Revisiting the pineal gland: a review of calcification, masses, precocious puberty, and melatonin functions

Neighbourhood environment and early menarche among adolescent girls of five countries

INTRODUCTION

We aim to investigate the relationship between individuals' perceptions of their neighbourhood environment and early menarche.

METHODS

This was a retrospective cohort study of 7,486 girls of Ethiopia, India, South Korea, the United Kingdom (UK), and the United States (US), born in 1997-2011 was analysed. Early menarche was defined as being below the 10th to 20th percentiles in each cohort, considering the varying distributions across countries. Perceived neighbourhood environments were assessed based on the responses for neighbourhood pollution, safety, and recreational facilities. We calculated the relative risk (RR) of early menarche for unfavourable environment.

RESULTS

The mean age at menarche was lowest in South Korea (10.6 years) and highest in Ethiopia (13.7 years). Unfavourable environment was associated with higher risk of early menarche overall (RR = 1.34, 95% confidence interval [CI]:1.09-1.65) and each country (3.03, 95% CI: 1.15-7.96 in Ethiopia; 1.99, 95% CI: 0.97-4.10 in India, 1.23, 95% CI: 0.67-2.27 in Korea; 1.26, 95% CI: 0.96-1.64 in the UK). Specifically, pollution (1.29, 95% CI: 1.03-1.62) and low safety (1.19, 95% CI: 1.60-1.88) were associated with early menarche.

CONCLUSIONS

Our finding highlights the potential role of perceived neighbourhood environment in the timing of puberty.

Modulating the Pronociceptive Effect of Sleep Deprivation: A Possible Role for Cholinergic Neurons in the Medial Habenula

Sleep deprivation has been shown to exacerbate pain sensitivity and may contribute to the onset of chronic pain, yet the precise neural mechanisms underlying this association remain elusive. In our study, we explored the contribution of cholinergic neurons within the medial habenula (MHb) to hyperalgesia induced by sleep deprivation in rats. Our findings indicate that the activity of MHb cholinergic neurons diminishes during sleep deprivation and that chemogenetic stimulation of these neurons can mitigate the results. Interestingly, we did not find a direct response of MHb cholinergic neurons to pain stimulation. Further investigation identified the interpeduncular nucleus (IPN) and the paraventricular nucleus of the thalamus (PVT) as key players in the pro-nociceptive effect of sleep deprivation. Stimulating the pathways connecting the MHb to the IPN and PVT alleviated the hyperalgesia. These results underscore the important role of MHb cholinergic neurons in modulating pain sensitivity linked to sleep deprivation, highlighting potential neural targets for mitigating sleep deprivation-induced hyperalgesia.

Ovarian overexpression of ASMT gene increases follicle numbers in transgenic sheep: Association with lipid metabolism

Melatonin plays an important role in mammalian reproductive activities, to further understand the effects of endogenous melatonin on functions of ovary, the transgenic sheep with overexpression of melatonin synthetic enzyme gene ASMT in ovary were generated. The results showed that total melatonin content in follicular fluid of transgenic sheep was significantly greater than that in the wild type. Accordingly, the follicle numbers of transgenic sheep were also significantly greater than those in the WT. The results of follicular fluid metabolites sequencing showed that compared with WT, the differential metabolites of the transgenic sheep were significantly enriched in several signaling pathways, the largest number of metabolites was lipid metabolism pathway and the main differential metabolites were lipids and lipoid molecules. SMART-seq2 were used to analyze the oocytes and granulosa cells of transgenic sheep and WT sheep. The main differential enrichment pathway was metabolic pathway, in which lipid metabolism genes accounted for the majority. In conclusion, this is the first report to show that ovary overexpression of ASMT increased local melatonin production and follicle numbers. These results may imply that ASMT plays an important role in follicle development and formation, and melatonin intervention may be a potential method to promote this process.

Structural brain abnormalities in Pallister-Killian syndrome: a neuroimaging study of 31 children

BACKGROUND

Pallister-Killian syndrome (PKS) is a rare genetic disorder caused by mosaic tetrasomy of 12p with wide neurological involvement. Intellectual disability, developmental delay, behavioral problems, epilepsy, sleep disturbances, and brain malformations have been described in most individuals, with a broad phenotypic spectrum. This observational study, conducted through brain MRI scan analysis on a cohort of patients with genetically confirmed PKS, aims to systematically investigate the neuroradiological features of this syndrome and identify the possible existence of a typical pattern. Moreover, a literature review differentiating the different types of neuroimaging data was conducted for comparison with our population.

RESULTS

Thirty-one individuals were enrolled (17 females/14 males; age range 0.1-17.5 years old at first MRI). An experienced pediatric neuroradiologist reviewed brain MRIs, blindly to clinical data. Brain abnormalities were observed in all but one individual (compared to the 34% frequency found in the literature review). Corpus callosum abnormalities were found in 20/30 (67%) patients: 6 had callosal hypoplasia; 8 had global hypoplasia with hypoplastic splenium; 4 had only hypoplastic splenium; and 2 had a thin corpus callosum. Cerebral hypoplasia/atrophy was found in 23/31 (74%) and ventriculomegaly in 20/31 (65%). Other frequent features were the enlargement of the cisterna magna in 15/30 (50%) and polymicrogyria in 14/29 (48%). Conversely, the frequency of the latter was found to be 4% from the literature review. Notably, in our population, polymicrogyria was in the perisylvian area in all 14 cases, and it was bilateral in 10/14.

