Association between inflammation and neural plasticity biomarkers in olfactory neuroepithelium – derived cells and cognitive performance in patients with major depressive disorder

Introduction

Inflammation and neural plasticity play a significant role in major depressive disorder (MDD) pathogenesis and cognitive dysfunction. The olfactory neuroepithelium (ON), closely related to the central nervous system (CNS), allows a non-invasive, low-cost study of neuropsychiatric disorders. However, few studies have used ON cells to ascertain them as biomarkers for MDD.

Objectives

Determine the relationship between inflammatory/neural plasticity markers and cognitive functioning in MDD patients and healthy controls.

Methods

Sample: 9 MDD patients and 7 healthy controls. Exclusion criteria: other Axis I mental disorders (patients) or any mental disorder (controls) and any inflammatory, autoimmune, or CNS diseases. Assessment: sociodemographic, clinical, and cognitive variables (CANTAB) were recorded. mRNA was isolated from ON cells and MAPK14, IL6, TNF-α, Mecp2, BDNF, GSK3, GRIA2, and FosB gene expression levels were quantified using quantitative polymerase chain reaction.

Results

MDD patients showed decreased levels of BDNF (p=0.022), GSK3 (p=0.027), and working memory (p=0.024) compared with healthy controls. In healthy controls, planning was positively correlated with NRF2, BDNF, and MAPK14 gene expression. In MDD patients no correlation between cognitive parameters and inflammation/neural plasticity biomarkers was found.

Conclusions

These results reveal that: (1) Plasticity biomarkers such as BDNF and GSK3 could be useful diagnostic tools for MDD (2) MDD is associated with working memory deficits; (3) no association could be determined between planning and NRF2, BDNF, and MAPK14 gene expression in MDD and (4) the ON is a promising model in the study of neuropsychiatric disorders.

Disclosure

No significant relationships.

Incidence, Clinical Characteristics and Management of Inflammatory Bowel Disease in Spain: Large-Scale Epidemiological Study

(1) Aims: To assess the incidence of inflammatory bowel disease (IBD) in Spain, to describe the main epidemiological and clinical characteristics at diagnosis and the evolution of the disease, and to explore the use of drug treatments. (2) Methods: Prospective, population-based nationwide registry. Adult patients diagnosed with IBD—Crohn’s disease (CD), ulcerative colitis (UC) or IBD unclassified (IBD-U)—during 2017 in Spain were included and were followed-up for 1 year. (3) Results: We identified 3611 incident cases of IBD diagnosed during 2017 in 108 hospitals covering over 22 million inhabitants. The overall incidence (cases/100,000 person-years) was 16 for IBD, 7.5 for CD, 8 for UC, and 0.5 for IBD-U; 53% of patients were male and median age was 43 years (interquartile range = 31–56 years). During a median 12-month follow-up, 34% of patients were treated with systemic steroids, 25% with immunomodulators, 15% with biologics and 5.6% underwent surgery. The percentage of patients under these treatments was significantly higher in CD than UC and IBD-U. Use of systemic steroids and biologics was significantly higher in hospitals with high resources. In total, 28% of patients were hospitalized (35% CD and 22% UC patients, p < 0.01). (4) Conclusion: The incidence of IBD in Spain is rather high and similar to that reported in Northern Europe. IBD patients require substantial therapeutic resources, which are greater in CD and in hospitals with high resources, and much higher than previously reported. One third of patients are hospitalized in the first year after diagnosis and a relevant proportion undergo surgery.

EpidemIBD: rationale and design of a large-scale epidemiological study of inflammatory bowel disease in Spain

BACKGROUND

Inflammatory bowel disease (IBD) is associated with a considerable burden to the patient and society. However, current data on IBD incidence and burden are limited because of the paucity of nationwide epidemiological studies, heterogeneous designs, and a low number of participating centers and sample size. The EpidemIBD study is a large-scale investigation to provide an accurate assessment of the incidence of IBD in Spain, as well as treatment patterns and outcomes.

METHODS

This multicenter, population-based incidence cohort study included patients aged >18 years with IBD (Crohn's disease, ulcerative colitis, or unclassified IBD) diagnosed during 2017 in 108 hospitals in Spain, covering 50% of the Spanish population. Each participating patient will attend 10 clinic visits during 5 years of follow up. Demographic data, IBD characteristics and family history, complications, treatments, surgeries, and hospital admissions will be recorded.

RESULTS

The EpidemIBD study is the first large-scale nationwide study to investigate the incidence of IBD in Spain. Enrollment is now completed and 3627 patients are currently being followed up.

CONCLUSIONS

The study has been designed to overcome many of the limitations of previous European studies into IBD incidence by prospectively recruiting a large number of patients from all regions of Spain. In addition to epidemiological information about the burden of IBD, the 5-year follow-up period will also provide information on treatment patterns, and the natural history and financial burden of IBD.

The Harvey-Bradshaw Index Adapted to a Mobile Application Compared with In-Clinic Assessment: The MediCrohn Study

Objectives: Mobile apps are useful tools in e-health and self-management strategies in disease monitoring. We evaluated the Harvey–Bradshaw index (HBI) mobile app self-administered by the patient to see if its results agreed with HBI in-clinic assessed by a physician.

Methods: Patients were enrolled in a 4-month prospective study with clinical assessments at months 1 and 4. Patients completed mobile app HBI and within 48 h, HBI was performed by a physician (gold standard). HBI scores characterized Crohn's disease (CD) as remission <5 or active ≥5. We determined agreement per item and total HBI score and intraclass correlation coefficients (ICCs). Bland–Altman plot was performed. HBI changes in disease activity from month 1 to month 4 were determined.

Results: A total of 219 patients were enrolled. All scheduled assessments (385 pairs of the HBI questionnaire) showed a high percentage of agreement for remission/activity (92.4%, κ = 0.796), positive predictive value (PPV) for remission of 98.2%, and negative predictive value of 76.7%. High agreement was also found at month 1 (93.15%, κ = 0.82) and month 4 (91.5%, κ = 0.75). Bland–Altman plot was more uniform when the HBI mean values were <5 (remission). ICC values were 0.82, 0.897, and 0.879 in all scheduled assessments, 1 and 4 months, respectively.

