scholarly journals Increase in 6-Hydroxymelatonin Excretion in Humans during Ascent to High Altitudes

2004 ◽  
Vol 89 (9) ◽  
pp. 4388-4390 ◽  
Author(s):  
Herwig Frisch ◽  
Franz Waldhauser ◽  
Thomas Waldhör ◽  
Andrea Müllner-Eidenböck ◽  
Pritam Neupane ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Pineal Gland ◽  
Diurnal Variation ◽  
Healthy Volunteers ◽  
High Altitude ◽  
Physiological Role ◽  
Physiological Significance ◽  
High Altitudes ◽  
Lower Altitude

Melatonin (MLT), the pineal gland hormone involved in the regulation of circadian rhythms, shows characteristic diurnal variation. Its physiological role in humans is not clear. Exposure to high altitudes may disrupt the circadian rhythm and lead to various endocrine changes. MLT in humans has not been studied under these conditions. Urinary 6-hydroxy-MLT sulfate (aMT6s) excretion was analyzed during the day (0700–2200 h) and night (2200–0700 h) phases. A cohort of 33 healthy volunteers, aged 19–65 yr, was studied during an ascent to a high altitude in the Himalayas on three occasions (at a lower altitude, at 3400 m, and after reaching maximal altitudes of 5600–6100 m). aMT6s excretion during the daytime remained unchanged during exposure to high altitudes. As expected, nocturnal values were higher than diurnal values at each point in time. However, there was a significant increase in nocturnal MLT excretion after the ascent to high altitudes. Ascent to high altitudes is associated with increased nocturnal excretion of aMT6s. The mechanism and physiological significance of this MLT increase are unclear.

Pineal gland

2018 ◽  
pp. 130-133
Author(s):  
Helen E. Turner ◽  
Richard Eastell ◽  
Ashley Grossman
Keyword(s):  
Circadian Rhythm ◽  
Clinical Practice ◽  
Circadian Rhythms ◽  
Pineal Gland ◽  
Mammalian Cell ◽  
Photoreceptor Cells ◽  
Secretory Function ◽  
Seasonal Rhythms ◽  
The Third ◽  
Therapeutic Benefits

This chapter describes the pineal gland’s structure, related hormones, and physiology. The pineal gland (epiphysis cerebri) is a small (100–150 mg in humans), unpaired central structure. The mammalian pineal is a secretory organ, whereas in fish and amphibians it is directly photoreceptive (the ‘third eye’) and in reptiles and birds it has a mixed photoreceptor and secretory function. The main mammalian cell type is the pinealocyte, considered to have evolved from photoreceptor cells. This chapter discusses melatonin’s metabolism, and the pineal gland’s function in seasonal rhythms and circadian rhythms. It discusses pineal gland-related pathology, including tumours and cancer. The chapter also discusses the use of melatonin, in clinical practice, describing the hormone’s therapeutic benefits in circadian rhythm disorders.

Entrainment of hamster pup circadian rhythms by prenatal melatonin injections to the mother

1988 ◽  
Vol 255 (3) ◽  
pp. R439-R448 ◽  
Author(s):  
F. C. Davis ◽  
J. Mannion
Keyword(s):  
Circadian Rhythms ◽  
Pineal Gland ◽  
Suprachiasmatic Nucleus ◽  
Experimental Approach ◽  
Physiological Role ◽  
Normal Phase ◽  
Daily Injection ◽  
Circadian Pacemaker ◽  
Prenatal Treatment ◽  
Subcutaneous Injections

A circadian pacemaker, thought to be within the suprachiasmatic nucleus (SCN) of the hypothalamus, begins to function before birth in rodents. Prenatal entrainment of the pacemaker appears to be mediated by signals regulated by the maternal SCN; ablation of the mother's SCN during gestation disrupts the normal phase of the pups' rhythms. The present paper presents an experimental approach for identifying candidate entraining signals and for testing when they are effective during development. The candidate signal examined in these experiments was the pineal gland hormone, melatonin. Female golden hamsters (Mesocricetus auratus) received SCN lesions on day 7 of gestation. During the last week of gestation, they were given two daily subcutaneous injections of oil 12 h apart. One of the injections each day contained melatonin (10, 50, or 100 micrograms). The phases of the pups' activity rhythms were measured at weaning and were found to be related to the timing of the daily injection that contained melatonin, demonstrating that the melatonin directly or indirectly set the phase of the pups' rhythms. Injections given over 4 days of gestation were found to be as effective as injections given over 7 days. Although a physiological role for melatonin as an entraining signal has not been demonstrated, the results show that exogenous, prenatal treatment can predictably set the phase of the offsprings' circadian rhythms.

