Differential role of Rac in the basolateral amygdala and cornu ammonis 1 in the reconsolidation of auditory and contextual Pavlovian fear memory in rats

RATIONALE AND OBJECTIVES

A conditioned stimulus (CS) is associated with a fearful unconditioned stimulus (US) in the traditional fear conditioning model. After fear conditioning, the CS-US association memory undergoes the consolidation process to become stable. Consolidated memory enters an unstable state after retrieval and requires the reconsolidation process to stabilize again. Evidence indicates the important role of Rac (Ras-related C3 botulinum toxin substrate) in the acquisition and extinction of fear memory. In the present study, we hypothesized that Rac in the amygdala is crucial for the reconsolidation of auditory and contextual Pavlovian fear memory.

METHODS

Auditory and contextual fear conditioning and microinjections of the Rac inhibitor NSC23766 were used to explore the role of Rac in the reconsolidation of auditory and contextual Pavlovian fear memory in rats.

RESULTS

A microinjection of NSC23766 into the basolateral amygdala (BLA) but not central amygdala (CeA) or cornu ammonis 1 (CA1) immediately after memory retrieval disrupted the reconsolidation of auditory Pavlovian fear memory. A microinjection of NSC23766 into the CA1 but not BLA or CeA after memory retrieval disrupted the reconsolidation of contextual Pavlovian fear memory.

CONCLUSIONS

Our experiments demonstrate that Rac in the BLA is crucial for the reconsolidation of auditory Pavlovian fear memory, whereas Rac in the CA1 is critical for the reconsolidation of contextual Pavlovian fear memory.

cRGD mediated liposomes enhanced antidepressant-like effects of edaravone in rats

The delayed onset of therapeutic outcomes is a major drawback of the current antidepressants. The blood-brain barrier is the most important bottleneck impeding drug transport into the brain. Therefore, development of novel antidepressant medications with rapid onset and sustained activity is urgent. RGD liposomes showed an excellent effect of brain-targeting drug delivery and increased the entering rate to the brain. In the present study, we prepared cyclic RGD liposomes loaded with edaravone (cRGD-ERLs) and evaluated the potential antidepressant-like effects of this drug delivery system in rats. The results showed single injection of cRGD-ERLs produced significant antidepressant-like effects in both forced swim and novelty suppressed feeding test. Moreover, acute cRGD-ERLs increased the expression of c-fos in the medial prefrontal cortex, suggesting that cRGD-ERLs could activate the neuronal function. Furthermore, cRGD-ERLs reversed the increase of lipopolysaccharides (LPS)-induced plasma cytokine IL-1β and IL-6, suggesting that normalization of cytokine level might be involved in the behavioral response of cRGD-ERLs. Finally, cRGD-ERLs prevented the increase of immobility induced by LPS in the forced swim test. Overall, the current data revealed a novel brain-target drug delivery system, which can be used to improve the therapeutic outcomes of antidepressants by increase of crossing rate to the brain.

Glycine site N-methyl-D-aspartate receptor antagonist 7-CTKA produces rapid antidepressant-like effects in male rats

BACKGROUND

Glutamate N-methyl-D-aspartate (NMDA) receptor antagonists exert fast-acting antidepressant effects, providing a promising way to develop a new classification of antidepressant that targets the glutamatergic system. In the present study, we examined the potential antidepressant action of 7-chlorokynurenic acid (7-CTKA), a glycine recognition site NMDA receptor antagonist, in a series of behavioural models of depression and determined the molecular mechanisms that underlie the behavioural actions of 7-CTKA.

METHODS

We administered the forced swim test, novelty-suppressed feeding test, learned helplessness paradigm and chronic mild stress (CMS) paradigm in male rats to evaluate the possible rapid antidepressant-like actions of 7-CTKA. In addition, we assessed phospho-glycogen synthase kinase-3β (p-GSK3β) level, mammalian target of rapamycin (mTOR) function, and postsynaptic protein expression in the medial prefrontal cortex (mPFC) and hippocampus.

RESULTS

Acute 7-CTKA administration produced rapid antidepressant-like actions in several behavioural tests. It increased p-GSK3β, enhanced mTOR function and increased postsynaptic protein levels in the mPFC. Activation of GSK3β by LY294002 completely blocked the antidepressant-like effects of 7-CTKA. Moreover, 7-CTKA did not produce rewarding properties or abuse potential.

