Olea europaea L-derived secoiridoids: Beneficial health effects and potential therapeutic approaches

Over the years, health challenges have become increasingly complex and global and, at the beginning of the 21st century, chronic diseases, including cardiovascular, neurological, and chronic respiratory diseases, as well as cancer and diabetes, have been identified by World Health Organization as one of the biggest threats to human health. Recently, antimicrobial resistance has also emerged as a growing problem of public health for the management of infectious diseases. In this scenario, the exploration of natural products as supplementation or alternative therapeutic options is acquiring great importance, and, among them, the olive tree, Olea europaea L, specifically leaves, fruits, and oil, has been increasingly investigated for its health promoting properties. Traditionally, these properties have been largely attributed to the high concentration of monounsaturated fatty acids, although, in recent years, beneficial effects have also been associated to other components, particularly polyphenols. Among them, the most interesting group is represented by Olea europaea L secoiridoids, comprising oleuropein, oleocanthal, oleacein, and ligstroside, which display anti-inflammatory, antioxidant, cardioprotective, neuroprotective and anticancer activities. This review provides an overview of the multiple health beneficial effects, the molecular mechanisms, and the potential applications of secoiridoids from Olea europaea L.

Early social isolation differentially affects the glucocorticoid receptor system and alcohol-seeking behavior in male and female Marchigian Sardinian alcohol-preferring rats

Adverse early life experiences during postnatal development can evoke long-lasting neurobiological changes in stress systems, thereby affecting subsequent behaviors including propensity to develop alcohol use disorder. Here, we exposed genetically selected male and female Marchigian Sardinian alcohol-preferring (msP) and Wistar rats to mild, repeated social deprivation from postnatal day 14 (PND14) to PND21 and investigated the effect of the early social isolation (ESI) on the glucocorticoid receptor (GR) system and on the propensity to drink and seek alcohol in adulthood. We found that ESI resulted in higher levels of GR gene and protein expression in the prefrontal cortex (PFC) in male but not female msP rats. In female Wistars, ESI resulted in significant downregulation of Nr3c1 mRNA levels and lower GR protein levels. In male and female msP rats, plasma corticosterone levels on PND35 were similar and unaffected by ESI. Wistar females exhibited higher levels of corticosterone compared with males, independently from ESI. In alcohol self-administration experiments we found that the pharmacological stressor yohimbine (0.0, 0.312, 0.625, and 1.25 mg/kg) increased alcohol self-administration in both rat lines, regardless of ESI. After extinction, 0.625 mg/kg yohimbine significantly reinstated alcohol seeking in female rats only. ESI enhanced reinstatement in female msP rats. Overall, the present results indicate that repeated social deprivation during the third week of postnatal life affects GR expression in a strain- and sex-dependent manner: such effect may contribute, at least partially, to the heightened sensitivity of female msP rats to the effects of yohimbine-induced alcohol seeking.

Chronic ethanol alters adrenergic receptor gene expression and produces cognitive deficits in male mice

Hyperkateifia and stress-induced alcohol cravings drive relapse in individuals with alcohol use disorder (AUD). The brain stress signal norepinephrine (also known as noradrenaline) tightly controls cognitive and affective behavior and was thought to be broadly dysregulated with AUD. The locus coeruleus (LC) is a major source of forebrain norepinephrine, and it was recently discovered that the LC sends distinct projections to addiction-associated regions suggesting that alcohol-induced noradrenergic changes may be more brain region-specific than originally thought. Here we investigated whether ethanol dependence alters adrenergic receptor gene expression in the medial prefrontal cortex (mPFC) and central amgydala (CeA), as these regions mediate the cognitive impairment and negative affective state of ethanol withdrawal. We exposed male C57BL/6J mice to the chronic intermittent ethanol vapor-2 bottle choice paradigm (CIE-2BC) to induce ethanol dependence, and assessed reference memory, anxiety-like behavior and adrenergic receptor transcript levels during 3-6 days of withdrawal. Dependence bidirectionally altered mouse brain α1 and β receptor mRNA levels, potentially leading to reduced mPFC adrenergic signaling and enhanced noradrenergic influence over the CeA. These brain region-specific gene expression changes were accompanied by long-term retention deficits and a shift in search strategy in a modified Barnes maze task, as well as greater spontaneous digging behavior and hyponeophagia. Current clinical studies are evaluating adrenergic compounds as a treatment for AUD-associated hyperkatefia, and our findings can contribute to the refinement of these therapies by increasing understanding of the specific neural systems and symptoms that may be targeted.

Chronic ethanol induces a pro-inflammatory switch in interleukin-1β regulation of GABAergic signaling in the medial prefrontal cortex of male mice

Neuroimmune pathways regulate brain function to influence complex behavior and play a role in several neuropsychiatric diseases, including alcohol use disorder (AUD). In particular, the interleukin-1 (IL-1) system has emerged as a key regulator of the brain's response to ethanol (alcohol). Here we investigated the mechanisms underlying ethanol-induced neuroadaptation of IL-1β signaling at GABAergic synapses in the prelimbic region of the medial prefrontal cortex (mPFC), an area responsible for integrating contextual information to mediate conflicting motivational drives. We exposed C57BL/6J male mice to the chronic intermittent ethanol vapor-2 bottle choice paradigm (CIE-2BC) to induce ethanol dependence, and conducted ex vivo electrophysiology and molecular analyses. We found that the IL-1 system regulates basal mPFC function through its actions at inhibitory synapses on prelimbic layer 2/3 pyramidal neurons. IL-1β can selectively recruit either neuroprotective (PI3K/Akt) or pro-inflammatory (MyD88/p38 MAPK) mechanisms to produce opposing synaptic effects. In ethanol naïve conditions, there was a strong PI3K/Akt bias leading to a disinhibition of pyramidal neurons. Ethanol dependence produced opposite IL-1 effects - enhanced local inhibition via a switch in IL-1β signaling to the canonical pro-inflammatory MyD88 pathway. Ethanol dependence also increased cellular IL-1β in the mPFC, while decreasing expression of downstream effectors (Akt, p38 MAPK). Thus, IL-1β may represent a key neural substrate in ethanol-induced cortical dysfunction. As the IL-1 receptor antagonist (kineret) is already FDA-approved for other diseases, this work underscores the high therapeutic potential of IL-1 signaling/neuroimmune-based treatments for AUD.

Reinterpretation of variant of unknown significance in the clinical setting of inherited cardiac conditions

Introduction

In the last years, genetic testing for inherited cardiac conditions (ICCs) is expanded and evolved at an incredible rate. This tool may inform treatment options and lifestyle choices to avoid arrhythmia triggers. Furthermore, identifying the genetic underpinning of the disorder improves risk assessment for asymptomatic or pre-symptomatic family members.