CONCLUSIONS

Brain abnormalities are very common in PKS and occur much more frequently than previously reported. Bilateral perisylvian polymicrogyria was a main aspect of our population. Our findings provide an additional tool for early diagnosis.Further studies to investigate the possible correlations with both genotype and phenotype may help to define the etiopathogenesis of the neurologic phenotype of this syndrome.

Pyroptosis-related non-coding RNAs emerging players in atherosclerosis pathology

Globally, atherosclerosis a persistent inflammatory condition of the artery walls continues to be the primary cause of cardiovascular illness and death. The ncRNAs are important regulators of important signalling pathways that affect pyroptosis and the inflammatory environment in atherosclerotic plaques. Comprehending the complex interaction between pyroptosis and non-coding RNAs (ncRNAs) offers fresh perspectives on putative therapeutic targets for ameliorating cardiovascular problems linked to atherosclerosis. The discovery of particular non-coding RNA signatures linked to the advancement of atherosclerosis could lead to the creation of novel biomarkers for risk assessment and customised treatment approaches. A thorough investigation of the regulatory networks regulated by these non-coding RNAs has been made possible by the combination of cutting-edge molecular methods and bioinformatics tools. Studying pyroptosis-related ncRNAs in detail appears to be a promising way to advance our understanding of disease pathophysiology and develop focused therapeutic methods as we work to unravel the complex molecular tapestry of atherosclerosis. This review explores the emerging significance of non-coding RNAs (ncRNAs) in the regulation of pyroptosis and their consequential impact on atherosclerosis pathology.

Pineal cysts may promote pubertal development in girls with central precocious puberty: a single-center study from China

Introduction

Pineal cysts have long been considered a benign intracranial variation. However, in our clinical practice, it has been observed that some children with central precocious puberty (CPP) who have pineal cysts experience rapid progression in adolescent development. In recent years, there has been a significant increase in the prevalence of CPP in girls, leading to more diagnoses of CPP among children with pineal cysts. Despite this, there is no consensus regarding whether pineal cysts contribute to CPP as one of its organic factors. This study aimed to analyze the clinical characteristics of pineal cysts in children with CPP and explore the potential effects of pineal cysts on puberty development.

Methods

This single-center study retrospectively analyzed clinical data from girls aged 3 to 10 years who underwent head/pituitary magnetic resonance imaging at the Children's Hospital Affiliated to Zhengzhou University between 2019 and 2022. The study categorized the detection rates of pineal cysts based on systematic disease classification and compared the rates of cyst detection between girls diagnosed with CPP and those without CPP. Subsequently, CPP-diagnosed girls with pineal cysts were examined. Among CPP-diagnosed girls meeting the study's criteria, those with pineal cysts formed the 'cyst group,' while those without cysts were matched in a 1:1 ratio based on age and body mass index to form the 'non-cyst group.' Comparative analyses were conducted to assess the clinical characteristics between these two groups. CPP-diagnosed girls with cysts were further subdivided into three groups according to cyst size (≤5 mm, 5.1-9.9 mm, and ≥10 mm) to investigate potential differences in clinical characteristics among these subgroups. The study involved an analysis of clinical data from girls diagnosed with CPP and included imaging follow-ups to explore the progression of pineal cysts over time.

Results

Among the 23,245 girls who underwent head/pituitary magnetic resonance imaging scans, the detection rate of pineal cysts was 3.6% (837/23,245), with most cases being associated with endocrine diseases. The detection rate of pineal cysts in CPP patients was 6.4% (262/4099), which was significantly higher than the 3.0% (575/19,146) in patients without CPP. In comparison to the non-cyst group, the cyst group exhibited statistically significant increases in estradiol levels, peak luteinizing hormone (LH) levels, peak LH/follicle-stimulating hormone (FSH) ratios, uterine body length, and cervix length (P < 0.001). As cyst size increased, there were significant rises in LH peak, peak LH/FSH ratio, uterine body length, and cervical length (P < 0.01). Estradiol levels and left ovarian volume also showed an increasing trend (P < 0.05). Among girls who underwent follow-up imaging, 26.3% (5/19) exhibited an increase in cyst size.

Conclusion

Pineal cysts are relatively common in children with CPP. They may affect the pubertal development process, with larger cysts correlating to faster pubertal development. Therefore, the authors hypothesize that pineal cysts may trigger CPP in some cases, especially when the cysts are larger than 5 mm in size, as indicated by our data.

