Neuroendocrine Gland Research Articles

The central control of energy metabolism; hypothalamic obesity is not one disease.

Background The hypothalamus, a neuro-endocrine gland located centrally in the brain, weighs only on average 4 grams but is the captain on the ship of our energy balance. In the hypothalamus, signals of the satiety and hunger hormones are integrated and individuals with a dysfunctional hypothalamus develop obesity. The hypothalamus, however, integrates much more than the satiety and hunger hormones and hypothalamic obesity may be the result of a combination of factors. Summary The consequences of hypothalamic dysfunction can be categorized in six different domains. By systematically evaluating each domain, the underlying cause for obesity may be better understood and doors for successful management can be opened. The different domains are; pituitary gland dysfunction, behavioral problems, disturbance of the circadian rhythm, hyperphagia, low resting energy expenditure and temperature dysregulation. All of these domains may contribute to the development of obesity and may be more or less present in the individual patient. Key Messages Hypothalamic obesity is not one disease, but different underlying contributing factors may be present. Consequently, hypothalamic obesity management is not one-size-fits-all but needs to be personalized. In this paper, the current state of the art for both the diagnostics and approach of acquired hypothalamic obesity is reviewed.

Pineal gland: Sleep, malignancy and statistics.

e14042 Background: The pineal gland is a neuroendocrine gland located deep in the middle brain that regulates the circadian rhythm through Melatonin. Pineal parenchymal tumors arise from pineocytes, have no sexual predominance, occur most frequently in the pediatric population and result in melatonin level disruptions.Pineal region tumors can spread via CSF to other areas in the CNS. The first treatment for pineal region tumors is surgery. Treatments after surgery may include radiation, chemotherapy or clinical trials. Methods: Data was collected from Surveillance, Epidemiology and End Result database Research Plus Data, 17 Registries, Nov 2022 Sub (2000-2020). Pineal gland tumor cases that were labeled as the primary site were extracted from the data base. Further selection was made using the ICD Code D75.3 for neoplasm of pineal gland-primary site labelled. The data was stratified based on age, sex, race and survival curves were compared using the Log-Rank test (GraphPad Prism). Results: A total of 416 pineal gland tumor cases were found, of which ~ 50.48% were males. These tumors were most commonly seen in White (51.68%) patients followed by Hispanic (23.32%), Black (16.10%), Asians/Pacific Islander (6.97%) and Alaskans/Native American (0.96%) patients. The median age of diagnosis was 24.5 years. The incidence rate (per 1,000,000 population) for the general population has increased from 0.69 in 2000 to 0.73 in 2020. As of 2020, the incidence was noted to be higher in males, although overall the incidence among females has been ion the rise. Incidence rate was highest among the Native Americans/Alaskans population followed by Hispanics, Asians/Pacific Islanders, Blacks and Whites. Within the races, incidence was noted to be increasing in the Native Americans/Alaskans & Hispanic populations, stable in the Asians/Pacific Islanders & Black populations and decreasing amongst the White population over the period of 20 years. When the survival curves were compared on the basis of gender and race, the data was clinically significant only for gender. The median of survival (mOS) for males was 146 months but was undefined for females (CI:5.344-12.55, HR: 8.191, p <0.0001) mostly likely due to zero death events being recorded for females. Conclusions: Pineal gland tumors are rarely encountered malignancy with only 416 case reported in the last two decades. It has an almost equal predilection for males and females, more common in the younger population. The incidence is higher among males, although being relatively constant since 2000, and is trending up in females. Overall survival was superior in females with no reported death events. Native Americans/Alaskans are more affected overall survival is independent of the race.

Comparative exploration of the carotid body in domestic animals: morphology, physiology, histology, and pathology.

The aim of the study was to present a review of the literature and research on the carotid body (CB) over the past years and update the latest findings. The purpose of this article is to present a general overview and comparative analysis of CB between species, from the microanatomy to the pathology of CB. This study gives information about the embryological development and physiological aspects of anatomical findings and their differences. The second part of the article gives a comparative analysis of the pathology of CB. Neoplasia of the CB in humans, namely, paraganglioma, in most cases, is part of a genetic MEN syndrome (multiple endocrine neoplasia). In dogs, paraganglioma is also involved with multiple neoplasia formations throughout the body, including endocrine and neuroendocrine glands. From this perspective, dogs are the most suitable specimens for studying carotid body tumors and their involvement in a MEN-like syndrome.