Conclusions: We found a high percentage of agreement between patients' self-administered mobile app HBI and in-clinic physician assessment to detect CD activity with a remarkably high PPV for remission. The mobile app HBI might allow a strict control of inflammation by remote monitoring and flexible follow-up of CD patients. Reduction of sanitary costs could be possible.

For the good of the nation: scientific discourses endorsing the medicalization of childbirth in Peru, 1900-1940

Over the course of the twentieth century, a series of changes occurred in the understanding of childbirth, which went from being a natural reproductive phenomenon belonging to the female, domestic sphere to a professional medical matter handled in an institutional setting. Through procedures like the use of anesthesia, Cesarean sections, ultrasound and other techno-scientific interventions, rapid and significant improvements and changes took place in the health and life of society and of women. The medicalization of childbirth in the early twentieth century was part of a broader process of constructing the state and institutionalizing the patriarchy that was common throughout the region.

Prevalence of Malnutrition and Nutritional Characteristics of Patients With Inflammatory Bowel Disease

BACKGROUND AND AIMS

This study sought to determine the prevalence of malnutrition in patients with inflammatory bowel disease, to analyse the dietary beliefs and behaviours of these patients, to study their body composition, to evaluate their muscular strength and to identify the factors associated with malnutrition in these patients.

METHODS

This was a prospective, multicentre study. Crohn's disease and ulcerative colitis patients from 30 Spanish centres, from the outpatient clinics, were included. A questionnaire of 11 items was applied to obtain data from patients' dietary behaviour and beliefs. Patients who accepted were evaluated to assess their nutritional status using Subjective Global Assessment and body mass index. Body composition was evaluated through bioelectrical impedance.

RESULTS

A total of 1271 patients were included [51% women, median age 45 years, 60% Crohn's disease]. Of these, 333 patients underwent the nutritional evaluation. A total of 77% of patients declared that they avoided some foods to prevent disease relapse. Eighty-six per cent of patients avoided some foods when they had disease activity because of fear of worsening the flare. Sixty-seven per cent of patients modified their dietary habits after disease diagnosis. The prevalence of malnutrition was 16% [95% confidence interval = 12-20%]. In the multivariate analysis, history of abdominal surgery, active disease and avoidance of some foods during flares were associated with higher risk of malnutrition.

CONCLUSIONS

The prevalence of malnutrition in inflammatory bowel disease patients was high. We identified some predictive factors of malnutrition. Most of the patients had self-imposed food restrictions, based on their beliefs.

CB1-5-HT2A heteromers in schizophrenia patients: Human studies in pro-neurons of the olfactory epithelium

Introduction

Despite multiple clinical and preclinical studies investigating schizophrenia, the neurobiological basis of this disease is still unknown. The dysregulation of the serotonergic system, in particular the 5-HT2A receptor and the endocannabinoid system have been postulated as possible causes of schizophrenia.

Objectives

The aim of this study is to evaluate the expression of CB1-5-HT2A receptor heteromers in primary cultures of pro-neurons from the olfactory epithelium in schizophrenia patients and control subjects.

Methods

We recruited a group of 10 healthy volunteers and 10 patients diagnosed with schizophrenia, who were treated with atypical antipsychotics, were clinically stable and had an illness duration range from 1 up to 15 years. The patients were diagnosed with schizophrenia from the medical record and confirmed by the structured clinical interview for DSM disorders. The expression of CB1-5-HT2A receptor heteromers in primary cultures of pro-neurons from the olfactory epithelium was quantified using proximity ligation assays and confocal microscopy.

Results

Olfactory epithelium pro-neurons were viable and expressed the neuronal marker, III-β tubulin. We also established the presence and the functionality of CB1-5-HT2A receptor heteromers in these cells using the proximity ligation and cAMP activity assays, respectively. Heteromer expression was significantly increased in schizophrenia patients with respect to controls.

Conclusions

This highly innovative methodology will allow the noninvasive, low-cost study of new biomarkers for schizophrenia in a model closely related to the central nervous system.

Disclosure of interest

The authors have not supplied their declaration of competing interest.Acknowledgments

This work was supported by grants from DIUE-Generalitat-de Catalunya (2014SGR 680), Instituto de Salud Carlos III (PI14/00210) and (PI10/01708) FIS-FEDER-Funds. LG is supported by the Instituto-de Salud Carlos III through a “Río Hortega” (CM14/00111).

Active and passive MDMA ('ecstasy') intake induces differential transcriptional changes in the mouse brain

3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') is a recreational drug widely used by adolescents and young adults. Although its rewarding effects are well established, there is controversy on its addictive potential. We aimed to compare the consequences of active and passive MDMA administration on gene expression in the mouse brain since all previous studies were based on passive MDMA administration. We used a yoked-control operant intravenous self-administration paradigm combined with microarray technology. Transcriptomic profiles of ventral striatum, frontal cortex, dorsal raphe nucleus and hippocampus were analysed in mice divided in contingent MDMA, yoked MDMA and yoked saline groups, and several changes were validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The comparison of contingent MDMA and yoked MDMA vs. yoked saline mice allowed the identification of differential expression in several genes, most of them with immunological and inflammatory functions, but others being involved in neuroadaptation. In the comparison of contingent MDMA vs. yoked MDMA administration, hippocampus and the dorsal raphe nucleus showed statistically significant changes. The altered expression of several genes involved in neuroadaptative changes and synapse function, which may be related to learning self-administration behaviour, could be validated in these two brain structures. In conclusion, our study shows a strong effect of MDMA administration on the expression of immunological and inflammatory genes in all the four brain regions studied. In addition, experiments on MDMA self-administration suggest that the dorsal raphe nucleus and hippocampus may be involved in active MDMA-seeking behaviour, and show specific alterations on gene expression that support the addictive potential of this drug.

[Reading comprehension of students with attention deficit hyperactivity disorder: what is the role of executive functions?]

INTRODUCTION

Deficits in reading comprehension of children with attention deficit hyperactivity disorder (ADHD) have received scarce attention. However, to establish the underlying cognitive processes of ADHD and deficits in reading comprehension association could be essential for deeply understanding neurobiological bases of reading comprehension.

