Dietary Interventions and Supplementation in Patients With an Ileal Pouch-Anal Anastomosis: A Systematic Review.

The restorative proctocolectomy with ileal pouch­anal anastomosis is the preferred surgery for patients with medically refractory ulcerative colitis. Although the ileal pouch­anal anastomosis provides gastrointestinal continuity and is an excellent alternative to a permanent end ileostomy, it is not without its complications including acute pouchitis, which occurs in up to 80% of patients. Diet may have a significant impact on pouch function and the development of pouchitis by virtue of its impact on motility and the microbiome. Multiple studies have evaluated the ability of different diets and supplements to improve pouch function and manage pouchitis, yet results are conflicting; thus, evidence-based dietary recommendations are lacking. Patients with an ileoanal pouch routinely ask about dietary interventions to maintain pouch health, and it is crucial that concrete evidence-based recommendations are identified to provide guidance. The goal of this systematic review is to summarize the available data on dietary patterns in patients with an ileoanal pouch, dietary interventions in this cohort, and the impact of supplements on pouch function and pouchitis.

Polarized localization of kinesin-1 and RIC-7 drives axonal mitochondria anterograde transport.

Mitochondria transport is crucial for mitochondria distribution in axons and is mediated by kinesin-1-based anterograde and dynein-based retrograde motor complexes. While Miro and Milton/TRAK were identified as key adaptors between mitochondria and kinesin-1, recent studies suggest the presence of additional mechanisms. In C. elegans, ric-7 is the only single gene described so far, other than kinesin-1, that is absolutely required for axonal mitochondria localization. Using CRISPR engineering in C. elegans, we find that Miro is important but is not essential for anterograde traffic, whereas it is required for retrograde traffic. Both the endogenous RIC-7 and kinesin-1 act at the leading end to transport mitochondria anterogradely. RIC-7 recruitment to mitochondria requires its N-terminal domain and partially relies on MIRO-1, whereas RIC-7 accumulation at the leading end depends on its disordered region, kinesin-1 and metaxin2. We conclude that polarized transport complexes containing kinesin-1 and RIC-7 form at the leading edge of mitochondria, and that these complexes are required for anterograde axonal transport.

The active zone protein Clarinet regulates synaptic sorting of ATG-9 and presynaptic autophagy.

Autophagy is essential for cellular homeostasis and function. In neurons, autophagosome biogenesis is temporally and spatially regulated to occur near presynaptic sites, in part via the trafficking of autophagy transmembrane protein ATG-9. The molecules that regulate autophagy by sorting ATG-9 at synapses remain largely unknown. Here, we conduct forward genetic screens at single synapses of C. elegans neurons and identify a role for the long isoform of the active zone protein Clarinet (CLA-1L) in regulating sorting of autophagy protein ATG-9 at synapses, and presynaptic autophagy. We determine that disrupting CLA-1L results in abnormal accumulation of ATG-9 containing vesicles enriched with clathrin. The ATG-9 phenotype in cla-1(L) mutants is not observed for other synaptic vesicle proteins, suggesting distinct mechanisms that regulate sorting of ATG-9-containing vesicles and synaptic vesicles. Through genetic analyses, we uncover the adaptor protein complexes that genetically interact with CLA-1 in ATG-9 sorting. We also determine that CLA-1L extends from the active zone to the periactive zone and genetically interacts with periactive zone proteins in ATG-9 sorting. Our findings reveal novel roles for active zone proteins in the sorting of ATG-9 and in presynaptic autophagy.

Turn that music down! Affective musical bursts cause an auditory dominance in children recognizing bodily emotions.

Previous work has shown that different sensory channels are prioritized across the life course, with children preferentially responding to auditory information. The aim of the current study was to investigate whether the mechanism that drives this auditory dominance in children occurs at the level of encoding (overshadowing) or when the information is integrated to form a response (response competition). Given that response competition is dependent on a modality integration attempt, a combination of stimuli that could not be integrated was used so that if children's auditory dominance persisted, this would provide evidence for the overshadowing over the response competition mechanism. Younger children (≤7 years), older children (8-11 years), and adults (18+ years) were asked to recognize the emotion (happy or fearful) in either nonvocal auditory musical emotional bursts or human visual bodily expressions of emotion in three conditions: unimodal, congruent bimodal, and incongruent bimodal. We found that children performed significantly worse at recognizing emotional bodies when they heard (and were told to ignore) musical emotional bursts. This provides the first evidence for auditory dominance in both younger and older children when presented with modally incongruent emotional stimuli. The continued presence of auditory dominance, despite the lack of modality integration, was taken as supportive evidence for the overshadowing explanation. These findings are discussed in relation to educational considerations, and future sensory dominance investigations and models are proposed.