LIMITATIONS

It is possible that 7-CTKA modulates glutamatergic transmission, thereby causing enduring alterations of GSK3β and mTOR signalling, although we did not provide direct evidence to support this possibility. Thus, the therapeutic involvement of synaptic adaptions engaged by 7-CTKA requires further study.

CONCLUSION

Our findings demonstrate that acute 7-CTKA administration produced rapid antidepressant-like effects, indicating that the behavioural response to 7-CTKA is mediated by GSK3β and mTOR signalling function in the mPFC.

Hippocampal CLOCK protein participates in the persistence of depressive-like behavior induced by chronic unpredictable stress

RATIONALE

Circadian disturbances are strongly linked with major depression. The circadian proteins CLOCK and BMAL1 are abundantly expressed but function differently in the suprachiasmatic nucleus (SCN) and hippocampus. However, their roles in depressive-like behavior are still poorly understood.

OBJECTIVES

To investigate the alterations of CLOCK and BMAL1 in the SCN and hippocampus in rats subjected to chronic unpredictable stress (CUS) and to explore the relationship of circadian protein and the depressive-like behavior.

RESULTS

Together with depressive-like behavior induced by CUS, CLOCK and BMAL1 in the SC were inhibited during the light period, and the peak expression of CLOCK in the hippocampus was shifted from the dark to light period. BMAL1 expression in the hippocampus was not significantly changed. Two weeks after the termination of CUS, abnormalities of CLOCK in the CA1 and CA3 endured, with unchanged depressive-like behavior, but the expression of CLOCK and BMAL1 in the SCN recovered to control levels. Knockdown of the Clock gene in CA1 induced depressive-like behavior in normal rats. CLOCK in the SCN and hippocampus may participate in the development of depressive-like behavior. However, CLOCK in the hippocampus but not SCN was involved in the long-lasting effects of CUS on depressive-like behavior. BMAL1 in the hippocampus appeared to be unrelated to the effects of CUS on depressive-like behavior.

CONCLUSION

CLOCK protein in the hippocampus but not SCN play an important role in the long-lasting depressive-like behavior induced by CUS. These findings suggest a novel therapeutic target in the development of new antidepressants focusing on the regulation of circadian rhythm.

PI3K/Akt signaling pathway in the basolateral amygdala mediates the rapid antidepressant-like effects of trefoil factor 3

Depression is one of the most common and debilitating psychiatric illnesses around the world, but the current antidepressants used to treat depression have many limitations. Progressively more studies have shown that neuropeptide systems are potential novel therapeutic targets for depression. However, whether the neuropeptide trefoil factor 3 (TFF3) participates in the development of depression has not been examined. In the current experiments, we assessed the antidepressant effects of TFF3 using the forced swim test (FST), tail suspension test (TST), and chronic mild stress (CMS) paradigm. Furthermore, we determined the mechanism that underlies the antidepressant-like effects of TFF3 in the rat FST. TFF3 dose-dependently reduced immobility time in both FST and TST. CMS elevated plasma TFF3 and decreased basolateral amygdala (BLA) TFF3 levels in rats, and acute TFF3 (0.1 mg/kg, i.p.) treatment reversed the depressive-like behaviors induced by CMS. Furthermore, TFF3 (0.1 mg/kg, i.p.) significantly increased Fos expression in the BLA, medial prefrontal cortex, and hypothalamus in rats subjected to the FST. Intra-BLA infusions of TFF3 (1 ng/side) exerted rapid antidepressant-like effects in the rat FST. Additionally, acute systemic TFF3 administration increased the level of phosphorylated-Akt (p-Akt) in the BLA. Finally, intra-BLA infusions of LY294002 (5 mM/side), a specific phosphatidylinositol 3-kinase (PI3K) inhibitor, significantly blocked the antidepressant-like effect of TFF3. Our results demonstrated that TFF3 exerts antidepressant-like effects that might be mediated by the PI3K/Akt signaling pathway in the BLA. These findings suggest a novel neuropeptide system target in the development of new antidepressants.

A memory retrieval-extinction procedure to prevent drug craving and relapse

Drug use and relapse involve learned associations between drug-associated environmental cues and drug effects. Extinction procedures in the clinic can suppress conditioned responses to drug cues, but the extinguished responses typically reemerge after exposure to the drug itself (reinstatement), the drug-associated environment (renewal), or the passage of time (spontaneous recovery). We describe a memory retrieval-extinction procedure that decreases conditioned drug effects and drug seeking in rat models of relapse, and drug craving in abstinent heroin addicts. In rats, daily retrieval of drug-associated memories 10 minutes or 1 hour but not 6 hours before extinction sessions attenuated drug-induced reinstatement, spontaneous recovery, and renewal of conditioned drug effects and drug seeking. In heroin addicts, retrieval of drug-associated memories 10 minutes before extinction sessions attenuated cue-induced heroin craving 1, 30, and 180 days later. The memory retrieval-extinction procedure is a promising nonpharmacological method for decreasing drug craving and relapse during abstinence.