AIM

To examine the contribution of verbal fluency, reading fluency, and executive functions (working memory, attention and suppression mechanism) in predicting mental processes of texts comprehension.

PATIENTS AND METHODS

The participants in the study were 42 students, 12 to 16 year old, with a clinical diagnosis of ADHD. A battery of tests was administered to measure cognitive processes and reading processes.

RESULTS AND CONCLUSIONS

Stepwise regression analysis carried out showed that the score in verbal fluency was the best single predictor of reading comprehension. Furthermore executive functions, but not reading fluency, made a significant contribution to reading comprehension. These findings underline the need for consideration of the role of executive functions in assessment and treatment of reading comprehension deficits of students with ADHD.

Oleoylethanolamide exerts partial and dose-dependent neuroprotection of substantia nigra dopamine neurons

Oleoylethanolamide (OEA), agonist of nuclear PPAR-alpha receptors and antagonist of vanilloid TRPV1 receptors, has been reported to show cytoprotective properties. In this study, OEA-induced neuroprotection has been tested in vitro and in vivo models of 6-OHDA-induced degeneration of substantia nigra dopamine neurons. First, PPAR-alpha receptors were confirmed to be located in the nigrostriatal circuit, these receptors being expressed by dopamine neurons of the substantia nigra, and intrinsic neurons and fibers bundles of the dorsal striatum. In the substantia nigra, their location was confined to the ventral tier. The in vitro study showed that 1 microM OEA exerted a significantly neuroprotective effect on cultured nigral dopamine neurons, effects following U-shaped dose-response curves. Regarding the in vivo study, rats were locally injected with OEA into the right striatum and vehicle into the left striatum 30 min before 6-OHDA-induced striatal lesion. In the short term, signals of heme oxygenase-1 (oxidation marker, 24 and 48 h post-lesion) and OX6 (reactive microglia marker, 96 h post-lesion) were found to be significantly less intense in the striatum pretreated with 5 microM OEA. In the long term (1 month), reduction in striatal TH and synaptophysin was less intense whether the right striatum was pretreated with 5 microM OEA, and nigral TH+ neuron death was significantly reduced after pretreatment with 1 and 5 microM OEA. In vivo effects also followed U-shaped dose-response curves. In conclusion, OEA shows U-shaped partial and dose-dependent neuroprotective properties both in vitro and in vivo models of substantia nigra dopamine neuron degeneration. The occurrence of U-shaped dose-response relationships normally suggests toxicity due to high drug concentration or that opposing intracellular pathways are activated by different OEA doses.

In vivo co-ordinated interactions between inhibitory systems to control glutamate-mediated hippocampal excitability

We present an overview of the long-term adaptation of hippocampal neurotransmission to cholinergic and GABAergic deafferentation caused by excitotoxic lesion of the medial septum. Two months after septal microinjection of 2.7 nmol alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA), a 220% increase of GABA(A) receptor labelling in the hippocampal CA3 and the hilus was shown, and also changes in hippocampal neurotransmission characterised by in vivo microdialysis and HPLC. Basal amino acid and purine extracellular levels were studied in control and lesioned rats. In vivo effects of 100 mm KCl perfusion and adenosine A(1) receptor blockade with 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) on their release were also investigated. In lesioned animals GABA, glutamate and glutamine basal levels were decreased and taurine, adenosine and uric acid levels increased. A similar response to KCl infusion occurred in both groups except for GABA and glutamate, which release decreased in lesioned rats. Only in lesioned rats, DPCPX increased GABA basal level and KCl-induced glutamate release, and decreased glutamate turnover. Our results evidence that an excitotoxic septal lesion leads to increased hippocampal GABA(A) receptors and decreased glutamate neurotransmission. In this situation, a co-ordinated response of hippocampal retaliatory systems takes place to control neuron excitability.

Absence of delta -9-tetrahydrocannabinol dysphoric effects in dynorphin-deficient mice

The involvement of dynorphin on Delta-9-tetrahydrocannabinol (THC) and morphine responses has been investigated by using mice with a targeted inactivation of the prodynorphin (Pdyn) gene. Dynorphin-deficient mice show specific changes in the behavioral effects of THC, including a reduction of spinal THC analgesia and the absence of THC-induced conditioned place aversion. In contrast, acute and chronic opioid effects were normal. The lack of negative motivational effects of THC in the absence of dynorphin demonstrates that this endogenous opioid peptide mediates the dysphoric effects of marijuana.

[Viability of colonoscopy without analgesia and conscious sedation]

AIM

To study the need for analgesia and sedation before colonoscopy.

PATIENTS AND STUDY DESIGN

Fifty consecutive outpatients were randomly assigned to receive meperidine (0.7 mg/kg) or midazolam (0-035 mg/kg) intravenously (n = 25) or to receive no medication (n = 25) before colonoscopy. Oxygen saturation (SaO2) and heart rate were monitored. Mean blood pressure (MBP) was recorded before and after endoscopy. Patients in the group receiving no medication who experienced marked abdominal pain received sedation and analgesia similar to the premedicated group. Twenty-four hours after the procedure, the patients evaluated the degree of abdominal pain experienced during colonoscopy on a scale from 0 to 9.

RESULTS

Complete colonoscopy was performed in 92% of the patients. No significant changes in heart rate were registered in either group. However, in the premedicated group mean blood pressure fell significantly (97.6 +/- 2.6 vs. 89.5 +/- 2.7 mmHg) before and after colonoscopy, respectively (p < 0.05). Nine patients experienced clinically relevant oxygen desaturation (SaO2 > 90%). Of these, five were from the premedicated group and four were from the group receiving no medication. In two patients, both from the premedicated group, the decrease in SaO2 was severe (SaO2 < 85%). The degree of abdominal pain was similar in both groups: 3.64_0.47 (premedicated) vs. 3.92 +/- 0.5 (non-medicated). In the non-medicated group, two patients required analgesia and sedation to complete the colonoscopy and 20 (80%) preferred not to receive sedation in future colonoscopies.

CONCLUSIONS

Colonoscopy may be well tolerated without systematic administration of sedation and analgesia, which could be administered selectively.