However, despite the large numbers of disease-causative genes identified in the last years, only 60% of the patients with a clinical diagnosis of ICCs carry a pathogenic or likely pathogenic variant. The remaining 40% of the cases have an inconclusive or ambiguous test caused by negative results or mainly by the identification of one or more variants of unknown significance (VUS). In this case, the test results are uninformative and clinically irrelevant, increasing uncertainty about medical management.

Purpose

We investigated whether a periodic re-evaluation of the detected VUS, using the American College of Medical Genetics and Genomics (ACMG) criteria, may impact the clinical setting of patients with suspected ICC and their family members.

Methods

We reevaluated 306 consecutive probands with suspected ICC undergoing genetic testing by next-generation sequencing using the Illumina TruSight Cardio Sequencing panel, from 2017 to 2021.

Results

Thirty-five percent of patients carried at least one variant in a gene associated with the phenotype. Of these, 94 had been previously classified as VUS and were not considered clinically actionable. After an average time of 36 months, they were reevaluated and 26.6% of the VUS were reclassified. In particular, 1 was downgraded to Benign and 24 were upgraded to Likely Pathogenic (16) or Pathogenic (8). According to the different phenotypes, the reclassification rate was 45.8% in Hypertrophic cardiomyopathy, 33.3% in Dilated cardiomyopathy, 27.3% in Arrhythmogenic cardiomyopathy, 12.5% in Brugada syndrome, and 50% in Long QT syndrome patients. This reclassification process allowed to recategorize 24 probands as clinically and molecularly diagnosed and to extend the genetic screening to their at-risk family members.

Conclusions

Given the extent of the clinical impact that genetic testing can have, these findings suggest that a periodic reevaluation of genetic test results, particularly VUS, should be a mandatory step in the ICC diagnostic workflow.

Funding Acknowledgement

Type of funding sources: None.

Do valve type and post-ballooning affect transprosthetic gradients in patients undergoing transcatheter aortic valve-in-valve procedure?

Introduction

Valve-in-Valve transcatheter aortic valve implantation (ViV-TAVI) is an appealing treatment option for patients with degenerated aortic bioprosthetic valves. However, high post-procedural transprosthetic gradients are very common after ViV-TAVI than after TAVI for native-valve aortic stenosis.

Aim

We sought to evaluate transprosthetic gradients (ΔP) and hemodynamic outcome in patients undergoing ViV-TAVI according to valve type and balloon post-dilation (balloon-expandable vs self-expandable with and without post-dilation).

Material and methods

We retrospectively analyzed 111 patients undergoing ViV-TAVI. A balloon-expandable valve was used in 35 patients (32%, Group 1), a self-expandable valve in 76 cases of which 39 (35%, Group 2) without balloon post-dilation and 37 (33%, Group 3) with balloon post-dilation. A comprehensive transthoracic echocardiography (TTE) was performed in all patients at baseline, at discharge and at 6-months follow-up.

Results

Successful ViV-TAVI was performed in 110 patients (99%). Baseline peak and mean ΔP, left ventricular volumes, ejection fraction, and pulmonary artery systolic pressure were similar among groups. A significant improvement in all echocardiographic parameters was observed in all groups over time (Table 1). In particular, a significant reduction in postprocedural gradients was observed at discharge and at 6-months follow-up compared to baseline in all groups. Immediately after ViV-TAVI procedure, the lowest value of mean ΔP was observed in Group 3 (12±7 mmHg) compared to both Group 1 (20±9 mmHg) and Group 2 (17±8 mmHg, p=0.001). This result was confirmed at 6-months follow-up (p=0.012). Rate of small valve size (≤23 mm) implanted was similar among groups (Group 1: 78%, Group 2: 60%, Group 3: 62%, p=0.123). Similar 1-year all-cause mortality was observed among groups (9%, 13%, 0%, respectively, p=0.135).

Conclusions

In patients with failed surgical aortic prosthesis, ViV-TAVI is an effective option and is associated with sustained improved hemodynamics in all patients. Anyway, the choice of prosthetic valve type and implantation technique are relevant on residual transprosthetic gradients and should be taken into account for a better long-term outcome.

Funding Acknowledgement

Type of funding sources: None.

Improving assessment of different flow state of aortic stenosis: implication for prognosis in patients undergoing transcatheter aortic valve replacement

Background

Low-flow low-gradient (LF-LG) aortic stenosis (AS) may occur with preserved or depressed left ventricular ejection fraction (EF), and both situations represent the most challenging subset of patients with AS to manage and generally have a poor prognosis with conservative therapy but a high operative mortality if treated surgically. Few and controversial data exist on the outcomes of these patients compared to normal-flow high-gradient (NF-HG) AS following transcatheter aortic valve replacement (TAVR).

Purpose

This study aims to better characterize patients with different transvalvular flow-gradient patterns undergoing TAVR and to examine the prognostic value of these flow state.

Methods

Overall, 1208 patients with severe symptomatic AS undergoing TAVR were categorized according to flow-gradient patterns as follow: 976 patients NF-HG (DPmean >40 mmHg), 107 paradoxical LF-LG (pLF-LG: DP mean <40 mmHg, EF >50%, and SVi <35 mL/m2), and 125 classical LF-LG (DP mean <40 mmHg, EF <50%, SVi <35 mL/m2).

Results

TAVR was feasible in all AS subtypes. When compared with NF-HG and pLF-LG, LF-LG had a worse symptomatic status (NYHA III–IV 86% vs 62% and 67%, respectively, p<0.001), a higher prevalence of eccentric hypertrophy (Figure 1, left), a higher level of LV global afterload reflected by a higher valvuloarterial impedance and a higher pulmonary pressure (Table). Valvular function after TAVR was excellent over time with respect to aortic pressure gradient (mean and peak) and aortic valve area regardless of flow state group. While intraoperative (p=0.935) and 30-day mortality (p=0.911) did not differ significantly among the 3 groups, LF-LG had a lower overall 5-year survival (LF-LG 50%, pLF-LG 65%, NF-HG 84%, p<0.001) (Figure 1, right). LF-LG AS was associated with a hazard ratio for 5-year mortality of 2.416 (95% CI: 1.658–3.520, p<0.001).

Conclusions

TAVR is an effective procedure in all patients with severe AS regardless of transvalvular flow-gradient patterns. However, special care should be given to characterized hemodynamic of AS, as patients with pLF-LG had similar survival rate than patients with NF-HG, whereas survival in LF-LG patients was 2-fold higher. Therefore, being able to identify patients less likely to improve after TAVR may help to guide treatment decision.

Funding Acknowledgement

Type of funding sources: None.