Circadian rhythm in wool depilation force in Merino and Merino X Border Leicester sheep

1985 ◽  
Vol 104 (2) ◽  
pp. 397-403 ◽  
Author(s):  
A. Foldes ◽  
J. B. Donnelly ◽  
C. A. Maxwell ◽  
S. B. James ◽  
S. L. Clancy
Keyword(s):  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Diurnal Variation ◽  
Plasma Cortisol ◽  
Wool Growth ◽  
Neuroendocrine Mechanisms ◽  
Pineal Serotonin

SummaryAs part of an ongoing investigation of ovine neuroendocrine mechanisms relating to photoperiod and eventually to wool growth, the diurnal variation of depilation force (an index of the strength of attachment of wool fibres to the skin of sheep) was investigated in Merino wethers and Border Leicester Merino ewes. Circadian rhythms were demonstrated in depilation force in both ewes and wethers. Further experiments were performed to investigate circadian endocrine rhythms which may have some bearing on the observed rhythm in depilation force. Circadian rhythms 180° out of phase with the depilation force rhythm were observed in plasma cortisol concentrations and in pineal serotonin N-acetyltransferase activities in Merino wethers.

Thymidine incorporation by cultured chick pineal glands is not subject to adrenergic regulation

1990 ◽  
Vol 68 (1) ◽  
pp. 145-147 ◽  
Author(s):  
S. D. Wainwright ◽  
Lillian K. Wainwright
Keyword(s):  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Pineal Gland ◽  
Thymidine Incorporation ◽  
Adrenergic Regulation ◽  
Acetyltransferase Activity

Norepinephrine is known to play a role in regulating the circadian rhythms of serotonin N-acetyltransferase activity and melatonin formation in the chick pineal gland. We have recently demonstrated that the cultured chick pineal exhibits a circadian rhythm in the incorporation of thymidine. In this study we show that this latter rhythm is not subject to adrenergic control.Key words: chick, pineal gland, thymidine incorporation, adrenergic regulation.

scholarly journals BMAL1 but not CLOCK is associated with monochromatic green light-induced circadian rhythm of melatonin in chick pinealocytes

2019 ◽  
Vol 8 (1) ◽  
pp. 57-68 ◽  
Author(s):  
Shuhui Ma ◽  
Zixu Wang ◽  
Jing Cao ◽  
Yulan Dong ◽  
Yaoxing Chen
Keyword(s):  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Pineal Gland ◽  
Clock Genes ◽  
Critical Role ◽  
Green Light ◽  
Circadian Oscillator ◽  
Melatonin Secretion ◽  
Expression Levels

The avian pineal gland, an independent circadian oscillator, receives external photic cues and translates them for the rhythmical synthesis of melatonin. Our previous study found that monochromatic green light could increase the secretion of melatonin and expression of CLOCK and BMAL1 in chick pinealocytes. This study further investigated the role of BMAL1 and CLOCK in monochromatic green light-induced melatonin secretion in chick pinealocytes using siRNAs interference and overexpression techniques. The results showed that si-BMAL1 destroyed the circadian rhythms of AANAT and melatonin, along with the disruption of the expression of all the seven clock genes, except CRY1. Furthermore, overexpression of BMAL1 also disturbed the circadian rhythms of AANAT and melatonin, in addition to causing arrhythmic expression of BMAL1 and CRY1/2, but had no effect on the circadian rhythms of CLOCK, BMAL2 and PER2/3. The knockdown or overexpression of CLOCK had no impact on the circadian rhythms of AANAT, melatonin, BMAL1 and PER2, but it significantly deregulated the circadian rhythms of CLOCK, BMAL2, CRY1/2 and PER3. These results suggested that BMAL1 rather than CLOCK plays a critical role in the regulation of monochromatic green light-induced melatonin rhythm synthesis in chicken pinealocytes. Moreover, both knockdown and overexpression of BMAL1 could change the expression levels of CRY2, it indicated CRY2 may be involved in the BMAL1 pathway by modulating the circadian rhythms of AANAT and melatonin.