Venlafaxine facilitates between-session extinction and prevents reinstatement of auditory-cue conditioned fear

Anxiety disorders, characterized by anxiety and fearfulness, are found to be able to cause abnormal emotional responses' associated with memories of negative events, which implicate pressure on society with an increasingly large burden. Better treatment has been of concern to the community. Venlafaxine (VEN), a nonclassical antidepressant agent, is applied in the treatment of social phobia, major depression (MD) and general anxiety disorder (GAD) and, to a certain extent, posttraumatic stress disorder (PTSD), which improves working memory and spatial memory as well as ameliorates emotion by affecting specified brain regions. In this study, we committed to seek a new way for using VEN on treatment of anxiety disorders. To investigate the effect of VEN on extinction of auditory-cue conditioned fear, conditioned rats received a treatment with VEN before extinction training and tests for freezing level of within-session and between-session extinction. To investigate the effect of VEN on reinstatement, all conditioned rats received a treatment with VEN over a period for 21 days. After a rest for 7 days, two tests for freezing level were conducted. We found that: (1) VEN (40mg/kg) treatment at 30min prior to extinction training significantly facilitated the between-session extinction, but not the within-session extinction; (2) chronic administration with VEN (40mg/kg) prevented the return of extinguished auditory-cue fear. These data elucidate the critical role of VEN in auditory-cue fear memory, suggesting that VEN may be an ideal choice for the exposure-based drug treatment and maintenance treatment in patients with GAD, SAD and PTSD.

A morphine/heroin vaccine with new hapten design attenuates behavioral effects in rats

Heroin use has seriously threatened public heath in many countries, but the existing therapies continue to have many limitations. Recently, immunotherapy has shown efficacy in some clinical studies, including vaccines against nicotine and cocaine, but no opioid vaccines have been introduced in clinical studies. The development of a novel opioid antigen designed specifically for the prevention of heroin addiction is necessary. A morphine-keyhole limpet hemocyanin conjugate was prepared and administered subcutaneously in rats. Antibody titers in plasma were measured using an enzyme-linked immunosorbent assay (ELISA). Competitive ELISA was used to assess the selectivity of the antibodies. Dopamine concentrations in the nucleus accumbens in rats after vaccine administration were determined by high-performance liquid chromatography with electrochemical detection. The effects of the vaccine on the heroin-primed restatement of self-administration and locomotor sensitization were evaluated. A novel hapten, 6-glutarylmorphine, was produced, and the vaccine generated a high antibody titer response. This vaccine displayed specificity for both morphine and heroin, but the anti-morphine antibodies could not recognize dissimilar therapeutic opioid compounds, such as buprenorphine, methadone, naloxone, naltrexone, codeine, and nalorphine. The morphine antibody significantly decreased morphine-induced locomotor activity in rats after immunization. Importantly, rats immunized with this vaccine did not exhibit heroin-primed reinstatement of heroin seeking when antibody levels were sufficiently high. The vaccine reduced dopamine levels in the nucleus accumbens after morphine administration, which is consistent with its behavioral effects. These results suggest that immunization with a novel vaccine is an effective means of inducing a morphine-specific antibody response that is able to attenuate the behavioral and psychoactive effects of heroin.

Effects of sleep deprivation on retrieval and reconsolidation of morphine reward memory in rats

Relapse induced by exposure to cues associated with drugs of abuse is a major challenge to the treatment of drug addiction. Drug seeking can be inhibited by manipulation of the reconsolidation of drug-related memory. Sleep has been proposed to be involved in various memory processes. However, the role of sleep in drug reward memory is not clear. The present study used conditioned place preference to examine the effects of total sleep deprivation on retrieval and reconsolidation of morphine reward memory in rats. Six-hour total sleep deprivation had no effect on the retrieval of morphine reward memory. However, sleep deprivation from 0-6 h, but not 6-12 h, after re-exposure disrupted the reconsolidation of morphine reward memory. This impairment was not attributable to the formation of an aversive associative memory between the drug-paired context and sleep deprivation. Our findings suggest that sleep plays a critical role in morphine reward memory reconsolidation, and sleep deprivation may be a potential non-pharmacotherapy for the management of relapse associated with drug-related memory.

