scholarly journals Modeling circadian regulation of ovulation timing: age-related disruption of estrous cyclicity

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Takayuki Ohara ◽  
Takahiro J. Nakamura ◽  
Wataru Nakamura ◽  
Isao T. Tokuda
Keyword(s):  
Endocrine System ◽  
Aging Effect ◽  
Neuronal Firing ◽  
Circadian Clocks ◽  
Circadian Regulation ◽  
Estrous Cycles ◽  
Age Related ◽  
Estrous Cyclicity ◽  
Central Clock ◽  
Parameter Values

Abstract The circadian clocks within the hypothalamic–pituitary–gonadal axis control estrous cycles in female rodents. The suprachiasmatic nucleus (SCN), where the central clock is located, generates daily signals to trigger surge release of luteinizing hormone (LH), which in turn induces ovulation. It has been observed in aged rodents that output from the SCN such as neuronal firing activity is declined, and estrous cycles become irregular and finally stop. Circadian clock mutants display accelerated reproductive aging, suggesting the complicated interplay between the circadian system and the endocrine system. To investigate such circadian regulation of estrous cycles, we construct a mathematical model that describes dynamics of key hormones such as LH and of circadian clocks in the SCN and in the ovary, and simulate estrous cycles for various parameter values. Our simulation results demonstrate that reduction of the amplitude of the SCN signal, which is a symptom of aging, makes estrous cycles irregular. We also show that variation in the phase of the SCN signal and changes in the period of ovarian circadian clocks exacerbates the aging effect on estrous cyclicity. Our study suggests that misalignment between the SCN and ovarian circadian oscillations is one of the primary causes of the irregular estrous cycles.

scholarly journals The Age-Sensitive Efficacy of Calorie Restriction on Mitochondrial Biogenesis and mtDNA Damage in Rat Liver

2021 ◽  
Vol 22 (4) ◽  
pp. 1665
Author(s):  
Guglielmina Chimienti ◽  
Anna Picca ◽  
Flavio Fracasso ◽  
Francesco Russo ◽  
Antonella Orlando ◽  
...  
Keyword(s):  
Calorie Restriction ◽  
Citrate Synthase ◽  
Aging Effect ◽  
Mtdna Damage ◽  
Mitochondrial Markers ◽  
Age Related ◽  
Efficacious Treatment ◽  
Mtdna Deletion ◽  
Cyt C ◽  
Ad Libitum

Calorie restriction (CR) is the most efficacious treatment to delay the onset of age-related changes such as mitochondrial dysfunction. However, the sensitivity of mitochondrial markers to CR and the age-related boundaries of CR efficacy are not fully elucidated. We used liver samples from ad libitum-fed (AL) rats divided in: 18-month-old (AL-18), 28-month-old (AL-28), and 32-month-old (AL-32) groups, and from CR-treated (CR) 28-month-old (CR-28) and 32-month-old (CR-32) counterparts to assay the effect of CR on several mitochondrial markers. The age-related decreases in citrate synthase activity, in TFAM, MFN2, and DRP1 protein amounts and in the mtDNA content in the AL-28 group were prevented in CR-28 counterparts. Accordingly, CR reduced oxidative mtDNA damage assessed through the incidence of oxidized purines at specific mtDNA regions in CR-28 animals. These findings support the anti-aging effect of CR up to 28 months. Conversely, the protein amounts of LonP1, Cyt c, OGG1, and APE1 and the 4.8 Kb mtDNA deletion content were not affected in CR-28 rats. The absence of significant differences between the AL-32 values and the CR-32 counterparts suggests an age-related boundary of CR efficacy at this age. However, this only partially curtails the CR benefits in counteracting the generalized aging decline and the related mitochondrial involvement.

scholarly journals Age-related differences in binaural masking level differences: behavioral and electrophysiological evidence

2018 ◽  
Vol 120 (6) ◽  
pp. 2939-2952 ◽  
Author(s):  
Samira Anderson ◽  
Robert Ellis ◽  
Julie Mehta ◽  
Matthew J. Goupell
Keyword(s):  
Aging Effect ◽  
Normal Hearing ◽  
Behavioral Experiment ◽  
Spatial Cues ◽  
Sound Sources ◽  
Frequency Following Response ◽  
Binaural Processing ◽  
Threshold Difference ◽  
Age Related ◽  
Effects Of Aging

