-
Endocrine Reviews Jun 2020The past decade has seen several critical advances in our understanding of hypothalamic-pituitary-adrenal (HPA) axis regulation. Homeostatic physiological circuits need... (Review)
Review
The past decade has seen several critical advances in our understanding of hypothalamic-pituitary-adrenal (HPA) axis regulation. Homeostatic physiological circuits need to integrate multiple internal and external stimuli and provide a dynamic output appropriate for the response parameters of their target tissues. The HPA axis is an example of such a homeostatic system. Recent studies have shown that circadian rhythmicity of the major output of this system-the adrenal glucocorticoid hormones corticosterone in rodent and predominately cortisol in man-comprises varying amplitude pulses that exist due to a subhypothalamic pulse generator. Oscillating endogenous glucocorticoid signals interact with regulatory systems within individual parts of the axis including the adrenal gland itself, where a regulatory network can further modify the pulsatile release of hormone. The HPA axis output is in the form of a dynamic oscillating glucocorticoid signal that needs to be decoded at the cellular level. If the pulsatile signal is abolished by the administration of a long-acting synthetic glucocorticoid, the resulting disruption in physiological regulation has the potential to negatively impact many glucocorticoid-dependent bodily systems. Even subtle alterations to the dynamics of the system, during chronic stress or certain disease states, can potentially result in changes in functional output of multiple cells and tissues throughout the body, altering metabolic processes, behavior, affective state, and cognitive function in susceptible individuals. The recent development of a novel chronotherapy, which can deliver both circadian and ultradian patterns, provides great promise for patients on glucocorticoid treatment.
Topics: Adrenocorticotropic Hormone; Animals; Bodily Secretions; Circadian Rhythm; Humans; Hydrocortisone; Hypothalamo-Hypophyseal System; Secretory Pathway
PubMed: 32060528
DOI: 10.1210/endrev/bnaa002 -
Molecular and Cellular Endocrinology May 2020Many physiological systems rely on hormones to communicate and time cellular and tissue-level functions. Most endocrine systems are dynamic and governed by complex...
Many physiological systems rely on hormones to communicate and time cellular and tissue-level functions. Most endocrine systems are dynamic and governed by complex regulatory systems and/or feedback mechanisms to generate precise patterns and modes of hormone release in order to optimize control of physiological and cellular processes. This Special Issue focuses on hormone release patterns (ultradian, infradian, pulsatile, circadian), with a special emphasis on the hypothalamic-pituitary axis as well as melatonin release, and how these patterns of hormone secretion change during life stages and disease.
Topics: Animals; Circadian Rhythm; Hormones; Humans; Mammals; Melatonin; Secretory Pathway
PubMed: 32119896
DOI: 10.1016/j.mce.2020.110781 -
Frontiers of Neurology and Neuroscience 2010Fetal neurobehavioral patterns have been considered as indicators of nervous system development. Moreover, the capacity of 4-dimensional sonography to evaluate complex... (Review)
Review
Fetal neurobehavioral patterns have been considered as indicators of nervous system development. Moreover, the capacity of 4-dimensional sonography to evaluate complex facial expressions allows recognition of common behaviors with which one can appreciate the prenatal functional development of the central nervous system. Using yawning as an example, we review this interpretation on the basis of knowledge derived from phylogeny and ontogeny. As a flip-flop switch, the reciprocal interactions between sleep- and wake-promoting brain regions allow the emergence of distinct states of arousal. By its ontogenic links with REM sleep, yawning appears to be a behavior which causes arousal reinforcement through the powerful stretching and the neuromuscular connections induced. Yawning indicates a harmonious progress in the development of both the brainstem and the peripheral neuromuscular function, testifying to the induction of an ultradian rhythm of vigilance. The lack of fetal yawn, frequently associated with lack of swallowing (associated or not with retrognathia), may be a key to predicting brainstem dysfunction after birth.
