DIURNAL RHYTHM OF VASOTOCIN IN THE PINEAL OF THE MALE RAT

1977 ◽  
Vol 84 (3) ◽  
pp. 523-526 ◽  
Author(s):  
Maria Calb ◽  
R. Goldstein ◽  
S. Pavel
Keyword(s):  
Diurnal Rhythm ◽  
Arginine Vasotocin ◽  
Constant Light ◽  
Male Rat ◽  
Constant Darkness ◽  
Diurnal Changes

ABSTRACT The pineal content of arginine vasotocin in the male rat is subject to diurnal changes, having a high value around noon and a low value around midnight. Since in rats exposed to 24 h constant light the pineal content in arginine vasotocin decreases, and in the rats exposed to 24 h constant darkness the pineal content in arginine vasotocin increases, it appears that during the night both the synthesis and release of arginine vasotocin is enhanced.

Solar and Lunar Rhythmicity in the Rat in ‘Constant Conditions’ and the Mechanism of Physiological Time Measurement

1956 ◽  
Vol 184 (3) ◽  
pp. 491-496 ◽  
Author(s):  
F. A. Brown ◽  
J. Shriner ◽  
C. L. Ralph
Keyword(s):  
Time Of Day ◽  
Day Length ◽  
Constant Light ◽  
Activity Period ◽  
Male Rat ◽  
Constant Darkness ◽  
Daily Cycles ◽  
The Hours ◽  
The Mean ◽  
Daily Period

The spontaneous activity of one male rat under constant conditions was recorded for 120 consecutive days. During the first 70 days in constant illumination of 1 fc the 12-hour daily period of activity occurred regularly about 1 1/4 hours later each day, with the period scanning the solar day about four times during the 70-day period. During the succeeding 25-day period in darkness the daily cycles averaged exactly 24 hours with the time of day of activity, that of the last day in constant light. This was followed by 8 days in constant light followed by 18 days in constant darkness with completely comparable results. The daily running cycle randomized relative to the hours of the solar day, exhibited a daily cycle of amount of activity at each hour of the solar day, and randomizing both the daily activity period and the solar-day basic cycle revealed a cycle of lunar-day length, with minimum of lunar zenith and a maximum at nadir. There were also strong suggestions in the mean daily activities of 27-day and synodic monthly cycles.

Diurnal changes in the plasma concentrations of LH and hypothalamic contents of LHRH-I and LHRH-II in the domestic hen

1991 ◽  
Vol 130 (3) ◽  
pp. 457-462 ◽  
Author(s):  
S. C. Wilson ◽  
R. T. Gladwell ◽  
F. J. Cunningham
Keyword(s):  
Plasma Concentration ◽  
Diurnal Rhythm ◽  
Laying Hens ◽  
Plasma Concentrations ◽  
Posterior Hypothalamus ◽  
Anterior Hypothalamus ◽  
Diurnal Changes ◽  
The Mean ◽  
The Times ◽  
Lh Secretion

ABSTRACT Diurnal changes of LH secretion in sexually immature hens of 9, 11, 13 and 15 weeks of age consisted of 25–40% increases in the mean concentrations of LH in plasma between 15.00 and 18.00 h, i.e. between 2 h before and 1 h after the onset of darkness. During this time there was a tendency for the mean contents of LHRH-I in the anterior hypothalamus and posterior hypothalamus to increase by 21–74% and 20–56% respectively. In hens of 9 and 15 weeks, diurnal changes in the plasma concentration of LH closely paralleled those of LHRH-I content in the posterior hypothalamus. In contrast, the diurnal rhythm of LH secretion in hens of 11 and 13 weeks was more marked and plasma concentrations of LH continued to rise steeply between 18.00 and 21.00 h, i.e. between 1 and 4 h after the onset of darkness. At 11 weeks, this was associated with a reduction (P<0·01) in the contents of LHRH-I and LHRH-II, particularly in the anterior hypothalamus. In laying hens, a diurnal decline (P<0·01) in the plasma concentration of LH between 1 and 4 h after the onset of darkness was preceded by a fall (P<0·05) in the content of LHRH-I in the posterior hypothalamus and in the total hypothalamic content of LHRH-II (P<0·01). In all groups of hens, irrespective of the times of day at which tissue was taken, significant (P<0·05–<0·001) correlations between the contents of LHRH-I and LHRH-II in the anterior hypothalamus were observed. It is concluded that a diurnal rhythm of release of LHRH-I may drive the diurnal rhythm of LH secretion. Thus, in sexually immature hens of 9 and 15 weeks and laying hens in which diurnal changes in plasma LH were small there were parallel changes in the content of LHRH-I in the posterior hypothalamus. However, where the plasma concentration of LH was increased substantially, as at 11 weeks, there was a decline in the hypothalamic contents of LHRH-I. A simultaneous fall in the hypothalamic content of LHRH-II raises the possibility of a causal relationship between the activities of LHRH-II, LHRH-I and the release of LH. Journal of Endocrinology (1991) 130, 457–462

Photic Response Parameters of Circadian Rhythms in The Spinifex Hopping Mouse, Notomys alexis.