The effects of aging and stimulus configuration on binaural masking level differences (BMLDs) were measured behaviorally and electrophysiologically, using the frequency-following response (FFR) to target brainstem/midbrain encoding. The tests were performed in 15 younger normal-hearing (<30 yr) and 15 older normal-hearing (>60 yr) participants. The stimuli consisted of a 500-Hz target tone embedded in a narrowband (50-Hz bandwidth) or wideband (1,500-Hz bandwidth) noise masker. The interaural phase conditions included NoSo (tone and noise presented interaurally in-phase), NoSπ (noise presented interaurally in-phase and tone presented out-of-phase), and NπSo (noise presented interaurally out-of-phase and tone presented in-phase) configurations. In the behavioral experiment, aging reduced the magnitude of the BMLD. The magnitude of the BMLD was smaller for the NoSo–NπSo threshold difference compared with the NoSo–NoSπ threshold difference, and it was also smaller in narrowband compared with wideband conditions, consistent with previous measurements. In the electrophysiology experiment, older participants had reduced FFR magnitudes and smaller differences between configurations. There were significant changes in FFR magnitude between the NoSo to NoSπ configurations but not between the NoSo to NπSo configurations. The age-related reduction in FFR magnitudes suggests a temporal processing deficit, but no correlation was found between FFR magnitudes and behavioral BMLDs. Therefore, independent mechanisms may be contributing to the behavioral and neural deficits. Specifically, older participants had higher behavioral thresholds than younger participants for the NoSπ and NπSo configurations but had equivalent thresholds for the NoSo configuration. However, FFR magnitudes were reduced in older participants across all configurations. NEW & NOTEWORTHY Behavioral and electrophysiological testing reveal an aging effect for stimuli presented in wideband and narrowband noise conditions, such that behavioral binaural masking level differences and subcortical spectral magnitudes are reduced in older compared with younger participants. These deficits in binaural processing may limit the older participant's ability to use spatial cues to understand speech in environments containing competing sound sources.

scholarly journals Sex-dependent Pathological Aging Effect on Caudate Functional Connectivity in Mild Cognitive Impairment

2021 ◽  
Author(s):  
Zhengshi Yang ◽  
Jessica Z.K. Caldwell ◽  
Jeffrey L. Cummings ◽  
Aaron Ritter ◽  
Jefferson W. Kinney ◽  
...  
Keyword(s):  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Functional Connectivity ◽  
Aging Effect ◽  
Analysis Of Covariance ◽  
Aging Effects ◽  
Mixed Effect ◽  
Effect Analysis ◽  
Pathological Aging ◽  
Age Related

Abstract Purpose To assess the pathological aging effect on caudate functional connectivity among mild cognitive impairment (MCI) participants and examine whether and how sex and amyloid contribute to this process. Materials and Methods 277 functional magnetic resonance imaging (fMRI) sessions from 163 cognitive normal (CN) older adults and 309 sessions from 139 participants with MCI were included as the main sample in our analysis. Pearson’s correlation was used to characterize the functional connectivity (FC) between caudate and each brain region, then caudate nodal strength was computed to quantify the overall caudate FC strength. Association analysis between caudate nodal strength and age was carried out in MCI and CN separately using linear mixed effect (LME) model with covariates (education, handedness, sex, Apolipoprotein E4 and intra-subject effect). Analysis of covariance was conducted to investigate sex, amyloid status and their interaction effects on aging with the fMRI data subset having amyloid status available. LME model was applied to women and men separately within MCI group to evaluate aging effects on caudate nodal strength and each region’s connectivity with caudate. We then evaluated the roles of sex and amyloid status in the associations of neuropsychological scores with age or caudate nodal strength. An independent cohort was used to validate the sex-dependent aging effects in MCI. Results The MCI group had significantly stronger age-related increase of caudate nodal strength compared to the CN group. Analyzing women and men separately revealed that the aging effect on caudate nodal strength among MCI participants was significant only for women (left: P=6.23x10−7, right: P=3.37x10−8), but not for men (P>0.3 for bilateral caudate). The aging effects on caudate nodal strength were not significantly mediated by brain amyloid burden. Caudate connectivity with ventral prefrontal cortex substantially contributed to the aging effect on caudate nodal strength in women with MCI. Higher caudate nodal strength is significantly related to worse cognitive performance in women but not in men with MCI. Conclusion Sex modulates the pathological aging effects on caudate nodal strength in MCI regardless of amyloid status. Caudate nodal strength may be a sensitive biomarker of pathological aging in women with MCI.