Neural plate progenitors give rise to both anterior and posterior pituitary cells

The pituitary is the master neuroendocrine gland, which regulates body homeostasis. It consists of the anterior pituitary/adenohypophysis harboring hormones producing cells and the posterior pituitary/neurohypophysis, which relays the passage of hormones from the brain to the periphery. It is accepted that the adenohypophysis originates from the oral ectoderm (Rathke's pouch), whereas the neural ectoderm contributes to the neurohypophysis. Single-cell transcriptomics of the zebrafish pituitary showed that cyp26b1-positive astroglial pituicytes of the neurohypophysis and prop1-positive adenohypophyseal progenitors expressed common markers implying lineage relatedness. Genetic tracing identifies that, in contrast to the prevailing dogma, neural plate precursors of zebrafish (her4.3+) and mouse (Sox1+) contribute to both neurohypophyseal and a subset of adenohypophyseal cells. Pituicyte-derived retinoic-acid-degrading enzyme Cyp26b1 fine-tunes differentiation of prop1+ progenitors into hormone-producing cells. These results challenge the notion that adenohypophyseal cells are exclusively derived from non-neural ectoderm and demonstrate that crosstalk between neuro- and adeno-hypophyseal cells affects differentiation of pituitary cells.

TLQP-21 is a low potency partial C3aR activator on human primary macrophages.

TLQP-21 is a 21-amino acid neuropeptide derived from the VGF precursor protein. TLQP-21 is expressed in the nervous system and neuroendocrine glands, and demonstrates pleiotropic roles including regulating metabolism, nociception and microglial functions. Several possible receptors for TLQP-21 have been identified, with complement C3a receptor (C3aR) being the most commonly reported. However, few studies have characterised the activity of TLQP-21 in immune cells, which represent the major cell type expressing C3aR. In this study, we therefore aimed to define the activity of both human and mouse TLQP-21 on cell signalling in primary human and mouse macrophages. We first confirmed that TLQP-21 induced ERK signalling in CHO cells overexpressing human C3aR, and did not activate human C5aR1 or C5aR2. TLQP-21 mediated ERK signalling was also observed in primary human macrophages. However, the potency for human TLQP-21 was 135,000-fold lower relative to C3a, and only reached 45% at the highest dose tested (10 μM). Unlike in humans, mouse TLQP-21 potently triggered ERK signalling in murine macrophages, reaching near full activation, but at ~10-fold reduced potency compared to C3a. We further confirmed the C3aR dependency of the TLQP-21 activities. Our results reveal significant discrepancy in TLQP-21 C3aR activity between human and murine receptors, with mouse TLQP-21 being consistently more potent than the human counterpart in both systems. Considering the supraphysiological concentrations of hTLQP-21 needed to only partially activate macrophages, it is likely that the actions of TLQP-21, at least in these immune cells, may not be mediated by C3aR in humans.

The First Pituitary Proteome Landscape From Matched Anterior and Posterior Lobes for a Better Understanding of the Pituitary Gland

To date, very few mass spectrometry (MS)–based proteomics studies are available on the anterior and posterior lobes of the pituitary. In the past, MS-based investigations have focused exclusively on the whole pituitary gland or anterior pituitary lobe. In this study, for the first time, we performed a deep MS-based analysis of five anterior and five posterior matched lobes to build the first lobe-specific pituitary proteome map, which documented 4090 proteins with isoforms, mostly mapped into chromosomes 1, 2, and 11. About 1446 differentially expressed significant proteins were identified, which were studied for lobe specificity, biological pathway enrichment, protein–protein interaction, regions specific to comparison of human brain and other neuroendocrine glands from Human Protein Atlas to identify pituitary-enriched proteins. Hormones specific to each lobe were also identified and validated with parallel reaction monitoring–based target verification. The study identified and validated hormones, growth hormone and thyroid-stimulating hormone subunit beta, exclusively to the anterior lobe whereas oxytocin–neurophysin 1 and arginine vasopressin to the posterior lobe. The study also identified proteins POU1F1 (pituitary-specific positive transcription factor 1), POMC (pro-opiomelanocortin), PCOLCE2 (procollagen C-endopeptidase enhancer 2), and NPTX2 (neuronal pentraxin-2) as pituitary-enriched proteins and was validated for their lobe specificity using parallel reaction monitoring. In addition, three uPE1 proteins, namely THEM6 (mesenchymal stem cell protein DSCD75), FSD1L (coiled-coil domain–containing protein 10), and METTL26 (methyltransferase-like 26), were identified using the NeXtProt database, and depicted tumor markers S100 proteins having high expression in the posterior lobe. In summary, the study documents the first matched anterior and posterior pituitary proteome map acting as a reference control for a better understanding of functional and nonfunctional pituitary adenomas and extrapolating the aim of the Human Proteome Project towards the investigation of the proteome of life.

