Circadian pacemaker in the suprachiasmatic nuclei of teleost fish revealed by rhythmic period2 expression

2012 ◽  
Vol 178 (2) ◽  
pp. 400-407 ◽  
Author(s):  
Nanako Watanabe ◽  
Kae Itoh ◽  
Makoto Mogi ◽  
Yuichiro Fujinami ◽  
Daisuke Shimizu ◽  
...  
Keyword(s):  
Teleost Fish ◽  
Circadian Pacemaker ◽  
Suprachiasmatic Nuclei

scholarly journals Morphological Changes in the Suprachiasmatic Nucleus of Aging Female Marmosets (Callithrix jacchus)

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Rovena Clara G. J. Engelberth ◽  
Kayo Diogenes de A. Silva ◽  
Carolina V. de M. Azevedo ◽  
Elaine Cristina Gavioli ◽  
Jose Ronaldo dos Santos ◽  
...  
Keyword(s):  
Nonhuman Primates ◽  
Morphological Changes ◽  
Neuronal Loss ◽  
Biological Rhythms ◽  
Circadian Pacemaker ◽  
Suprachiasmatic Nuclei ◽  
Nissl Staining ◽  
Morphological Aspects ◽  
Compensatory Process ◽  
Neurochemical Changes

The suprachiasmatic nuclei (SCN) are pointed to as the mammals central circadian pacemaker. Aged animals show internal time disruption possibly caused by morphological and neurochemical changes in SCN components. Some studies reported changes of neuronal cells and neuroglia in the SCN of rats and nonhuman primates during aging. The effects of senescence on morphological aspects in SCN are important for understanding some alterations in biological rhythms expression. Therefore, our aim was to perform a comparative study of the morphological aspects of SCN in adult and aged female marmoset. Morphometric analysis of SCN was performed using Nissl staining, NeuN-IR, GFAP-IR, and CB-IR. A significant decrease in the SCN cells staining with Nissl, NeuN, and CB were observed in aged female marmosets compared to adults, while a significant increase in glial cells was found in aged marmosets, thus suggesting compensatory process due to neuronal loss evoked by aging.

Anticipatory activity and entrainment of circadian rhythms in Syrian hamsters exposed to restricted palatable diets

1992 ◽  
Vol 263 (1) ◽  
pp. R116-R124 ◽  
Author(s):  
H. Abe ◽  
B. Rusak
Keyword(s):  
Circadian Rhythm ◽  
Food Restriction ◽  
Free Access ◽  
Circadian Pacemaker ◽  
Suprachiasmatic Nuclei ◽  
Experimental Animals ◽  
Daily Feeding ◽  
Free Running ◽  
Anticipatory Activity ◽  
Normal Food

Activity rhythms were recorded from hamsters in three conditions: during timed feedings of an attractive diet with free access to regular food, during restriction to 70% of normal food consumption, and during moderate food deprivation with limited temporal access to an attractive diet. An attractive diet given to intact animals did not induce anticipatory activity or entrainment, but damage to the suprachiasmatic nuclei (SCN) led to the development of anticipatory activity. Food restriction to 70% of normal intake led to anticipatory components in some intact animals, without entraining the dominant circadian pacemaker. The combination of a palatable diet and food restriction led to anticipatory activity before the daily feeding times and entrainment of a previously free-running circadian rhythm in some animals. Ablation of the SCN did not eliminate anticipatory activity in experimental animals, but did eliminate the free-running component of the rhythms. These results indicate that hamsters have a mechanism separate from the SCN that can anticipate daily feeding times, as rats do, and that they may show entrainment of the SCN-based pacemaker to such feeding schedules.

scholarly journals Melanopsin-dependent direct photic effects are equal to clock-driven effects in shaping the nychthemeral sleep-wake cycle

2020 ◽  
Author(s):  
Jeffrey Hubbard ◽  
Mio Kobayashi Frisk ◽  
Elisabeth Ruppert ◽  
Jessica W. Tsai ◽  
Fanny Fuchs ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Sleep Disorder ◽  
Jet Lag ◽  
Circadian Pacemaker ◽  
Suprachiasmatic Nuclei ◽  
Acute Effects ◽  
Dark Cycle ◽  
Direct Light ◽  
Light Effects

AbstractNychthemeral sleep-wake cycles (SWc) are known to be generated by the circadian clock in suprachiasmatic nuclei (SCN), entrained to the light-dark cycle. Light also exerts direct acute effects on sleep and waking. However, under longer photic exposure such as the 24-hour day, the precise significance of sustained direct light effects (SDLE) and circuitry involved have been neither clarified nor quantified, as disentangling them from circadian influence is difficult. Recording sleep in mice lacking a circadian pacemaker and/or melanopsin-based phototransduction, we uncovered, contrary to prevailing assumptions, that circadian-driven input shapes only half of SWc, with SDLE being equally important. SDLE were primarily mediated (>80%) through melanopsin, of which half were relayed through SCN, independent of clock function. These findings were used for a model that predicted SWc under simulated jet-lag, and revealed SDLE as a crucial mechanism influencing behavior, and should be considered for circadian/sleep disorder management and societal lighting optimization.

scholarly journals Nested calcium dynamics support daily cell unity and diversity in the suprachiasmatic nuclei of free-behaving mice

2021 ◽  
Author(s):  
Lama El Cheikh Hussein ◽  
Pierre Fontanaud ◽  
Patrice Mollard ◽  
Xavier Bonnefont
Keyword(s):  
Functional Organization ◽  
Activity Patterns ◽  
Time Of Day ◽  
Emergent Properties ◽  
Light Cycle ◽  
Circadian Pacemaker ◽  
Suprachiasmatic Nuclei ◽  
Neuronal Code ◽  
Clock Mechanism

