Circadian rhythm and response to light of extracellular glutamate and aspartate in rat suprachiasmatic nucleus

1996 ◽  
Vol 271 (3) ◽  
pp. R579-R585 ◽  
Author(s):  
S. Honma ◽  
Y. Katsuno ◽  
K. Shinohara ◽  
H. Abe ◽  
K. Honma
Keyword(s):  
Circadian Rhythm ◽  
Suprachiasmatic Nucleus ◽  
Light Pulse ◽  
Continuous Light ◽  
In Vivo Microdialysis ◽  
Dark Phase ◽  
Dark Cycle ◽  
Complete Darkness ◽  
Endogenous Circadian Rhythm

Extracellular concentrations of glutamate and aspartate were measured in the vicinity of rat suprachiasmatic nucleus (SCN) by means of in vivo microdialysis. The concentrations of both excitatory amino acids (EAAs) were higher during the dark phase than during the light under the light-dark cycle, showing pulsatile fluctuations throughout the day. When rats were released into the complete darkness, the 24-h pattern in the aspartate continued for at least one cycle, whereas that in the glutamate disappeared. The nocturnal increases in the EAA levels were not due to the increase of locomotor activity during the nighttime, because the 24-h rhythms were also detected in animals under urethan anesthesia. The patterns of extracellular EAA levels were changed when rats were released into the continuous light. Circadian rhythm was not detected in the glutamate, whereas the 24-h pattern was maintained in the aspartate with the levels increased to various extents. A 30-min light pulse given either at zeitgber time (ZT) 1 or ZT 13 elevated the EAA levels during the latter half of the light pulse, except glutamate by a pulse at ZT 1. The extracellular EAA levels in the vicinity of the rat SCN showed the circadian rhythm with a nocturnal peak and increased in response to the continuous light and a brief light pulse. The aspartate level is considered to be regulated by the endogenous circadian rhythm, but the glutamate levels seems to be modified by the light-dark cycle.

A circadian rhythm of behavioural thermoregulation in a freshwater gastropod, Helisoma trivolis

1980 ◽  
Vol 58 (11) ◽  
pp. 2152-2155 ◽  
Author(s):  
Martin Kavaliers
Keyword(s):  
Circadian Rhythm ◽  
Constant Darkness ◽  
Dark Phase ◽  
Behavioural Thermoregulation ◽  
Dark Cycle ◽  
Preferred Temperature ◽  
Temperature Selection ◽  
Freshwater Gastropod ◽  
Free Running ◽  
Maximum Temperatures

The behaviour of the aquatic gastropod Helisoma trivolis was examined in a thermal gradient. Under a 12 h light: 12 h dark cycle gastropods displayed a diel rhythm of preferred temperature selection. Maximum temperatures (21–22 °C) were selected during the dark phase and minimum temperatures (17–18 °C) were selected during the light phase of the light–dark cycle. Under constant darkness temperature selection continued as an endogenous free-running circadian rhythm of behavioural thermoregulation.

In Vivo Assessment of the Midbrain Raphe Nuclear Regulation of Serotonin Release in the Hamster Suprachiasmatic Nucleus

1999 ◽  
Vol 81 (4) ◽  
pp. 1469-1477 ◽  
Author(s):  
Thomas E. Dudley ◽  
Lisa A. Dinardo ◽  
J. David Glass
Keyword(s):  
Suprachiasmatic Nucleus ◽  
In Vivo Microdialysis ◽  
Serotonin Release ◽  
Significant Inhibition ◽  
Serotonergic Activity ◽  
Way 100635 ◽  
Drug Actions ◽  
In Vivo Assessment ◽  
Stimulation Of