High Prevalence of Malnutrition and Micronutrient Deficiencies in Patients With Inflammatory Bowel Disease Early in Disease Course.

BACKGROUND: Patients with inflammatory bowel disease (IBD) are at an increased risk of malnutrition. The goal of this study was to define the prevalence of malnutrition and micronutrient deficiencies in recently diagnosed IBD patients and to compare the performance of existing malnutrition screening tools in identifying IBD patients at increased risk for malnutrition. METHODS: This was a retrospective cohort study of adult patients with recently diagnosed IBD (≤18 months disease duration). A diagnosis of malnutrition was made utilizing the European Society for Clinical Nutrition and Metabolism malnutrition criteria. Serum micronutrient levels were included. The sensitivity of 5 malnutrition screening tools in identifying patients at moderate-high risk of malnutrition was determined based on the European Society for Clinical Nutrition and Metabolism malnutrition definition. Descriptive statistics summarized the data and univariate analyses tested associations. RESULTS: A total of 182 patients were included for analysis; 65 (36%) met criteria for malnutrition. A total of 135 (74%) patients had ≥1 micronutrient level checked and 105 (78%) had ≥1 deficiency. Patients with prior surgery (odds ratio [OR], 4.5; P = .004), active Crohn's disease (OR, 2.8; P = .03), and diarrhea (OR, 2.1; P = .02) were more likely to be malnourished. The Malnutrition Universal Screening Tool and Saskatchewan IBD Nutrition Risk Tool had the highest sensitivity (100%) in predicting those at moderate-high risk of malnutrition at the time of screening. CONCLUSIONS: Patients with recently diagnosed IBD have a high prevalence of malnutrition and micronutrient deficiencies. Both the Malnutrition Universal Screening Tool and Saskatchewan IBD Nutrition Risk Tool can be used to identify those at increased risk of malnutrition. Future studies and screening tool development are necessary to identify those at risk of developing malnutrition to facilitate timely referral for nutritional evaluation and prevent disease related complications.

This retrospective cohort study identified that patients with recently diagnosed inflammatory bowel disease have a high prevalence of malnutrition as well as micronutrient deficiencies and compared the utility of 5 available malnutrition screening tools in this population.

Feasibility and impact of a quality improvement initiative to screen for malnutrition in an Inflammatory Bowel Disease clinic.

BACKGROUND AND AIMS: Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract that is associated with malnutrition. Malnutrition is associated with poor clinical outcomes in patients with IBD and therefore early identification of those at risk for malnutrition is crucial. We aimed to evaluate how frequently nutrition screening occurs in a large, tertiary care outpatient IBD center and to initiate an intervention to improve malnutrition screening for patients with IBD. METHODS: We used a traditional plan-do-study-act quality improvement technique to understand our current malnutrition screening practices and institute an intervention to improve screening. To do this, we utilized a modified Malnutrition Universal Screening Tool (mMUST) and integrated this into the electronic health record. We then evaluated the intervention and the impact on IBD related clinical outcomes. RESULTS: Prior to the intervention, few patients with IBD were screened for malnutrition. However, the number of patients screened for malnutrition significantly improved with the study intervention and those who were identified as high-risk had increased nutrition follow up including serum micronutrient evaluations and referral to a dedicated registered dietician. CONCLUSION: This study demonstrated the feasibility and impact of a malnutrition screening program in ambulatory IBD patients. Those patients identified as high risk for malnutrition who engaged in nutrition care had improved clinical outcomes including reduced hospitalizations and emergency room visits.

AGA Clinical Practice Update on the Role of Diet in Irritable Bowel Syndrome: Expert Review.

