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PTPRD expression regulates sleep consolidation in Drosophila
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Abstracts / Sleep Medicine 14S (2013) e18–e92
Materials and methods: A total of 18 subjects (9 patients and 9 age and sex-matched controls) were included in the study. The tissue pO2 and pCO2 were estimated by transcutaneous measurements on the instep of the foot and on the chest. The measurements were performed in the evening, during two repeated suggested immobilization tests (SIT), two and four hours before bedtime. RLS patients went through the measurements once without medication and a second time with dopaminergic therapy. At the same time, arterial oxygen saturation (SaO2) was measured from the toe. Results: The mean tissue pO2 during SIT was lower in the legs of RLS patients than controls (5.1 kPa vs. 7.4 kPa, p < 0.05). The oxygen gradient from chest to foot (=pO2(chest)-pO2(foot)) was higher in RLS compared to controls (3.5 kPa vs. 1.5 kPa, p < 0.05). The oxygen gradient showed a strong positive correlation with IRLSSG severity score (Pearson’s r = 0.570). Dopaminergic therapy resolved the hypoxia, raising the pO2 of the legs almost to the level of the control patients (pO2 = 6.4 kPa, p < 0.05). There was no significant difference in SaO2 or pCO2 measures. Conclusion: Our results confirm that there is a significant peripheral hypoxia in the legs of RLS patients during the symptomatic period. Control subjects showed normal oxygen levels. The strong positive correlation with RLS severity suggests that the leg hypoxia could be a major factor in RLS pathophysiology. The finding that dopaminergic therapy abolishes both the symptoms and the hypoxia may suggest that the site of action of dopamine in RLS is in the periphery. Acknowledgement: The study was supported by Tuberculosis Foundation of Tampere, Finland. http://dx.doi.org/10.1016/j.sleep.2013.11.057
PTPRD expression regulates sleep consolidation in Drosophila A. Freeman 1, D. Rye 1, S. Sanyal 2 1 Emory University, Department of Neurology, United States 2 Biogen Idec, United States
Introduction: Restless legs syndrome/Willis-Ekbom Disease (RLS/ WED) is a common sleep disorder, yet its underlying pathophysiology is poorly understood. Genome-wide association studies (GWAS) point to allelic variants in multiple genes that confer susceptibility to RLS/WED. They offer potential insights into molecular pathways that govern expressivity of symptoms and signs. We used Drosophila melanogaster to explore sleep related physiology of two genes harboring at-risk alleles for RLS which also have highly conserved fly homologs, BTBD9 and PTPRD. Here, we complement our recent report of RLS phenotypes in BTBD9 mutants by exploring whether similar phenotypes exist in PTPRD mutants and probe whether sleep phenotypes are mimicked by dual mutants (i.e., suggesting a common molecular pathway) or are more severely disrupted (i.e., consistent with parallel pathways). Materials and methods: Sleep phenotypes resulting from mutations in the fly homolog of PTPRD (dLar) were assayed with the Drosophila Activity Monitor. Flies transgenic for either mutated or wild-type dLar protein allowed for cell-specific manipulation of expression levels. The impact of combined dLar and BTBD9 mutations on sleep architecture was also assessed. Results: Disruption of dLar/PTPRD expression in flies yielded viable, hyperlocomotive animals. dLar mutants exhibit sleep fragmentation and increased wake after sleep onset similar to that observed in BTBD9 mutant flies, the latter of which bears close resemblance to human RLS. The magnitude of fragmentation, as measured by sleep bout number and average sleep bout length, was not further increased by introduction of BTBD9 mutations into
the dLar mutant background. Neuron specific expression of dLar constructs, using the GAL4-UAS system, yielded disrupted sleep consolidation similar to whole animal dLar mutants. Conclusion: These results further validate GWAS as a hypothesis independent means to delineate the molecular pathophysiology underlying RLS/WED. While the role of PTPRD in neuronal development and plasticity has been studied previously in flies, this is the first exploration of its function in the context of sleep and, more specifically, RLS/WED. Our results suggest neuronal PTPRD expression regulates sleep architecture and most likely operates in a molecular pathway that also includes BTBD9. Ongoing efforts to delineate the mechanistic basis of sleep regulation by PTPRD and BTBD9 are underway. Acknowledgements: Supported by RLS Foundation, Sleep Research Society, and Emory Neuroscience Initiative grants to S.S. http://dx.doi.org/10.1016/j.sleep.2013.11.058
