76
|
Heller K, Montgomery C, Shontz K, Malik V, Janssen P, Clark KR, Rodino-Klapac L, Mendell J. Overexpression of Human Alpha7 Integrin as a Potential Therapy for Duchenne Muscular Dystrophy (PD6.004). Neurology 2012. [DOI: 10.1212/wnl.78.1_meetingabstracts.pd6.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
77
|
Grose W, Griffin D, Shontz K, Malik V, Montgomery C, Janssen P, Clark R, Mendell J, Rodino-Klapac L. Correction of Membrane Repair Defects in Dysferlin Deficient Muscle Following AAV5 Gene Transfer (S55.006). Neurology 2012. [DOI: 10.1212/wnl.78.1_meetingabstracts.s55.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
78
|
Janssen P, Verschueren S, Rotondo A, Tack J. Role of Y(2) receptors in the regulation of gastric tone in rats. Am J Physiol Gastrointest Liver Physiol 2012; 302:G732-9. [PMID: 22268097 DOI: 10.1152/ajpgi.00404.2011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We set out to determine the effect of peptide YY(3-36) (PYY(3-36)) on the gastric muscle tone in conscious rats by measuring intragastric pressure (IGP) during intragastric nutrient drink infusion. After an overnight fast, a chronically implanted gastric fistula was connected to a custom-made nutrient drink infusion system and a catheter to measure IGP. IGP was measured before and during the infusion of a nutrient drink (Nutridrink; 0.5 ml/min) until 10 ml was infused. Rats were treated with PYY(3-36) (0, 33, and 100 pmol·kg(-1)·min(-1)) in combination with a subcutaneous injection of the Y(2) receptor antagonists JNJ31020028 (10 mg/kg) or BIIE0246 (2 mg/kg). Experiments were also performed after subdiaphragmatic vagotomy and after pretreatment with 3 ml of nutrient drink (to mimic a fed state). IGP was compared as the average IGP during nutrient infusion, represented as means ± SE and compared using ANOVA. PYY(3-36) dose dependently increased the IGP during nutrient infusion (4.7 ± 0.3, 5.7 ± 0.5 and 7.3 ± 0.7 mmHg; P < 0.01) while JNJ31020028 and BIIE0246 could block this increase [4.4 ± 0.5 (P < 0.001) and 4.8 ± 0.4 (P < 0.05) mmHg, respectively]. Also in vagotomized rats, PYY(3-36) was able to significantly increase the IGP during, an effect attenuated by JNJ31020028. BIIE0246 and JNJ31020028 were not able to decrease the IGP when no PYY(3-36) was administered. PYY(3-36) increased gastric tone through an Y(2) receptor-mediated mechanism that does not involve the vagus nerve. Y(2) receptor antagonists were not able to decrease gastric tone without exogenous administration of PYY(3-36), indicating that Y(2) receptors do not play a crucial role in the determination of gastric tone in physiological conditions.
Collapse
|
79
|
Theys T, Srivastava S, van Loon J, Goffin J, Janssen P. Selectivity for three-dimensional contours and surfaces in the anterior intraparietal area. J Neurophysiol 2012; 107:995-1008. [DOI: 10.1152/jn.00248.2011] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The macaque anterior intraparietal area (AIP) is crucial for visually guided grasping. AIP neurons respond during the visual presentation of real-world objects and encode the depth profile of disparity-defined curved surfaces. We investigated the neural representation of curved surfaces in AIP using a stimulus-reduction approach. The stimuli consisted of three-dimensional (3-D) shapes curved along the horizontal axis, the vertical axis, or both the horizontal and the vertical axes of the shape. The depth profile was defined solely by binocular disparity that varied along either the boundary or the surface of the shape or along both the boundary and the surface of the shape. The majority of AIP neurons were selective for curved boundaries along the horizontal or the vertical axis, and neural selectivity emerged at short latencies. Stimuli in which disparity varied only along the surface of the shape (with zero disparity on the boundaries) evoked selectivity in a smaller proportion of AIP neurons and at considerably longer latencies. AIP neurons were not selective for 3-D surfaces composed of anticorrelated disparities. Thus the neural selectivity for object depth profile in AIP is present when only the boundary is curved in depth, but not for disparity in anticorrelated stereograms.
