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035 a| (Sirsi) o624184814;

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040 a| NEHc| NEHd| NEHd| UtOrBLW;

049 a| NEHH;

100 1 a| Vijayakumar, Sarath.?| UNAUTHORIZED;

245 14 a| The role of mediators of neuronal plasticity in the circadian regulation of suprachiasmatic nucleus by light /c| by Sarath Vijayakumar.;

260 a| [Greenville, N.C.] :b| East Carolina University,c| 2009.;

300 a| 147 pages :b| illustrations (some color), digital, PDF file.;

336 a| text2| rdacontent;

337 a| computer2| rdamedia;

338 a| online resource2| rdacarrier;

490 1 a| ECU Brody School of Medicine thesis;

500 a| Presented to the faculty of the Department of Physiology.;

500 a| Advisor: Jian Ding.;

500 a| Title from PDF t.p. (viewed June 12, 2010).;

502 b| Ph.D.c| East Carolina Universityd| 2009.;

504 a| Includes bibliographical references.;

520 3 a| Circadian rhythms are highly conserved physiological functions that are present in almost all living organisms. In mammals, circadian rhythms are synchronized to the environmental light:dark cycle by daily adjustments in the hypothalamic suprachiasmatic nucleus (SCN), the location of the master circadian pacemaker. We hypothesize that light entrainment of the circadian clock involves neural plastic adaptations in the SCN. The mechanism of neural plasticity has been intensively studied in the hippocampus and the dentate gyrus. However, the cell and molecular mechanism underlying circadian clock resetting in the SCN remains poorly understood. Thus, we sought to investigate whether modulators that are known to regulate neural plasticity in the hippocampus play a role in the signal transduction of circadian clock resetting. Light induced expression of tissue-type plasminogen activator (tPA) in the SCN, maximal induction was seen one hour following a light pulse at circadian time (CT) 16. A corresponding increase in the tPA proteolytic activity was also observed. tPA-STOP TM (an inhibitor of tPA)-infused animals exhibited attenuated light-induced phase delay of circadian wheel running activity. The levels of cyclin-dependent kinase 5 activators, p35 and p25 were decreased at Zeitgeber Time (ZT) 16, at ZT22 the levels were increased whereas, no change was observed at ZT6. The bi-transgenic animal, CK-p25 demonstrated increased phase delay at CT16 and attenuated phase advance at CT22 following transient overexpression of p25. SCN neurons expressing p25 co-localized with phosphorylated-extracellular signal-regulated kinase and Gastrin Releasing Peptide. This is one of the first studies to report the involvement of these neuromodulators in circadian light entrainment. Mounting evidence shows that circadian rhythm disturbances may be associated with increased health risks, such as jet-lag, cancer development, cardiovascular and metabolic disorders. The findings of this study have improved our understanding of the complex and intricate pathways involved in light entrainment and may lead to development of novel therapeutic avenues in treating circadian rhythm disturbances.;

538 a| System requirements: Adobe Reader.;

538 a| Mode of access: World Wide Web.;

650 0 a| Circadian rhythms.=| ^A9157;

650 2 a| Circadian Rhythm.=| ^A919175;

650 2 a| Suprachiasmatic Nucleus.=| ^A1018024;

653 a| Biology, Physiology;

653 a| Biology, Neuroscience;

700 1 a| Ding, Jian.=| ^A1014613;

710 2 a| East Carolina University.b| Department of Physiology.?| UNAUTHORIZED;

830 0 a| ECU Brody School of Medicine thesis.=| ^A964744;

856 40 z| Access via ScholarShipu| http://hdl.handle.net/10342/2215;

949 a| Click on web addressw| ASISh| JOYNER101;

949 a| Click on web addressw| ASISh| HSL111;

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998 a| 2282003;

999 a| CLICK ON WEB ADDRESSw| ASISc| 1i| 2282003-1001l| JNETm| JOYNERr| Ys| Yt| JNE3ETDu| 7/9/2010x| ETDz| JERESOURCE;

999 a| CLICK ON WEB ADDRESSw| ASISc| 1i| 2282003-2001l| HSLELECm| HSLr| Ys| Yt| HEETDu| 7/9/2010x| ETDz| HERESOURCE;

The role of mediators of neuronal plasticity in the circadian regulation of suprachiasmatic nucleus by light / by Sarath Vijayakumar.

Author/creator	Vijayakumar, Sarath
Other author	Ding, Jian.
Other author	East Carolina University. Department of Physiology.
Format	Theses and dissertations
Publication Info	[Greenville, N.C.] : East Carolina University, 2009.
Description	147 pages : illustrations (some color), digital, PDF file.
Supplemental Content	Access via ScholarShip
Subjects	Circadian rhythms. Circadian Rhythm. Suprachiasmatic Nucleus.

Series	ECU Brody School of Medicine thesis ECU Brody School of Medicine thesis. ^A964744
Summary	Circadian rhythms are highly conserved physiological functions that are present in almost all living organisms. In mammals, circadian rhythms are synchronized to the environmental light:dark cycle by daily adjustments in the hypothalamic suprachiasmatic nucleus (SCN), the location of the master circadian pacemaker. We hypothesize that light entrainment of the circadian clock involves neural plastic adaptations in the SCN. The mechanism of neural plasticity has been intensively studied in the hippocampus and the dentate gyrus. However, the cell and molecular mechanism underlying circadian clock resetting in the SCN remains poorly understood. Thus, we sought to investigate whether modulators that are known to regulate neural plasticity in the hippocampus play a role in the signal transduction of circadian clock resetting. Light induced expression of tissue-type plasminogen activator (tPA) in the SCN, maximal induction was seen one hour following a light pulse at circadian time (CT) 16. A corresponding increase in the tPA proteolytic activity was also observed. tPA-STOP TM (an inhibitor of tPA)-infused animals exhibited attenuated light-induced phase delay of circadian wheel running activity. The levels of cyclin-dependent kinase 5 activators, p35 and p25 were decreased at Zeitgeber Time (ZT) 16, at ZT22 the levels were increased whereas, no change was observed at ZT6. The bi-transgenic animal, CK-p25 demonstrated increased phase delay at CT16 and attenuated phase advance at CT22 following transient overexpression of p25. SCN neurons expressing p25 co-localized with phosphorylated-extracellular signal-regulated kinase and Gastrin Releasing Peptide. This is one of the first studies to report the involvement of these neuromodulators in circadian light entrainment. Mounting evidence shows that circadian rhythm disturbances may be associated with increased health risks, such as jet-lag, cancer development, cardiovascular and metabolic disorders. The findings of this study have improved our understanding of the complex and intricate pathways involved in light entrainment and may lead to development of novel therapeutic avenues in treating circadian rhythm disturbances.
General note	Presented to the faculty of the Department of Physiology.
General note	Advisor: Jian Ding.
General note	Title from PDF t.p. (viewed June 12, 2010).
Dissertation note	Ph.D. East Carolina University 2009.
Bibliography note	Includes bibliographical references.
Technical details	System requirements: Adobe Reader.
Technical details	Mode of access: World Wide Web.

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The role of mediators of neuronal plasticity in the circadian regulation of suprachiasmatic nucleus by light / by Sarath Vijayakumar.

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