DESCRIPTION: Irritable bowel syndrome (IBS) is a commonly diagnosed gastrointestinal disorder that can have a substantial impact on quality of life. Most patients with IBS associate their gastrointestinal symptoms with eating food. Mounting evidence supports dietary modifications, such as the low-fermentable oligo-, di-, and monosaccharides and polyols (FODMAP) diet, as a primary treatment for IBS symptoms. The aim of this American Gastroenterological Association (AGA) Clinical Practice Update (CPU) is to provide best practice advice statements, primarily to clinical gastroenterologists, covering the role of diet in IBS treatment. METHODS: This expert review was commissioned and approved by the AGA CPU Committee and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPU Committee and external peer review through standard procedures of Gastroenterology. The best practice advice statements were drawn from reviewing existing literature combined with expert opinion to provide practical advice on the role of diet in treating patients with IBS. Because this was not a systematic review, formal rating of the quality of evidence or strength of the presented considerations was not performed. Best Practice Advice Statements BEST PRACTICE ADVICE 1: Dietary advice is ideally prescribed to patients with IBS who have insight into their meal-related gastrointestinal symptoms and are motivated to make the necessary changes. To optimize the quality of teaching and clinical response, referral to a registered dietitian nutritionist (RDN) should be made to patients who are willing to collaborate with a RDN and patients who are not able to implement beneficial dietary changes on their own. If a gastrointestinal RDN is not available, other resources can assist with implementation of diet interventions. BEST PRACTICE ADVICE 2: Patients with IBS who are poor candidates for restrictive diet interventions include those consuming few culprit foods, those at risk for malnutrition, those who are food insecure, and those with an eating disorder or uncontrolled psychiatric disorder. Routine screening for disordered eating or eating disorders by careful dietary history is critical because they are common and often overlooked in gastrointestinal conditions. BEST PRACTICE ADVICE 3: Specific diet interventions should be attempted for a predetermined length of time. If there is no clinical response, the diet intervention should be abandoned for another treatment alternative, for example, a different diet, medication, or other form of therapy. BEST PRACTICE ADVICE 4: In preparation for a visit with a RDN, patients should provide dietary information that will assist in developing an individualized nutrition care plan. BEST PRACTICE ADVICE 5: Soluble fiber is efficacious in treating global symptoms of IBS. BEST PRACTICE ADVICE 6: The low-FODMAP diet is currently the most evidence-based diet intervention for IBS. Healthy eating advice as described by the National Institute of Health and Care Excellence Guidelines, among others, also offers benefit to a subset of patients with IBS. BEST PRACTICE ADVICE 7: The low-FODMAP diet consists of the following 3 phases: 1) restriction (lasting no more than 4-6 weeks), 2) reintroduction of FODMAP foods, and 3) personalization based on results from reintroduction. BEST PRACTICE ADVICE 8: Although observational studies found that most patients with IBS improve with a gluten-free diet, randomized controlled trials have yielded mixed results. BEST PRACTICE ADVICE 9: There are limited data showing that selected biomarkers can predict response to diet interventions in patients with IBS, but there is insufficient evidence to support their routine use in clinical practice.

Presynaptic autophagy is coupled to the synaptic vesicle cycle via ATG-9.

Autophagy is a cellular degradation pathway essential for neuronal health and function. Autophagosome biogenesis occurs at synapses, is locally regulated, and increases in response to neuronal activity. The mechanisms that couple autophagosome biogenesis to synaptic activity remain unknown. In this study, we determine that trafficking of ATG-9, the only transmembrane protein in the core autophagy pathway, links the synaptic vesicle cycle with autophagy. ATG-9-positive vesicles in C. elegans are generated from the trans-Golgi network via AP-3-dependent budding and delivered to presynaptic sites. At presynaptic sites, ATG-9 undergoes exo-endocytosis in an activity-dependent manner. Mutations that disrupt endocytosis, including a lesion in synaptojanin 1 associated with Parkinson's disease, result in abnormal ATG-9 accumulation at clathrin-rich synaptic foci and defects in activity-induced presynaptic autophagy. Our findings uncover regulated key steps of ATG-9 trafficking at presynaptic sites and provide evidence that ATG-9 exo-endocytosis couples autophagosome biogenesis at presynaptic sites with the activity-dependent synaptic vesicle cycle.

Resilience-based Integrated IBD Care Is Associated With Reductions in Health Care Use and Opioids.

