring','Buzzing Dragonflies in Summer','Golden Dreams of Autumn'and'Proud Plum Trees and Pines in Winter'. More than fifty sets of designs perfectly belended traditional culture elements with modern fashion, which inspired the audience and awakened their internal pride for the national culture.

5-HT_2AReceptor Activation Normalizes Exaggerated Fear Behavior in <i>p</i>-Chlorophenylalanine (PCPA)-Treated Rats

Deficits in serotonin (5-hydroxytryptamine, 5-HT) neurotransmission are implicated in abnormal emotional behaviors such as aggression, anxiety, and depression. However, the specific 5-HT receptor mechanisms involved are not well understood. The role of 5-HT2 receptors in fear potentiated startle, (FPS) was examined in rats chronically treated with pchlorophenylalanine (PCPA) to reduce brain 5-HT. PCPA-treated rats show an enhanced magnitude of FPS. Systemic administration of the 5-HT2 receptor agonist (±)-2,5-Dimethoxy-4-iodoamphetamine hydrochloride (DOI) reduced FPS in both PCPA-treated and saline (SAL)-treated control animals, normalizing the exaggerated fear response in PCPA-treated rats. In both SAL- and PCPA-treated animals, the DOI-induced reduction of learned fear was reversed by the 5-HT2 antagonist ketanserin, but not by the 5-HT2B/2C antagonist SB 206553. Together, these findings suggest 5-HT2A receptors are critical regulators of learned fear, and that 5-HT2A receptors may be an important pharmacological target to normalize exaggerated learned fear resulting from chronic 5-HT-ergic disruption.

Cued aversive classical conditioning in humans: The role of trait-anxiety

No study so far has specifically addressed the influence of individual differences in trait-anxiety on aversive classical conditioning as indexed by the startle reflex response. We compared the startle reflex responses between participants classified as high (n = 25) and low (n = 26) in trait-anxiety while undergoing a single-cue aversive classical conditioning procedure. High trait-anxiety group showed a greater startle response to the CS relative to the ITI at the post-acquisition compared with the pre-acquisition phase. Low trait-anxiety group did not show such a clear pattern of conditioning, and results from this group seem to be concealed by differences in the startle responses to the CS and the ITI during the pre-acquisition phase. However, a post-hoc analysis in which such differences at pre-conditioning were removed showed no conditioning effects in low trait-anxiety participants. Taking together, these results suggest differences between high and low trait-anxiety groups in the acquisition of the CS-US association. However, further research should clarify the unexpected pattern of responses shown by low trait-anxiety group.

Female Carriers of the Met Allele of the BDNF Val66Met Polymorphism Develop Weaker Fear Memories in a Fear-Potentiated Startle Paradigm

The val66met polymorphism of the bdnf gene, which is associated with compromised brain-derived neurotrophic factor (BDNF) signaling, impaired synaptic plasticity, and impaired learning, may increase one’s susceptibility to stress- and anxiety-related disorders. Indeed, previous work has reported greater anxiety-related behaviors and impairments of fear conditioning and extinction in individuals who carry the met allele that results from this polymorphism. Nevertheless, findings in this area of research have been equivocal. Thus, we examined the influence of the val66met polymorphism on fear conditioning, extinction, and extinction memory testing. One hundred and twenty healthy participants completed differential fear conditioning in a fear-potentiated startle paradigm, followed by extinction and extinction memory testing 24 and 48 hr later, respectively. Participants were genotyped for the val66met polymorphism and divided into met allele carriers and non-carriers. Results revealed that, although both met-carriers and non-carriers developed conditioned fear, met-carriers exhibited significantly weaker fear acquisition than non-carriers. This difference persisted throughout extinction and extinction memory testing and, during these last two days of testing, was primarily evident in females. These results are consistent with previous work demonstrating that this polymorphism is associated with impaired amygdala-dependent fear learning and extend such findings by demonstrating that females may be more sensitive to such effects.

Sex Differences in the Effects of Sertraline and Stressors in Rats Previously Exposed to Restraint Stress

The serotonergic system in the brain plays a major role in mood and anxiety regulation when exposed to stress. The aim of the present study was to evaluate the effects of Sertraline administration in coping with stress using the behavioural paradigms of the acoustic startle reflex (ASR) and its prepulse inhibition (PPI) in both sexes. Wistar rats were divided into two groups: intact animals and exposed to restraint stress (RS) 3 times per day during 7 days, which were then subdivided into three other groups: injected with Sertraline (5 mg/kg/day) or the drug vehicle saline for 8 consecutive days, and non-injected. ASR and PPI values were analyzed along 4 sessions to determine behavioral changes. Upon it, we also determine the effects of acute immobilization stress analyzing physiological stress indicators in blood. Our data show sex differences in response to stress paradigms. RS affected more intensely males than females, disturbing the males’ growth and the long-term startle habituation that were not affected in females. PPI increased in the vehicle-injected animals when compared to baseline in both sexes, and Sertraline reversed more efficiently it in females. Moreover, despite both sexes exposed to stressful paradigms exhibited a significant increase in serum glutamic-oxaloacetic transaminase and lactate dehydrogenase enzymes when compared with intact controls, as well as leucopenia, some differences according to sex were found in the haemostatic response to stress. Notably, the repeated injections procedure disturbed the early response to stress, which Sertraline only attenuated in both sexes. Our data suggest that 8-day Sertraline administration is effective in reversing stress-induced changes in some physio-logical parameters, but insufficient to return immunological values to normality.