Divergent Evolutionary Rates of Primate Brain Regions as Revealed by Genomics and Transcriptomics

Although the primate brain contains numerous functionally distinct structures that have experienced diverse genetic changes during the course of evolution and development, these changes remain to be explored in detail. Here we utilize two classic metrics from evolutionary biology, the evolutionary rate index (ERI) and the transcriptome age index (TAI), to investigate the evolutionary alterations that have occurred in each area and developmental stage of the primate brain. We observed a higher evolutionary rate for those genes expressed in the non-cortical areas during primate evolution, particularly in human, with the highest rate of evolution being exhibited at brain developmental stages between late infancy and early childhood. Further, the transcriptome age of the non-cortical areas was lower than that of the cerebral cortex, with the youngest age apparent at brain developmental stages between late infancy and early childhood. Our exploration of the evolutionary patterns manifest in each brain area and developmental stage provides important reference points for further research into primate brain evolution.

Dietary pattern and precocious puberty risk in Chinese girls: a case-control study

BACKGROUND

The role of dietary intake on precocious puberty remains unclear. This study aimed to investigate the association between the amount and frequency of dietary intake and the risk of precocious puberty in Chinese girls.

METHODS

In this case-control study, we enrolled 185 precocious puberty girls and 185 age-matched controls. Their dietary intake was assessed through a semi-quantitative food frequency questionnaire. Their sociodemographic and lifestyle data were collected. The associations between dietary intake and risk of precocious puberty were assessed by conditional logistic regression models.

RESULTS

After multivariate adjustment, consuming a higher amount of red meat was associated with higher precocious puberty risk (OR = 2.74, 95% CI: 1.25-6.02), while a higher frequency of fruit ( P for trend = 0.024) and amount of vegetable intake was associated with a lower risk of precocious puberty (P for trend = 0.002). The high vegetable and protein dietary pattern was significantly negatively associated with precocious puberty (OR = 0.78, 95% CI: 0.63-0.97), whereas the high animal food and fruits dietary pattern was remarkably positively associated with precocious puberty (OR = 1.36, 95% CI: 1.09-1.69), after adjusting for age and body mass index.

CONCLUSIONS

High vegetable and protein dietary pattern is a protective factor against precocious puberty, while high animal food and fruits dietary pattern is a risk factor for precocious puberty in Chinese girls. Attentions should be paid to a reasonable intake of red meat, eggs, and fruits in children's daily diet, increase their intake of vegetables, in order to reduce the risk of precocious puberty.

Sleep duration in middle childhood and age at menarche

OBJECTIVE

Puberty affects sleep phasing. However, it is unclear if sleep duration earlier in childhood could influence the timing of pubertal events. We aimed to assess the association between middle childhood nighttime sleep duration and age at menarche (AAM).

METHODS

In a cohort of 819 premenarcheal Colombian girls who were followed annually for the occurrence of menarche, we estimated adjusted hazard ratios (HR) with 95% confidence intervals (CI) for menarche by categories of recommended sleep duration in middle childhood using Cox models. Analyses were stratified by age at sleep assessment.

RESULTS

Among girls aged 9 to <11 years, compared with girls who slept within recommendations, sleeping above recommendations was related to an adjusted 76% (95% CI: 4%, 198%; p = .04) higher probability of experiencing menarche during follow up. In girls aged ≥11 years, compared with girls who slept within recommendations, sleeping under recommendations was related to an adjusted 42% (95% CI: 5%, 93%; p = .03) higher probability of experiencing menarche during follow-up. Sleep duration was not associated with AAM in girls aged <9 years at the time of sleep assessment.

CONCLUSIONS

Sleeping above recommendations in girls 9 to <11 years-old and sleeping under recommendations in girls ≥11 years-old is associated with earlier menarche.

A protein-coding gene expression atlas from the brain of pregnant and non-pregnant goats

Background: The brain is an extraordinarily complex organ with multiple anatomical structures involved in highly specialized functions related with behavior and physiological homeostasis. Our goal was to build an atlas of protein-coding gene expression in the goat brain by sequencing the transcriptomes of 12 brain regions in seven female Murciano-Granadina goats, from which three of them were 1-month pregnant. Results: Between 14,889 (cerebellar hemisphere) and 15,592 (pineal gland) protein-coding genes were expressed in goat brain regions, and most of them displayed ubiquitous or broad patterns of expression across tissues. Principal component analysis and hierarchical clustering based on the patterns of mRNA expression revealed that samples from certain brain regions tend to group according to their position in the anterior-posterior axis of the neural tube, i.e., hindbrain (pons and medulla oblongata), midbrain (rostral colliculus) and forebrain (frontal neocortex, olfactory bulb, hypothalamus, and hippocampus). Exceptions to this observation were cerebellum and glandular tissues (pineal gland and hypophysis), which showed highly divergent mRNA expression profiles. Differential expression analysis between pregnant and non-pregnant goats revealed moderate changes of mRNA expression in the frontal neocortex, hippocampus, adenohypophysis and pons, and very dramatic changes in the olfactory bulb. Many genes showing differential expression in this organ are related to olfactory function and behavior in humans. Conclusion: With the exception of cerebellum and glandular tissues, there is a relationship between the cellular origin of sampled regions along the anterior-posterior axis of the neural tube and their mRNA expression patterns in the goat adult brain. Gestation induces substantial changes in the mRNA expression of the olfactory bulb, a finding consistent with the key role of this anatomical structure on the development of maternal behavior.