BACKGROUND & AIMS: Integrated inflammatory bowel disease (IBD) care is effective but not routinely implemented. Validated methods that simultaneously address mind and body targets such as resilience may improve access and outcomes. We describe the development and implementation of the GRITT method and its impact on resilience, health care utilization (HCU), and opioid use in IBD. METHODS: Consecutive patients from an academic IBD center were evaluated for low resilience on the basis of provider referral. Low resilience patients were invited to participate in the GRITT program. Primary outcome was % reduction in HCU. Secondary outcomes were change in resilience and corticosteroid and opioid use. Patients were allocated into 2 groups for analysis: GRITT participants (GP) and non-participants (NP). Clinical data and HCU in the year before enrollment were collected at baseline and 12 months. One-way repeated measures multivariate analysis of covariance evaluated group × time interactions for the primary outcome. Effect size was calculated for changes in resilience over time. RESULTS: Of 456 screened IBD patients 394 were eligible, 184 GP and 210 NP. GP had greater reduction in HCU than NP: 71% reduction in emergency department visits, 94% reduction in unplanned hospitalizations. There was 49% reduction in opioid use and 73% reduction in corticosteroid use in GP. Resilience increased by 27.3 points (59%), yielding a large effect size (d = 2.4). CONCLUSIONS: Mind-body care that focuses on building resilience in the context of IBD care may be a novel approach to reduce unplanned HCU and opioid use, but large, multicenter, randomized controlled trials are needed.

Vitamin C Deficiency in Inflammatory Bowel Disease: The Forgotten Micronutrient.

BACKGROUND: Micronutrient deficiencies are common in patients with inflammatory bowel disease (IBD). To date, the literature has focused on vitamin D, vitamin B12, and iron deficiencies. METHODS: We report a case series of 20 patients with IBD and vitamin C deficiency treated at a single tertiary care center. RESULTS: Sixteen (80%) patients had symptoms of clinical scurvy, including arthralgia, dry brittle hair, pigmented rash, gingivitis, easy bruising, and/or brittle nails. Eighteen patients underwent a nutritional assessment, 10 (56%) patients reported complete avoidance of fruits and vegetables, and 3 (17%) reported reduced intake of fruits and vegetables. CONCLUSIONS: Vitamin C deficiency should be considered in IBD patients, particularly those with reduced fruit/vegetable intake, as it can lead to significant signs and symptoms.

Transcriptional control of parallel-acting pathways that remove specific presynaptic proteins in remodeling neurons.

Synapses are actively dismantled to mediate circuit refinement, but the developmental pathways that regulate synaptic disassembly are largely unknown. We have previously shown that the epithelial sodium channel ENaC/UNC-8 triggers an activity-dependent mechanism that drives the removal of presynaptic proteins liprin-α/SYD-2, Synaptobrevin/SNB-1, RAB-3 and Endophilin/UNC-57 in remodeling GABAergic neurons in C. elegans (Miller-Fleming et al., 2016). Here, we report that the conserved transcription factor Iroquois/IRX-1 regulates UNC-8 expression as well as an additional pathway, independent of UNC-8, that functions in parallel to dismantle functional presynaptic terminals. We show that the additional IRX-1-regulated pathway is selectively required for the removal of the presynaptic proteins, Munc13/UNC-13 and ELKS, which normally mediate synaptic vesicle fusion and neurotransmitter release. Our findings are notable because they highlight the key role of transcriptional regulation in synapse elimination during development and reveal parallel-acting pathways that coordinate synaptic disassembly by removing specific active zone proteins.SIGNIFICANT STATEMENT:Synaptic pruning is a conserved feature of developing neural circuits but the mechanisms that dismantle the presynaptic apparatus are largely unknown. We have determined that synaptic disassembly is orchestrated by parallel-acting mechanisms that target distinct components of the active zone. Thus, our finding suggests that synaptic disassembly is not accomplished by en masse destruction but depends on mechanisms that dismantle the structure in an organized process.

A muscle-epidermis-glia signaling axis sustains synaptic specificity during allometric growth in Caenorhabditis elegans.

Synaptic positions underlie precise circuit connectivity. Synaptic positions can be established during embryogenesis and sustained during growth. The mechanisms that sustain synaptic specificity during allometric growth are largely unknown. We performed forward genetic screens in C. elegans for regulators of this process and identified mig-17, a conserved ADAMTS metalloprotease. Proteomic mass spectrometry, cell biological and genetic studies demonstrate that MIG-17 is secreted from cells like muscles to regulate basement membrane proteins. In the nematode brain, the basement membrane does not directly contact synapses. Instead, muscle-derived basement membrane coats one side of the glia, while glia contact synapses on their other side. MIG-17 modifies the muscle-derived basement membrane to modulate epidermal-glial crosstalk and sustain glia location and morphology during growth. Glia position in turn sustains the synaptic pattern established during embryogenesis. Our findings uncover a muscle-epidermis-glia signaling axis that sustains synaptic specificity during the organism's allometric growth.

