Elizabeth L. Meyer-Bernstein

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The suprachiasmatic nucleus (SCN) is the neuroanatomical locus of the mammalian circadian pacemaker. Here we demonstrate that an abrupt shift in the light/dark (LD) cycle disrupts the synchronous oscillation of circadian components in the rat SCN. The phases of the RNA cycles of the period genes Per1 and Per2 and the cryptochrome gene Cry1 shifted rapidly(More)
Grafts of fetal tissue including the suprachiasmatic nucleus (SCN) of the hypothalamus restore locomotor rhythmicity to behaviorally arrhythmic, SCN-lesioned Syrian hamsters. We sought to determine whether such transplants also reinstate endocrine rhythms in SCN-lesioned hamsters. In Exp 1, SCN lesions interrupted estrous cycles in a 14 h light, 10 h dark(More)
Serotonergic innervation is believed to inhibit the effects of light on the mammalian circadian timing system. Two anatomical components of this system, the suprachiasmatic nucleus (SCN) and the intergeniculate leaflet (IGL), receive serotonergic input from midbrain raphe nuclei. The present studies use retrograde and anterograde tracing as well as(More)
The ascending serotonergic projections are derived largely from the midbrain median and dorsal raphe nuclei, and contribute to the regulation of many behavioral and physiological systems. Serotonergic innervation of the hamster circadian system has been shown to be substantially different from earlier results obtained with other methods and species. The(More)
Systematic treatment of hamsters with triazolam (TRZ) or novel wheel (NW) access will yield PRCs similar to those for neuropeptide Y. Both TRZ and NW access require an intact intergeniculate leaflet (IGL) to modulate circadian rhythm phase. It is commonly suggested that both stimulus types influence rhythm phase response via a mechanism associated with(More)
BACKGROUND Although much is known about how circadian systems control daily cycles in the physiology and behavior of Drosophila and several vertebrate models, marine invertebrates have often been overlooked in circadian rhythms research. This study focuses on the starlet sea anemone, Nematostella vectensis, a species that has received increasing attention(More)
The suprachiasmatic nucleus (SCN) is densely innervated by serotonergic fibers originating in the median raphe nucleus (MR). Serotonin (5-HT) specific lesions of the MR alter entrainment and eliminate 5-HT fibers in the SCN, as well as in all other MR-recipient areas. The present study used 5-HT specific lesions of the SCN or the MR to determine the role of(More)
BACKGROUND Recent molecular studies suggest that mammals and Drosophila utilize similar components to generate circadian (approximately equal to 24 h) rhythms. The first identified circadian clock gene, the period (per) gene, is indispensable for behavioural rhythms in Drosophila and is represented in mammals by three orthologues, the relative roles of(More)
Several pharmacological studies have suggested that the large median raphe serotonergic projection to the circadian clock in the suprachiasmatic nucleus may modulate circadian rhythm phase. The present experiments studied the role of dorsal and median raphe nuclei as regulators of circadian rhythmicity by evaluating the ability of electrical stimulation to(More)
An endogenous biological clock located in the hypothalamic suprachiasmatic nucleus (SCN) regulates the timing of an organism's physiology and behavior. A variety of receptors are found on SCN pacemaker cells which permit the clock mechanism to respond to extra- and intra-SCN chemical messengers. A subset of these receptors is coupled to G-proteins, which(More)