Effects of sub-chronic combined treatment with pergolide and caffeine on contralateral rotational behavior in unilateral 6-hydroxydopamine-denervated rats

We studied the synergistic effects of pergolide and bromocriptine with caffeine on turning behavior in 6-OHDA denervated rats. Both pergolide and bromocriptine were synergistic with caffeine, and prevented tolerance to caffeine-induced turning. When caffeine was removed, tolerance to bromocriptine effects was observed for 1 day only, while no tolerance was observed to pergolide. These results suggest that caffeine could be useful in the treatment of Parkinson's disease, preferentially as an adjuvant of mixed dopaminergic agonists like pergolide.

Methylxanthines reverse the adipsic and aphagic syndrome induced by bilateral 6-hydroxydopamine lesions of the nigrostriatal pathway in rats

This study investigated whether methylxanthines (caffeine and theophylline) would restore food and water intake in rats made aphagic and adipsic by bilateral 6-hydroxydopamine lesions of the nigrostriatal bundle, and these results were compared with the effects of d-amphetamine, the dopamine D(1) agonist SKF 38393, and the D(2/3) agonist quinpirole. In a separate experiment, we investigated whether the selective D(1) antagonist, SCH 23390, or the selective D(2) antagonist, sulpiride, would prevent the caffeine-induced restoration of food and water intake in bilaterally 6-hydroxydopamine denervated rats. The results showed that caffeine, theophylline, and quinpirole significantly reversed the aphagia and adipsia observed in lesioned animals. SKF 38393 had no significant effects on water intake, while it significantly restored food intake at the highest dose used. In contrast, d-amphetamine had no significant effects on food or water intake. Results from the second experiment showed that sulpiride attenuated the caffeine-induced restoration of food and water intake in lesioned rats to a greater extent than did SCH 23390. These data suggest that methylxanthines may mediate their effects on food and water intake in bilateral 6-hydroxydopamine-lesioned rats through an action at the dopaminergic system.

Repeated co-administration of caffeine and bromocriptine prevents tolerance to the effects of caffeine in the turning behavior animal model

The present study examined the effects of repeated co-administrations of caffeine and bromocriptine for 9 consecutive days on contralateral turning in unilateral nigrostriatal 6-hydroxydopamine denervated rats. In agreement with previous data, our results showed that on the first administration, both caffeine and bromocriptine injected plus saline produced a significant increase in contralateral rotational behavior as compared to saline-saline injections. However, with repeated administrations, tolerance was observed to caffeine, but not to bromocriptine. The combination of different doses of bromocriptine (0.1, 0.2, 0.4 and 0.8 mg/kg) with caffeine (40 mg/kg) significantly enhanced the effects of either drug injected with saline on rotational behavior, and no tolerance was observed with repeated treatment. The continuous co-administration of both substances was necessary to maintain elevated levels of rotational behavior, since withdrawing one or the other drug led to decreased contralateral turning. These results demonstrate that when caffeine is administered repeatedly in combination with bromocriptine, tolerance to its psychostimulant effects is not observed, suggesting that caffeine could be used as an adjunctive therapeutic agent with dopamine agonists for the treatment of Parkinson's disease.

Effects of adenosine and gamma-aminobutyric acid A receptor antagonists on N-methyl-D-aspartate induced neurotoxicity in the rat hippocampus

This study investigated the modulatory actions of adenosine and gamma-aminobutyric acid (GABA) on several aspects of N-methyl-D-aspartate (NMDA)-induced neurotoxicity, including neuronal loss, atrophy, necrosis, and calcium accumulation in the hippocampus. For this purpose, we combined unilateral intrahippocampal injections of NMDA (24 nmoles) with acute injections of the selective A1 adenosine receptor antagonist DPCPX (0.03 pmoles), the selective adenosine A2a receptor antagonist CSC (1.5 pmoles), a combination of these two antagonists, and injections of the selective GABA A receptor antagonist bicuculline (60 pmoles). Fifteen days after NMDA injection, neuronal loss with preservation of architecture was observed in stratum oriens, pyramidale, radiatum, lacunosum-moleculare, and stratum moleculare of Ammon's horn, and in radial and granular layers of the dentate gyrus. NMDA plus vehicle also produced a small degree of brain tissue necrosis (holes in the structure) in four of five brains. Acute injections of CSC, but not DPCPX or bicuculline, significantly increased the extent of neuronal loss produced by NMDA plus vehicle. CSC in combination with NMDA induced significantly more necrosis than NMDA plus vehicle. A significant degree of atrophy was observed in the hippocampus after treatment with NMDA plus vehicle, and bicuculline significantly increased the magnitude of this atrophy. NMDA-induced calcium deposits were detected within the radiatum and lacunosum-moleculare layers of the hippocampus and in the hilus of the dentate, but not in the stratum oriens, stratum pyramidale, or in the granular layer of the dentate gyrus. However, treatment with the different antagonists did not significantly modify the magnitude of the NMDA-induced calcium deposits. These results reveal a selective vulnerability of certain areas of the hippocampus to the accumulation of calcium deposits, and a selective interaction between adenosine receptors and NMDA-induced neurotoxicity in the hippocampus.

Associative processes in addiction and reward. The role of amygdala-ventral striatal subsystems

Only recently have the functional implications of the organization of the ventral striatum, amygdala, and related limbic-cortical structures, and their neuroanatomical interactions begun to be clarified. Processes of activation and reward have long been associated with the NAcc and its dopamine innervation, but the precise relationships between these constructs have remained elusive. We have sought to enrich our understanding of the special role of the ventral striatum in coordinating the contribution of different functional subsystems to confer flexibility, as well as coherence and vigor, to goal-directed behavior, through different forms of associative learning. Such appetitive behavior comprises many subcomponents, some of which we have isolated in these experiments to reveal that, not surprisingly, the mechanisms by which an animal sequences responding to reach a goal are complex. The data reveal how the different components, pavlovian approach (or sign-tracking), conditioned reinforcement (whereby pavlovian stimuli control goal-directed action), and also more general response-invigorating processes (often called "activation," "stress," or "drive") may be integrated within the ventral striatum through convergent interactions of the amygdala, other limbic cortical structures, and the mesolimbic dopamine system to produce coherent behavior. The position is probably not far different when considering aversively motivated behavior. Although it may be necessary to employ simplified, even abstract, paradigms for isolating these mechanisms, their concerted action can readily be appreciated in an adaptive, functional setting, such as the responding by rats for intravenous cocaine under a second-order schedule of reinforcement. Here, the interactions of primary reinforcement, psychomotor activation, pavlovian conditioning, and the control that drug cues exert over the integrated drug-seeking response can be seen to operate both serially and concurrently. The power of our analytic techniques for understanding complex motivated behavior has been evident for some time. However, the crucial point is that we are now able to map these components with increasing certainty onto discrete amygdaloid, and other limbic cortical-ventral striatal subsystems. The neural dissection of these mechanisms also serves an important theoretical purpose in helping to validate the various hypothetical constructs and further developing theory. Major challenges remain, not the least of which is an understanding of the operation of the ventral striatum together with its dopaminergic innervation and its interactions with the basolateral amygdala, hippocampal formation, and prefrontal cortex at a more mechanistic, neuronal level.