In vivo assessment of the midbrain raphe nuclear regulation of serotonin release in the hamster suprachiasmatic nucleus. Serotonin (5-HT) plays important regulatory roles in mammalian circadian timekeeping; however, little is known concerning the regulation of serotonergic activity in the circadian clock located in the suprachiasmatic nuclei (SCN). By using in vivo microdialysis to measure 5-HT release we demonstrated that electrical or pharmacological stimulations of the dorsal or median raphe nuclei (DRN and MRN, respectively) can alter basal release of 5-HT in the hamster SCN. There were similar increases in SCN 5-HT release after electrical stimulation of either the MRN or DRN, indicating that both could contribute to the serotonergic activity in the SCN. Systemic pretreatment with the 5-HT antagonist metergoline abolished DRN-induced SCN 5-HT release but had little effect on MRN-induced SCN 5-HT release, suggesting different pathways for these nuclei in regulating 5-HT output in the SCN. Microinjections of the 5-HT1A autoreceptor agonist 8-OH-DPAT or antagonist WAY 100635 into the MRN caused significant inhibition and stimulation of SCN 5-HT release, respectively. Both drugs had substantially less effect in the DRN. These differential drug actions indicate that somatodendritic 5-HT1A autoreceptors on MRN neurons provide the prominent raphe autoregulation of 5-HT output in the SCN. Collectively the current results are evidence that DRN as well as MRN neurons can contribute to the regulation of 5-HT release in the hamster SCN. On the basis of the current observations and those from recent anatomic tracing studies of serotonergic projections to SCN it is hypothesized that DRN input to the SCN could be mediated by a DRN → MRN → SCN pathway involving a 5-HT–sensitive multisynaptic interaction between the DRN and MRN neurons.

Immediate response to light of rat pineal melatonin rhythm: analysis by in vivo microdialysis

1994 ◽  
Vol 266 (6) ◽  
pp. R1849-R1855 ◽  
Author(s):  
N. Kanematsu ◽  
S. Honma ◽  
Y. Katsuno ◽  
K. Honma
Keyword(s):  
Phase Shift ◽  
Light Pulse ◽  
In Vivo Microdialysis ◽  
Melatonin Level ◽  
Melatonin Rhythm ◽  
Pineal Melatonin ◽  
Circadian Time ◽  
Rhythm Analysis ◽  
Onset Phase

Melatonin in the extracellular space of the pineal gland was measured continuously for 4 consecutive days from single, freely moving rats by means of in vivo microdialysis. A robust circadian rhythm was observed in the pineal extracellular melatonin under both light-dark (LD) and continuous dark (DD) conditions, the patterns of which were almost identical for 4 days within individuals but varied substantially among individuals. The offset phase of melatonin rhythm was more stable than the onset phase. Light-induced phase shift of melatonin rhythm was measured in individual rats, which had been entrained to LD and subsequently released into DD. On the 1st day in DD, a 3-min light pulse of 200 lx was applied either at circadian time (CT) of 17 or 22 h (5 and 10 h after the dark onset, respectively). The light pulse rapidly suppressed the nocturnal melatonin level. The rate as well as the level of melatonin suppression was significantly greater by the pulse at CT22 than at CT17. A phase shift of the melatonin rhythm was calculated on the 2nd and 3rd days in DD. Significant phase delay shift was observed after the pulse at CT17 and advance shift after the pulse at CT22 of approximately 1 h in either case. Because the amount of phase shift was not different between the 2nd and 3rd days in DD, the phase shift of pineal melatonin rhythm by single light pulse seems to be completed immediately.

scholarly journals Adrenocorticotropin Response and Nicotine-Induced Norepinephrine Secretion in the Rat Paraventricular Nucleus Are Mediated through Brainstem Receptors*

Endocrinology ◽  
1997 ◽  
Vol 138 (5) ◽  
pp. 1935-1943 ◽  
Author(s):  
Yitong Fu ◽  
Shannon G. Matta ◽  
James D. Valentine ◽  
Burt M. Sharp
Keyword(s):  
Paraventricular Nucleus ◽  
Fourth Ventricle ◽  
Presynaptic Receptors ◽  
In Vivo Microdialysis ◽  
Dark Phase ◽  
Acth Secretion ◽  
Nicotinic Cholinergic Receptors ◽  
Dose Dependent ◽  
Made In