Where do we stand with acute myocardial infarction patients with severely reduced left ventricular ejection fraction? insights from AMIS Plus Registry

Background

Left ventricular ejection fraction (LVEF) represents one of the strongest predictors of both in-hospital and long-term prognosis in acute myocardial infarction (AMI). Temporal trends data coming from real-word experiences focused on AMI patients with severely reduced LVEF (i.e. <30%) are lacking.

Purpose

The present study aims at providing a comprehensive picture on temporal trends in AMI patients with severely reduced LVEF, with a particular focus on prevalence, in-hospital management/prognosis and pharmacological therapy at discharge. These data could shed light on the implementation in the clinical arena of guideline-directed therapies in this fragile subgroup of patients and on their effect on real-word short-term prognosis.

Methods

On a total of 48,543 screened AMI patients included in AMIS Plus Registry between 2005 and 2020, data on LVEF were available for 23,510 patients. Study patients were classified according to LVEF as AMI patients with or without severely reduced LVEF (i.e. patients with LVEF <30% and ≤30%, respectively).

Results

Overall, 1657 AMI patients (7%) presented with severely reduced LVEF. Prevalence of severe LVEF reduction constantly decreased over the study period (from 11% to 4%, p<0.001; Figure 1). In the subgroup of patients with severely reduced LVEF a significant increase in revascularisation (percutaneous and/or surgical) rate was observed (from 61% to 84%, p<0.001); in-hospital access to advanced short-term mechanical circulatory support (both ECMO and/or Impella) significantly increased from 0% in 2011 to 17% (p=0.05). Rate of cardiogenic shock developed during hospitalization remained stable over time (from 21% to 16%, p=0.7); in-hospital mortality did not significantly decrease and remained well above 20% all over the study period (from 23% to 26%, p=0.65; Figure 2). At discharge, prescription of optimal anti-ischaemic therapy (defined as an association of dual antiplatelet therapy and statine) significantly increased (from 47% to 75%, p<0.001), mainly driven by an increase in dual antiplatelet therapy prescription; however, prescription of optimal cardio-protective therapy (defined as an association of renin-angiotensin-aldosterone-system inhibitors, beta-blocker and mineralcorticoid receptor antagonist) remained low across the study period (from 17% in 2011 to 20%, p=0.96).

Conclusion

AMI patients with severely reduced ejection fraction still remain a fragile subgroup of patients; in-hospital mortality did not significantly decrease and remained exceedingly high and well above 20% all over the study period; efforts are, therefore, urgently needed to develop therapeutic strategies focused on this subgroup of patients and aiming at improving short-term prognosis. Moreover, access at discharge to optimal cardio-protective therapy remains suboptimal; efforts are needed to improve access to guidelines-directed therapy both at discharge and follow-up in this fragile population.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): Swiss Heart Fundation

Prosthesis-patient mismatch after aortic valve in valve procedure: incidence, predictors and clinical outcomes

Funding Acknowledgements

Type of funding sources: None.

Background. Transcatheter aortic valve-in-valve (TAVI ViV) implantation is an appealing treatment option for patients with degenerated bioprostheses. However, elevated residual gradients after TAVI ViV procedure are very common. These are an unwanted effects of prosthesis-patient mismatch (PPM). Currently, the actual incidenceof PPM, its predictors and its clinical outcomes have not been completely investigated.

Purpose. The aims of this study was to investigate the incidence, predictors and clinical outcome of PPM and therefore of elevated gradients after TAVI ViV.

Methods. 75 patients (age 78 ± 9 years, 36 male), who underwent TAVI-ViV due to failed aortic biological valve (60 stented, 15 stentless), were enrolled. Mechanism of bioprosthetic valve failure was stenosis (34 cases, 45%), regurgitation (24 cases, 32%) or combination (17 cases, 23%). Elevated residual gradients were defined as a mean DP> 20 mmHg. PPM was identified by the indexed effective orifice area (EOAi) measured by echocardiography (moderate PPM if 0.65 < EOAi < 0.85 cm²/m²; severe PPM if EOAi < 0.6 cm²/m²).

Results. ViV TAVI was feasible in all patients, 33 patients (44%) were implanted with a balloon-expandable valve and 42 (56%) with a self-expandable valve. Post-procedural post-ballooning was performed in 16 out of 42 patients (38%) receiving a self-expandable valve. Post-operative mean DP> 20 mmHg was found in 35 patients (48%). Moderate PPM was found in 24 cases (33%) and severe PPM in 15 (20%). A logistic regression analyses identified small size of surgical prosthesis (size < 23 mm) [OR: 6.061(2.127-17.267), p = 0.001] and failed stented valve [OR: 20.727(2.522-170.364), p = 0.005] as independent predictors for the occurrence PPM. Interestingly PPM did not affect early and 1 years mortality (1 years mortality 1.3 %), while mortality was higher in pts with stentless prostheses (9%)

Conclusions. PPM is a frequent finding after ViV procedures. Despite elevated residual gradients, TAVI ViV resolved prosthetic dysfunction and PPM did not affect mortality.  Therefore, this procedure represents a promising new option for patients with failed biological prosthetic valves.

Alcohol dependence potentiates substance P/neurokinin-1 receptor signaling in the rat central nucleus of amygdala

Behavioral and clinical studies suggest a critical role of substance P (SP)/neurokinin-1 receptor (NK-1R) signaling in alcohol dependence. Here, we examined regulation of GABA transmission in the medial subdivision of the central amygdala (CeM) by the SP/NK-1R system, and its neuroadaptation following chronic alcohol exposure. In naïve rats, SP increased action potential-dependent GABA release, and the selective NK-1R antagonist L822429 decreased it, demonstrating SP regulation of CeM activity under basal conditions. SP induced a larger GABA release in alcohol-dependent rats accompanied by decreased NK-1R expression compared to naïve controls, suggesting NK-1R hypersensitivity which persisted during protracted alcohol withdrawal. The NK-1R antagonist blocked acute alcohol-induced GABA release in alcohol-dependent and withdrawn but not in naïve rats, indicating that dependence engages the SP/NK-1R system to mediate acute effects of alcohol. Collectively, we report long-lasting CeA NK-1R hypersensitivity corroborating that NK-1Rs are promising targets for the treatment of alcohol use disorder.

624 Is TAVI a useful procedure in paradoxical low flow-low gradient aortic stenosis? A long-term mortality study

Background

Clinical outcomes of patients with paradoxical low-flow, low-gradient aortic stenosis (PLF-LG) undergoing valve replacement are controversial. PLF-LG is a combination of a small aortic valve area (AVA < 1cm²), a preserved left ventricular (LV) ejection fraction (LVEF≥50%), and a ‘paradoxical’ low mean gradient due to the presence of low LV stroke volume (≤35 mL/m²). The low flow state is explained by the presence of a high afterload and pronounced LV concentric remodeling, with impaired LV filling. Surgical aortic valve replacement has been associated with very positive outcomes in normal-flow high-gradient (NF-HG) AS, whereas poorer outcomes has been reported in patients with PLF-LG AS.