Sentryn and SAD Kinase Link the Guided Transport and Capture of Dense Core Vesicles in Caenorhabditis elegans.

Dense core vesicles (DCVs) can transmit signals by releasing neuropeptides from specialized synaptic regions called active zones. DCVs reach the active zone by motorized transport through a long axon. A reverse motor frequently interrupts progress by taking DCVs in the opposite direction. "Guided transport" refers to the mechanism by which outward movements ultimately dominate to bring DCVs to the synaptic region. After guided transport, DCVs alter their interactions with motors and enter a "captured" state. The mechanisms of guided transport and capture of DCVs are unknown. Here, we discovered two proteins that contribute to both processes in Caenorhabditis elegans SAD kinase and a novel conserved protein we named Sentryn are the first proteins found to promote DCV capture. By imaging DCVs moving in various regions of single identified neurons in living animals, we found that DCV guided transport and capture are linked through SAD kinase, Sentryn, and Liprin-α. These proteins act together to regulate DCV motorized transport in a region-specific manner. Between the cell body and the synaptic region, they promote forward transport. In the synaptic region, where all three proteins are highly enriched at active zones, they promote DCV pausing by inhibiting transport in both directions. These three proteins appear to be part of a special subset of active zone-enriched proteins because other active zone proteins do not share their unique functions.

Sentryn Acts with a Subset of Active Zone Proteins To Optimize the Localization of Synaptic Vesicles in Caenorhabditis elegans.

Synaptic vesicles (SVs) transmit signals by releasing neurotransmitters from specialized synaptic regions of neurons. In the synaptic region, SVs are tightly clustered around small structures called active zones. The motor KIF1A transports SVs outward through axons until they are captured in the synaptic region. This transport must be guided in the forward direction because it is opposed by the dynein motor, which causes SVs to reverse direction multiple times en route. The core synapse stability (CSS) system contributes to both guided transport and capture of SVs. We identified Sentryn as a CSS protein that contributes to the synaptic localization of SVs in Caenorhabditis elegans Like the CSS proteins SAD Kinase and SYD-2 (Liprin-α), Sentryn also prevents dynein-dependent accumulation of lysosomes in dendrites in strains lacking JIP3. Genetic analysis showed that Sentryn and SAD Kinase each have at least one nonoverlapping function for the stable accumulation of SVs at synapses that, when combined with their shared functions, enables most of the functions of SYD-2 (Liprin-α) for capturing SVs. Also like other CSS proteins, Sentryn appears enriched at active zones and contributes to active zone structure, suggesting that it is a novel, conserved active zone protein. Sentryn is recruited to active zones by a process dependent on the active zone-enriched CSS protein SYD-2 (Liprin-α). Our results define a specialized group of active zone enriched proteins that can affect motorized transport throughout the neuron and that have roles in both guided transport and capture of SVs.

Clarinet (CLA-1), a novel active zone protein required for synaptic vesicle clustering and release.

Active zone proteins cluster synaptic vesicles at presynaptic terminals and coordinate their release. In forward genetic screens, we isolated a novel Caenorhabditis elegans active zone gene, clarinet (cla-1). cla-1 mutants exhibit defects in synaptic vesicle clustering, active zone structure and synapse number. As a result, they have reduced spontaneous vesicle release and increased synaptic depression. cla-1 mutants show defects in vesicle distribution near the presynaptic dense projection, with fewer undocked vesicles contacting the dense projection and more docked vesicles at the plasma membrane. cla-1 encodes three isoforms containing common C-terminal PDZ and C2 domains with homology to vertebrate active zone proteins Piccolo and RIM. The C-termini of all isoforms localize to the active zone. Specific loss of the ~9000 amino acid long isoform results in vesicle clustering defects and increased synaptic depression. Our data indicate that specific isoforms of clarinet serve distinct functions, regulating synapse development, vesicle clustering and release.

The DEG/ENaC cation channel protein UNC-8 drives activity-dependent synapse removal in remodeling GABAergic neurons.