Beyond Visual Assessment of Basal Ganglia Uptake: Can Automated Method and Pineal Body Uptake Assessment Improve Identification of Nigrostriatal Dysfunction on 18F-DOPA PET/CT?

The interpretation of 18F-DOPA PET/CT performed for assessing nigrostriatal dysfunction (NSD) is usually based on visual assessment of the uptake in the basal ganglia (VA-BG). In the present study, we evaluate the diagnostic performance of an automated method that assesses BG uptake (AM-BG) and of methods that assess pineal body uptake, and examine whether these methods can enhance the diagnostic performance of VA-BG alone. We retrospectively included 112 scans performed in patients with clinically suspected NSD who also had a subsequent final clinical diagnosis provided by a movement disorder specialist (69 NSD and 43 non-NSD patients). All scans were categorized as positive or negative based on (1) VA-BG, (2) AM-BG, and (3) qualitative and semiquantitative assessment of pineal body uptake. VA-BG, AM-BG, assessment of pineal body 18F-DOPA uptake by VA (uptake > background), by SUVmax (≥0.72), and by pineal to occipital ratio (POR ≥ 1.57) could all significantly differentiate NSD from non-NSD patients (Pv < 0.01 for all five methods). Of these methods, VA-BG provided the highest sensitivity (88.4%) and accuracy (90.2%). Combining VA-BG with AM-BG did not improve diagnostic accuracy. An interpretation algorithm that combines VA-BG with pineal body uptake assessment by POR calculation increased sensitivity to 98.5%, at the expense of decreased specificity. In conclusion, an automated method that assesses 18F-DOPA uptake in the BG and assessment of pineal body 18F-DOPA uptake can significantly separate NSD from non-NSD patients, with apparent inferior diagnostic performance when applied alone compared with VA-BG. When VA-BG categorizes a scan as negative or equivocal, assessment of the 18F-DOPA uptake in the pineal body has the potential to minimize the rate of false negative reports. Further research is essential to validate this approach and to study the pathophysiologic relationship between 18F-DOPA uptake in the pineal body and nigrostriatal dysfunction.

Melatonin Treatment in Kidney Diseases

Melatonin is a neurohormone that is mainly secreted by the pineal gland. It coordinates the work of the superior biological clock and consequently affects many processes in the human body. Disorders of the waking and sleeping period result in nervous system imbalance and generate metabolic and endocrine derangements. The purpose of this review is to provide information regarding the potential benefits of melatonin use, particularly in kidney diseases. The impact on the cardiovascular system, diabetes, and homeostasis causes melatonin to be indirectly connected to kidney function and quality of life in people with chronic kidney disease. Moreover, there are numerous reports showing that melatonin plays a role as an antioxidant, free radical scavenger, and cytoprotective agent. This means that the supplementation of melatonin can be helpful in almost every type of kidney injury because inflammation, apoptosis, and oxidative stress occur, regardless of the mechanism. The administration of melatonin has a renoprotective effect and inhibits the progression of complications connected to renal failure. It is very important that exogenous melatonin supplementation is well tolerated and that the number of side effects caused by this type of treatment is low.

Cross-sectional analysis of potential risk factors of the pineal gland calcification

The Pineal gland (PG) is the site of production of melatonin as an important central hormone in the body. It is not known yet whether PG calcification (PGC) is an age-associated physiological process or a pathologic condition caused by lifestyle-factors and metabolic-dysregulations.Here, we performed a cross-sectional analysis on 586 patients referred to have Computed Tomographic (CT) scans (above 15 years old), in the Ali Ebne Abi Taleb hospital radiology center in 2017-2018. Based on the CT-scans of the brain, the presence of PGC was recorded and a score of scale 0 to 6 (PGC_score) was calculated for its intensity based on the volume and the Hounsfield units of the calcified pineal. Logistic and ordered logistic regression tests were employed to determine potential risk factor of PGC and higher PGC_score, respectively, testing the factors age, sex, history of cardiovascular and metabolic diseases, smoking and opioid use. We found male sex (OR: 2.30 (95% CI:1.39-3.82) and smoking cigarettes (OR: 4.47 (95% CI:1.01-19.78)) as the main potential risk factors for the pineal gland calcification. For PGC_score, we found age to be dose-dependently associated with PGC_score only in patients aged below 63 (p-trend < 0.001). Stratifying for age, in patients < 63 years old, we found age, male sex (positive association) and dyslipidemia (negative association) as the main significantly associated factors of PGC_score. On the contrary, in patients aged >  = 63, cigarette smoking was the only significantly associated factor of higher PGC_score.In conclusion, our results indicate that at ages below 63, age, male sex and blood lipid are the main associated factors of higher PGC, but at ages above that, the lifestyle factor smoking is significantly associated with higher pineal gland calcification.