Rubidium chloride increases lifespan through an AMPK/FOXO-dependent pathway in Caenorhabditis elegans

2021 ◽  
Author(s):  
Mengjiao Hao ◽  
Zhikang Zhang ◽  
Yijun Guo ◽  
Huihao Zhou ◽  
Qiong Gu ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Stress Responses ◽  
Aging Effect ◽  
Stress Effect ◽  
Neuroprotective Effects ◽  
C Elegans ◽  
Cycle Arrest ◽  
Age Related ◽  
Promising Target ◽  
Amp Activated Protein Kinase

Abstract AMP-activated protein kinase (AMPK) is involved in life span maintenance, stress responses, and germ cell cycle arrest upon dauer entry. AMPK is currently considered a promising target for preventing age-related diseases. Rubidium is one of the trace elements in human body. As early as the 1970s, RbCl has been was reported to have neuroprotective effects. In this work, we report the anti-aging effect of RbCl in Caenorhabditis elegans. Specifically, we reveal that (1) RbCl does increase the lifespan and enhance stress resistance in C. elegans without disturbing their fecundity. (2) RbCl induces superoxide dismutase (SOD) expression, which is essential for its anti-aging and anti-stress effect. (3) AAK-2 and DAF-16 are essential to the anti-aging efficacy of RbCl, and RbCl can promote DAF-16 translocating into the nucleus, suggesting that RbCl delays aging through regulating AMPK/FOXO pathway. RbCl can be a promising agent against aging related diseases.

Effects of the fructose analog, 2,5-anhydro-D-mannitol, on food intake and estrous cyclicity in Syrian hamsters

1997 ◽  
Vol 272 (3) ◽  
pp. R935-R939
Author(s):  
J. E. Schneider
Keyword(s):  
Food Intake ◽  
Plasma Glucose ◽  
Acid Oxidation ◽  
Estrous Cycles ◽  
Syrian Hamsters ◽  
Glucose Levels ◽  
Fuel Metabolism ◽  
Increase Food Intake ◽  
Estrous Cyclicity ◽  
Estrous Cycling

Hyperphagia and anovulation are both triggered by prior food deprivation or other treatments that decrease intracellular availability of metabolic fuels in most species studied. Syrian hamsters fail to show compensatory hyperphagia, but do show anestrus in response to these energetic challenges. In the present experiments, we examined food intake, plasma glucose levels, and estrous cyclicity in Syrian hamsters in response to 2,5-anhydro-D-mannitol (2,5-AM), a fructose analog that is thought to trigger eating in rats by depleting intracellular levels of ATP. In experiment 1, female estrous cycling hamsters were treated with 100, 200, 400, or 800 mg/kg 2,5-AM or the vehicle by intraperitoneal injection. Food intake was measured 1, 2, 4, 8, and 24 h after treatment. There were no statistically significant increases in food intake in response to any dose of 2,5-AM. In experiment 2, blood samples were drawn at 0, 1, 3, 5, 7, and 25 h after hamsters were treated with 0 or 400 mg/kg 2,5-AM. 2,5-AM treatment resulted in a mild but significant decrease in plasma glucose levels similar to those seen in 2,5-AM-treated rats, suggesting that 2,5-AM has similar effects on fuel metabolism in rats and hamsters. In experiment 3, hamsters received 2,5-AM, 2,5-AM plus the fatty acid oxidation inhibitor methyl palmoxirate, or vehicle every 6 h over the first 48 h of the estrous cycle and were tested for indexes of estrous cyclicity at the end of the cycle. All hamsters showed normal estrous cycles, regardless of treatment. If 2,5-AM has similar metabolic consequences in rats and hamsters, the present results suggest that decreased intracellular levels of ATP and mild hypoglycemia do not increase food intake or inhibit estrous cyclicity in Syrian hamsters.

scholarly journals Abnormal Response of the Neuropeptide Y-Deficient Mouse Reproductive Axis to Food Deprivation But Not Lactation

Endocrinology ◽  
2003 ◽  
Vol 144 (5) ◽  
pp. 1780-1786 ◽  
Author(s):  
Jennifer W. Hill ◽  
Jon E. Levine
Keyword(s):  
Neuropeptide Y ◽  
Food Consumption ◽  
Food Deprivation ◽  
Normal Female ◽  
Estrous Cycles ◽  
Energy Deficiency ◽  
Steroid Dependent ◽  
Reproductive Axis ◽  
Estrous Cyclicity ◽  
Lh Release