Collapse
|
80
|
Evens N, Vandeputte C, Coolen C, Janssen P, Sciot R, Baekelandt V, Verbruggen AM, Debyser Z, Van Laere K, Bormans GM. Preclinical evaluation of [11C]NE40, a type 2 cannabinoid receptor PET tracer. Nucl Med Biol 2011; 39:389-99. [PMID: 22154685 DOI: 10.1016/j.nucmedbio.2011.09.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/16/2011] [Accepted: 09/06/2011] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Up-regulation of the type 2 cannabinoid receptor (CB(2)R) has been reported in (neuro)inflammatory diseases. In this study, we report the preclinical evaluation of [(11)C]NE40 as positron emission tomography (PET) radioligand for visualization of the CB(2)R. METHODS The selectivity of NE40 for CB(2)R and its toxicity and mutagenicity were determined. [(11)C]NE40 was evaluated by biodistribution and autoradiography studies in normal rats and a microPET study in normal mice, rats and a rhesus monkey. Specific in vivo binding of [(11)C]NE40 to human CB(2)R (hCB(2)R) was studied in a rat model with hCB(2)R overexpression. RESULTS [(11)C]NE40 shows specific CB(2)R binding in the spleen and blood of normal rats and high brain uptake in rhesus monkey. [(11)C]NE40 showed specific and reversible binding to hCB(2)R in vivo in a rat model with local hCB(2)R overexpression. CONCLUSIONS [(11)C]NE40 shows favorable characteristics as radioligand for in vivo visualization of the CB(2)R and is a promising candidate for hCB(2)R PET imaging.
Collapse
|
81
|
Enzmann D, Schaufeli WB, Janssen P, Rozeman A. Dimensionality and validity of the Burnout Measure. JOURNAL OF OCCUPATIONAL AND ORGANIZATIONAL PSYCHOLOGY 2011. [DOI: 10.1111/j.2044-8325.1998.tb00680.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
82
|
Janssen P, Verschueren S, Van Heijningen C, Tack J. Peripheral Y2 receptor activation inhibits gastric accommodation during intragastric nutrient infusion in rats. Appetite 2011. [DOI: 10.1016/j.appet.2011.05.187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
83
|
Deloose E, Janssen P, van Oudenhove L, van den Bergh O, Depoortere I, Tack J. Hunger fluctuates during the interdigestive state in man. Appetite 2011. [DOI: 10.1016/j.appet.2011.05.157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
84
|
Rotondo A, Janssen P, Tack J. Effect of liraglutide on intragastric pressure (IGP) and satiation during intragastric nutrient drink infusion in healthy volunteers. Appetite 2011. [DOI: 10.1016/j.appet.2011.05.256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
85
|
Janssen P, Janssen S, Depoortere I, Tack J. Intragastric administration of the bitter agonist denatonium benzoate (DB) increases satiation in healthy volunteers. Appetite 2011. [DOI: 10.1016/j.appet.2011.05.186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
86
|
Vandeputte C, Evens N, Toelen J, Deroose CM, Bosier B, Ibrahimi A, Van der Perren A, Gijsbers R, Janssen P, Lambert DM, Verbruggen A, Debyser Z, Bormans G, Baekelandt V, Van Laere K. A PET brain reporter gene system based on type 2 cannabinoid receptors. J Nucl Med 2011; 52:1102-9. [PMID: 21680683 DOI: 10.2967/jnumed.110.084426] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
UNLABELLED PET of gene expression in the brain may greatly facilitate neuroscience research and potential clinical implementation of gene or cell therapy of central nervous system diseases. To date, no adequate PET reporter system is available for the central nervous system because available tracers either do not cross the intact blood-brain barrier or have high background signals. Here we report the first, to our knowledge, PET reporter system for imaging gene expression in the intact brain. METHODS We selected the human type 2 cannabinoid receptor (hCB(2)) as a reporter because of its low basal expression in the brain. An inactive mutant (D80N) was chosen so as not to interfere with signal transduction. As a reporter probe we used the (11)C-labeled CB(2) ligand, (11)C-GW405833, which readily crosses the blood-brain barrier. Dual-modality imaging lentiviral and adeno-associated viral vectors encoding both hCB(2)(D80N) and firefly luciferase or enhanced green fluorescent protein were engineered and validated in cell culture. Next, hCB(2)(D80N) was locoregionally overexpressed in rat striatum by stereotactic injection of lentiviral and adeno-associated viral vectors. RESULTS Kinetic PET revealed specific and reversible CB(2) binding of (11)C-GW405833 in the transduced rat striatum. hCB(2) and firefly luciferase expression was followed until 9 mo and showed similar kinetics. Both hCB(2) expression and enhanced green fluorescent protein expression were confirmed by immunohistochemistry. CONCLUSION Dual-modality imaging viral vectors encoding hCB(2)(D80N) were engineered, and the reporter system was validated in different animal species. The results support the potential future clinical use of CB(2) as a PET reporter in the intact brain.