Pediatric Pineal Region Tumors: Special Reference to Posterior Interhemispheric Trans-Tentorial Approach

Pediatric pineal region tumors consist of tumors of pineal gland origin and parapineal origin. The former are comprised of germ cell tumor (GCT) and pineal parenchymal tumor. The latter originate from the surrounding neural structures, such as the midbrain and thalamus; thus, they are often benign gliomas during childhood. Pineal region tumors often cause obstructive hydrocephalus, which is the main cause of presenting symptoms. Advanced imaging discloses precise location and extension of the tumor and associated anomalies such as hydrocephalous, dissemination, hemorrhage, etc. Hydrocephalus has been managed with CSF diversion, mostly using an endoscopic third ventriculostomy. Because of different treatment paradigms for each tumor type, histological confirmation is needed either through biopsy, tumor markers for GCTs, and/or surgical resection sampling. Radical resection of these tumors remains a challenge due to their deep-seated location and involvement of delicate neural and vascular structures. Comparison of common craniotomy approaches, occipital transtentorial (OT) and infratentorial supracerebellar (ITSC), is reviewed for their advantages and disadvantages. Surgical area exposure and blind spots are important factors for successful tumor removal. The surgical techniques and nuances that the author employs for tumor resection via a posterior interhemispheric transtentorial approach are presented.

A 2-step prediction model for diagnosis of germinomas in the pineal region

Background

Germinomas are sensitive to radiation and chemotherapy, and their management distinctly differs from other kinds of pineal region tumors. The aim of this study was to construct a prediction model based on clinical features and preoperative magnetic resonance (MR) manifestations to achieve noninvasive diagnosis of germinomas in pineal region.

Methods

A total of 126 patients with pineal region tumors were enrolled, including 36 germinomas, 53 nongerminomatous germ cell tumors (NGGCTs), and 37 pineal parenchymal tumors (PPTs). They were divided into a training cohort (n = 90) and a validation cohort (n = 36). Features were extracted from clinical records and conventional MR images. Multivariate analysis was performed to screen for independent predictors to differentiate germ cell tumors (GCTs) and PPTs, germinomas, and NGGCTs, respectively. From this, a 2-step nomogram model was established, with model 1 for discriminating GCTs from PPTs and model 2 for identifying germinomas in GCTs. The model was tested in a validation cohort.

Results

Both model 1 and model 2 yielded good predictive efficacy, with c-indexes of 0.967 and 0.896 for the diagnosis of GCT and germinoma, respectively. Calibration curve, decision curve, and clinical impact curve analysis further confirmed their predictive accuracy and clinical usefulness. The validation cohort achieved areas under the receiver operating curves of 0.885 and 0.926, respectively.

Conclusions

The 2-step model in this study can noninvasively differentiate GCTs from PPTs and further identify germinomas, thus holding potential to facilitate treatment decision-making for pineal region tumors.

Digital histological morphometry of the human pineal gland in a postmortem study, with endocrine and neurological clinical implications

The pineal gland is a small-sized, photo neuroendocrine organ in the midline of the brain that synthesises and secretes melatonin and serotonin. Chords and islands of pinealocytes constitute the secretory parenchyma, while glial tissue and calcifications represent degenerative changes. This study examined human postmortem pineal glands to microscopically assess morphological changes possibly associated with clinical data, by using digital techniques. A retrospective autopsy study has been performed on 72 paediatric and adult autopsy cases. The glands have been processed for histological analysis and immunohistochemical staining with synaptophysin (SYN), neuron-specific enolase (NSE), and neurofilament (NF). Slides were digitally scanned. Morphometric data were obtained using CaseViewer and ImageJ. The comorbidities used for correlation with morphometric data were obesity, type 2 diabetes, adrenal gland adenoma, goitre, chronic pancreatitis, arterial hypertension, and mixed dementia. Thirty-three females and 39 males were included in the study. Increased secretory parenchyma was found in patients with chronic pancreatitis, arterial hypertension, and adrenal gland adenoma. Reduced activity was found in patients with type 2 diabetes, obesity, advanced pineal calcification, mixed dementia, and old age. There were no changes associated with goitre, cachexia, or Willis's polygon atherosclerosis. No significant differences between gender were found. The activity of the pineal gland can be assessed by quantitative immunohistochemistry of neuroendocrine and structural pinealocyte markers and observation of glial tissue and calcifications. There is a need for further research to evaluate the clinical impact of these morphological changes on the neuroendocrine systems, with clinical implications in endocrinology, neurology, and even psychiatry. Digital techniques offer a more exact analysis of histological data.