Abstract Nicotine is a potent stimulus for the secretion of ACTH, and norepinephrinergic neurons originating in the brainstem are involved. Prior reports using in vivo microdialysis in alert rats have shown that nicotine, administered ip or into the fourth ventricle, stimulated the release of norepinephrine (NE) into the hypothalamic paraventricular nucleus (PVN), the site of neurons containing CRH. In the present studies, rats received an iv infusion of nicotine into the jugular vein on alternate days during their active (dark) phase; therefore, direct correlations between the levels of NE microdialyzed from the PVN and plasma ACTH could be made in each animal. Nicotine administered iv (0.045–0.135 mg/kg) elicited dose-dependent increases in both NE and ACTH (P < 0.01). A significant correlation was found between nicotine-stimulated NE release in the PVN and ACTH secretion (r = 0.91, P < 0.01). To address whether the site(s) of action of nicotine was on presynaptic receptors on NE terminals in the PVN or on receptors on neurons in brainstem regions accessible from the fourth ventricle, the nicotinic cholinergic antagonist, mecamylamine (0.1–4.8 μg), was microinjected directly into the PVN or into the fourth ventricle before nicotine infusion. Fourth-ventricular administration of mecamylamine (1.6 μg) or higher, before iv nicotine (0.09 mg/kg), completely blocked both NE release in the PVN (IC50 = 0.64 μg) and ACTH secretion (IC50 = 0.40 μg) (P < 0.01, compared with vehicle before nicotine), whereas it was ineffective when injected directly into the PVN. The results demonstrate that the nicotinic cholinergic receptors in the brainstem, rather than presynaptic receptors within the PVN itself, mediate nicotine-stimulated PVN NE release and ACTH secretion.

scholarly journals DOES CHRYSANTHEMUM DISPLAY AN ENDOGENOUS CIRCADIAN RHYTHM OF STEM ELONGATION?

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1077f-1077
Author(s):  
Jason Tutty ◽  
Peter Hicklenton
Keyword(s):  
Circadian Rhythm ◽  
Constant Temperature ◽  
Dark Period ◽  
Stem Elongation ◽  
Continuous Light ◽  
Linear Displacement ◽  
Dendranthema Grandiflora ◽  
Diurnal Cycles ◽  
Diurnal Patterns ◽  
Endogenous Circadian Rhythm

The rate of internodal extension of chrysanthemum (Dendranthema grandiflora Tzvelev. cv. Envy) under various temperature and photoperiod conditions was studied to determine whether reproducible diurnal patterns of growth existed and whether any such patterns conformed to an endogenous circadian rhythm. Stem growth was monitored continuously by means of linear displacement voltage transducers. At constant temperature and under 11 h light/13 h dark photoperiod, stem elongation followed a clearly defined pattern consisting of a peak in rate immediately after the dark to light transition and then a gradual decline until the start of the dark period. During darkness, elongation rate increased and reached a maximum approximately 8 hours after the light to dark transition. This pattern differed when light period temperature was either above or below dark period temperature, but these patterns were also highly reproducible. When plants were subjected to continuous light at constant temperature, the rhythm of stem elongation initially showed a periodicity of approximately 27 hours. After 2 or 3 diurnal cycles the rhythm was less distinct and the rate became essentially constant. Furthermore, the interruption of a long period of continuous light with a 13 h dark period did not restore the rhythm. These findings do not support the existence of an endogenous circadian rhythm of stem elongation. Diurnally-cued rhythms do, however, exist and can be modified by temperature.

scholarly journals Neuronal histamine release shows a clear circadian rhythm: an in vivo microdialysis study

1992 ◽  
Vol 58 ◽  
pp. 90
Author(s):  
Takatoshi Mochizuki ◽  
Atsushi Yamatodani ◽  
Kaori Okakura ◽  
Arata Horii ◽  
Hiroshi Wada
Keyword(s):  
Circadian Rhythm ◽  
Histamine Release ◽  
In Vivo Microdialysis ◽  
Microdialysis Study ◽  
Neuronal Histamine

scholarly journals Conditional Controlled Light/Dark Cycle Influences Exercise-Induced Benefits in a Rat Model with Osteoarthritis: In Vitro and In Vivo Study