Rotational behavior in dopamine nigrostriatal denervated rats: effects of a wide range of time intervals between apomorphine administrations

Previous studies using the turning behavior animal model have shown both increases and decreases in rotational behavior following successive administrations of dopamine agonists. To clarify the results obtained with this model, we studied the variability of rotational behavior after repeated challenges with low doses of apomorphine (0.05 mg/kg) at different time intervals ranging between 2 h and 14 days. Results show a decrease in the total number of turns with time intervals of 2, 6, and 12 h between administrations, and an increase in the total number of turns when apomorphine was administered once every 24 h. In contrast, when animals were tested at 7- and 14-day intervals, a stable number of turns in successive challenges was obtained. These results suggest that when successive injections of dopamine agonists are administered at sufficiently long intervals of time, the neuroadaptations that take place due to repeated drug exposure may not be apparent. These findings are relevant for the design of future experiments using this model.

Scopolamine prevents tolerance to the effects of caffeine on rotational behavior in 6-hydroxydopamine-denervated rats

Continuous administration of caffeine has been shown to induce tolerance to its psychostimulant effects. In this study, using unilateral 6-hydroxydopamine nigrostriatal denervated rats, we tested the hypothesis that the muscarinic receptor antagonist, scopolamine, would prevent the tolerance to caffeine-induced contralateral rotational behavior. For that purpose we administered either caffeine (40 mg/kg) plus saline or scopolamine (5, 10 and 20 mg/kg) plus saline, as well as caffeine in combination with the various doses of scopolamine for 7 consecutive days, and measured ipsilateral and contralateral rotational behavior. The results showed that acute injections of scopolamine plus saline produced similar levels of both ipsilateral and contralateral turning, while caffeine produced more contralateral than ipsilateral turning. Tolerance to caffeine-induced contralateral turning was observed as of the second administration, while scopolamine plus saline injections did not produce significant changes in rotational behavior with repeated treatment. Scopolamine co-administered with caffeine significantly attenuated the increased contralateral turning produced by acute injections of caffeine plus saline, but significantly prevented the tolerance effects with repeated administration. These findings strongly suggest that muscarinic cholinergic processes may be involved in tolerance to caffeine-induced contralateral turning. The results are interpreted in terms of the possible interactions between dopamine, adenosine and acetylcholine neurotransmitter systems within the basal ganglia circuitry involved in motor behavior.

Effects of lesions of the nucleus basalis magnocellularis on the acquisition of cocaine self-administration in rats

The nucleus basalis magnocellularis (NBM) is one element in the limbic cortical-ventral striatal circuitry that has been implicated in reinforcement processes. The present study examined the involvement of the cholinergic neurons of the NBM in mediating aspects of cocaine reinforcement. Lesions of the NBM were made by injecting 0.01 M AMPA into the subpallidal basal forebrain. Following 4 days' recovery, rats were implanted chronically with catheters in the jugular vein. In three separate experiments, rats were trained to acquire cocaine self-administration under a FR1 schedule of reinforcement at doses of 0.25, 0.083 and 0.028 mg/injection. A dose-effect function was also determined at the end of the acquisition experiments using five different doses of cocaine (0.009, 0.028, 0.083, 0.25, 0.50 mg/injection) and saline which were presented once daily in a Latin square design. There were no significant differences between groups in the acquisition of cocaine self-administration at any of the three doses studied (0.028, 0.083 and 0.25 mg/injection), although at the lowest dose, lesioned animals responded at greater levels on both active and inactive levers. However, a shift to the left in the cocaine dose-response function was observed revealing that the lesioned group self-administered significantly higher amounts of low doses of cocaine than control rats. These data suggest that the integrity of the NBM is not a critical determinant of the reinforcing effects of cocaine during the acquisition of self-administration of the drug, but that NBM-dependent cholinergic mechanisms may nevertheless interact with the neural substrates mediating the reinforcing properties of cocaine. The data are relevant to recent hypotheses of functional interactions between the dopaminergic system and the cholinergic NBM.

Long latency event-related potentials in rats: response of amygdala, nucleus accumbens, dorsal hippocampus and frontal cortex to changes in reward characteristics of conditioned stimuli

Circuits involving major afferents to the ventral striatum from the frontal cortex, amygdala and hippocampus have been implicated in the selective processing of conditioned stimuli predictive of 'important events' or reward-related processes. We utilized an animal model of event-related potentials (ERPs) to explore the relationship between these brain areas during the performance of a conditioning/extinction task. Significant reductions in the N1 component in cortex and P2 component in amygdala of the rat ERP were found as a consequence of removal of the food reward previously associated with the stimuli. Lesions of the nucleus basalis magnocellularis were without effect on the pattern of ERP morphology changes associated with the removal of the reward. Since the N1 component of the ERP has been linked to attentional processes, these studies suggest that elimination of reward characteristics of conditioning stimuli can lead to a specific reductions in 'attention' and or 'sensory reaction' in frontal cortex and amygdala but not to general habituation to these stimuli or in other areas of the CNS.