Collapse
|
87
|
Janssen P, Van Oudenhove L, Vos R, Verbeke K, Tack J. Effect of mianserin on gastric sensorimotor function and gastric emptying: a randomized, placebo-controlled, double-blind, crossover study in healthy volunteers. Neurogastroenterol Motil 2011; 23:433-8, e174. [PMID: 21255195 DOI: 10.1111/j.1365-2982.2011.01671.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Antidepressants such as mianserin can improve symptoms in some functional dyspeptic patients but their mechanism of action remains unclear. We aimed to assess the effects of mianserin on gastric sensorimotor function in man. METHODS In this randomized, placebo-controlled, double-blind, crossover study 12 healthy subjects (six men) underwent a gastric barostat study and a gastric emptying breath test after 7 days pretreatment with placebo or mianserin (20 mg; p.o.). Graded isobaric and isovolumetric distentions were performed to determine gastric compliance and sensitivity. Subsequently, intrabag pressure was held constant and the volume increase after administration of a liquid meal (200 mL; 300 kcal) was studied. Breath was sampled before and after ingestion of a test meal and half-emptying times for solids and liquids were determined from the breath samples. Mianserin was compared to placebo using t-tests and mixed model analysis (mean ± SD). KEY RESULTS Mianserin did not affect pressures or volumes needed to induce first perception or discomfort. During isovolumetric distensions compliance was decreased after mianserin treatment (1.8 ± 0.4 vs 2.0 ± 0.3 mmHg 100 mL(-1); P < 0.05). Premeal volumes were comparable in both treatment arms (221 ± 99 vs 220 ± 88 mL), but meal-induced relaxation during the first 30 min was significantly inhibited after mianserin treatment (F(6,40) = 2.58, P < 0.05). Mianserin did not affect either solid or liquid gastric emptying. CONCLUSIONS & INFERENCES Mianserin does not alter gastric emptying rate or sensitivity to gastric distension, but inhibits gastric accommodation to a meal in its early phase. These observations provide no explanation for the effects of mianserin in functional dyspeptic patients.