2019 ◽  
Vol 8 (11) ◽  
pp. 1855 ◽  
Author(s):  
Hong ◽  
Lee ◽  
Choi ◽  
Jin ◽  
Won ◽  
...  
Keyword(s):  
Rat Model ◽  
Inflammatory Responses ◽  
Continuous Light ◽  
Moderate Intensity ◽  
Dark Cycle ◽  
Lighting Condition ◽  
Inflammatory Microenvironment ◽  
Exercise Induced

Physical exercise has long been recommended as a treatment for osteoarthritis (OA), though its effects vary based on the exercise protocol. Here, we examined whether environmental lighting conditions influence the anti-inflammatory benefits of exercise in a rat model of OA. Moderate-intensity treadmill exercise (Ex) was performed for six weeks under a 12:12 h light/dark (L/D) cycle, and compared against rats housed in a 24 h continuous light (L/L) environment. L/L conditions were associated with serological changes shortly after OA induction, which exacerbated the inflammatory microenvironment in the joint. Differentiation capacity was also impaired in bone precursor cells isolated from normal rats maintained under L/L conditions, despite elevated inflammatory responses. Exercise training under L/L conditions led to increased corticosterone levels in the blood, which exacerbated the progression of cartilaginous and synovial lesions. Osteoporotic phenomena were also observed in exercise-trained rats maintained under L/L conditions, along with inflammation-induced catabolism in the gastrocnemius muscle. Aberrant light/dark cycle conditions were also found to be associated with suppression of splenic Cry1 expression in exercise-trained rats, leading to dysregulation of immune responses. Taken together, these data suggest that lighting condition may be an important environmental factor influencing the exercise-induced benefits on OA.

scholarly journals Spontaneous c-Fos rhythm in the rat suprachiasmatic nucleus: location and effect of photoperiod

2000 ◽  
Vol 279 (6) ◽  
pp. R2262-R2269 ◽  
Author(s):  
Alena Sumová ◽  
Zdeňka Trávníčková ◽  
Helena Illnerová
Keyword(s):  
Circadian Rhythm ◽  
Suprachiasmatic Nucleus ◽  
Arginine Vasopressin ◽  
Day Length ◽  
Short Photoperiod ◽  
Dark Cycle ◽  
Vasopressinergic Cells ◽  
Long Photoperiod ◽  
Fine Adjustment

A recently reported circadian rhythm in the spontaneous c-Fos immunoreactivity in the rat suprachiasmatic nucleus (SCN) is expressed mostly in the dorsomedial (dm) SCN, where vasopressinergic cells are located. The aim of the present study is to find out whether day length, i.e., photoperiod, affects the dm-SCN rhythm and, if so, how the rhythm adjusts to a change from a long to a short photoperiod. In addition, a question of whether the spontaneous c-Fos production is localized in vasopressin- producing cells or in other cells is also studied to characterize further the dm-SCN rhythmicity. Combined immunostaining for c-Fos and arginine vasopressin (AVP) revealed that most of c-Fos immunopositive cells were devoid of AVP; the results suggest that c-Fos-producing cells in the dm-SCN are mostly not identical with those producing AVP. In rats maintained under a long photoperiod with 16:8-h light-dark cycle (LD 16:8) daily and then released into darkness, the time of the afternoon and evening decline of the spontaneous c-Fos immunoreactivity in the dm-SCN differed just slightly from the time in rats maintained originally under a short LD 8:16 photoperiod; however, the morning c-Fos rise occurred about 4 h earlier under the long than under the short photoperiod. After a change from a long to a short photoperiod, a rough but not yet a fine adjustment of the morning c-Fos rise to the change was accomplished within 3–6 days. The results show that similar to the recently reported ventrolateral SCN rhythmicity, the intrinsic dm-SCN rhythmicity is also affected by the photoperiod and suggest that the whole SCN state is photoperiod dependent.

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