A time-temperature rheological study of konjac glucomannan hydrocolloid

Konjac glucomannan (KGM) is one of the most versatile soluble biomaterials having wide-ranging applications. The shear storage, G', and loss, G", moduli of this hydrocolloid were recorded as functions of angular frequency varying from 0.1 to 100.0 rad/s and temperature from 5 to 50 degrees C. It was found that both G' and G" mainly increase with angular frequency in the range from 0.1 to 100 rad/s. As the temperature increases from 5 to 95 degrees C, the values of G' and G" decrease. A novel criterion for the thermorheologically simple material, and a procedure to calculate the shift factor from the angular frequency sweep and temperature ramp data were presented. By these methods, the KGM hydrocolloid is found to obey the TTS principle as log G" and log G' are less than 1.529 and 1.436, respectively. The Williams-Landel-Ferry equation can describe the shift factor of the KGM hydrocolloid.

[Evaluation of clinical application of intravascular ultrasound image]

OBJECTIVE

To prospectively evaluate the clinical applications of intravascular ultrasound (IVUS).

METHODS

Four hundred and thirty seven patients with coronary artery disease (CAD) or suspect CAD were imaged with CAD and IVUS, including (1) assessment IVUS in 135 cases with normal coronary angiography (CAG) (2) comparison IVUS with CAG pre and after angioplasty in 52 patients with CAD (3) assessment of detecting calcification lesions with CAG and IVUS in 150 patients (4) predicting the cardiac events after stent implantation guided by IVUS (n = 47) and CAG (N = 53).

RESULTS

IVUS may detect coronary atherosclerosis lesions with normal by CAG. CAG overestimated effect of angioplasty. IVUS was more accurate to determine effect and complications of PTCA compared with CAG. IVUS interpreted the mechanism of vessel dilatation in PTCA. The cardiac events after stent implantation were significantly reduced after IVUS examination as compared with CAG.

CONCLUSIONS

IVUS represents a radically different approach to vascular anatomy. Unlike angiography, which displays the coronary artery as a silhouette of the contrast-filled lumen, IVUS generates a cross-sectional tomographic image of the lumen and vessel wall. IVUS plays an important role as a guidance in cardiac intervention.

Engineering principles applied to implantable otologic devices

The engineering principles of possible actuators and sensors for totally implantable mid-ear or cochlear hearing devices are summarized. The selection considerations are discussed. The frequency response, and the needed force and displacement at the ossicular chain sites were measured on fresh temporal bones to determine approximately the middle ear device requirements and design considerations. A design example of the actuator and sensor is outlined with laboratory and acute animal evaluation results.

Molecular modeling on kappa opioid receptor and its interaction with nonpeptide kappa opioid agonists

AIM

To study the interaction between kappa-opioid receptor and its nonpeptide agonists.

METHODS

The "conservation patterns" for G-protein coupled receptors (GPCR) were used to determine 7 transmembrane (TM) regions. Taking the crystallographic coordinates of bacteriorhodopsin (BR) as the template, the 3D structural model was constructed for 7 TM of kappa-opioid subtype with molecular mechanics (MM) method. Five highly active nonpeptide kappa-opioid agonists were docked into the 7 helices of kappa-opioid receptor to study the ligand-receptor interaction.

RESULTS

Four important interactions between U-50488-like agonists and kappa-opioid receptors were drawn according to our modeling study: (1) the protonated pyrrolidine nitrogen of the ligands formed a hydrogen-bond with the carboxyl of Asp138; (2) the carbonyl oxygen of ligands forms a hydrogen bond to the hydroxyl of Ser187; (3) the aryl groups connected to acylamide of the agonists inserted into a hydrophobic cavity enclosed by residues Val239, Val236, Phe235, Val232, Leu186, and Trp183; (4) the pyrrolidine of the ligands in the complexes was surrounded by Ile290, Asp138, Ile194, Ile135, and Cys131.

CONCLUSION

The proposed interaction mechanism is helpful for further mutant experiments and designing novel potent kappa-opioid agonists.

A 3D-QSAR study on ginkgolides and their analogues with comparative molecular field analysis

Comparative molecular field analysis (CoMFA), a three-dimensional quantitative structure-activity relationship (3D-QSAR) paradigm was used to study the correlation between the physicochemical properties and the in vitro bioactivities of ginkgolide analogues. The correlation derived from CoMFA analysis has a good predictive capability. Based on the result of CoMFA analysis, we designed some compounds. Pharmacological assay indicated that three of these new designed compounds are 2 and 4 times more potent than that of ginkgolides.