Activity and sleep in a mouse model of Parkinson disease I. Zavalko 1, Y. Ukraintseva 2, A. Manolov 3, V. Dolgikh 4, V. Dorokhov 3, V. Kovalzon 4 1 Institute for Bio-Medical Problems, RAS, Russia 2 Institute of Higher Nervous Activity/Neurophysiology, RAS, Russia 3 Higher Nervous Activity/Neurophysiology, RAS, Russia 4 Severtsov Institute Ecology/Evolution, RAS, Russia
Introduction: The search for early markers of Parkinson’s disease (PD) is one of the most important problems in the struggle against neurodegenerative illnesses. It is well known that large set of sleep-wake disorders occur with PD, including RBD, daytime sleepiness, night sleep disturbance etc. The nature of these is generally unknown. Not infrequently such disorders appear several years (up to 20 years) before motor symptoms of PD. Recently, a new murine model of early stages of PD has been developed [Ugrumov et al., Neuroscience 181 (2011) 175–188]. In this model, two successive subcutaneous injections in C57 black mice (with 2-h interval) of 12 mg/kg MPTP (specific neurotoxin of dopamine neurons) serve to imitate two weeks later pre-clinical PD, and four injections early clinical forms of PD. Materials and methods: A group of mice with preliminary implanted (under general anesthesia) electrodes for cortical EEG and nuchal EMG after a period of postoperative rest and adaptation to recording conditions was subjected to continuous 24-h video and digital polysomnographic recording in individual experimental chambers with 12/12 light/dark schedule, constant temperature (24–260C) and food and water ad lib. After the baseline recording of video-tracking activity and sleep-wake EEG, mice were injected with 24 or 48 mg/kg b.w. of MPTP. Control group was injected with a saline. The recordings were continued for 2 more weeks. Results: A significant increase in activity and decrease in slow wave sleep (SWS) percentage during the dark period ( 25%) as compared to baseline and control recording (100%) was found. The effect was seen just at the 7th day following MPTP administration and became significant by the 14th day. The effect was more pronounced after 48 mg/kg injection than after 24. There was no change in paradoxical sleep (PS). Also, there were no changes either in SWS or PS during the light period. The reason for this increasing activity and diminished SWS level during the dark period in MPTP-treated mice is under study now. Conclusion: The reason for this increasing activity and diminished SWS level during the dark period in MPTP-treated mice is under study now.
Abstracts / Sleep Medicine 14S (2013) e18–e92
Materials and methods: A total of 18 subjects (9 patients and 9 age and sex-matched controls) were included in the study. The tissue pO2 and pCO2 were estimated by transcutaneous measurements on the instep of the foot and on the chest. The measurements were performed in the evening, during two repeated suggested immobilization tests (SIT), two and four hours before bedtime. RLS patients went through the measurements once without medication and a second time with dopaminergic therapy. At the same time, arterial oxygen saturation (SaO2) was measured from the toe. Results: The mean tissue pO2 during SIT was lower in the legs of RLS patients than controls (5.1 kPa vs. 7.4 kPa, p < 0.05). The oxygen gradient from chest to foot (=pO2(chest)-pO2(foot)) was higher in RLS compared to controls (3.5 kPa vs. 1.5 kPa, p < 0.05). The oxygen gradient showed a strong positive correlation with IRLSSG severity score (Pearson’s r = 0.570). Dopaminergic therapy resolved the hypoxia, raising the pO2 of the legs almost to the level of the control patients (pO2 = 6.4 kPa, p < 0.05). There was no significant difference in SaO2 or pCO2 measures. Conclusion: Our results confirm that there is a significant peripheral hypoxia in the legs of RLS patients during the symptomatic period. Control subjects showed normal oxygen levels. The strong positive correlation with RLS severity suggests that the leg hypoxia could be a major factor in RLS pathophysiology. The finding that dopaminergic therapy abolishes both the symptoms and the hypoxia may suggest that the site of action of dopamine in RLS is in the periphery. Acknowledgement: The study was supported by Tuberculosis Foundation of Tampere, Finland. http://dx.doi.org/10.1016/j.sleep.2013.11.057
PTPRD expression regulates sleep consolidation in Drosophila A. Freeman 1, D. Rye 1, S. Sanyal 2 1 Emory University, Department of Neurology, United States 2 Biogen Idec, United States