Purpose

The aim of this study is to determine the clinical outcomes in patients with PLF-LG AS undergoing transcatheter aortic valve implantation (TAVI) compare to NF-HG patients.

Methods

A total of 624 patients (age 81 ± 7 years) with symptomatic severe AS and preserved LVEF who underwent TAVI, was enrolled and divided in 2 groups: group NF-HG included 554 patients (89%) and group PLF-LG including 70 patients (11%). At 1-year follow-up, death and clinical events were reported.

Results

TAVI was feasible in all patients. A significant reduction in mean aortic pressure gradient was observed after TAVI both in PLF-LG (baseline, 30 ± 6 mmHg; 1-year, 12 ± 4 mmHg; p < 0.001) and in NF-HG (baseline, 55 ± 12 mmHg; 1-year, 11 ± 4 mmHg; p < 0.001) together with an increase in AVA (PLF-LG: baseline, 0.73 ± 0.16 cm², 1-year: 1.82 ± 0.43 cm², p < 0.001; NF-HG: baseline, 0.66 ± 0.18 cm², 1-year: 1.84 ± 0.38cm², p < 0.001). Perioperative mortality at 30-days was similar in group NF-HG (17/554, 3%) and in group PLF-LG (2/70, 3%). Figure shows the survival curves up to 5 years follow-up according to the two groups. PLF-LG and HG-AS had similar survival rate throughout the long-term follow-up. Similarly, rehospitalization rate was not different in the two groups (PLF-LG: 12% vs NF-HG: 7%, p = 0.127).

Conclusions

Differently from surgical series, TAVI in PLF-LG AS is a useful procedure showing similar mortality and rehospitalization rates compared to NF-HG AS patients.

Abstract 624 Figure. Survival curve

463Temporal trends in latecomer ST-segment elevation myocardial infarction patients: Insights from the AMIS Plus Registry 1997–2017

Introduction

A relevant proportion of patients experiencing ST-segment elevation myocardial infarction (STEMI) has a late presentation after symptoms onset. Temporal trends deriving from a large real-word scenario for this subgroup of patients are lacking.

Purpose

The aim of the present study was to provide a comprehensive analysis of temporal trends in latecomer STEMI patients, with particular regard to implementation of evidence-based treatments in this population and major in-hospital outcomes.

Methods

All STEMI patients included in the AMIS Plus Registry from January 1997 to December 2017 were included and patient-related delay was assessed: 27 231 patients were available for the final analysis. STEMI patients were classified as early or latecomers according to patient-related delay (≤ or >12 hours, respectively).

Results

22 928 patients were earlycomers (84%) and 4303 patients were classified as latecomers (16%). Across the study period we observed a significant decrease in prevalence of late presentation from 22% to 12.3% (p<0.001, Figure 1). In latecomer STEMI patients there was a gradual uptake of evidence-based pharmacological treatments with an increase in discharge prescription of P2Y12 inhibitors from 6% to 90.7% (p<0.001). Similarly, a marked increase in percutaneous coronary intervention (PCI) rate was observed (12.1–86.6%; p<0.001). Across this 20-year period, in-hospital mortality was reduced to a third (to an absolute rate of 4.5%, p<0.001) and a significant reduction in prevalence of both cardiogenic shock (14.6–4.3%) and re-infarction (5.4–0.2%) during the index hospitalisation was observed (p<0.001 for both variables). Length of hospitalisation in acute care facilities significantly decreased from 10 (6,14) days to 4 (1,7) days (p<0.001). At multivariate analysis, PCI had a strong independent protective effect toward in-hospital mortality (odds ratio 0.3, 95% confidence interval 0.187 to 0.480).

Figure 1

Conclusion

The present study provides a comprehensive picture of temporal trends in late presentation in STEMI over the last 20 years in Switzerland. During the study period in latecomer STEMI population there was a gradual uptake of evidence-based pharmacological treatments and a marked increase in PCI rate. In-hospital mortality was reduced to a third (to an absolute rate of 4.5%) and this reduction seems to be mainly associated with the increasing implementation of PCI.

P927Long-term mortality in patients with paradoxical low-flow low-gradient versus normal-flow high-gradient aortic stenosis undergoing transcatheter aortic valve implantation

Background

Controversial data exist on clinical outcomes of patients with paradoxical low-flow, low-gradient aortic stenosis (PLF-LG) undergoing valve replacement. This entity is a combination of a small aortic valve area (AVA<1cm2), a preserved left ventricular ejection fraction (LVEF≥50%), and a “paradoxical” low mean gradient due to the presence of low LV stroke volume (≤35 mL/m2). The low flow state is explained by the presence of a high afterload and pronounced LV concentric remodeling, with impaired LV filling. Currently, poorer outcomes have been reported after surgical aortic valve replacement in patients with PLF-LG AS compared with the normal-flow high-gradient (NF-HG) AS.

Purpose

The aim of this study was to determine the clinical outcomes in patients with PLF-LG AS undergoing transcatheter aortic valve implantation (TAVI) compare to NF-HG patients.

Methods

A total of 609 patients (age 81±6 years) with symptomatic severe AS and preserved LVEF who underwent TAVI, was enrolled and divided in two groups: group A included patients with NF-HG (542 patients) and group B including those with PLF-LG (66 patients). At 1-year follow-up, death and clinical events were reported.

Results

TAVI was feasible in all patients. A significant reduction in mean aortic pressure gradient was observed after TAVI both in PLF-LG (baseline, 30±5 mmHg; 1-year, 11±4 mmHg; p<0.001) and in NF-HG (baseline, 53±11 mmHg; 1-year, 12±4 mmHg; p<0.001) together with an increase in AVA (PLF-LG: baseline, 0.74±0.16 cm2, 1-year: 1.83±0.41 cm2, p<0.001; NF-HG: baseline, 0.65±0.16 cm2, 1-year: 1.84±0.35cm2, p<0.001). Perioperative mortality at 30-days was similar in group A (17/542, 3%) and in group B (2/66, 3%). Figure shows the survival curves up to 5 years follow-up according to the two groups. PLF-LG and HG-AS had similar survival rate throughout the long-term follow-up. Similarly, rehospitalization rate was not different in the two groups (PLF-LG: 12% vs NF-HG: 7%, p=0.121).