Engineering principles of mechanical stimulation of the middle ear

This article presents the transducer principles of possible middle ear hearing devices with their characteristics and selection considerations summarized. The frequency response and the needed force and displacement at the ossicular chain sites were measured to determine approximately the system requirements and design considerations. The power required to vibrate the ossicular chain is estimated to be of the order of 0.1 watt, which is three orders of magnitude smaller than the power consumption of devices being developed in various laboratories. Careful engineering design and evaluation is needed. A design example of the transducer used with a partially implantable, noncontact electromagnetic hearing device is presented in this article with laboratory evaluation results.

Contactless semi-implantable electromagnetic middle ear device for the treatment of sensorineural hearing loss. Short-term and long-term animal experiments

A contactless electromagnetic hearing device has been designed following basic science experiments, improvement of electronics, and precision micromechanics. Different prototypes have been developed and tested in the laboratory, fresh human temporal bones, and acute and chronic animal experimentation. A conductive hearing loss model was first developed in the cat using samarium cobalt as the target magnet. Later, a highly efficient electromagnetic air-core coil was selected to vibrate a neodymium iron boron magnet cemented to the body of the incus and tested in acute and chronic experiments using the cat as the model. In this group of animals, the ossicular chain was left intact. There was no failure of the target magnet, driving coil, or implanted electronics. The only problem encountered in this evaluation was a malfunction of the receiving antenna that had to be redesigned and retrofitted into the implanted units. This system would be suitable for the treatment of moderate to severe sensorineural hearing loss. Planning to begin human clinical trials is ongoing.

[Analysis of risk factors in postinfarction angina]

The clinical and echocardiographic variables related to postinfarction angina were evaluated in 54 patients with acute myocardial infarction. All patients underwent 2D echocardiography at 2-3 weeks after infarction. Wall motion analysis was quantified with a wall motion score index (WMSI) based on 16 left ventricular wall segments. Among the 54 patients with acute myocardial infarction 23 (42.6%) had early postinfarction angina. Multiple regression analysis demonstrated no significant difference between the patients with and without postinfarction angina in age, sex, location of infarction, Killip classification, previous angina, hypertension, hyperlipidemia, diabetes mellitus, creatine kinase level and left ventricular ejection fraction. In comparison with patients without postinfarction angina, patients with postinfarction angina had higher WMSI. It indicates that postinfarction angina appears to be related more to myocardial ischemia rather than to the infarct of myocardium.

A contactless electromagnetic implantable middle ear device for sensorineural hearing loss

Following basic science experiments, improvement of precision micromechanics and electronics design, and development of different prototypes, a contactless electromagnetic hearing device has been successfully implanted in cats (acute experiments). Chronic animal experiments using the cat as well as the rabbit are ongoing to test the components of the device. A highly efficient air core coil is used to vibrate a neodymium-iron-boron magnet cemented to the body of the incus. The parts of the system, including implanted electronics (hybrid circuit, solid state), are laser welded and hermetically sealed. The system allows for the generation of enough force which vibrates the magnet implanted on the incus. It would be suitable for the treatment of moderate to severe sensorineural hearing loss.

[Prognosis and factors predicting the long-term prognosis of myocardial infarction]

200 cases of consecutively admitted acute myocardial infarction (AMI), who had survived for at least 2 weeks, were studied prospectively. 193 cases were followed-up for 0.5-27 (average 15) months; 41 of them (21.2%) had cardiac events, including 3 sudden cardiac death (1.6%) and 35 obvious cardiac failure (18.1%). 11 patients died of heart failure and 4 of reinfarction. Before discharge, noninvasive tests were done: LVEF < or = 40%, age > or = 60, maximum value of creatinine-phosphokinase > or = 1000 IU/dl and positive ventricular late potential were the 4 factors of high risk. Patients with 3 or 4 positive risk factors had poorer prognosis, if they were compared with those with one or none.

[Hemochromatosis: a review of 22 Chinese cases]

22 cases of hemochromatosis were analysed. 19 cases were collected from Chinese medical journals and 3 from our hospital. We showed the similarities and differences between Chinese and western patients. The diagnosis, mode of heredity, possible pathogenesis and management of idiopathic hemochromatosis were also briefly discussed.