Neuropeptide Y (NPY) plays a key role in both food intake and GnRH secretion. Food deprivation elevates hypothalamic NPY activity and suppresses LH and gonadal steroid secretion. Similarly, lactation up-regulates NPY expression as food consumption increases and estrous cycles cease. These observations suggest that NPY coordinates reproductive suppression in response to energy deficiency; if so, the reproductive axis of NPY knockout (KO) mice should be impervious to lactation and food deprivation. We monitored food consumption, body weight, and estrous cyclicity during lactation in NPY KO mice with large and small litters. NPY KO mice with either litter size resembled wild types (WTs) in weight regulation and food consumption. Large-litter mothers had longer anestrous periods and smaller pups at weaning, but NPY KOs and WTs did not differ in either respect. We also examined the LH response of NPY KO mice to 48 h without food. Basal levels of LH in ovariectomized NPY KO animals decreased in response to fasting, but LH levels in intact and estrogen-treated ovariectomized NPY KO animals did not. In contrast, WTs consistently showed fasting-induced suppression of LH. Our findings suggest that other systems can sustain the hyperphagia of lactation and NPY alone is not responsible for suppressing cyclicity during lactation. Nevertheless, the suppression of basal LH release that accompanies food deprivation in normal female mice appears to require the steroid-dependent actions of NPY.

scholarly journals The Effect of Exercise on Glucoregulatory Hormones: A Countermeasure to Human Aging: Insights from a Comprehensive Review of the Literature

2019 ◽  
Vol 16 (10) ◽  
pp. 1709 ◽  
Author(s):  
Maha Sellami ◽  
Nicola Luigi Bragazzi ◽  
Maamer Slimani ◽  
Lawrence Hayes ◽  
Georges Jabbour ◽  
...  
Keyword(s):  
Human Physiology ◽  
Exercise Training ◽  
Hormone Secretion ◽  
Endocrine System ◽  
Aging Effect ◽  
Older Individuals ◽  
Combined Training ◽  
Diet And Exercise ◽  
Glucoregulatory Hormones ◽  
Aging Adults

Hormones are secreted in a circadian rhythm, but also follow larger-scale timetables, such as monthly (hormones of the menstrual cycle), seasonal (i.e., winter, summer), and, ultimately, lifespan-related patterns. Several contexts modulate their secretion, such as genetics, lifestyle, environment, diet, and exercise. They play significant roles in human physiology, influencing growth of muscle, bone, and regulating metabolism. Exercise training alters hormone secretion, depending on the frequency, duration, intensity, and mode of training which has an impact on the magnitude of the secretion. However, there remains ambiguity over the effects of exercise training on certain hormones such as glucoregulatory hormones in aging adults. With advancing age, there are many alterations with the endocrine system, which may ultimately alter human physiology. Some recent studies have reported an anti-aging effect of exercise training on the endocrine system and especially cortisol, growth hormone and insulin. As such, this review examines the effects of endurance, interval, resistance and combined training on hormones (i.e., at rest and after) exercise in older individuals. We summarize the influence of age on glucoregulatory hormones, the influence of exercise training, and where possible, examine masters’ athletes’ endocrinological profile.

scholarly journals Interactions between endocrine and circadian systems

2013 ◽  
Vol 52 (1) ◽  
pp. R1-R16 ◽  
Author(s):  
Anthony H Tsang ◽  
Johanna L Barclay ◽  
Henrik Oster
Keyword(s):  
Cognitive Performance ◽  
Hormonal Regulation ◽  
Circadian Clocks ◽  
Circadian Regulation ◽  
Metabolic Homeostasis ◽  
Peripheral Tissues ◽  
Hormonal Factors ◽  
Circadian Timing ◽  
Downstream Processes ◽  
The Brain

In most species, endogenous circadian clocks regulate 24-h rhythms of behavior and physiology. Clock disruption has been associated with decreased cognitive performance and increased propensity to develop obesity, diabetes, and cancer. Many hormonal factors show robust diurnal secretion rhythms, some of which are involved in mediating clock output from the brain to peripheral tissues. In this review, we describe the mechanisms of clock–hormone interaction in mammals, the contribution of different tissue oscillators to hormonal regulation, and how changes in circadian timing impinge on endocrine signalling and downstream processes. We further summarize recent findings suggesting that hormonal signals may feed back on circadian regulation and how this crosstalk interferes with physiological and metabolic homeostasis.

Sign in / Sign up

Export Citation Format

Share Document