1996 ◽  
Vol 19 (1) ◽  
pp. 11
Author(s):  
A.J.P. Francis ◽  
G.J. Coleman
Keyword(s):  
Circadian Rhythms ◽  
Phase Relations ◽  
Constant Light ◽  
Constant Darkness ◽  
Biological Clocks ◽  
Circadian Activity ◽  
Activity Rhythms ◽  
Controlled Conditions ◽  
Australian Native Rodent ◽  
Photic Response

Circadian rhythms are generated endogenously by biological clocks or &apos;pacemakers&apos;, which are responsive to significant environmental stimuli termed zeitgebers. Interactions between pacemakers and zeitgebers provide the basis for synchronisation by light-dark (LD) cycles, and the characteristics of each of these elements determines the phase-relations maintained between an animal&apos;s circadian activity rhythms and the natural temporal environment. We report here the basic photic response parameters for an Australian native rodent, Notomys alexis. Under controlled conditions of constant darkness or constant light, N. alexis were found to &apos;free-run&apos;, and with periods different from 24 hours. Under LD cycles N. alexis were strictly nocturnal although, compared to other rodents, entrainment to LD cycles was relatively unstable. This may indicate that N. alexis are not strongly dependent on the LD cycle as a zeitgeber.

Altered circadian responses to light in streptozotocin-induced diabetic mice

1999 ◽  
Vol 277 (2) ◽  
pp. E232-E237 ◽  
Author(s):  
Etienne Challet ◽  
Olivier van Reeth ◽  
Fred W. Turek
Keyword(s):  
Daily Variation ◽  
Serum Glucose ◽  
Temporal Organization ◽  
Constant Darkness ◽  
Diurnal Changes ◽  
Ambient Light ◽  
Circadian Pacemaker ◽  
Diabetic Mice ◽  
Phase Resetting ◽  
Insulin Producing Cells

Diabetes mellitus affects the daily expression of many behavioral and metabolic processes. Recent studies indicate that changes in brain glucose metabolism alter the entraining effects of light of the circadian pacemaker. To test whether diabetes-associated diurnal changes are related to alterations in the responses of the circadian pacemaker to light, photic phase resetting of the circadian rhythm of locomotor activity was analyzed in diabetic mice housed in constant darkness. Multiple low doses of streptozotocin, which damages pancreatic β-insulin-producing cells, were used to render C57BL/6J mice mildly diabetic. In those mice treated with streptozotocin, serum glucose was increased by 25% and circadian responses to light either were increased by 40% for phase delays or were close to those observed in control animals for phase advances. Furthermore, insulin-induced hypoglycemia normalized light-induced phase delays in diabetic animals, without altering those in nondiabetic mice. These results show that abnormalities of daily temporal organization associated with diabetes can result from altered circadian responses to the daily variation in ambient light. Such alterations could be normalized with appropriate insulin therapy.

scholarly journals INFLUENCE OF LIGHT ON THE GROWTH AND MALIGNANCY OF A TRANSPLANTABLE NEOPLASM OF THE RABBIT

1927 ◽  
Vol 45 (4) ◽  
pp. 727-751 ◽  
Author(s):  
Louise Pearce ◽  
Wade H. Brown
Keyword(s):  
Bone Metastases ◽  
Experimental Evidence ◽  
Malignant Disease ◽  
External Factor ◽  
Wave Length ◽  
Continuous Light ◽  
Constant Light ◽  
Constant Darkness ◽  
Special Character

Experiments are reported in which an environment of constant and continuous light with a wave-length of from 3022 to 5790 Ångström units, supplied by mercury arcs in crown glass, and of constant darkness, have influenced the course and character of a malignant disease of rabbits induced by a transplantable neoplasm. Under the influence of constant light the level of malignancy was lower than in control animals living under ordinary conditions of diffused sunlight. Under the influence of constant darkness the level of malignancy was somewhat lower than in control animals but the effect of this environment was modified by the special character of the disease prevailing at this time. The incidence of bone metastases was unusually high, but it was greatly increased in the rabbits kept in constant darkness. These observations furnish experimental evidence in support of the belief that there is a correlation between the external factor of light and the manifestations of an experimental malignant disease.