The suprachiasmatic nuclei (SCN) of the anterior hypothalamus host the circadian pacemaker that synchronizes mammalian rhythms with the day-night cycle. SCN neurons are intrinsically rhythmic, thanks to a conserved cell-autonomous clock mechanism. In addition, circuit-level emergent properties confer a unique degree of precision and robustness to SCN neuronal rhythmicity. However, the multicellular functional organization of the SCN is not yet fully understood. Although SCN neurons are well coordinated, experimental evidences indicate that some neurons oscillate out of phase in SCN explants, and possibly to a larger extent in vivo. Here, we used microendoscopic Ca2+i imaging to investigate SCN rhythmicity at a single cell resolution in free-behaving mice. We found that SCN neurons in vivo exhibited fast Ca2+i spikes superimposed upon slow changes in baseline Ca2+i levels. Both spikes and baseline followed a time-of-day modulation in many neurons, but independently from each other. Daily rhythms in basal Ca2+i were well coordinated, while spike activity from the same neurons peaked at multiple times of the light cycle, and unveiled clock-independent interactions at the multicellular level. Hence, fast Ca2+i spikes and slow changes in baseline Ca2+i levels highlighted how diverse activity patterns could articulate within the temporal network unity of the SCN in vivo, and provided support for a multiplex neuronal code in the circadian pacemaker.

Different in vivo metabolic activities of suprachiasmatic nuclei of Turkish and golden hamsters

1990 ◽  
Vol 259 (5) ◽  
pp. R1083-R1085 ◽  
Author(s):  
W. J. Schwartz
Keyword(s):  
Energy Metabolism ◽  
Glucose Utilization ◽  
High Energy ◽  
Circadian Pacemaker ◽  
Suprachiasmatic Nuclei ◽  
Light Phase ◽  
Dark Cycle ◽  
Golden Hamsters ◽  
Metabolic Activities

The 14C-labeled 2-deoxy-D-glucose technique was used to measure in vivo glucose utilization of the suprachiasmatic nuclei (SCN) of Turkish and golden hamsters during the middle hours of the light phase of the 12:12 h light-dark cycle. The nuclei were clearly visible on autoradiographs made from the brains of Turkish hamsters, and their rate of glucose utilization (69 +/- 6 mumol.100 g-1.min-1) was similar to that previously measured in other rodents, whereas the nuclei were hardly visible on autoradiographs from golden hamsters, and their rate (33 +/- 2 mumol.100 g-1.min-1) was less than half this value. Thus the high energy metabolism characteristic of the SCN of most species is not required for the circadian pacemaker in the nuclei to generate its oscillation.

scholarly journals The roles of vasoactive intestinal polypeptide in the mammalian circadian clock

2003 ◽  
Vol 177 (1) ◽  
pp. 7-15 ◽  
Author(s):  
HD Piggins ◽  
DJ Cutler
Keyword(s):  
Circadian Clock ◽  
Vasoactive Intestinal Polypeptide ◽  
Chemical Constituents ◽  
Neural Pathways ◽  
Circadian Pacemaker ◽  
Suprachiasmatic Nuclei ◽  
Environmental Signals ◽  
Intestinal Polypeptide

Biological oscillations with an endogenous period of near 24 h (circadian rhythms) are generated by the master circadian pacemaker or clock located in the suprachiasmatic nuclei (SCN) of the hypothalamus. This clock is synchronised to recurring environmental signals conveyed by selective neural pathways. One of the main chemical constituents of SCN neurones is vasoactive intestinal polypeptide (VIP). Such neurones are retinorecipient and activated by light. Exogenous application of VIP resets the SCN circadian clock in a light-like manner, both in vivo and in vitro. These resetting actions appear to be mediated through the VPAC2 receptor (a type of receptor for VIP). Unexpectedly, genetically ablating expression of the VPAC2 receptor renders the circadian clock arrhythmic at the molecular, neurophysiological and behavioural levels. These findings indicate that this intrinsic neuropeptide acting through the VPAC2 receptor participates in both resetting to light and maintenance of ongoing rhythmicity of the SCN.

scholarly journals Effect of Transplanting Suprachiasmatic Nuclei from Donors of Different Ages into Completely SCN Lesioned Hamsters

1993 ◽  
Vol 4 (4) ◽  
pp. 257-265 ◽  
Author(s):  
Claire M. Kaufman ◽  
Michael Menaker
Keyword(s):  
Vasoactive Intestinal Peptide ◽  
Suprachiasmatic Nucleus ◽  
Neural Tissue ◽  
Circadian Pacemaker ◽  
Suprachiasmatic Nuclei ◽  
Graft Success ◽  
Wheel Activity ◽  
Genetically Determined ◽  
Age Range ◽  
New Evidence

The suprachiasmatic nucleus (SCN) is the primary circadian pacemaker in mammals. Ralph and colleagues/14/provided recent new evidence for this by transplanting SCNs between golden hamsters with different genetically determined periods and producing circadian rhythmsof running wheel activity with periods characteristic of the donor. We have extended these studies in order to evaluate the age range of donor tissue that can be used for transplantation. SCN of hamsters from embryonic day 11 through postnatal day 12 can serve as functional grafts to restore rhythmicity to arrhythmic SCN lesioned animals. The time between SCN transplantation and onset of rhythmicity does not depend on the age of the donor. The presence of patches containing vasoactive intestinal peptide (VIP) immunoreactive cells is a good indicator of graft success, while its absence is correlated with a lack of transplant effect. The 18 day span during which SCN tissue can be harvested for transplantation should expand the uses to which this technique can be put. Our results also suggest that it would be advantageous to examine the age range of neural tissue that ca’n be used in other transplantation models.

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