Topics: Animals; Arousal; Central Nervous System; Fetal Development; Fetus; Humans; Yawning
PubMed: 20357460
DOI: 10.1159/000307075 -
International Journal of Molecular... May 2016Circadian rhythms, ≈24 h oscillations in behavior and physiology, are reflected in all cells of the body and function to optimize cellular functions and meet... (Review)
Review
Circadian rhythms, ≈24 h oscillations in behavior and physiology, are reflected in all cells of the body and function to optimize cellular functions and meet environmental challenges associated with the solar day. This multi-oscillatory network is entrained by the master pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus, which directs an organism's rhythmic expression of physiological functions and behavior via a hierarchical system. This system has been highly conserved throughout evolution and uses transcriptional-translational autoregulatory loops. This master clock, following environmental cues, regulates an organism's sleep pattern, body temperature, cardiac activity and blood pressure, hormone secretion, oxygen consumption and metabolic rate. Mammalian peripheral clocks and clock gene expression have recently been discovered and are present in all nucleated cells in our body. Like other essential organ of the body, the skin also has cycles that are informed by this master regulator. In addition, skin cells have peripheral clocks that can function autonomously. First described in 2000 for skin, this review summarizes some important aspects of a rapidly growing body of research in circadian and ultradian (an oscillation that repeats multiple times during a 24 h period) cutaneous rhythms, including clock mechanisms, functional manifestations, and stimuli that entrain or disrupt normal cycling. Some specific relationships between disrupted clock signaling and consequences to skin health are discussed in more depth in the other invited articles in this IJMS issue on Sleep, Circadian Rhythm and Skin.
Topics: Animals; Circadian Clocks; Circadian Rhythm; Gene Expression; Gene Expression Regulation; Humans; Skin Physiological Phenomena; Suprachiasmatic Nucleus
PubMed: 27231897
DOI: 10.3390/ijms17060801 -
Trends in Neurosciences Jan 2024Among the central goals of stress neurobiology research is to understand the mechanisms by which stressors change neural circuit function to precipitate or exacerbate... (Review)
Review
Among the central goals of stress neurobiology research is to understand the mechanisms by which stressors change neural circuit function to precipitate or exacerbate psychiatric symptoms. Yet despite decades of effort, psychiatric medications that target the biological substrates of the stress response are largely lacking. We propose that the clinical advancement of stress response-based therapeutics for psychiatric disorders may be hindered by 'hidden variables' in stress research, including considerations of behavioral study design (stressors and outcome measures), individual variability, sex differences, and the interaction of the body's stress hormone system with endogenous circadian and ultradian rhythms. We highlight key issues and suggest ways forward in stress neurobiology research that may improve the ability to assess stress mechanisms and translate preclinical findings.
Topics: Humans; Male; Female; Circadian Rhythm; Neurobiology; Hypothalamo-Hypophyseal System; Pituitary-Adrenal System; Sex Characteristics; Stress, Physiological; Stress, Psychological
PubMed: 37985263
DOI: 10.1016/j.tins.2023.10.006 -
Trends in Endocrinology and Metabolism:... Apr 2019Hormone rhythms are ubiquitous and essential to sustain normal physiological functions. Combined mathematical modelling and experimental approaches have shown that these... (Review)
Review
Hormone rhythms are ubiquitous and essential to sustain normal physiological functions. Combined mathematical modelling and experimental approaches have shown that these rhythms result from regulatory processes occurring at multiple levels of organisation and require continuous dynamic equilibration, particularly in response to stimuli. We review how such an interdisciplinary approach has been successfully applied to unravel complex regulatory mechanisms in the metabolic, stress, and reproductive axes. We discuss how this strategy is likely to be instrumental for making progress in emerging areas such as chronobiology and network physiology. Ultimately, we envisage that the insight provided by mathematical models could lead to novel experimental tools able to continuously adapt parameters to gradual physiological changes and the design of clinical interventions to restore normal endocrine function.
Topics: Chronotherapy; Circadian Rhythm; Endocrine System; Hormones; Humans; Hypothalamo-Hypophyseal System; Models, Theoretical; Ultradian Rhythm
PubMed: 30799185
DOI: 10.1016/j.tem.2019.01.008 -
International Journal of... Aug 2013Dreaming occurs during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, which both are regulated by homeostatic, ultradian, and circadian processes.... (Review)
Review
Dreaming occurs during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, which both are regulated by homeostatic, ultradian, and circadian processes. However, the magnitude of how ultradian REM and NREM sleep and its EEG correlates impact onto dream recall remains fairly unknown. In this review, we address three questions: 1. Is there an ultradian NREM-REM sleep modulation in successful dream recall, which is gated by the circadian clock? 2. What are the key electrophysiological correlates that account for dream recall during NREM and REM sleep and 3. Are there age-related changes in the ultradian and circadian regulation in dream recall and its electrophysiological correlates? Knowledge on the specific frequency and topography NREM and REM sleep differences prior to dream recall may pinpoint to the cerebral correlates that account for this cognitive process, and hint to their possible physiological meaning.