Impaired prepulse inhibition of acoustic startle in Chinese patients with first-episode, medication-naive schizophrenia

Background Patients with schizophrenia have prominent abnormality in information processing that can be observed by measures of prepulse inhibition （PPI） of acoustic startle reflex and PPI deficits have been considered as a candidate endophenotypic marker of schizophrenia. However, there has been little information on PPI and related measures in Chinese patients with schizophrenia. The research was to explore the deficits of acoustic startle reflex that might exist in Chinese patients with schizophrenia. Methods Startle response to acoustic stimuli, habituation, and PPI were examined in 31 Chinese patients with first-episode, medication-naive schizophrenia and 30 age-and sex-matched healthy Chinese controls. At the same day of startle testing, psychopathological symptoms of the patients were assessed with the Positive and Negative Syndrome Scale （PANSS）. Results Compared with healthy controls, patients exhibited the significant reduction in startle response and PPI deficits at 60 milliseconds （ms） intervals （PP160, P 〈0.05） but not at 30 or 120 ms intervals. Furthermore, there was a relatively strong correlation between PPI60 （P 〈0.05） and scores of positive scale of PANSS in patients with schizophrenia. Conclusion Our findings confirmed impaired PPI in Chinese patients with schizophrenia and suggested that a relationship between sensorimotor gating deficits and clinical symptoms of patients with schizophrenia might exist.

Differences in P50 and prepulse inhibition of the startle reflex between male smokers and non-smokers with first episode schizophrenia without medical treatment

Backgorund Nicotine may improve schizophrenia patient＇s cognitive deficit symptoms.This study was to explore the chronic effects of smoking on prepulse inhibition of the startle reflex （PPI） and P50 in the patients with first-episode schizophrenia （FES）.Methods The event-related potentials （ERP） recording and analysis instrument made by Brain Products,Germany,was used to detect PPI and P50 in 49 male FES patients （FES group,n=21 for smokers and n=28 for non-smokers） and 43 normal male controls （control group,n=19 for smokers and n=24 for non-smokers）.Results Compared with normal controls,the FES group had prolonged PPI latency when elicited by single stronger stimulus （P ＜0.05）; the FES group had prolonged PPI latency and increased PPI amplitude （P ＜0.05,0.01） when elicited by weak and strong stimuli.The FES group had lower PPI inhibition rate than normal controls （P ＜0.05）.Compared with normal controls,the FES group had increased P50-S2 amplitude and increased amplitude ratio S2/S1 （both P ＜0.05）.In the control group,the smokers had a tendency of increase in P50-S2 amplitude （P ＞0.05） and shorter P50-S2 latency （P ＜0.05） than the non-smokers.The smokers had higher PPI amplitude than the non-smokers （P ＜0.05）.In the FES group,the smokers had higher P50-S1 amplitude,shorter P50-S2 latency,and higher amplitude ratio S2/S1 than the non-smokers （P ＜0.05,0.01）.The smokers had higher PPI amplitude than the non-smokers （P ＜0.05）.Conclusions There is obvious PPI and P50 deficits in schizophrenic patients.However,these deficits are relatively preserved in the smokers compared with the non-smokers,which suggests that long-term smoking might partially improve the sensory gating in schizophrenic patients.Whether this conclusion can be deduced to female patients requires further follow-ups.

Finger or Light:Stimulation Sensitivity of Visual Startle in the Coma Recovery Scale-Revised for Disorders of Consciousness

Dear Editor,Coma, the vegetative state （VS）, and the minimally- conscious state （MCS）, often collectively referred to as disorders of consciousness （DOCs）, typically occur after severe traumatic or non-traumatic brain injury [1]. The boundary between awareness and unawareness remains elusive, making it difficult to correctly distinguish MCS from VS patients. It is possible to employ noninvasive neuroimaging techniques, such as functional MRI （fMRI） [2] to assess residual cognitive processing as well as consciousness. However, the causal link between neural activity in specific brain areas and specific behavioral tasks is hard to dissect using fMRI [3]. Therefore, detecting residual cognitive function and consciousness in patients surviving severe brain injury remains extremely challenging.