Genetic programming and neural activity drive synaptic remodeling in developing neural circuits, but the molecular components that link these pathways are poorly understood. Here we show that the C. elegans Degenerin/Epithelial Sodium Channel (DEG/ENaC) protein, UNC-8, is transcriptionally controlled to function as a trigger in an activity-dependent mechanism that removes synapses in remodeling GABAergic neurons. UNC-8 cation channel activity promotes disassembly of presynaptic domains in DD type GABA neurons, but not in VD class GABA neurons where unc-8 expression is blocked by the COUP/TF transcription factor, UNC-55. We propose that the depolarizing effect of UNC-8-dependent sodium import elevates intracellular calcium in a positive feedback loop involving the voltage-gated calcium channel UNC-2 and the calcium-activated phosphatase TAX-6/calcineurin to initiate a caspase-dependent mechanism that disassembles the presynaptic apparatus. Thus, UNC-8 serves as a link between genetic and activity-dependent pathways that function together to promote the elimination of GABA synapses in remodeling neurons.

High-Pressure Freeze and Freeze Substitution Electron Microscopy in C. elegans.

While traditional chemical fixation methods for C. elegans electron microscopy (EM) have provided invaluable anatomical and structural information, the development of high-pressure freeze (HPF) and freeze substitution (FS) protocols offers advantages for high-resolution imaging. Specimens prepared using HPF methodology exhibit fewer distortion artifacts due to fixation and dehydration, have improved antigenicity, and result in a more physiologically accurate structural representation of the worm. In the HPF technique, freely moving worms are frozen at high-pressure (2100 bar) and low temperature (-180 °C) within milliseconds. These conditions prevent the formation of ice crystals that can damage cellular structures. Samples then undergo FS, during which worms are slowly brought to room temperature while substituting amorphous ice with organic solvents to preserve tissue in its near native state and provide contrast for imaging. FS can be performed in an automatic freeze substitution (AFS) machine or in makeshift, temperature controlled chambers. Fixed worms can be embedded in plastic resin and further processed for a variety of imaging techniques. Samples then viewed using scanning (SEM) or transmission electron microscopy (TEM) will show enhanced preservation of organelles, cell morphology, and antigenicity for immunocytochemistry.

Performance- and task-dependent effects of the dopamine D1/D5 receptor agonist SKF 38393 on learning and memory in the rat.

Dopamine D(1)/D(5) receptor agonists may enhance cognition by mimicking dopamine's neurophysiological actions on the processes underlying learning and memory. The present study examined the task- and performance- dependence of the cognitive effects of a partial agonist at dopamine D(1)/D(5) receptors, SKF 38393 [(+/-)-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzazepine-7,8-diol hydrobromide], in rats. Spatial working memory was assessed in a T-maze, spatial reference memory in a water maze and habituation learning in a novel environment, a hole board. The muscarinic acetylcholine receptor antagonist scopolamine (1.5 mg/kg, i.p.) was used to cause an impairment of performance of these learning tasks. Administration of SKF 38393 (6 mg/kg, i.p.) alone had no significant effect on spontaneous alternation in the T-maze, latency to escape to a hidden platform in the water maze or the habituation of spontaneous behaviour in the hole board. In contrast, in scopolamine-treated rats, whereas SKF 38393 prevented the scopolamine-induced deficit in the T-maze, it exacerbated the impairment in the water maze and did not significantly alter the disruption of habituation. These results suggest that dopamine D(1)/D(5) receptor activation has performance- and task-dependent effects on cognitive function.

Effects of acute and repeated administration of a cholinesterase inhibitor on timing behaviour.

It has been hypothesised that a leftward shift in the response distribution obtained in the peak interval (PI) procedure is a characteristic of cognitive enhancement in which mental processes are speeded. Metrifonate, a cholinesterase inhibitor with reported cognitive enhancing properties in many animal models of learning and memory, was tested in the PI procedure. Acute administration of 3 and 60 mg/kg but not 1 and 30 mg/kg in fully trained rats shifted the response distribution to the right, whereas subchronic administration of 10, 30 or 50 mg/kg during task acquisition had no effect on timing behaviour. On the basis of the present data, it can be concluded that the effects of a cognition enhancer in the PI procedure cannot be predicted from the scalar expectancy theory (SET). Furthermore, SET does not appear to be an appropriate tool for analysing the acquisition of timing behaviour.