Introduction: Restless legs syndrome/Willis-Ekbom Disease (RLS/ WED) is a common sleep disorder, yet its underlying pathophysiology is poorly understood. Genome-wide association studies (GWAS) point to allelic variants in multiple genes that confer susceptibility to RLS/WED. They offer potential insights into molecular pathways that govern expressivity of symptoms and signs. We used Drosophila melanogaster to explore sleep related physiology of two genes harboring at-risk alleles for RLS which also have highly conserved fly homologs, BTBD9 and PTPRD. Here, we complement our recent report of RLS phenotypes in BTBD9 mutants by exploring whether similar phenotypes exist in PTPRD mutants and probe whether sleep phenotypes are mimicked by dual mutants (i.e., suggesting a common molecular pathway) or are more severely disrupted (i.e., consistent with parallel pathways). Materials and methods: Sleep phenotypes resulting from mutations in the fly homolog of PTPRD (dLar) were assayed with the Drosophila Activity Monitor. Flies transgenic for either mutated or wild-type dLar protein allowed for cell-specific manipulation of expression levels. The impact of combined dLar and BTBD9 mutations on sleep architecture was also assessed. Results: Disruption of dLar/PTPRD expression in flies yielded viable, hyperlocomotive animals. dLar mutants exhibit sleep fragmentation and increased wake after sleep onset similar to that observed in BTBD9 mutant flies, the latter of which bears close resemblance to human RLS. The magnitude of fragmentation, as measured by sleep bout number and average sleep bout length, was not further increased by introduction of BTBD9 mutations into
the dLar mutant background. Neuron specific expression of dLar constructs, using the GAL4-UAS system, yielded disrupted sleep consolidation similar to whole animal dLar mutants. Conclusion: These results further validate GWAS as a hypothesis independent means to delineate the molecular pathophysiology underlying RLS/WED. While the role of PTPRD in neuronal development and plasticity has been studied previously in flies, this is the first exploration of its function in the context of sleep and, more specifically, RLS/WED. Our results suggest neuronal PTPRD expression regulates sleep architecture and most likely operates in a molecular pathway that also includes BTBD9. Ongoing efforts to delineate the mechanistic basis of sleep regulation by PTPRD and BTBD9 are underway. Acknowledgements: Supported by RLS Foundation, Sleep Research Society, and Emory Neuroscience Initiative grants to S.S. http://dx.doi.org/10.1016/j.sleep.2013.11.058
Activity and sleep in a mouse model of Parkinson disease I. Zavalko 1, Y. Ukraintseva 2, A. Manolov 3, V. Dolgikh 4, V. Dorokhov 3, V. Kovalzon 4 1 Institute for Bio-Medical Problems, RAS, Russia 2 Institute of Higher Nervous Activity/Neurophysiology, RAS, Russia 3 Higher Nervous Activity/Neurophysiology, RAS, Russia 4 Severtsov Institute Ecology/Evolution, RAS, Russia
Introduction: The search for early markers of Parkinson’s disease (PD) is one of the most important problems in the struggle against neurodegenerative illnesses. It is well known that large set of sleep-wake disorders occur with PD, including RBD, daytime sleepiness, night sleep disturbance etc. The nature of these is generally unknown. Not infrequently such disorders appear several years (up to 20 years) before motor symptoms of PD. Recently, a new murine model of early stages of PD has been developed [Ugrumov et al., Neuroscience 181 (2011) 175–188]. In this model, two successive subcutaneous injections in C57 black mice (with 2-h interval) of 12 mg/kg MPTP (specific neurotoxin of dopamine neurons) serve to imitate two weeks later pre-clinical PD, and four injections early clinical forms of PD. Materials and methods: A group of mice with preliminary implanted (under general anesthesia) electrodes for cortical EEG and nuchal EMG after a period of postoperative rest and adaptation to recording conditions was subjected to continuous 24-h video and digital polysomnographic recording in individual experimental chambers with 12/12 light/dark schedule, constant temperature (24–260C) and food and water ad lib. After the baseline recording of video-tracking activity and sleep-wake EEG, mice were injected with 24 or 48 mg/kg b.w. of MPTP. Control group was injected with a saline. The recordings were continued for 2 more weeks. Results: A significant increase in activity and decrease in slow wave sleep (SWS) percentage during the dark period ( 25%) as compared to baseline and control recording (100%) was found. The effect was seen just at the 7th day following MPTP administration and became significant by the 14th day. The effect was more pronounced after 48 mg/kg injection than after 24. There was no change in paradoxical sleep (PS). Also, there were no changes either in SWS or PS during the light period. The reason for this increasing activity and diminished SWS level during the dark period in MPTP-treated mice is under study now. Conclusion: The reason for this increasing activity and diminished SWS level during the dark period in MPTP-treated mice is under study now.