Putative roles for phospholipase Cη enzymes in neuronal Ca2+ signal modulation

2012 ◽  
Vol 40 (1) ◽  
pp. 282-286 ◽  
Author(s):  
Petra Popovics ◽  
Alan J. Stewart
Keyword(s):  
Circadian Rhythm ◽  
Pineal Gland ◽  
Neurodegenerative Disorders ◽  
Physiological Role ◽  
Memory Formation ◽  
Hormone Release ◽  
Signal Modulation ◽  
Brain Areas ◽  
Neural Processes ◽  
Specific Localization

The most recently identified PLC (phospholipase C) enzymes belong to the PLCη family. Their unique Ca2+-sensitivity and their specific appearance in neurons have attracted great attention since their discovery; however, their physiological role(s) in neurons are still yet to be established. PLCη enzymes are expressed in the neocortex, hippocampus and cerebellum. PLCη2 is also expressed at high levels in pituitary gland, pineal gland and in the retina. Driven by the specific localization of PLCη enzymes in different brain areas, in the present paper, we discuss the roles that they may play in neural processes, including differentiation, memory formation, circadian rhythm regulation, neurotransmitter/hormone release and the pathogenesis of neurodegenerative disorders associated with aberrant Ca2+ signalling, such as Alzheimer's disease.

Circadian rhythms of enzyme and running activity under ultradian lighting schedule.

1977 ◽  
Vol 232 (4) ◽  
pp. E375
Author(s):  
T Deguchi
Keyword(s):  
Circadian Rhythm ◽  
Circadian Rhythms ◽  
Pineal Gland ◽  
Dark Period ◽  
Foster Mother ◽  
Lighting Condition ◽  
Acetyltransferase Activity ◽  
Lighting Conditions ◽  
Running Activity ◽  
Circadian Change

Serotonin N-acetyltransferase activity in the pineal gland and running acitvity of rats were measured under an ultradian lighting schedule (light/dark 6:6). When rats were moved from a diurnal lighting condition to the ultradian conditions, N-acetyltransferase activity showed a circadian rhythm, increasing once a day. N-acetyltransferase activity in the pups born and raised under the ultradian lighting conditions also exhibited a circadian change, the phase of which coincided with that of their mothers. When pups were raised by a foster mother with an inverted rhythmic phase from that of the original mother, the phase of the rhythm in N-acetyltransferase activity of the pups synchronized with that of the foster mother. When pups were separated from their mothers for 12 h/day, the circadian increase of N-acetyltransferase activity appeared during the dark period when they were separated from their mothers. The circadian rhythms of running acitvity were in phase with those of N-acetyltransferase activity in the pineal gland.

The waterscape at high altitudes

2017 ◽  
Author(s):  
Dean Jacobsen ◽  
Olivier Dangles
Keyword(s):  
High Altitude ◽  
Regional Climate ◽  
Water Source ◽  
Aquatic Systems ◽  
Running Waters ◽  
High Altitudes ◽  
Different Types ◽  
Geological Origin ◽  
Broad Variety ◽  
The Tropics

Chapter 2 presents the amazing variety of running waters, lakes, ponds, and wetlands found at high altitudes. These waterbodies are not equally distributed among the world’s high altitude places, but tend to be concentrated in certain areas, primarily determined by regional climate and topography. Thus, a large proportion of the world’s truly high altitude aquatic systems are found at lower latitudes, mostly in the tropics. The chapter presents general patterns in the geographical distribution of high altitude waters, and gives examples of some of the most extreme systems. High altitude aquatic systems and habitats cover a broad variety in dynamics and physical appearance. These differences may be related to, for example, water source (glacier-fed, rain-fed, or groundwater-fed streams), geological origin (e.g. glacial, volcanic, or tectonic lakes), or catchment slope and altitude (different types of peatland wetlands). This is exemplified and richly illustrated through numerous photos.

Sign in / Sign up

Export Citation Format

Share Document