Collapse
|
88
|
Janssen P, Vos R, Van Oudenhove L, Tack J. Influence of the 5-HT3 receptor antagonist ondansetron on gastric sensorimotor function and nutrient tolerance in healthy volunteers. Neurogastroenterol Motil 2011; 23:444-9, e175. [PMID: 21199175 DOI: 10.1111/j.1365-2982.2010.01655.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Serotonin is believed to be involved in the regulation of the gastric accommodation reflex in man however which receptor subtype(s) are involved remains to be elucidated. METHODS Eleven healthy subjects (nine men, age 19-30) underwent a gastric barostat and a drinking test after treatment with either placebo or ondansetron (8 mg intravenously). During the barostat protocol an intragastric flaccid bag was stepwise distended (2 mmHg increments 2 min) to determine gastric compliance and sensitivity to distention. Subsequently, the pressure level was set at intra-abdominal pressure +2 mmHg while volume was followed before and after administration of a liquid meal (200 mL; 300 kcal). During the drink test volunteers drank at a rate of 15 mL min(-1) until maximal satiation. Results (mean ± SEM) were compared using t-tests and mixed model analysis. KEY RESULTS Gastric compliance was not significantly altered by ondansetron (51.5 ± 5.6 vs 49.2 ± 5.2 mL mmHg(-1)), neither were the pressure thresholds for first perception or discomfort. Ondansetron treatment did not affect basal gastric tone (173 ± 14 vs 156 ± 12 mL), neither did it affect the amplitude of the meal-induced relaxation (160 ± 52 vs 131 ± 43 mL) or the maximum volume increase after the meal (264 ± 54 mL vs 234 ± 51 mL). During the drinking test the amount of liquid meal ingested at maximum satiation was significantly increased by ondansetron (784 ± 74 vs 907 ± 64 mL, P < 0.05). CONCLUSIONS & INFERENCES These data suggest that 5-HT acting at 5-HT(3) receptors is not involved in the control of gastric sensorimotor function, but contributes to the regulation of hunger and satiation in man.
Collapse
|
89
|
Janssen P, Verschueren S, Ly HG, Vos R, Van Oudenhove L, Tack J. Intragastric pressure during food intake: a physiological and minimally invasive method to assess gastric accommodation. Neurogastroenterol Motil 2011; 23:316-22, e153-4. [PMID: 21299720 DOI: 10.1111/j.1365-2982.2011.01676.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND The stomach relaxes upon food intake and thereby provides a reservoir while keeping the intragastric pressure (IGP) low. We set out to determine whether we could use IGP as a measurement for stomach accommodation during food intake. METHODS In fasted healthy volunteers (n = 7-17) a manometer and an infusion catheter were positioned in the proximal stomach. After a stabilization period a nutrient drink was intragastrically infused at 15, 30 and 60 mL min(-1). To investigate the effect of impaired accommodation the effect of N(G)-monomethyl-L-arginine (L-NMMA) was examined. The volunteers scored satiation until maximum, when the experiment ended. The IGP was presented as a change from baseline (mean ± SEM) and compared with repeated measures anova. KEY RESULTS Independent on the ingestion speed, the IGP decreased initially and gradually increased thereafter. Volunteers scored maximal satiation after 699 ± 62, 809 ± 90 and 997 ± 120 mL nutrient drink infused (15, 30 and 60 mL min(-1) respectively; P < 0.01). Maximum IGP decrease was 3.4 ± 0.5 mmHg after 205 ± 28 mL, 5.1 ± 0.7 mmHg after 212 ± 46 mL, and 5.2 ± 0.7 mmHg after 296 ± 28 mL infused volume [15, 30 and 60 mL min(-1) respectively; not significant (ns)]. Post hoc analysis showed significant correlations between IGP and satiation score increase. During L-NMMA infusion IGP was significantly increased while subjects drank significantly less (816 ± 91 vs 1032 ± 71 mL; P < 0.005). Interestingly, the correlation between IGP increase and satiation score increase did not differ after L-NMMA treatment. CONCLUSIONS & INFERENCES The IGP during nutrient drink ingestion provides a minimally invasive alternative to the barostat for the assessment of gastric accommodation. These findings furthermore indicate that IGP is a major determinant of satiation.