Effects of excitotoxic lesions of the central amygdaloid nucleus on the potentiation of reward-related stimuli by intra-accumbens amphetamine

The present study examined the effects of lesions of the central nucleus of the amygdala (CeA) on the acquisition of a new response with conditioned reinforcement (CR) and its potentiation by intra-accumbens infusions of d-amphetamine (1, 3, 10, and 20 microg/microl). Rats were trained to associate a light-plus-noise compound stimulus with the availability of a sucrose solution before receiving both bilateral ibotenic acid lesions of the CeA and cannulas implanted above the nucleus accumbens. Lesions of the central nucleus did not impair the performance of positively reinforced discriminated approach, nor did they impair the acquisition of a new response with conditioned reinforcement. However, the potentiation of responding with CR following intra-accumbens amphetamine was blocked in lesioned animals. These results are discussed in terms of the possible interactions between associative mechanisms in the amygdala and the mesolimbic dopamine projection.

Effects of excitotoxic lesions of the central amygdaloid nucleus on the potentiation of reward-related stimuli by intra-accumbens amphetamine

The present study examined the effects of lesions of the central nucleus of the amygdala (CeA) on the acquisition of a new response with conditioned reinforcement (CR) and its potentiation by intra-accumbens infusions of d-amphetamine (1, 3, 10, and 20 microg/microl). Rats were trained to associate a light-plus-noise compound stimulus with the availability of a sucrose solution before receiving both bilateral ibotenic acid lesions of the CeA and cannulas implanted above the nucleus accumbens. Lesions of the central nucleus did not impair the performance of positively reinforced discriminated approach, nor did they impair the acquisition of a new response with conditioned reinforcement. However, the potentiation of responding with CR following intra-accumbens amphetamine was blocked in lesioned animals. These results are discussed in terms of the possible interactions between associative mechanisms in the amygdala and the mesolimbic dopamine projection.

Endoscopic anal dilatation for fissure-in-ano: a new outpatient treatment modality

We describe a new therapeutic procedure for fissure-in-ano, endoscopic anal dilatation. Anal dilatation is performed with a two-valved anoscope under local anesthesia in an ambulatory setting. We report our results using this technique in 62 patients after a mean follow-up of 19 months (range: 12-24 months). Thirty days after the procedure, 55 patients (93%) were symptom-free, whereas 3 of them (4.8%) failed to improve. After nineteen months, one patient out of 47 in follow-up had a recurrence. No bleeding, discharge or defects of continence, either transient or permanent, were noted. The results of endoscopic anal dilatation are comparable with those of lateral sphincterotomy, can be achieved at a lower complication rate, with only minor and temporary complications, and performed by physicians with no specific surgical training.

Effects of neurotensin on EEG and event-related potentials in the rat

Neurotensin has neuromodulatory actions on multiple brain functions including motor, sensory and limbic processes. However, little is known about how neurotensin affects general arousal and/or attention states. The present study evaluated the effects of neurotensin on spontaneous brain activity as well as auditory evoked responses using electrophysiological measures. Electroencephalographic and event-related potential recordings were obtained in awake animals following intracerebroventricular administration of neurotensin (1.0, 10.0 and 30.0 micrograms). Twenty rats were implanted with recording electrodes in the frontal cortex, dorsal hippocampus, amygdala and nucleus accumbens. Neurotensin was found to produce a dose-related effect on behavior and electrophysiological measures. Lower doses (10 micrograms) produced no obvious behavioral changes, but significantly reduced EEG power in the lower frequency ranges (2-6 Hz) in the frontal cortex, the anterior amygdaloid complex and the nucleus accumbens. At higher doses (30 micrograms), rats appeared behaviorally inactivated, and EEG power was reduced in all structures in both the lower frequency ranges (2-6 Hz) and the higher frequency ranges (8-32 Hz). Auditory processing, as assessed by event-related potentials, was affected most significantly in amygdala and dorsal hippocampus. In the amygdala, the amplitude of the P3 component of the auditory event-related potential was increased significantly by doses of 10.0 and 30.0 micrograms. In the dorsal hippocampus, the amplitude and the area of the N1 component was increased dose dependently and significance was reached at the 30 micrograms dose. These electrophysiological findings indicate that neurotensin does not reduce the arousal level of the animals and in fact may enhance neurosensory processing in limbic areas through increased arousal and/or enhanced stimulus evaluation.

Long-latency event-related potentials in rats: effects of task and stimulus parameters

Animal models of event-related potentials have recently been developed in rats in order to gain further understanding of the psychobiological variables which underlie these waveforms. In the present study, unanesthetized male Wistar rats, chronically implanted with electrodes, were utilized in order to: (i) compare event-related potentials recorded following the presentation of passively presented auditory stimuli from different neocortical, hippocampal and perihippocampal sites; (ii) test the effects of changes in stimulus probability and loudness on event-related potentials recorded from those sites; and (iii) record event-related potentials from rats who were actively performing in a tone discrimination task. The results of these studies showed that in all electrode sites (frontal cortex, parietal cortex, entorhinal cortex, hippocampus) a series of large amplitude potentials in the 10-200 ms latency range could be recorded in response to passively presented stimuli. Late positive potentials in the 300-400 ms range were only identified in recordings from the posterior cortex, entorhinal area, and dorsal hippocampus. Some of these late positive components were also found to be sensitive to changes in stimulus probability. A similar series of waves were detected in a paradigm where rats were required to actively discriminate between two tones; however, the morphologies of the waveforms were found to be more distinct. These studies suggest that rats may be good subjects for the exploration of the neural origins of event-related potentials. These studies demonstrate that rats performing in an auditory discrimination task can generate electrophysiological potentials which are time locked to the onset of a "cognitively relevant" stimulus (event-related potentials). These potentials can be recorded in limbic (hippocampus and amygdala) and cortical (parietal cortex) brain sites. The event-related potentials recorded in rats respond to changes in stimulus parameters in a similar fashion to those previously described in monkeys and human subjects. The identification of a rat model of event-related potentials provides an opportunity to further explore the neural origins of event-related potentials, to estimate the role of genetics in determining individual variation in waveforms, as well as to provide electrophysiological assays of the effects of various drugs on neurosensory and cognitive processing.