The Pathogenetic Role of Melatonin in Migraine and Its Theoretic Implications for Pharmacotherapy: A Brief Overview of the Research

Migraine is a chronic disease of global concern, regardless of socio-economic and cultural background. It most often and intensely affects young adults, especially women. Numerous mechanisms of a migraine attack have been identified (disturbances in the reaction of vessels, functions of neurotransmitters, cortical neurons, ion channels, receptors, the process of neurogenic inflammation), and many of its symptoms can be explained by activation of the hypothalamus and disturbances in its communication with other brain regions (including the brainstem). Numerous neuropeptides and neurochemical systems also play a role in migraine. One of them is melatonin, a hormone that allows the body to adapt to cyclically changing environmental and food conditions. In this article, we present the pathophysiological basis of melatonin release from the pineal gland and other tissues (including the intestines) under the influence of various stimuli (including light and food), and its role in stimulating the brain structures responsible for triggering a migraine attack. We analyze publications concerning research on the role of melatonin in various headaches, in various stages of migraine, and in various phases of the menstrual cycle in women with migraine, and its impact on the occurrence and severity of migraine attacks. Melatonin as an internally secreted substance, but also present naturally in many foods. It is possible to supplement melatonin in the form of pharmaceutical preparations, and it seems, to be a good complementary therapy (due to the lack of significant side effects and pharmacological interactions) in the treatment of migraine, especially: in women of childbearing age, in people taking multiple medications for other diseases, as well as those sensitive to pharmacotherapy.

Astrocyte Dysregulation and Calcium Ion Imbalance May Link the Development of Osteoporosis and Alzheimer’s Disease

The typical symptoms of patients with Alzheimer’s disease (AD) are amyloid-β (Aβ) plaques and tau hyperphosphorylation. However, recent studies show that these symptoms are not the cause of the disease but are generated after the pathogenesis. Compared with other types of dementia, AD has the obvious features of pineal gland calcification and decreased melatonin production. The pineal gland is mainly composed of pinealocytes that release melatonin and astrocytes. Astrocytes function to maintain a balanced concentration of calcium ions, provide nerve cell nutrients, and migrate nutrients in vivo. Calcium ions are among the most important neurotransmitters. Once triggered, a calcium wave can be formed between astrocytes to activate other astrocytes to transmit information. Most calcium is stored in the skeleton. Bone tissue is composed mainly of osteocytes, osteoblasts, and osteoclasts. Of these, osteocyte is a kind of astrocyte which regulates the activity of osteoclasts and osteoblasts. The pineal gland is composed mainly of astrocytes; osteocytes are also a kind of astrocyte. Therefore, we conclude that when astrocytes are gradually disabled, calcium may be lost from the bones, prompting osteoporosis. The calcium ions then released into the blood may accumulate and cause ectopic calcification in the pineal gland, which promotes the occurrence of AD. Finally, this study used aspects of drugs and hormones (bone and calcium metabolism hormones and melatonin) to infer the hypothesis, which proposes that astrocyte dysregulation promotes the long-term imbalance of calcium ions in vivo and leads to osteoporosis and AD.

Protective Effect of Melatonin for Renal Ischemia-Reperfusion Injury: A Systematic Review and Meta-Analysis

Background: Renal ischemia-reperfusion (I/R) injury is one of the major causes related to acute kidney damage. Melatonin has been shown as a powerful antioxidant, with many animal experiments have been designed to evaluate the therapeutic effect of it to renal I/R injury.

Objectives: This systematic review aimed to assess the therapeutic effect of melatonin for renal I/R injury in animal models.

Methods and Results: The PubMed, Web of Science, Embase, and Science Direct were searched for animal experiments applying melatonin to treat renal I/R injury to February 2021. Thirty-one studies were included. The pooled analysis showed a greater reduction of blood urea nitrogen (BUN) (21 studies, weighted mean difference (WMD) = −30.00 [−42.09 to −17.91], p < 0.00001), and serum creatinine (SCr) (20 studies, WMD = −0.91 [−1.17 to −0.66], p < 0.00001) treated with melatonin. Subgroup analysis suggested that multiple administration could reduce the BUN compared with control. Malondialdehyde and myeloperoxidase were significantly reduced, meanwhile, melatonin significantly improved the activity of glutathione, as well as superoxide dismutase. The possible mechanism for melatonin to treat renal I/R injury is inhibiting endoplasmic reticulum stress, apoptosis, inflammation, autophagy, and fibrillation in AKI to chronic kidney disease.

Conclusions: From the available data of small animal studies, this systematic review demonstrated that melatonin could improve renal function and antioxidative effects to cure renal I/R injury through, then multiple administration of melatonin might be more appropriate. Nonetheless, extensive basic experiments are need to study the mechanism of melatonin, then well-designed randomized controlled trials to explore the protective effect of melatonin.