Collapse
|
90
|
Janssen P, Vanden Berghe P, Verschueren S, Lehmann A, Depoortere I, Tack J. Review article: the role of gastric motility in the control of food intake. Aliment Pharmacol Ther 2011; 33:880-94. [PMID: 21342212 DOI: 10.1111/j.1365-2036.2011.04609.x] [Citation(s) in RCA: 213] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND From a classical point of view, gastric motility acts to clear the stomach between meals, whereas postprandial motility acts to provide a reservoir for food, mixing and grinding the food and to assure a controlled flow of food to the intestines. AIM To summarise findings that support the role of gastric motility as a central mediator of hunger, satiation and satiety. METHODS A literature review using the search terms 'satiety', 'satiation' and 'food intake' was combined with specific terms corresponding to the sequence of events during and after food intake. RESULTS During food intake, when gastric emptying of especially solids is limited, gastric distension and gastric accommodation play an important function in the regulation of satiation. After food intake, when the stomach gradually empties, the role of gastric distension in the determination of appetite decreases and the focus will shift to gastric emptying and intestinal exposure of the nutrients. Finally, we have discussed the role of the empty stomach and the migrating motor complex in the regulation of hunger signals. CONCLUSIONS Our findings indicate that gastric motility is a key mediator of hunger, satiation and satiety. More specifically, gastric accommodation and gastric emptying play important roles in the regulation of gastric (dis)tension and intestinal exposure of nutrients and hence control satiation and satiety. Correlations between gastric accommodation, gastric emptying and body weight indicate that gastric motility can also play a role in the long-term regulation of body weight.
Collapse
|
91
|
Janssen P, Pottel H, Vos R, Tack J. Endogenously released opioids mediate meal-induced gastric relaxation via peripheral mu-opioid receptors. Aliment Pharmacol Ther 2011; 33:607-14. [PMID: 21198709 DOI: 10.1111/j.1365-2036.2010.04557.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND The centrally acting mu-opioid receptor antagonist naloxone inhibits meal-induced gastric accommodation. AIM To study the role of peripheral mu-opioid receptors in the regulation of gastric tone and food intake by comparing the effects of naloxone with the peripherally restricted mu-opioid receptor antagonist methylnaltrexone. METHODS Methylnaltrexone (12 mg s.c.), naloxone (20 μg/kg/h intravenous infusion after 0.4 mg bolus) and placebo were studied in 23 healthy volunteers. Gastric volume was recorded using an intragastric bag held at constant pressure connected to a barostat, with administration of a nutrient drink after 30 min. Pressure in the stomach was measured during intragastric nutrient drink infusion until the volunteers scored maximal satiation. RESULTS Methylnaltrexone inhibited significantly the volume increase after food intake as assessed with the barostat (P < 0.01). During nutrient drink infusion the intragastric pressure significantly decreased as compared with the preprandial pressure after placebo treatment. Both methylnaltrexone and naloxone significantly inhibited this intragastric pressure decrease (P < 0.001 and P < 0.05, respectively). Volunteers scored maximal satiation after 979 ± 96, 958 ± 84 and 1124 ± 107 mL nutrient drink infused (for naloxone, methylnaltrexone and placebo treatment, respectively; P < 0.05). CONCLUSIONS These results indicate that endogenous opioids mediate gastric accommodation and satiation via peripheral mu-opioid receptors. Effects were less pronounced after naloxone treatment, which indicates that centrally involved mu-opioid receptors mediate an opposing effect.
Collapse
|
92
|
Ang D, Talley NJ, Simren M, Janssen P, Boeckxstaens G, Tack J. Review article: endpoints used in functional dyspepsia drug therapy trials. Aliment Pharmacol Ther 2011; 33:634-49. [PMID: 21223343 DOI: 10.1111/j.1365-2036.2010.04566.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND The measurement of patient-reported outcomes (PRO) in treatment trials for functional gastrointestinal disorders is a matter of controversy. AIM To focus on instruments and endpoints that have been used to evaluate the efficacy of therapeutic agents in functional dyspepsia (FD) trials, also considering the newly defined Rome III FD criteria. METHODS A Medline search was conducted to identify relevant studies pertaining to FD treatment, with particular emphasis on the studies to date which have used validated outcome measures. RESULTS Currently available outcome measures are heterogeneous across studies. They include global binary endpoints, analogue or categorical scoring scales, uni- or multi-dimensional disease specific questionnaires, global outcome evaluations and quality of life questionnaires. Across the available outcome measures, substantial heterogeneity is found, not only in the type of endpoint measure, but also in the number and types of symptoms that are considered to be part of the FD symptom complex. Especially based on content validity, none of the existing questionnaires or endpoints can be considered sufficiently validated to be recommended unequivocally as the primary outcome measure for FD trials according to the Rome III criteria. On the other hand, existing well-validated multi-dimensional questionnaires that include many non-FD symptoms can be narrowed down to evaluate only the cardinal symptoms according to Rome III. CONCLUSIONS There is an urgent need to develop Rome III-based patient-reported outcomes for functional dyspepsia. Well-validated multi-dimensional questionnaires may serve as a guidance for this purpose, and could also be considered for use in ongoing clinical trials.
