Until recently, it was assumed that the circadian rhythm is entrained in the embryos independent of the brooding female and that the ambient light/dark cycle is the agent that sets the rhythm (zeitgeber
Supplementary exposure to bright light (i.e., light therapy) has beneficial effects on sleep, depression, bradykinesia, rigidity, and dyskinesias in PD patients, as light activates the suprachiasmatic nucleus and is the most effective zeitgeber
of the circadian timing system.
So, the current study was aimed to evaluate impact of inflammation and anesthesia on cognition by quantifying BDNF protein in the hippocampus and cortical areas at 3rd day of treatment at ZT5 (Zeitgeber
After 52 wk of exposure, 4 to 5 mice from each experimental group were daily randomly sacrificed (in total, 16 to 20 animals from the four experimental groups were sacrificed per day) by cervical dislocation at Zeitgeber
time 17 (i.e., in the fed state) at which hepatic activities are optimal (Lu et al.
Wever, "Re entrainment of circadian rhythms after phase shifts of the Zeitgeber
," Chronobiologia, vol.
Stephan, "The "other" circadian system: food as a zeitgeber
," Journal of Biological Rhythms, vol.
Though light operates as their chief zeitgeber
(from the German zeit = time; geber = giver, or synchronizing agent), the SCN can interpret several exogenous and physiological time-of-day cues to entrain other satellite oscillators in the periphery and their respective signaling networks .
The German ornithologists also found that light intensity is a primary factor, a "Zeitgeber
" for the birds' dispersal and their circadian activity.
The SCN needs daily synchronization to adapt to environmental 24- light-dark cycles, and light is the major synchronizer (zeitgeber
All animals were exposed to 1.5% concentration of isoflurane or to 6 L [min.sup.-1] [O.sub2] for six hours between Zeitgeber
Time (ZT) 0-ZT06 (day-time administration) or ZT12-ZT18 (night-time administration).
Results of several murine studies showed that timing to food access, in the fasting state, is the cue "Zeitgeber
" to entrain hepatic oscillators [33, 52-55, 59] and thereby evoke upregulation of mRNA and various protein synthetic pathways, including enzymes that play a role in carbohydrate and lipid metabolism [33,59].
LD cycle is a well-known zeitgeber
that synchronize the clock components both in vitro and in vivo, allowing the rhythmic expression of several clock-controlled molecules.