Early menarche in visually impaired girls: evidence and hypothesis of light-dark cycle disruption and blindness effect on puberty onset

Puberty onset is tightly regulated by a broad spectrum of neuroendocrine signals and peripheral stimuli which coordinate the hypothalamic-pituitary-gonadal (HPG) axis activation. Numerous studies suggest that light stimulation influences HPG axis function; however, the effect of blindness on puberty timing remains controversial. Given that menarche is a suitable marker for sexual development initiation, the evaluation of the age at which blind girls attain it allows to indirectly assess the effect of light-dark cycle disruption on pubertal development. The present investigation aimed to review the evidence regarding menarcheal age drift in visually impaired girls, as well as to discuss the findings based on the existing hypotheses of the physiological mechanisms linking the light-dark cycle and photic sensitivity loss to the onset of puberty. Eleven studies were retrieved from a literature search conducted in PubMed, Scopus, ScienceDirect, SpringerLink, and Google Scholar databases. Eight studies concluded that light perception impairment is related to a moderately earlier age at menarche. Moreover, the evidence gathered in this review suggests a positive association between the degree of light perception loss and precocious menarcheal onset; yet, no conclusive outcomes were found regarding menarche advancement in acquired versus congenital blindness. We encourage further research aiming to elucidate the physiological mechanism underlying photosensitive regulation and blindness effect on the neuroendocrine pathways involved in human sexual maturation.

NLRP3 inflammasome activation and oxidative stress status in the mild and moderate SARS-CoV-2 infected patients: impact of melatonin as a medicinal supplement

The inflammasome as a multiprotein complex has a role in activating ASC and caspase-1 resulting in activating IL-1β in various infections and diseases like corona virus infection in various tissues. It was shown that these tissues are affected by COVID-19 patients. According to the current evidence, melatonin is not veridical while possessing a high safety profile, however, it possesses indirect anti-viral actions owing to its anti-oxidation, anti-inflammation, and immune improving properties. This study aims to assess the impacts of melatonin as the complementary treatments on oxidative stress agents and inflammasome activation in patients with COVID-19. Melatonin supplement (9 mg daily, orally) was provided for the patients hospitalized with a COVID-19 analysis for 14 days. For measuring IL-10, IL-1β, and TNF-α cytokines and malondialdehyde (MDA), nitric oxide (NO), and superoxide dismutase (SOD) level and the expression of CASP1 and ASC genes, blood samples were gathered from the individuals at the start and termination of the therapy. Our findings indicated that melatonin is used as a complementary treatment to reduce the levels of TNF-α and IL-1β cytokines, MDA, and NO levels in COVID-19 patients and significantly increase SOD level, however, the levels of IL-10 cytokine possesses no considerable changes. The findings revealed that genes of CASP1 and ASC were dysregulated by melatonin regulating the inflammasome complex. Based on the findings of the current study, it is found that melatonin can be effective as a medicinal supplement in decreasing the inflammasome multiprotein complex and oxidative stress along with beneficial impacts on lung cytokine storm of COVID-19 patients.

Is there any relationship between autism and pineal gland volume?

Purpose

Abnormalities in melatonin physiology and circadian rhythm are detected in patients with autism. Melatonin is produced predominantly in the pineal gland and the amount of melatonin released is proportional to the pineal gland volume. This study aimed to examine whether the pineal gland volume in children with autism is different from that in healthy children.

Material and methods

Brain magnetic resonance images (MRI) of 120 paediatric patients with autism and 82 control paediatric subjects were examined; pineal parenchymal volume (PPV), pineal cyst rate (PCR), and total pineal gland volume (TPGV) were measured using a multimodality viewer (MMV), but only the TPGVs were measured using a tumour tracking (TT) method. Measurements were taken by 2 separate radiologists.

Results

In patients with autism, the PPV and TPGV according to MMV, and the TPGV according to TT were significantly lower, and the PCR was significantly higher. Moreover, the ratio of PPV to TPGV was significantly lower in the autism patient group. In both groups, the TPGVs were significantly lower in the autism patient group than the controls among all age groups.

Conclusions

Our study was the first to examine TPGVs in detail in paediatric patients with autism using 2 different methods. Low PPV-TPGV and high PCR have been observed in autism. This study also provides comparable reference values for pineal gland size in healthy children or autistic children aged 2-17 years. These results show promising potential for further research to understand the relationship between autism pathogenesis and the pineal gland.

Melatonin Modulates the Antioxidant Defenses and the Expression of Proinflammatory Mediators in Pancreatic Stellate Cells Subjected to Hypoxia

Pancreatic stellate cells (PSC) play a major role in the formation of fibrotic tissue in pancreatic tumors. On its side, melatonin is a putative therapeutic agent for pancreatic cancer and inflammation. In this work, the actions of melatonin on PSC subjected to hypoxia were evaluated. Reactive oxygen species (ROS) generation reduced (GSH) and oxidized (GSSG) levels of glutathione, and protein and lipid oxidation were analyzed. The phosphorylation of nuclear factor erythroid 2-related factor (Nrf2), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB), and the regulatory protein nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor-alpha (IκBα) was studied. The expression of Nrf2-regulated antioxidant enzymes, superoxide dismutase (SOD) enzymes, cyclooxygenase 2 (COX-2), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were also studied. Total antioxidant capacity (TAC) was assayed. Finally, cell viability was studied. Under hypoxia and in the presence of melatonin generation of ROS was observed. No increases in the oxidation of proteins or lipids were detected. The phosphorylation of Nrf2 and the expression of the antioxidant enzymes catalytic subunit of glutamate-cysteine ligase, catalase, NAD(P)H-quinone oxidoreductase 1, heme oxygenase-1, SOD1, and of SOD2 were augmented. The TAC was increased. Protein kinase C was involved in the effects of melatonin. Melatonin decreased the GSH/GSSG ratio at the highest concentration tested. Cell viability dropped in the presence of melatonin. Finally, melatonin diminished the phosphorylation of NF-kB and the expression of COX-2, IL-6, and TNF-α. Our results indicate that melatonin, at pharmacological concentrations, modulates the red-ox state, viability, and the expression of proinflammatory mediators in PSC subjected to hypoxia.