Kaplan-Meier analysis

Conclusions

Differently from surgical series, TAVI patients with PLF-LG AS had showed similar mortality and rehospitalization rates compared to NF-HG.

PACAP regulation of central amygdala GABAergic synapses is altered by restraint stress

The pituitary adenylate cyclase-activating polypeptide (PACAP) system plays a central role in the brain's emotional response to psychological stress by activating cellular processes and circuits associated with threat exposure. The neuropeptide PACAP and its main receptor PAC1 are expressed in the rodent central amygdala (CeA), a brain region critical in negative emotional processing, and CeA PACAPergic signaling drives anxiogenic and stress coping behaviors. Despite this behavioral evidence, PACAP's effects on neuronal activity within the medial subdivision of the CeA (CeM, the major output nucleus for the entire amygdala complex) during basal conditions and after psychological stress remain unknown. Therefore, in the present study, male Wistar rats were subjected to either restraint stress or control conditions, and PACAPergic regulation of CeM cellular function was assessed using immunohistochemistry and whole-cell patch-clamp electrophysiology. Our results demonstrate that PACAP-38 potentiates GABA release in the CeM of naïve rats, via its actions at presynaptic PAC1. Basal PAC1 activity also enhances GABA release in an action potential-dependent manner. Notably, PACAP-38's facilitation of CeM GABA release was attenuated after a single restraint stress session, but after repeated sessions returned to the level observed in naïve animals. A single restraint session also significantly decreased PAC1 levels in the CeM, with repeated restraint sessions producing a slight recovery. Collectively our data reveal that PACAP/PAC1 signaling enhances inhibitory control of the CeM and that psychological stress can modulate this influence to potentially disinhibit downstream effector regions that mediate anxiety and stress-related behaviors. This article is part of the special issue on 'Neuropeptides'.

Role of TLR4 in the Modulation of Central Amygdala GABA Transmission by CRF Following Restraint Stress

Aims

Stress induces neuroimmune responses via Toll-like receptor 4 (TLR4) activation. Here, we investigated the role of TLR4 in the effects of the stress peptide corticotropin-releasing factor (CRF) on GABAergic transmission in the central nucleus of the amygdala (CeA) following restraint stress.

Methods

Tlr4 knock out (KO) and wild-type rats were exposed to no stress (naïve), a single restraint stress (1 h) or repeated restraint stress (1 h per day for 3 consecutive days). After 1 h recovery from the final stress session, whole-cell patch-clamp electrophysiology was used to investigate the effects of CRF (200 nM) on CeA GABAA-mediated spontaneous inhibitory postsynaptic currents (sIPSCs).

Results

TLR4 does not regulate baseline GABAergic transmission in the CeA of naive and stress-treated animals. However, CRF significantly increased the mean sIPSC frequencies (indicating enhanced GABA release) across all genotypes and stress treatments, except for the Tlr4 KO rats that experienced repeated restraint stress.

Conclusions

Overall, our results suggest a limited role for TLR4 in CRF's modulation of CeA GABAergic synapses in naïve and single stress rats, though TLR4-deficient rats that experienced repeated psychological stress exhibit a blunted CRF cellular response.

Short Summary

TLR4 has a limited role in CRF's activation of the CeA under basal conditions, but interacts with the CRF system to regulate GABAergic synapse function in animals that experience repeated psychological stress.

Complete response in advanced breast cancer patient treated with a combination of capecitabine, oral vinorelbine and dasatinib

Background

Currently, there are no data available on the best choice of treatment in heavily pretreated patients with advanced breast cancer. However, the combination of oral vinorelbine and capecitabine has been demonstrated to be effective and safe in patients with advanced breast cancer pretreated with anthracycline. Furthermore, some studies assessed the activity of dasatinib, an oral tyrosine kinase inhibitor that inhibits five oncogenic tyrosine kinase families, alone or in combination with different chemotherapy in patients affected with advanced breast cancer.

Case presentation

A patient with metastatic breast cancer, hormone receptor positive and human epidermal grow factor receptor 2 negative, pretreated with epirubicine, taxanes and nab-paclitaxel, was submitted to third line chemotherapy with vinorelbine 60 mg/m² on day 1, 8 plus capecitabine 1000 mg/m² twice daily from day 1 to day 14 every 21 days. The patient was taking also dasatinib 100 mg once daily for chronic myeloid leukemia. The treatment was well tolerated and, after 15 months, computed tomography scan showed a complete response of liver metastases and bone stable disease. After another 28 months, a 18-fluorodeoxyglucose positron emission tomography scan showed a metabolic response of bone metastases without other site of disease.

Conclusions

This is the first case in literature about activity of dasatinib in combination with a chemotherapy schedule of oral vinorelbine and capecitabine in advanced breast cancer. This treatment showed both good tolerability and great activity with a long progression free survival of 54 months.

P/Q-type voltage-gated calcium channels mediate the ethanol and CRF sensitivity of central amygdala GABAergic synapses

The central amygdala (CeA) GABAergic system is hypothesized to drive the development of alcohol dependence, due to its pivotal roles in the reinforcing actions of alcohol and the expression of negative emotion, anxiety and stress. Recent work has also identified an important role for the CeA corticotropin-releasing factor (CRF) system in the interaction between anxiety/stress and alcohol dependence. We have previously shown that acute alcohol and CRF each increase action potential-independent GABA release in the CeA via their actions at presynaptic CRF type 1 receptors (CRF₁s); however, the shared mechanism employed by these two compounds requires further investigation. Here we report that acute alcohol interacts with the CRF/CRF₁ system, such that CRF and alcohol act via presynaptic CRF₁s and P/Q-type voltage-gated calcium channels to promote vesicular GABA release and that both compounds occlude the effects of each other at these synapses. Chronic alcohol exposure does not alter P/Q-type voltage-gated calcium channel membrane abundance or this CRF₁/P/Q-type voltage-gated calcium channel mechanism of acute alcohol-induced GABA release, indicating that alcohol engages this molecular mechanism at CeA GABAergic synapses throughout the transition to dependence. Thus, P/Q-type voltage-gated calcium channels, like CRF₁s, are key regulators of the effects of alcohol on GABAergic signaling in the CeA.

Evaluation of TLR4 Inhibitor, T5342126, in Modulation of Ethanol-Drinking Behavior in Alcohol-Dependent Mice

AIMS

Several lines of evidence support a critical role of TLR4 in the neuroimmune responses associated with alcohol disorders and propose inhibitors of TLR4 signaling as potential treatments for alcoholism. In this work, we investigated the effect of T5342126 compound, a selective TLR4 inhibitor, on excessive drinking and microglial activation associated with ethanol dependence.