Collapse
|
93
|
Verhoef BE, Vogels R, Janssen P. Synchronization between the end stages of the dorsal and the ventral visual stream. J Neurophysiol 2011; 105:2030-42. [PMID: 21325682 DOI: 10.1152/jn.00924.2010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The end stage areas of the ventral (IT) and the dorsal (AIP) visual streams encode the shape of disparity-defined three-dimensional (3D) surfaces. Recent anatomical tracer studies have found direct reciprocal connections between the 3D-shape selective areas in IT and AIP. Whether these anatomical connections are used to facilitate 3D-shape perception is still unknown. We simultaneously recorded multi-unit activity (MUA) and local field potentials in IT and AIP while monkeys discriminated between concave and convex 3D shapes and measured the degree to which the activity in IT and AIP synchronized during the task. We observed strong beta-band synchronization between IT and AIP preceding stimulus onset that decreased shortly after stimulus onset and became modulated by stereo-signal strength and stimulus contrast during the later portion of the stimulus period. The beta-coherence modulation was unrelated to task-difficulty, regionally specific, and dependent on the MUA selectivity of the pairs of sites under study. The beta-spike-field coherence in AIP predicted the upcoming choice of the monkey. Several convergent lines of evidence suggested AIP as the primary source of the AIP-IT synchronized activity. The synchronized beta activity seemed to occur during perceptual anticipation and when the system has stabilized to a particular perceptual state but not during active visual processing. Our findings demonstrate for the first time that synchronized activity exists between the end stages of the dorsal and ventral stream during 3D-shape discrimination.
Collapse
|
94
|
Tack J, Janssen P, Bisschops R, Vos R, Phillips T, Tougas G. Influence of tegaserod on proximal gastric tone and on the perception of gastric distention in functional dyspepsia. Neurogastroenterol Motil 2011; 23:e32-9. [PMID: 20979591 DOI: 10.1111/j.1365-2982.2010.01613.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND Abnormalities in gastric sensorimotor function (hypersensitivity to distention and impaired meal accommodation) have been implicated in the pathophysiology of functional dyspepsia (FD). To study the effect of the 5-HT(4) agonist tegaserod on sensitivity to gastric distention and gastric accommodation in FD. METHODS Thirty FD patients (7 males, mean age 42 ± 2 years) underwent a gastric barostat study on two separate occasions, 2 weeks apart, after 5 days of pretreatment with placebo or tegaserod 6 mg b.i.d. in a double-blind randomized order. After introduction of the barostat bag, graded isobaric distentions (2 mmHg increments/2 min) were performed to determine gastric compliance and sensitivity to distention. Subsequently, the pressure level was set at intra-abdominal pressure [minimal distending pressure (MDP)] + 2 mmHg for 90 min, with administration of a liquid meal (200 mL; 300 kcal) after 30 min. KEY RESULTS Tegaserod had no influence on MDP (7.9 ± 0.4 vs 7.4 ± 0.4 mmHg) or fasting gastric compliance (44 ± 10 vs 61 ± 6 mL mmHg(-1)) and on fasting thresholds for first perception (3.6 ± 0.4 vs 4.2 ± 0.2 mmHg above MDP) or discomfort (9.9 ± 0.7 vs 10.5 ± 0.5 mmHg above MDP). Tegaserod did not alter intra-balloon volumes before and after the meal [respectively 146 ± 14 vs 120 ± 11 and 297 ± 28 vs 283 ± 29 mL, not significant (NS)], or the amplitude of the meal-induced gastric relaxation (151 ± 23 vs 162 ± 23 mL, NS). In the subgroup with normal gastric emptying (n = 22), tegaserod significantly enhanced meal-induced accommodation (126 ± 23 vs 175 ± 29 mL, ANOVA P < 0.001). CONCLUSIONS & INFERENCES Tegaserod does not alter gastric sensorimotor function in FD patients as a group. In the subgroup with normal gastric emptying, tegaserod 6 mg b.i.d enhanced gastric accommodation.