Neurobiology of puberty and its disorders

Puberty, which in humans is considered to include both gonadarche and adrenarche, is the period of becoming capable of reproducing sexually and is recognized by maturation of the gonads and development of secondary sex characteristics. Gonadarche referring to growth and maturation of the gonads is fundamental to puberty since it encompasses increased gonadal steroid secretion and initiation of gametogenesis resulting from enhanced pituitary gonadotropin secretion, triggered in turn by robust pulsatile GnRH release from the hypothalamus. This chapter reviews the development of GnRH pulsatility from before birth until the onset of puberty. In humans, GnRH pulse generation is restrained during childhood and juvenile development. This prepubertal hiatus in hypothalamic activity is considered to result from a neurobiological brake imposed upon the GnRH pulse generator resident in the infundibular nucleus. Reactivation of the GnRH pulse generator initiates pubertal development. Current understanding of the genetics and physiology of the brake will be discussed, as will hypotheses proposed to account for timing the resurgence in pulsatile GnRH and initiation of puberty. The chapter ends with a discussion of disorders associated with precocious or delayed puberty with a focus on those with etiologies attributed to aberrant GnRH neuron anatomy or function. A pediatric approach to patients with pubertal disorders is provided and contemporary treatments for both precocious and delayed puberty outlined.

The role of photoperiod and melatonin in the control of seasonal reproduction in mammals

<b>Melatonin secreted by pineal cells is a hormone whose biosynthesis is coordinated by neurons of the master clock located in the hypothalamic suprachiasmatic nuclei (SCN), characterized by the generation of a 24-hour rhythm. In many species of mammals, fluctuations in melatonin secretion affect reproductive functions, e.g. by regulating the frequency and amount of pulsatile secretion of hypothalamic and gonadotropic hormones. Seasonal breeding is a common adaptive strategy among mammals, allowing them to reproduce during the periods of the year that are most favourable for the later survival and growth of the offspring. This type of reproduction is characteristic of sheep, with winter reproductive activity, and hamsters, with summer reproductive activity. In these animals, melatonin synthesis is largely regulated by the photoperiod, which indirectly influences the period of reproductive activity or passivity. The aim of this study was to gather available knowledge on melatonin as a key element controlling seasonal reproduction. The paper presents the general shape of the circadian rhythm and the neuroendocrine mechanism regulating animal reproduction depending on the variable photoperiod. The collected results suggest that melatonin, kisspeptins, gonadotropin-releasing hormone (GnRH), sex hormones and thyroid hormones participate in the regulation of seasonal reproduction in mammals. </b>

Thymus-Pineal Gland Axis: Revisiting Its Role in Human Life and Ageing

For years the thymus gland (TG) and the pineal gland (PG) have been subject of increasingly in-depth studies, but only recently a link that can associate the activities of the two organs has been identified. Considering, on the one hand, the well-known immune activity of thymus and, on the other, the increasingly emerging immunological roles of circadian oscillators and the rhythmically secreted main pineal product, melatonin, many studies aimed to analyse the possible existence of an interaction between these two systems. Moreover, data confirmed that the immune system is functionally associated with the nervous and endocrine systems determining an integrated dynamic network. In addition, recent researches showed a similar, characteristic involution process both in TG and PG. Since the second half of the 20th century, evidence led to the definition of an effectively interacting thymus-pineal axis (TG-PG axis), but much has to be done. In this sense, the aim of this review is to summarize what is actually known about this topic, focusing on the impact of the TG-PG axis on human life and ageing. We would like to give more emphasis to the implications of this dynamical interaction in a possible therapeutic strategy for human health. Moreover, we focused on all the products of TG and PG in order to collect what is known about the role of peptides other than melatonin. The results available today are often unclear and not linear. These peptides have not been well studied and defined over the years. In this review we hope to awake the interest of the scientific community in them and in their future pharmacological applications.

Fluoride and Pineal Gland

The pineal gland is an endocrine gland whose main function is the biosynthesis and secretion of melatonin, a hormone responsible for regulating circadian rhythms, e.g., the sleep/wake cycle. Due to its exceptionally high vascularization and its location outside the blood–brain barrier, the pineal gland may accumulate significant amounts of calcium and fluoride, making it the most fluoride-saturated organ of the human body. Both the calcification and accumulation of fluoride may result in melatonin deficiency.