METHODS

We used 2BC-CIE (two-bottle choice-chronic ethanol intermittent vapor exposure) paradigm to induce ethanol dependence in mice. After induction of the ethanol dependence, we injected T5342126 (i.p., 57 mg/kg) for 14 days while monitoring ethanol intake by 2BC (limited access to ethanol) method.

RESULTS

T5342126 decreased ethanol drinking in both ethanol-dependent and non-dependent mice but T5342126 showed also dose-dependent non-specific effects represented by decreased animal locomotor activity, saccharine intake, and body core temperature. Six days after the last ethanol-drinking session, we examined the immunohistochemical staining of Iba-1 (ionized calcium-binding adapter molecule 1), a microglial activation marker, in the central nucleus of the amygdala (CeA) and dentate gyrus (DG) of the hippocampus. Notably, T5342126 reduced Iba-1 density in the CeA of both ethanol-dependent and non-dependent mice injected with T5342126. There were no significant differences in the DG Iba-1 density among the treatment groups.

CONCLUSIONS

Collectively, our data suggest that T5342126, via blocking TLR4 activation, contributes to the reduction of ethanol drinking and ethanol-induced neuroimmune responses. However, the non-specific effects of T5342126 may play a significant role in the T5342126 effects on ethanol drinking and thus, may limit its therapeutic potential for treatment of alcohol dependence.

SHORT SUMMARY

T5342126, an experimental TLR4 inhibitor, is effective in reducing ethanol drinking and inhibiting the activation and proliferation of microglia in both ethanol-dependent and non-dependent mice. However, T5342126's use as a potential candidate for the treatment of alcohol addiction may be limited due to its non-specific effects.

Role of the IL-1 receptor antagonist in ethanol-induced regulation of GABAergic transmission in the central amygdala

The IL-1 receptor antagonist (IL-1ra), encoded by the Il1rn gene, is an endogenous antagonist of the IL-1 receptor. Studies of Il1rn knockout (KO) and wild type (WT) mice identified differences in several ethanol-related behaviors, some of which may be mediated by GABAergic transmission in the central nucleus of the amygdala (CeA). In this study we examined phasic (both evoked and spontaneous) and tonic GABAergic transmission in the CeA of Il1rn KO and WT mice and the ethanol sensitivity of these GABAergic synapses. The mean amplitude of baseline evoked GABAA-inhibitory postsynaptic potentials (IPSPs), and the baseline frequency of spontaneous GABAA-inhibitory postsynaptic currents (sIPSCs), but not the frequency of miniature GABAA-IPSCs (mIPSCs), were significantly increased in KO compared to WT mice, indicating enhanced presynaptic action potential-dependent GABA release in the CeA of KO mice. In KO mice, we also found a cell-type specific switch in the ongoing tonic GABAA receptor conductance such that the tonic conductance in low threshold bursting (LTB) neurons is lost and a tonic conductance in late spiking (LS) neurons appears. Notably, the ethanol-induced facilitation of evoked and spontaneous GABA release was lost in most of the CeA neurons from KO compared to WT mice. Ethanol superfusion increased the sIPSC rise and decay times in both KO and WT mice, suggesting ethanol-induced postsynaptic effects. The pretreatment of CeA slices with exogenous IL-1ra (Kineret; 100ng/ml) returned sIPSC frequency in KO mice to the levels found in WT. Importantly, Kineret also restored ethanol-induced potentiation of the sIPSC frequency in the KO mice. These results show that IL-1ra regulates baseline GABAergic transmission in the CeA and is critical for the ethanol effects at these synapses.

Fractal structures in nonlinear plasma physics

Fractal structures appear in many situations related to the dynamics of conservative as well as dissipative dynamical systems, being a manifestation of chaotic behaviour. In open area-preserving discrete dynamical systems we can find fractal structures in the form of fractal boundaries, associated to escape basins, and even possessing the more general property of Wada. Such systems appear in certain applications in plasma physics, like the magnetic field line behaviour in tokamaks with ergodic limiters. The main purpose of this paper is to show how such fractal structures have observable consequences in terms of the transport properties in the plasma edge of tokamaks, some of which have been experimentally verified. We emphasize the role of the fractal structures in the understanding of mesoscale phenomena in plasmas, such as electromagnetic turbulence.

Basis of the gabamimetic profile of ethanol

This article summarizes the proceedings of a symposium held at the 2005 Research Society on Alcoholism meeting. The initial presentation by Dr. Wallner provided evidence that selected GABA(A) receptors containing the delta subunit display sensitivity to low intoxicating ethanol concentrations and this sensitivity is further increased by a mutation in the cerebellar alpha6 subunit, found in alcohol-hypersensitive rats. Dr. Mameli reported that ethanol affects gamma-aminobutyric acid (GABA) function by affecting neural circuits that influence GABA release. Dr. Parsons presented data from electrophysiological and microdialysis investigations that ethanol is capable of releasing GABA from presynaptic terminals. Dr. Morrow demonstrated that systemic ethanol increases neuroactive steroids in brain, the absence of which alters various functional responses to ethanol. Dr. Criswell presented evidence that the ability of ethanol to increase GABA was apparent in some, but not all, brain regions indicative of regional specificity. Further, Dr. Criswell demonstrated that neurosteroids alone and when synthesized locally by ethanol act postsynaptically to enhance the effect of GABA released by ethanol in a region specific manner. Collectively, this series of reports support the GABAmimetic profile of acutely administered ethanol being dependent on several specific mechanisms distinct from a direct effect on the major synaptic isoforms of GABA(A) receptors.

Epipregnanolone and a novel synthetic neuroactive steroid reduce alcohol self-administration in rats