Estudo morfológico da glândula pineal de Alouatta belzebul

ABSTRACT The pineal is a neuroendocrine gland responsible for the synthesis and release of melatonin. It is present in the brain of vertebrates, but its morphology and location vary considerably among species. For the species Alouatta belzebul, although some anatomical aspects of the nervous system have been described, there is no information on the morphology and histological composition of this gland. Thus, the present study aimed to describe the morphological, morphometric, and histological aspects of the pineal of Alouatta belzebul. Seven adult specimens were dissected from which the location of the gland in relation to the surrounding brain structures was described, and its length and width were measured. Histological slides were then prepared and stained using hematoxylin-eosin and PAS techniques. It was observed that the pineal of Alouatta belzebul is located superior and cranial to the cerebellum, superior to the superior colliculi and below the splenium of the corpus callosum and was classified as sub-callosal. It had an average length of 2.6mm and an average width of 1.14mm. Histologically the gland is composed of irregular strands of pinealocytes and gliocytes. The pinealocytes showed pigments similar to melanin.

Evidence for the Benefits of Melatonin in Cardiovascular Disease.

The pineal gland is a neuroendocrine gland which produces melatonin, a neuroendocrine hormone with critical physiological roles in the circadian rhythm and sleep-wake cycle. Melatonin has been shown to possess anti-oxidant activity and neuroprotective properties. Numerous studies have shown that melatonin has significant functions in cardiovascular disease, and may have anti-aging properties. The ability of melatonin to decrease primary hypertension needs to be more extensively evaluated. Melatonin has shown significant benefits in reducing cardiac pathology, and preventing the death of cardiac muscle in response to ischemia-reperfusion in rodent species. Moreover, melatonin may also prevent the hypertrophy of the heart muscle under some circumstances, which in turn would lessen the development of heart failure. Several currently used conventional drugs show cardiotoxicity as an adverse effect. Recent rodent studies have shown that melatonin acts as an anti-oxidant and is effective in suppressing heart damage mediated by pharmacologic drugs. Therefore, melatonin has been shown to have cardioprotective activity in multiple animal and human studies. Herein, we summarize the most established benefits of melatonin in the cardiovascular system with a focus on the molecular mechanisms of action.

Von Hippel-Lindau disease: Updated guideline for diagnosis and surveillance

von Hippel Lindau disease (vHL) is caused by a hereditary predisposition to multiple neoplasms, especially hemangioblastomas in the retina and CNS, renal cell carcinomas (RCC), pheochromocytomas, neuroendocrine pancreatic tumours (PNET) and endolymphatic sac tumours. Evidence based approaches are needed to ensure an optimal clinical care, while minimizing the burden for the patients and their families.This guideline is based on evidence from the international vHL literature and extensive research of geno- and phenotypic characteristics, disease progression and surveillance effect in the national Danish vHL cohort. We included the views and preferences of the Danish vHL patients, ensured consensus among Danish experts and compared with international recommendations. RecommendationsvHL can be diagnosed on clinical criteria, only; however, in most cases the diagnosis can be supported by identification of a pathogenic or likely pathogenic variant in VHL. Surveillance should be initiated in childhood in persons with, or at risk of, vHL, and include regular examination of the retina, CNS, inner ear, kidneys, neuroendocrine glands, and pancreas. Treatment of vHL manifestations should be planned to optimize the chance of cure, without unnecessary sequelae. Most manifestations are currently treated by surgery. However, belzutifan, that targets HIF-2α was recently approved by the U.S. Food and Drug Administration (FDA) for adult patients with vHL-associated RCC, CNS hemangioblastomas, or PNETs, not requiring immediate surgery. Diagnostics, surveillance, and treatment of vHL can be undertaken successfully by experts collaborating in multidisciplinary teams. Systematic registration, collaboration with patient organisations, and research are fundamental for the continuous improvement of clinical care and optimization of outcome with minimal patient inconvenience.

