Physiological stimulation of the hypothalamo-neurohypophysial system by salt loading rats resulted in a dramatically increased glucose utilization posterior pituitary but not paraventricular or supraoptic nuclei. The good correlation between and neural activity (that is, nerve terminals) contrasted with lack nuclei sites cell bodies same neurons). This difference metabolic response to functional two regions these neurons can be explained differences surface-to-volume ratios regions.

Glucose consumption of the rat suprachiasmatic nuclei (SCN) was studied under various experimental conditions by means [14C]deoxyglucose (DG) technique. The results show that glucose SCN, in contrast to other brain structures, is a function both time day and environmental lighting conditions. These data are consistent with hypothesis SCN have an essential role circadian rhythm regulation indicate DG technique may provide novel approach for study central neural mechanisms underlying regulation.

Mammalian circadian rhythmicity is endogenously generated by a pacemaker in the suprachiasmatic nuclei and precisely entrained to 24-hr day/night cycle periodic environmental light cues. We show that alters immunoreactive levels of transcriptional regulatory protein, Fos, albino rats. Photic regulation Fos immunoreactivity does not occur other retino-recipient brain areas except for intergeniculate leaflet, which appears be involved mediating some complex effects on expressed rhythms. Our...

An unusual property of the circadian timekeeping systems animals is rhythm “splitting,” in which a single daily period physical activity (usually measured as wheel running) dissociates into two stably coupled components about 12 hours apart; this behavior has been ascribed to clock composed oscillators cycling antiphase. We analyzed gene expression hypothalamic clock, suprachiasmatic nucleus (SCN), behaviorally “split” hamsters housed constant light. The results show that underlying split...

Tetrodotoxin was infused into the suprachiasmatic nuclei of unanesthetized and unrestrained rats continuously for 14 days. The internal timekeeping mechanism circadian pacemaker in continued to oscillate unaffected by this treatment, although toxin reversibly blocked function both input pathway entrainment an output expression drinking rhythm. Thus, Na+-dependent action potentials appear necessary overt rhythms, but they do not seem keep accurate time. experimental approach presented paper...

Deoxyglucose labeled with carbon-14 was used in studying the utilization of glucose suprachiasmatic nuclei fetal rats. The results showed that an entrainable circadian clock is present during development and maternal system coordinates phase to environmental lighting conditions.

Abstract The suprachiasmatic nucleus (SCN) has been proposed as a site for an endogenous circadian oscillator in mammals, since lesions of the abolish wide spectrum overt rhythms. To demonstrate that directly measurable property SCN itself intact (unlesioned) animals is affected by environmental light and exhibits rhythmicity, we used autoradiographic 2‐deoxy‐D‐[ 14 C]glucose method to determine glucose utilization rat under variety lighting conditions. Our experiments indicate important...

The hypothesis is advanced that the circadian pacemaker in mammalian suprachiasmatic nucleus (SCN) composed at molecular level of a nonredundant double complex genes (per1, cry1, and per2, cry2). Each one these sets would be sufficient for maintenance endogenous rhythmicity thus constitute an oscillator. have slightly different temporal dynamics light responses. per1/cry1 oscillator accelerated by decelerated darkness thereby tracks dawn when day length changes. per2 /cry2 dusk. These M...

Daily variation has been found in the length of polyadenylate tail attached to vasopressin messenger RNA suprachiasmatic nuclei, which is location an endogenous circadian pacemaker mammals. No such was supraoptic or paraventricular nuclei. This may underlie rhythm peptide levels cerebrospinal fluid and a unique example daily structure.

Seasonal changes of daylength (photoperiod) affect the expression hormonal and behavioral circadian rhythms in a variety organisms. In mammals, such effects might reflect photoperiodic pace-making system [located suprachiasmatic nucleus (SCN) hypothalamus] that governs these rhythms, but to date no functionally relevant, intrinsic property SCN has been shown be photoperiod dependent. We have analyzed temporal regulation light-induced c-fos gene rats maintained long or short photoperiods....

Abstract The 2‐deoxy‐D‐[ 14 C]‐glucose (2‐DG) autoradiographic method for determining regional brain glucose consumption has been applied successfully by a number of workers mapping the alterations which occur in association with experimental functional activity. This paper provides framework interpretation these and further studies presenting: (1) pattern normal, resting, awake rat; (2) anatomical identities structures on autoradiographs appear only as variations optical density. For this...