This study was designed to compare the effects of several neuroactive steroids with varying patterns of modulation of gamma-aminobutyric acid (GABA)(A) and NMDA receptors on operant self-administration of ethanol or water. Once stable responding for 10% (w/v) ethanol was achieved, separate test sessions were conducted in which male Wistar rats were allowed to self-administer ethanol or water following pre-treatment with vehicle or one of the following neuroactive steroids: (3beta,5beta)-3-hydroxypregnan-20-one (epipregnanolone; 5, 10, 20 mg/kg; n=12), (3alpha,5beta)-20-oxo-pregnane-3-carboxylic acid (PCA; 10, 20, 30 mg/kg n=10), (3alpha,5beta)-3-hydroxypregnan-20-one hemisuccinate (pregnanolone hemisuccinate; 5, 10, 20 mg/kg; n=12) and (3alpha,5alpha)-3-hydroxyandrostan-17-one hemisuccinate (androsterone hemisuccinate; 5, 10, 20 mg/kg; n=11). The effect of the 3beta-epimer of PCA, (3beta,5beta)-20-oxo-pregnane-3-carboxylic acid (10, 20, 30 mg/kg; n=9), on ethanol self-administration was also examined. The compounds were administered using a Latin-square design 45 min prior to the weekly test sessions. The effects of the 30 mg/kg dose of the steroidal hemisuccinates on ethanol intake were also examined 5 min after administration of these drugs. Both epipregnanolone and PCA attenuated ethanol self-administration. However, neither of the hemisuccinate compounds significantly altered this behavior. The steroidal hemisuccinates (30 mg/kg; n=7) were also tested 5 min before behavior testing and had no effect on ethanol intake 5 min after administration. The 3beta-epimer of PCA also failed to alter ethanol intake. None of the test compounds altered water intake. In electrophysiological studies, the effects of PCA and androsterone hemisuccinate on evoked GABA(A) receptor-mediated inhibitory postsynaptic currents (GABA(A)-IPSCs) was examined in brain slices of the amygdala. PCA had a stimulatory effect at concentrations of 5 and 25 muM. Androsterone hemisuccinate had no agonist activity. The ability of epipregnanolone and PCA to alter ethanol intake appears to be related to different inhibitory actions of these compounds on either GABA(A) or NMDA receptors, respectively. Thus, dual modulation of these systems by selected neuroactive steroids may offer potential for modifying the reinforcing effects of alcohol.

Risk reduction of cardiac events by screening of unknown asymptomatic coronary artery disease in subjects with type 2 diabetes mellitus at high cardiovascular risk: an open-label randomized pilot study

BACKGROUND

Evaluated the efficacy of reducing the risk of cardiac events by a preclinical diagnosis of CAD in subjects with type 2 diabetes mellitus with 2 or more cardiovascular risk factors.

METHODS

One hundred forty-one subjects with type 2 diabetes mellitus without known cardiac disease and asymptomatic, aged >45 to <76 years, were randomized into the screening arm for CAD (71 patients) or to the control arm (70 patients). The screening consisted in performing an exercise electrocardiogram test and dipyridamole stress echocardiography; if 1 test was abnormal, coronary angiography is done. Screening was positive in 15 subjects (21.4%). At coronary angiography, which was performed in 14 of 15 patients, stenoses > or =50% of vessel diameter were present in 9 patients, of these 4 underwent coronary artery bypass grafting and 4 underwent percutaneous transluminal coronary angioplasty. Stenoses <50% of vessel diameter were present in 5 patients.

RESULTS

Mean follow-up was 53.5 months (range, 42-54 months). During this period, 1 major (myocardial infarction) and 3 minor events (angina) occurred in the screening arm. Eleven major and 4 minor events occurred in the control arm. In the screened arm, the proportion of all events was significantly less (P = .018) (RR .226, 95% CI 0.707-0.719, P = .012); the proportion of major to minor events was significantly less (P = .006) (RR .07, 95% CI 0.0087-0.565, P = .013).

CONCLUSIONS

The preclinical diagnosis of CAD is effective in reducing the risk of cardiac events, especially major events, in subjects with type 2 diabetes mellitus at high cardiovascular risk.

The transient depression of hippocampal CA1 LTP induced by chronic intermittent ethanol exposure is associated with an inhibition of the MAP kinase pathway

Using electrophysiological and biochemical approaches, we investigated the effects of chronic, intermittent ethanol (CIE) treatment on activation of the mitogen activated protein kinase (MAPK), also known as extracellular signal regulated protein kinase 1 and 2. In hippocampal slices taken from control rats, brief high-frequency stimulation to Schaffer collateral fibers induced a large post-tetanic potentiation (PTP) in the CA1 region that decayed to stable long-term potentiation (LTP) of field extracellular postsynaptic potentials. Western blot analyses showed that phosphorylation of MAPK was increased during PTP and returned to baseline levels during LTP. In slices from the rats removed immediately from CIE treatment, PTP and MAPK activation during the PTP was significantly less than that observed in control slices and LTP was absent. In slices from rats subjected to 1 day withdrawal from CIE treatment, both the reduction in MAPK phosphorylation during PTP and the impairment of PTP and LTP were still evident. Recovery of PTP and partial recovery of LTP was observed in slices obtained from 5-day withdrawn rats. However, MAPK activation during PTP was still attenuated significantly. Interestingly, MAPK activation was enhanced significantly during LTP in 5-day withdrawn rats as well as the sensitivity to MAPK inhibitor PD 098059. In addition to these changes in HFS-induced MAPK activation, we also observed a significant reduction in the basal phosphorylation of MAPK in slices removed from rats immediately after CIE treatment. These results implicate the MAPK signal transduction pathway as a potential cellular target of ethanol. Alterations in MAPKs could play an important role in the alcohol-induced changes in synaptic plasticity associated with the effects of alcohol abuse on learning and memory processes.

Long-term potentiation in the rat hippocampus is reversibly depressed by chronic intermittent ethanol exposure

Alcohol exposure induces multiple neuroadaptive changes in the CNS that can have serious long-term consequences on CNS function including cognitive effects and attenuation of learning and memory. The cellular mechanisms underlying the CNS effects of alcohol have yet to be fully elucidated and are likely to depend on the pattern and dose of alcohol exposure. Using electrophysiological recordings from hippocampal slices obtained from control and chronic alcohol-treated rats, we have investigated the effects of a binge pattern of alcohol abuse on synaptic plasticity in the CNS. The alcohol-treated animals were exposed to ethanol vapor for 12-14 days using an intermittent exposure paradigm (14 h ethanol exposure/10 h ethanol withdrawal daily; blood alcohol levels approximately 180 mg/dl), a paradigm that models human binge alcohol use. Induction of long-term potentiation (LTP) in the CA1 region of the hippocampus by tetanic stimulation of Schaffer collaterals was completely blocked in slices from the chronic alcohol-treated animals. LTP remained blocked 1 day after withdrawal of animals from alcohol, indicating that the neuroadaptive changes produced by alcohol were not readily reversible. Partial recovery was observed after withdrawal from alcohol for 5 days. Other measures of synaptic plasticity including posttetanic potentiation and paired-pulse facilitation were also altered by the intermittent alcohol treatment paradigm. The results suggest that alterations in synaptic plasticity induced by chronic intermittent ethanol consumption play an important role in the effects of binge alcohol use on learning and memory function.