Pineal gland: structural variants and their role in neurological and psychiatric disorders

The pineal gland is a small and poorly studied neuroendocrine gland located in the epithalamus. There is growing interest in the pineal gland due to its role in regulating human biological rhythms, which is associated with melatonin production, and its close neuroendocrine link between the brain's hormonal and neurally mediated activity. The paper examines the anatomical and physiological features of the pineal gland, its structural variations, and the role of the melatonin it produces in the pathogenesis of several mental and neurological disorders.

Understanding pancreatic cancer stem cells and their role in carcinogenesis: a narrative review.

The purpose of this review article is to describe the pathogenesis of pancreatic cancer and to better understand the role of abnormal stem cells in the development of pancreatic cancer. Pancreatic cancer is a highly fatal disease that is caused by the uncontrolled proliferation of pancreatic exocrine or neuroendocrine glands. It is believed that pancreatic cancers arise from a small population of abnormal cancer stem cells (CSCs) that promote tumorigenesis, tumor metastasis and therapeutic resistance. The molecular markers CD133, CXCR4, DCLK1, c-MET, ABCG2 and Lgr5 are routinely used to detected and observe the behaviours of pancreatic cancer stem cells (PCSCs). A comprehensive search was performed on PubMed, Google Scholar, Scopus, Clinicaltrials.gov and Web of Science using related keywords. Articles focusing on PCSCs and pancreatic cancer pathogenesis, biochemistry and clinical trials were selected. Although very little is known about the exact cause of pancreatic cancer, PCSCs seem to play an important role in carcinogenesis. Mutated biochemical cascades include Sonic Hedgehog, K-RAS-JNK, DLL4/Notch and Nodal/Activin. Several clinical trials are trying to determine if the transplantation of hematopoietic stem cell or peripheral stem cells could be useful for the treatment of such an aggressive tumor.

Anatomical identification of the neuroendocrine system in the Nothobranchius furzeri brain

The hypophysis functions as a central gland of the neuroendocrine system for regulating fundamental body physiology. Upon aging, several hormones produced by the endocrine system are dramatically altered. Recently, Nothobranchius furzeri (the turquoise killifish) has become a popular model for aging studies because of its short lifespan and highly conserved aging phenotypes. However, the anatomical details of the major neuroendocrine system of the killifish have not been investigated so far. In this study, we have identified the pituitary and pineal glands of the turquoise killifish, which are critical components of the brain endocrine system. These two neuroendocrine glands were weakly attached to the main body of the killifish brain. The pineal gland was located on the dorsal part of the brain, while the pituitary gland was located on the ventral part. Brain sections revealed that cells in the pituitary and pineal glands were more densely situated than in other regions of the brain. Further, three-dimensional images of the pineal and pituitary glands demonstrated their distinctive cellular arrangements. Vasopressin intestinal peptide (VIP) was strongly expressed in the neurohypophysis of the pituitary gland. Glial cells were found inside the pineal gland, while astrocytes covered the outside. These findings illustrate basic features of the neuroendocrine system of N. furzeri.

MO087PLASMALEMMAL VESICLE-ASSOCIATED PROTEIN-1 (PLVAP) INDICATES THE FORMATION OF DIAPHRAGM-BRIDGED FENESTRATIONS OF GLOMERULAR ENDOTHELIAL CELLS IN KIDNEY DISEASE