Effects of MK 801 and diazepam on the EEG of P and NP rats

The selectively bred alcohol-preferring (P) and alcohol-nonpreferring (NP) rats have been shown to possess a number of behavioral and electrophysiological differences in response to alcohol. We sought to evaluate whether or not P and NP rats would respond differently to other sedative-hypnotic drugs related to ethanol. EEG recordings were conducted following systemic administration of the NMDA receptor antagonist MK 801 (0.1 mg/kg, ip) and the GABA/benzodiazepine receptor complex agonist diazepam (1.5 mg/kg, ip). Nine P and nine NP rats was implanted with bipolar stainless steel electrodes in the frontal cortex, the dorsal hippocampus, the ventral thalamus, and the anterior amygdala. In the vehicle condition, P rats showed significantly greater power of the EEG in the slow frequencies as compared with NP rats in the frontal cortex. Furthermore, P rats were found to have lower peak theta frequency (6-8 Hz) than NP rats in the frontal cortex, the dorsal hippocampus, and the ventral thalamus. MK 801 produced a significantly greater increase in the mean power of the EEG in NP rats in the 8-16 Hz than in P rats, whereas diazepam was found to decrease theta peak frequency (6-8 Hz), but more so in NP rats that in P rats. These data suggest that, in addition to differential responsiveness to alcohol, P and NP rats also differ in response to drugs that modify GABA and glutamate neurotransmission.

The effects of acute cocaine administration on auditory event-related potentials in rats

Cocaine administration has been shown to affect several sites in the limbic forebrain. The nucleus accumbens has been implicated as an important site for the reinforcing aspects of this drug whereas, the amygdala and hippocampus may be more involved in drug conditioning and/or drug induced changes in the perception of stimuli. In the present study, auditory event-related potentials (ERPs) were utilized to explore the effects of cocaine on sensory processing in several limbic sites. Eleven adult male Wistar rats were stereotaxically implanted with electrodes aimed at the dentate gyrus, dorsal hippocampus (CA1-CA2), amygdala, and nucleus accumbens. The rats received intraperitoneal injections of either saline, 2.5, 5.0, 10.0 or 20 mg/kg of cocaine. The ERPs were recorded in response to an auditory 'oddball' paradigm consisting of frequently and infrequently presented tones. Cocaine was found to produce a dose dependent decrease in the variance of the amplitude of several ERP components in the amygdala and the hippocampal formation but not in the nucleus accumbens. Cocaine also produced a decrease in the latency of the N1 component in the amygdala. No significant changes were observed in the amplitude of the ERP components following any of the cocaine doses studied, suggesting that cocaine may not increase the salience of auditory stimuli in these structures. The observed reduction in the variance of the ERPs may suggest an increased focussing of the animals' attention to the auditory stimuli. These studies also suggest that the sensory/cognitive aspects involved in cocaine's actions, as quantified by ERPs, may primarily involve the hippocampal formation and the amygdala, but not the nucleus accumbens.

Neurotensin injected into the nucleus accumbens blocks the psychostimulant effects of cocaine but does not attenuate cocaine self-administration in the rat

The neuropeptide neurotensin (NT) has been shown to modulate mesolimbic dopaminergic activity. Neurotensin injected into the VTA produces motor stimulation and release of dopamine in the nucleus accumbens. In contrast, when neurotensin is administered into the nucleus accumbens, it produces neuroleptic-like effects such as attenuation of the locomotor activity elicited by psychostimulants. In the present study, the hypothesis that neurotensin injected into the nucleus accumbens might modulate the psychostimulant and reinforcing actions of cocaine was tested. In experiment one, rats were trained to self-administer cocaine intravenously on an FR5 schedule of reinforcement. Following the establishment of baseline responding, rats were implanted with bilateral cannulae in the nucleus accumbens. One week later, rats were injected into the nucleus accumbens with various doses of neurotensin (4.2, 8.4 and 16.7 micrograms, total doses bilaterally) immediately prior to the self-administration session. No significant effects were found with any of the doses of neurotensin tested on the self-administration of cocaine. However, in experiment 2, neurotensin at doses of 4.2 and 16.7 micrograms injected into the nucleus accumbens significantly reduced the locomotor activation induced by an acute injection of cocaine (15 mg/kg i.p.) and a dose of 16.7 micrograms attenuated the locomotor activation induced by amphetamine (0.75 mg/kg i.p.). Thus, neurotensin in the nucleus accumbens appears to specifically modulate the acute locomotor activating properties of cocaine but not cocaine self-administration. Different mechanisms by which NT interacts with dopamine in the nucleus accumbens may provide a means of selectively altering psychostimulant motor actions without affecting psychostimulant reinforcement.

Two discrete nucleus accumbens projection areas differentially mediate cocaine self-administration in the rat

The region of the nucleus accumbens and its connections have been implicated in the reinforcing actions of cocaine as measured by intravenous self-administration. Our previous work has demonstrated that ibotenic acid lesions of one of the output regions of the nucleus accumbens, the sublenticular region of the extended amygdala (SEA), resulted in significant decreases in the highest ratio obtained in rats self-administering cocaine. In the present study, the importance of another nucleus accumbens output, the subcommissural ventral pallidum (SVP), in mediating the self-administration of cocaine in the rat was explored. Animals were trained to self administer cocaine (0.75 mg/kg/inj) via an intravenous catheter on a FR5 schedule of reinforcement. Subsequently, subjects were either given bilateral intracerebral injections (0.5 microliter per side) of ibotenic acid (10 micrograms/microliter lesion group) or vehicle (sham group) into the SVP or into the SEA. Four days postlesion, cocaine self-administration on a FR5 schedule was resumed for 3 days. Next, a dose effect function was determined in one 3-h session. Finally, a progressive ratio probe in which the ratio requirement was increased after each reinforcement was tested. Lesions of both the SVP and the SEA produced significant changes in responding for intravenous cocaine on a FR5 schedule of reinforcement as compared to sham lesioned controls, although the effect was found to be greater for the rats bearing lesions of the SEA. While the lesions produced decreases in responding for cocaine at all doses tested in the dose-effect function, the rate of responding was still inversely proportional to the dose in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

D1 dopamine receptors in the nucleus accumbens modulate cocaine self-administration in the rat

Previous work using systemic injections of dopamine receptor antagonists has established that dopamine D1 receptors may have a role in cocaine self-administration. The purpose of the present study was to test the hypothesis that these effects were mediated by dopamine D1 receptors in the region of the nucleus accumbens. Animals were trained to perform operant responses to self-administer cocaine via an IV catheter on a fixed-ratio 5 (FR 5) schedule of reinforcement. SCH23390, a selective D1 dopamine antagonist, significantly increased the self-administration of cocaine when injected into the nucleus accumbens. This increase in self-administration is thought to reflect decreases in the magnitude of the reinforcer, similar to the increase observed when the dose of cocaine is reduced. Similar doses of SCH23390 injected into the posterior caudate nucleus failed to alter cocaine self-administration. These data suggest that D1 receptors in the nucleus accumbens are important for the reinforcing properties of cocaine.