Topics: Activity Cycles; Aging; Circadian Rhythm; Dreams; Electroencephalography; Humans; Mental Recall
PubMed: 23524011
DOI: 10.1016/j.ijpsycho.2013.03.006 -
Clinical Endocrinology Sep 2019There is an increased mortality associated with adrenal insufficiency despite glucocorticoid replacement therapy with a standardized mortality ratio greater than two.... (Review)
Review
There is an increased mortality associated with adrenal insufficiency despite glucocorticoid replacement therapy with a standardized mortality ratio greater than two. The cause of the increased mortality is yet to be definitively elucidated, but may be due to excess steroid exposure, or replacement regimens that are uncoupled from the normal physiological cortisol profile. Cortisol secretion follows an ultradian pattern which is not possible to reproduce using oral replacement. With the advent of new pumps, it is now possible to mimic the pulsatility of the adrenal glands. While the cognitive and emotional benefits of reproducing the ultradian rhythm are known, the presence of long-term benefits is not yet clear. There is a dearth of evidence and high-quality studies to underline our current understanding of the pathophysiology of adrenal insufficiency and replacement therapy. There is a particular lack of research comparing objective outcomes between patients receiving hydrocortisone replacement (either standard therapy or new sustained release preparations), prednisolone replacement and ultradian pumps. Direct comparative studies are now warranted to understand the optimal approach.
Topics: Adrenal Insufficiency; Glucocorticoids; Hormone Replacement Therapy; Humans; Ultradian Rhythm
PubMed: 31017681
DOI: 10.1111/cen.13999 -
Development (Cambridge, England) Oct 2014Biological clocks play key roles in organismal development, homeostasis and function. In recent years, much work has focused on circadian clocks, but emerging studies... (Review)
Review
Biological clocks play key roles in organismal development, homeostasis and function. In recent years, much work has focused on circadian clocks, but emerging studies have highlighted the existence of ultradian oscillators - those with a much shorter periodicity than 24 h. Accumulating evidence, together with recently developed optogenetic approaches, suggests that such ultradian oscillators play important roles during cell fate decisions, and analyzing the functional links between ultradian oscillation and cell fate determination will contribute to a deeper understanding of the design principle of developing embryos. In this Review, we discuss the mechanisms of ultradian oscillatory dynamics and introduce examples of ultradian oscillators in various biological contexts. We also discuss how optogenetic technology has been used to elucidate the biological significance of ultradian oscillations.
Topics: Activity Cycles; Animals; Apoptosis; Cell Cycle Checkpoints; Cell Differentiation; Cell Lineage; Cellular Senescence; Cleavage Stage, Ovum; Embryonic Development; Feedback, Physiological; Humans; Mammals; Models, Biological; Optogenetics
PubMed: 25249457
DOI: 10.1242/dev.104497 -
Dialogues in Clinical Neuroscience Dec 2012Integration of several approaches concerning time and temporality can enhance the pathophysiological study of major mood disorders of unknown etiology. We propose that... (Review)
Review
Integration of several approaches concerning time and temporality can enhance the pathophysiological study of major mood disorders of unknown etiology. We propose that these conditions might be interpreted as disturbances of temporal profile of biological rhythms, as well as alterations of time-consciousness. Useful approaches to study time and temporality include philological suggestions, phenomenological and psychopathological conceptualizatíons, clinical descriptions, and research on circadian and ultradían rhythms, as well as nonlinear dynamics approaches to their analysis.
Topics: Biological Clocks; Circadian Rhythm; Humans; Mood Disorders
PubMed: 23393414
DOI: 10.31887/DCNS.2012.14.4/psalvatore