Caulerpenyne, a toxin from the seaweed Caulerpa taxifolia, depresses afterhyperpolarization in invertebrate neurons

The massive invasion of the Mediterranean Sea by the tropical seaweed Caulerpa taxifolia (Vahl) C. Agardh has stimulated several investigations in order to test the environmental risk from an ecotoxicological point of view. The studies carried out on various experimental models have shown that caulerpenyne, the major metabolite synthesized by the seaweed, affects several cellular and molecular targets. In addition, neurological disorders have been reported in patients who accidentally ate C. taxifolia, but no evidence about the potential effects of the seaweed and of its metabolites on nerve cells were up to now available. Herein we describe that caulerpenyne modifies the electrical properties of touch mechanosensory cells of the leech Hirudo medicinalis. The physiological firing of these cells causes an afterhyperpolarization that is mainly due to the activity of the Na+/K+-ATPase and to a lesser extent to a calcium-dependent potassium current. Caulerpenyne depressed this afterhyperpolarization; the effect was dose-dependent and partially reversible. Experiments have been carried out in order to understand the mechanism through which caulerpenyne reduced the afterhyperpolarization. The action of the biotoxin has been tested in the presence of pharmacological blockers of calcium-dependent potassium channels such as cadmium and apamin. In these experimental conditions, caulerpenyne still reduced the residual afterhyperpolarization, suggesting a direct effect of the toxin on the Na+/K+-ATPase. In order to test this hypothesis, we have performed experiments where the Na+/K+-ATPase was activated by the intracellular injection of sodium and where also its basal activity was modified as well. From the data collected we suggest that caulerpenyne inhibits both the basal and the sodium-induced activity of the Na+/K+-ATPase in leech touch neurons.

Differential effects of PACAP-38 on synaptic responses in rat hippocampal CA1 region

Pituitary adenylate cyclase-activating polypeptide (PACAP-38) is a member of the vasointestinal polypeptide (VIP)/secretin/glucagon family of neuropeptides for which neuroregulatory functions have been postulated. PACAP-38 receptors are expressed in different brain regions, including hippocampus. In this study, we examined the dose-dependent effects of PACAP-38 on the excitatory postsynaptic field potential (fEPSP) evoked at the Schaffer collateral-CA1 synapse in rat hippocampal slices. Bath application of low dose (0.05 nM) of PACAP-38 induced long-lasting facilitation of the fEPSP. This enhancement was blocked by the cholinergic receptor antagonist atropine and partially by the NMDA receptor antagonist 2-amino-5-phosphonovalerate (APV) and therefore, shares a common mechanism with LTP. In contrast, a high dose (1 microM) of PACAP-38 induced a persistent depression of the fEPSP that was not blocked by antagonists of cholinergic receptors (i.e., atropine and mecamylamine), adenosine receptors (i.e., DCPCX), or glutamatergic NMDA receptors (APV). Intermediate doses (0.1-0.5 microM) of PACAP-38 produced an initial decrease of the fEPSP followed by an enhancement. This decrease was not blocked by atropine whereas the facilitation was. These results show that PACAP-38 modulates CA1 synaptic transmission in a dose-dependent manner and that the peptide interacts with cholinergic and glutamatergic systems.

Pituitary adenylate cyclase-activating polypeptide hormone (PACAP) at very low dosages improves memory in the rat

To ascertain whether very low dosages of pituitary adenylate cyclase-activating polypeptide (PACAP) influence learning in mammals, immediately after the acquisition trial of a passive avoidance response (PAR) paradigm, PACAP-38 was administered intracerebroventricularly at increasing dosages (0, 0.02, 0.2, 2, 20, and 200 ng in 10 microl saline) to different groups of rats. The mnemonic effects were measured by means of retention testing 48 and 96 h later. At intermediate PACAP-38 concentrations there was a significant mnemonic improvement of the PAR. The maximal effect was observed after the 0.2-ng PACAP-38 administration (longer step-through latencies). There was a lesser effect at the subsequent higher concentration, 2 ng. Higher dosages had no effects. It is concluded that PACAP-38 acts as an enhancer of mammalian mnemonic processes even at very low dosages. The positive effect follows an inverted U-shaped dose-response curve. The results may be of interest for the therapy of some neuropathological conditions.

Long-lasting hippocampal potentiation and contextual memory consolidation

In order to ascertain whether there are hippocampal electrophysiological modifications specifically related to memory, exploratory activity and emotional stress, extracellular electrical activity was recorded in hippocampal slices prepared from the brains of male adult rats. Several groups of animals were employed: (i) rats which had freely explored the experimental apparatus (8 min exposure); (ii) rats which had been subjected, in the same apparatus, to a fear conditioning paradigm training entailing the administration of aversive electrical footshocks (8 min exposure); (iii) rats to which the same number of aversive shocks had been administered in the same apparatus, but temporally compressed so as to make difficult the association between painful stimuli and the apparatus (30 s exposure); (iv) naïve rats never placed in the apparatus. Half of the rats from each treatment group were used for retrieval testing and the other half for hippocampal excitability testing. The conditioned freezing response was exhibited for no less than 4 weeks. Hippocampal excitability was measured by means of input-output curves (IOC) and paired-pulse facilitation curves (PPF). Retrieval testing or brain slices preparation were performed at increasing delays after the training sessions: immediately afterwards or after 1, 7 or 28 days. Only the rats subjected to the fear conditioning training exhibited freezing when placed again in the apparatus (retrieval testing). It was found that IOCs, with respect to naïve rats, increased in the conditioned animals up to the 7-day delay. In free exploration animals the IOCs increased only immediately after the training session. In all other rats no modification of the curves was observed. IOC increases do not appear to imply presynaptic transmitter release modifications, because they were not accompanied by PPF modifications. In conclusion, a clear-cut correlation was found between the increase in excitability of the Schaffer collateral-CA1 dendrite synapses and freezing response consolidation.

PACAP-38 enhances excitatory synaptic transmission in the rat hippocampal CA1 region

Specific receptors for pituitary adenylate cyclase-activating polypeptide (PACAP), a novel peptide with neuroregulatory and neurotrophic functions, have been identified recently in different brain regions, including the hippocampus. In this study, we examined the effects of PACAP-38 on the excitatory postsynaptic field potentials (fEPSPs) evoked at the Schaffer collateral-CA1 synapses. Brief bath application of PACAP-38 (0.05 nM) induced a long-lasting facilitation of the basal transmission. Enhancement of this response was occluded in part by previous high-frequency-induced long-term potentiation (LTP). PACAP-38 did not significantly alter the paired-pulse facilitation (PPF). PACAP-38 has been shown to have a presynaptic effect on the septohippocampal cholinergic terminals, which results in an increase in basal acetylcholine (ACh) release. To assess whether the PACAP-38 enhancement of CA1 synapses was related to the activation of the cholinergic system we examined the effect of this peptide in the presence of atropine, a muscarinic receptor antagonist. The enhancement of the fEPSPs by PACAP-38 was blocked by bath application of atropine. These results show that PACAP-38 induces facilitation of hippocampal synaptic transmission through activation of the cholinergic system via the muscarinic receptors.