Acute Effects of Arginine Vasotocin on Plasma and Pituitary Levels of Prolactin in the Male Rat: Influence of Urethane Anesthesia

1980 ◽  
Vol 13 (2) ◽  
pp. 109-120 ◽  
Author(s):  
Linda Y Johnson ◽  
Mary K Vaughan ◽  
Russel J. Reiter ◽  
Larry J. Petterborg ◽  
Hsien-jen Chen
Keyword(s):  
Arginine Vasotocin ◽  
Male Rat ◽  
Acute Effects ◽  
Urethane Anesthesia

scholarly journals Suppression of voluntary ethanol intake in mice under constant light and constant darkness

Alcohol ◽  
2020 ◽  
Vol 83 ◽  
pp. 37-46 ◽  
Author(s):  
Alan M. Rosenwasser ◽  
Walter D. McCulley ◽  
Matthew C. Hartmann ◽  
Michael C. Fixaris ◽  
John C. Crabbe
Keyword(s):  
Ethanol Intake ◽  
Constant Light ◽  
Constant Darkness

Sperm Transfer in Gypsy Moths: Effect of Constant or Cyclic Temperature and Constant Light or Darkness during the Pupal Stage

1997 ◽  
Vol 32 (3) ◽  
pp. 321-331 ◽  
Author(s):  
F. I. Proshold
Keyword(s):  
Light Intensity ◽  
Constant Temperature ◽  
Lymantria Dispar ◽  
Pupal Stage ◽  
Sperm Transfer ◽  
Constant Light ◽  
Constant Darkness ◽  
Gypsy Moths ◽  
Cyclic Temperature ◽  
Full Complement

Sperm transfer and fertility of the gypsy moth, Lymantria dispar (L.), held as pupae under constant temperature and 24-h light, 24-h darkness, or a photoperiod of 16:8 (L:D) h were compared with males held in cyclic temperature and 24-h light, 24-h darkness, or a photoperiod of 16:8 (L:D) h. Constant temperature and constant light or darkness severely reduced its ability to transfer sperm. Males held under constant light were more severely affected than males held in darkness, but sperm transfer was not correlated with light intensity (between 80 and 3960 lux). Nearly all males held under constant light and most held under constant darkness were sterile or partially sterile. In either case, sterility was caused by poor sperm transfer. Females with a full complement of sperm were fertile regardless of holding condition of male pupae. The sterilizing effect of constant light or darkness was overridden by cyclic temperature of 28°C for 16 h and 22°C for 8 h. At a photoperiod of 16:8 h, pupae held in constant 28°C transferred less sperm than those held at 25°C. Pupae held at constant 30°C were sterile, but those held at 30°C for 16 h and 25°C for 8 h transferred similar quantities of sperm as males held at constant 28°C.

Diurnal Rhythm in Proopiomelanocortin mRNA in the Arcuate Nucleus of the Male Rat

1994 ◽  
Vol 6 (6) ◽  
pp. 603-608 ◽  
Author(s):  
Robert A. Steiner ◽  
Emilia Kabigting ◽  
Karin Lent ◽  
Donald K. Clifton
Keyword(s):  
Diurnal Rhythm ◽  
Arcuate Nucleus ◽  
Male Rat

EFFECTS OF PINEALECTOMY AND CONSTANT LIGHT AND DARKNESS ON PROLACTIN LEVELS IN THE PITUITARY AND PLASMA AND ON PITUITARY ULTRASTRUCTURE OF THE RAT

1972 ◽  
Vol 54 (2) ◽  
pp. 263-NP ◽  
Author(s):  
R. RELKIN ◽  
M. ADACHI ◽  
S. A. KAHAN
Keyword(s):  
Plasma Concentrations ◽  
Virgin Female ◽  
Female Rats ◽  
Constant Light ◽  
Constant Darkness ◽  
Plasma Prolactin ◽  
Continuous Darkness ◽  
Prolactin Content ◽  
Intermediate Degree ◽  
Pituitary Prolactin

SUMMARY The effects of constant light, constant darkness and diurnal lighting, in combination with pinealectomy or sham-pinealectomy, on pituitary and plasma concentrations of radioimmunoassayable prolactin were investigated in 8-week-old male and virgin female rats. Two to three days after operation random groups of pinealectomized and sham-pinealectomized animals of the same sex were placed together in either continous light, continuous darkness or diurnal light, and killed 21 days later. Compared with sham-operated diurnally-illuminated controls, constant darkness caused a decrease in pituitary prolactin content and a rise in plasma prolactin levels. Pinealectomy or constant illumination reversed the effect of constant darkness, resulting in an increase in pituitary prolactin content and a fall in plasma prolactin levels when compared with sham-operated diurnally-illuminated controls. Electron microscopy of lactotrophic cells of the sham-pinealectomized animals exposed to constant darkness revealed few cytoplasmic granules, whereas these cells in the sham-pinealectomized animals exposed to constant light contained abundant granules; compared with the former groups, lactotrophic cells of sham-pinealectomized rats exposed to diurnal lighting revealed an intermediate degree of granulation.

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