Abstract Background and Aims Plasmalemmal vesicle-associated protein-1 (PLVAP or PV-1) is a major protein of diaphragm-bridged fenestrated endothelial cells found in capillaries of neuroendocrine glands and peritubular capillaries. In contrast to peritubular capillaries, the glomerulus is known for its unique fenestrated endothelium without any diaphragm formation thereby ensuring free filtration. Here we aimed to investigate whether PLVAP is expressed in glomerular endothelial cells in various glomerular diseases and whether PLVAP expression is associated with the formation of diaphragm-bridged endothelial cells. Method A total number of 114 biopsy samples of glomerular diseases including diabetic nephropathy, FSGS, IgA-Nephritis, ANCA-GN and Lupus–Nephritis were analyzed immunohistochemistically for glomerular PLVAP expression. A fraction of PLVAP positive cases was subsequently investigated ultrastrucurally for the formation of diaphragm-bridged glomerular endothelial cells. Results One third of all cases showed at least one glomerulus with one single circumferential PLVAP staining. Interestingly, the most prominent staining, affecting the entire glomerular tuft, was observed in diabetic nephropathy and ANCA-GN. Ultrastructurally, such cases exhibited injured endothelium with focal detachment from the glomerular basement membrane, loss of pore formation and frequently diaphragm-bridged fenestrations reminiscent of peritubular capillaries. Conclusion Our data show that injured glomerular endothelium is capable of forming true diaphragm-bridged fenestrations, suggesting a possible role in preventing glomerular protein leakage and limiting its detachment from the GBM.

A sodium background conductance controls the spiking pattern of mouse adrenal chromaffin cells in situ.

Key points Mouse chromaffin cells in acute adrenal slices exhibit two distinct spiking patterns, a repetitive mode and a bursting mode.A sodium background conductance operates at rest as demonstrated by the membrane hyperpolarization evoked by a low Na+‐containing extracellular saline.This sodium background current is insensitive to TTX, is not blocked by Cs+ ions and displays a linear I‐V relationship at potentials close to chromaffin cell resting potential. Its properties are reminiscent of those of the sodium leak channel NALCN.In the adrenal gland, Nalcn mRNA is selectively expressed in chromaffin cells.The study fosters our understanding of how the spiking pattern of chromaffin cells is regulated and adds a sodium background conductance to the list of players involved in the stimulus‐secretion coupling of the adrenomedullary tissue. Chromaffin cells (CCs) are the master neuroendocrine units for the secretory function of the adrenal medulla and a finely‐tuned regulation of their electrical activity is required for appropriate catecholamine secretion in response to the organismal demand. Here, we aim at deciphering how the spiking pattern of mouse CCs is regulated by the ion conductances operating near the resting membrane potential (RMP). At RMP, mouse CCs display a composite firing pattern, alternating between active periods composed of action potentials spiking with a regular or a bursting mode, and silent periods. RMP is sensitive to changes in extracellular sodium concentration, and a low Na+‐containing saline hyperpolarizes the membrane, regardless of the discharge pattern. This RMP drive reflects the contribution of a depolarizing conductance, which is (i) not blocked by tetrodotoxin or caesium, (ii) displays a linear I‐V relationship between −110 and −40 mV, and (iii) is carried by cations with a conductance sequence g Na > g K > g Cs. These biophysical attributes, together with the expression of the sodium‐leak channel Nalcn transcript in CCs, state credible the contribution of NALCN. This inaugural report opens new research routes in the field of CC stimulus‐secretion coupling, and extends the inventory of tissues in which NALCN is expressed to neuroendocrine glands.

Developmental stage-specific A-to-I editing pattern in the postnatal pineal gland of pigs (Sus scrofa)

BackgroundRNA editing is a widespread post-transcriptional modification mechanism in mammalian genomes. Although many editing sites have been identified in domestic pigs (Sus scrofa), little is known about the characteristics and dynamic regulation of RNA editing in the pineal gland (PG), a small neuroendocrine gland that synthesizes and secretes melatonin, which is primarily responsible to modulate sleep patterns.ResultsThis study analyzed the expression of adenosine-to-inosine (A-to-I) editing regulators and profiled the first dynamic A-to-I RNA editome during postnatal PG development. The results identified ADAR1 as the most abundantly expressed ADAR enzyme, which was down-regulated during postnatal PG development. Furthermore, 47,284 high-confidence RNA editing sites were identified, the majority of which (93.6%) were of the canonical A-to-I editing type, followed by C-to-T editing. Analysis of its characteristics showed that the A-to-I editing sites mostly localized in SINE retrotransposons PRE-1/Pre0_SS. Moreover, a strong deficiency and preference for guanine nucleotides at positions of one base upstream or downstream were found, respectively. The overall editing level at the puberty stage was higher than at both infancy and adulthood stages. Additionally, genome-wide RNA editing was found to exhibit a dynamic stage-specific fashion (postnatally). Genes that underwent developmental changes in RNA editing were associated with catabolic processes as well as protein localization and transport functions, implying that RNA editing might be responsible for the molecular machineries of the postnatal developing PG. Remarkably, RNA editing in 3′-UTRs might regulate gene expression by influencing miRNA binding during PG development.ConclusionsThis study profiles the first comprehensive developmental RNA editome in the pig PG, which contributes to the understanding of the importance of post-transcriptionally mediated regulation during mammalian postnatal PG development. Moreover, this study widely extends RNA editome resources in mammals.