Effects of oral ethanol self-administration on the EEG of alcohol preferring and -nonpreferring rats

EEG measures have been shown to differ in human subjects who are at genetically increased risk for the development of alcoholism. In the present study, EEG was recorded in rats that were selectively bred for alcohol-preferring (P) and nonpreferring (NP) behaviors during an ethanol self-administration paradigm. In this paradigm, rats initially learned to press a lever for a 0.2% saccharin solution. Ethanol was then added to the saccharin solution in increasing concentrations while saccharin was faded progressively. EEG recordings were analyzed under three different conditions: baseline, 0.2% saccharin and 10% ethanol. Statistical analyses were carried out within each group of rats for three 10-min intervals in each condition. NP rats showed increases in EEG power in the 6-32 Hz frequency ranges 20-30 min following ethanol availability. In contrast, no significant EEG effects were found for P rats in the 10% ethanol condition with respect to time. EEG power in the three time periods (0-10, 10-20, 20-30 min) was also compared between conditions (baseline, saccharin, 10% ethanol). For NP rats, a significant increase in EEG power during the 20-30 min time interval was found in the 10% ethanol session for the 16-32 Hz frequency range as compared to baseline and saccharin. In P rats, a significant increase in the power of the EEG was found during the first 10 min in the 10% ethanol session in the 8-16 Hz frequency range as compared to baseline and saccharin. The two rat lines also differed in their behavioral responses to the self-administration paradigm.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute monoaminergic depletion in the rat potentiates the excitatory effect of the subthalamic nucleus in the substantia nigra pars reticulata but not in the pallidal complex

Recent neurochemical evidence suggests that chemical or electrical stimulation of the subthalamic nucleus (STH) increases dopamine release in the substantia nigra (SN) with a subsequent decrease in the striatum. In a previous paper, we reported that bicuculline-induced activation of the STH increases neuronal activity in the substantia nigra pars reticulata (SNpr) and in the pallidal complex. In order to investigate the role played by the dopaminergic system in the observed activation, the neuronal responses of subthalamic nucleus target structures were studied in amine depleted rats following subthalamic stimulation. Amine depletion was accomplished by pretreating the rats with reserpine (2 mg/kg; S.C.) and with alpha-methyl-para-tyrosine (alpha-mpt; 50 mg/kg; I.P.). Following this treatment, dopamine levels were reduced by 94% in the striatum as measured by HPLC. Amine depletion significantly increased the spontaneous activity of subthalamic cells by 53%. In the SNpr, no significant changes in the spontaneous neuronal activity were observed, but the excitatory responses to bicuculline-induced stimulation of the STH were potentiated as compared to non-treated animals. In the pallidial complex (GP-EP), no potentiation was found. The data suggest that the spontaneous pattern of discharge of the STH is probably under monoaminergic control. They also suggest a reciprocal interaction between dopamine and glutamatergic afferent terminals from the STH within the SNpr, but not in the pallidal complex.

Combined effects of ethanol and MK 801 on locomotor activity in the rat

The present study examined the effects of ethanol (0.75 g/kg IP) alone and in combination with the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist MK 801 (0.1 mg/kg SC) on the locomotor activity of rats. Sixteen rats were treated with vehicle plus saline, MK 801 plus saline, vehicle plus ethanol, and MK 801 plus ethanol. Locomotor activity was quantified for a period of 12 hours following drug administration. Ethanol was found to significantly decrease locomotor activity whereas MK 801 significantly increased locomotion during the first 2 hours postdrug. In addition, there was a significant additive interaction between ethanol and MK 801 during this time period. Two to four hours postdrug, MK 801 was observed to significantly decrease locomotion. Four to six hours postdrug, ethanol-treated rats had significantly increased locomotor activity whereas MK 801-treated rats displayed significantly decreased locomotion. No significant interaction was found between ethanol and MK 801 4 to 6 hours postdrug. No significant effects of any of the drugs on locomotor activity were observed from 6 to 12 hours postdrug. These results suggest that ethanol and MK 801 produce a pattern of effects on locomotor activity which depend on the time elapsed following drug administration.

Excitatory influence of rat subthalamic nucleus to substantia nigra pars reticulata and the pallidal complex: electrophysiological data

By selective chemical stimulation of the subthalamic nucleus (STh) with the gamma-aminobutyric acid (GABA) antagonist bicuculline, we have studied the effect of its projections to the target nuclei. Results show that bicuculline (0.39 mM) produced a mean activation of 358% in subthalamic neurons. Most of the cells recorded in the substantia nigra pars reticulata (SNpr), the entopenduncular nucleus (EP), and the globus pallidus (GP) were also significantly activated. In the substantia nigra pars compacta (SNpc), slight and opposite changes were produced: half of the cells were activated and half were inhibited. In the striatum, 3 types of responses were recorded: activation, inhibition, and biphasic effect. Inhibition of subthalamic neurons by local microinjection of muscimol (0.95 mM), produced reductions in the neuronal activity of cells in the SNpr, the EP, and the GP. These results suggest that the STh conveys an important and permanent excitatory influence onto its target nuclei. In another set of experiments, in order to investigate whether or not the STh utilizes glutamate for neurotransmission in the SNpr, we injected the glutamate receptor antagonist kynurenic acid (2.6 mM) into the SNpr, later followed by an injection of bicuculline in the STh. Kynurenic acid alone produced a mean inhibition of 30% in non-dopaminergic nigral cells, and antagonized the subsequent bicuculline-induced activating effect of the STh. These results further confirm recent data showing that the STh exerts an excitatory action on its efferent structures, and provide new evidence for glutamatergic transmission in subthalamic projections.(ABSTRACT TRUNCATED AT 250 WORDS)