Collapse
|
95
|
Janssen P, Van Oudenhove L, Casteels C, Vos R, Verbeke K, Tack J. The effects of acute citalopram dosing on gastric motor function and nutrient tolerance in healthy volunteers. Aliment Pharmacol Ther 2011; 33:395-402. [PMID: 21118281 DOI: 10.1111/j.1365-2036.2010.04522.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND It is unclear whether endogenous serotonin release is involved in the regulation of gastric motility and food intake. AIM To study the effect of acute administration of the selective serotonin reuptake inhibitor citalopram on gastric motor function in man. METHODS Nineteen healthy volunteers underwent a gastric barostat, gastric emptying and/or a drinking test after dosing with either placebo or citalopram (20 mg intravenously). In the barostat protocol, a flaccid bag was introduced in the stomach and inflated at intra-abdominal pressure +2 mmHg, volume was recorded before and after administration of a liquid meal (300 kcal). Gastric emptying for solids and liquids was simultaneously assessed using the ¹⁴C-octanoic acid/¹³C-glycine breath test. During the drink test, volunteers drank at a rate of 15 mL/min until maximal satiation. Citalopram was compared with placebo using t-tests and mixed model analysis. RESULTS Citalopram induced a significant preprandial gastric relaxation (volume increase of 154 ± 55 mL vs. -38 ± 33 mL after placebo dosing; P < 0.05), whereas the postprandial volume increase was significantly decreased after citalopram treatment (F₁₂.₈₀ = 4.78, P < 0.0001; maximum volume increase was 304 ± 40 vs. 201 ± 54 mL after placebo and citalopram treatment respectively). Citalopram enhanced solid (123 ± 17 vs. 77 ± 6 min, P < 0.05) but not liquid emptying (62 ± 6 vs. 57 ± 4 min). Satiation scores during the drink test were lower after citalopram (F₁₉.₁₅₃ = 2.02, P = 0.01; volunteers drank 998 ± 129 vs. 765 ± 79 mL after citalopram and placebo treatment respectively). CONCLUSION The observed effects indicate a role for serotonin in the control of gastric motility and food intake.
Collapse
|
96
|
Abstract
Functional gastrointestinal disorders (FGIDs) are very common (up to 98%) in patients with an eating disorder (ED). Boyd et al. discuss in this issue of Neurogastroenterology & Motility that FGIDs can persist independently on the outcome of the ED. Their findings leave room for speculation on the mechanisms underlying FGIDs in patients with an ED. FGIDs result from a complex interaction of biological, psychosocial and social factors. The altered eating behavior seen in EDs is strongly associated with disturbed gastrointestinal sensitivity and motor physiology. Moreover, psychiatric co-morbidities in ED patients are also frequently found in FGIDs. The motor and sensitivity disturbances together with psychiatric co-morbidities can lay the foundation of a FGID. Once established the psychological and physiological disturbances can perpetuate and strengthen each other resulting in a FGID that can persist independently of the ED that originally caused the motor and sensitivity disturbances.
