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Dissertation
Circadian regulation of sleep-wake: a neural pathway from the suprachiasmatic nucleus to the locus coeruleus in the rat-transynaptic tracing with pseudorabies virus
Doctor of Philosophy (Ph.D.), Allegheny University of the Health Sciences
Jun 1998
DOI:
https://doi.org/10.17918/00003400
Abstract
It has been proposed that the suprachiasmatic nucleus (SCN) assures sleep-wake circadian rhythms by actively promoting wakefulness. The locus coeruleus (LC) has been widely implicated in mechanisms regulating arousal and alertness. We hypothesize that SCN's arousal promoting effect may be mediated, at least in part, via the LC-noradrenergic system. Although the SCN does not directly innervate the LC, we investigated possible indirect projections using transsynaptic tracing with pseudorabies virus (PRV). First, a methodological characterization of transsynaptic tracing with central application of PRV was conducted. Our data indicate that (i) centrally injected PRV diffuses very little and produces focal injection sites; (ii) PRV is taken up and transported by fibers of passage, although less prominently than found for cholera toxin subunit B; (iii) PRV produces specific and easily identifiable ependymal cell as well as neutonal labeling following ventricular injection. Second, a temporal analysis of PRV labeling in the SCN following LC injection was conducted. The possible relay between the SCN and the LC was also investigated. In addition, double immunostaining was conducted to examine whether SCN neurons that indirectly project to the LC contain vasoactive intestinal peptide (VIP) or vasopressin (VP), two major neuropeptides found in the SCN. Data from this set of experiments indicate that (i) The circuitry from the SCN to the LC is a two-neuron pathway; (ii) neurons in the medial preoptic area are likely relays between the SCN and LC; and (iii) the SCN neurons that regulate the LC are separate from those containing neuropeptide VEP or VP. In summary, the present study provides the first anatomical evidence of a neural pathway from the SCN to the LC, and supports the idea that SCN's effect on the sleepwake cycle may be mediated via the LC-noradrenergic system. In addition, the present study also provides new and important information about using pseudorabies virus to trace central multisynaptic circuitry.
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Details
- Title
- Circadian regulation of sleep-wake
- Creators
- Sheng Chen
- Contributors
- Gary Aston-Jones (Advisor) - Drexel University, Allegheny University of the Health Sciences (1996-1998)
- Awarding Institution
- Allegheny University of the Health Sciences
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Allegheny University of the Health Sciences; Philadelphia, Pennsylvania
- Number of pages
- xii, 82 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Allegheny University of the Health Sciences (1996-1998); School of Medicine (1996-1998)
- Other Identifier
- 991021888805804721