Collapse
|
97
|
Janssen P, Verhoef BE. Neurons selective to disparity defined shape in the temporal and parietal cortex. J Vis 2010. [DOI: 10.1167/10.7.7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
98
|
Janssen P, Vos R, Tack J. The influence of citalopram on interdigestive gastrointestinal motility in man. Aliment Pharmacol Ther 2010; 32:289-95. [PMID: 20456311 DOI: 10.1111/j.1365-2036.2010.04351.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Administration of 5-hydroxytryptamine (5HT) and selective 5HT receptor ligands modifies interdigestive motility in animals and in man. AIM To study the effect of citalopram, a selective 5-HT reuptake inhibitor, on interdigestive motility in man. METHODS In 20 healthy subjects, antroduodenojejunal motor activity was studied manometrically. Basal interdigestive motor activity was recorded until the passage of two activity fronts. Ten minutes after the second activity front, placebo or 20 mg of citalopram was administered intravenously in a double-blind randomized fashion. Recording continued until the passage of two more activity fronts had occurred. RESULTS Administration of citalopram induced a premature small intestinal phase 3 after 35 +/- 6.4 min, compared to 120 +/- 17 min after placebo P < 0.01. Citalopram shortened MMC cycle length at the expense of phase 1 and phase 2 and significantly increased the motility index during phase 2 in the antrum and the small intestine. CONCLUSIONS In the interdigestive state in man, intravenous administration of the selective 5-HT reuptake inhibitor citalopram induces a premature intestinal phase 3 and suppresses gastric activity fronts. Phase 2 motility is stimulated both in the stomach and in the small bowel after citalopram. These data suggest that 5HT is involved in the control of interdigestive motility.
Collapse
|
99
|
Ameloot K, Janssen P, Scarpellini E, Vos R, Boesmans W, Depoortere I, Vanden Berghe P, Tack J. Endocannabinoid control of gastric sensorimotor function in man. Aliment Pharmacol Ther 2010; 31:1123-31. [PMID: 20146701 DOI: 10.1111/j.1365-2036.2010.04259.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
BACKGROUND Little is known about the physiological role of the endocannabinoid system in the regulation of the motility and the sensitivity of the stomach. Endocannabinoid system dysfunction has been hypothesized to contribute to the control of food intake and the pathogenesis of functional dyspepsia. AIM To study the influence of rimonabant, the endocannabinoid 1 (CB1) receptor antagonist, on gastric sensorimotor function in healthy controls. METHODS After 4 days of pre-treatment with rimonabant 20 mg/day or placebo, 12 healthy volunteers (mean age 34 +/- 12 years, six men) participated in a placebo-controlled, double-blind, randomized, crossover study with a gastric barostat assessment of gastric sensitivity to distension, gastric compliance, gastric accommodation and phasic motility on day 3 and a liquid nutrient challenge test on day 4. RESULTS Rimonabant did not influence gastric compliance and sensitivity to distension. The meal-induced gastric accommodation reflex was significantly inhibited by rimonabant (154.3 +/- 30.9 vs. 64.3 +/- 32.4 mL, P = 0.02). Rimonabant did not affect maximal nutrient tolerance or meal-related symptoms during the satiety drinking test. CONCLUSION Endocannabinoids acting on the CB1 receptor are involved in the control of gastric accommodation in man.
Collapse
|
100
|
Verhoef BE, Vogels R, Janssen P. Contribution of inferior temporal and posterior parietal activity to three-dimensional shape perception. Curr Biol 2010; 20:909-13. [PMID: 20434342 DOI: 10.1016/j.cub.2010.03.058] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 03/12/2010] [Accepted: 03/12/2010] [Indexed: 10/19/2022]
Abstract
One of the fundamental goals of neuroscience is to understand how perception arises from the activity of neurons in the brain. Stereopsis is a type of three-dimensional (3D) perception that relies on two slightly different projections of the world onto the retinas of the two eyes, i.e., binocular disparity. Neurons selective for curved surfaces defined by binocular disparity may contribute to the perception of an object's 3D structure. Such neurons have been observed in both the anterior lower bank of the superior temporal sulcus (TEs, part of the inferior temporal cortex [IT]) and the anterior intraparietal area (AIP). However, the specific contributions of IT and AIP to depth perception remain unknown. We simultaneously recorded multiunit activity in IT and AIP while monkeys discriminated between concave and convex 3D shapes. We observed a correlation between the neural activity and behavioral choice that arose early and during perceptual decision formation in IT but later and after perceptual decision formation in AIP. These results suggest a role for IT, but not AIP, in 3D shape discrimination. Furthermore, the results demonstrate that similar neuronal stimulus selectivities in two areas do not imply a similar function.
Collapse
|