Pineal progenitors originate from a non-neural territory limited by FGF signalling.

ABSTRACTThe embryonic development of the pineal organ, a neuroendocrine gland on top of the diencephalon, remains enigmatic. Classic fate-mapping studies suggested that pineal progenitors originate from the lateral border of the anterior neural plate. We show here, using gene expression and fate mapping/lineage tracing in zebrafish, that pineal progenitors originate, at least in part, from the non-neural ectoderm. Gene expression in chick indicates that this non-neural origin of pineal progenitors is conserved in amniotes. Genetic repression of placodal, but not neural crest, cell fate results in pineal hypoplasia in zebrafish, while mis-expression of transcription factors known to specify placodal identity during gastrulation promotes the formation of ectopic pineal progenitors. We also demonstrate that fibroblast growth factors (FGFs) position the pineal progenitor domain within the non-neural border by repressing pineal fate and that the Otx transcription factors promote pinealogenesis by inhibiting this FGF activity. The non-neural origin of the pineal organ reveals an underlying similarity in the formation of the pineal and pituitary glands, and suggests that all CNS neuroendocrine organs may require a non-neural contribution to form neurosecretory cells.

Pineal gland calcification under hypoxic conditions

The pineal gland (glandula pinealis) is neuroendocrine gland located at the epithalamus of the brain secreting melatonin. The aim of this study was to explore effects of prenatal hypoxia in rats at the age of 33 weeks on the occurrence of pineal gland calcification. Distribution and chemical composition of calcerous material by light, scanning and transmission electron microscopy was investigated. Melatonin concentrations in blood plasma by direct radioimmunoassay were measured. Rats were exposed to prenatal hypoxia for 12 h at day 20 of development and second group to prenatal hypoxia for 2x8 h at days 19 and 20 of development. Vacuoles of intracellular edema in the pineal samples after 12 h hypoxia were found. Their size ranges up to 30 µm. Some of them were filled with the flocculent and fibrous material. Samples of pineal glands after 2 x 8 h hypoxia revealed the pericellular edema of pinealocytes. The amount of calcium rich particles in 2 x 8 h hypoxia group was lower than in 12 h hypoxia group. Plasma melatonin levels did not differ between control and both hypoxia groups. We concluded that calcification is a process induced by osteoblasts and osteocytes with melatonin as a promotor and it is favored under hypoxic conditions.

Melatonin and age-related cardiovascular diseases.

The pineal gland is a neuroendocrine gland closely related to human aging. Melatonin is a kind of indole neuroendocrine hormone secreted by the pineal gland, which is essential for maintaining physiological function. Many researches found that melatonin plays a key role in anti‐aging‐related cardiovascular diseases. In this paper, the latest advances in the study of melatonin and aging‐related cardiovascular diseases are reviewed, and their related physiological functions and mechanisms are discussed.

Changes in Pinealocytes type I and II of Adult Albino Rat Exposed to Different Wavelengths of Light or Confined to Constant Darkness: A Morphological and Electron Microscopic Study

Introduction: the pineal gland is a neuro-endocrine gland that secretes melatonin hormone whichregulates the circadian rhythm, psychiatric disorder and age changes resulting from exposure to differentlight wavelengths or darkness. Intensity, duration and wavelength of light control the activity of pinealgland.Aim of work: the purpose of this study was to monitor the morphological and electron microscopicchanges in the pinealocytes type I and II of albino rats exposed to either constant (24hrs/day) red light(long wavelength) or blue light (short wavelength) as well as confined to constant darkness as comparedto control group subjected to normal diurnal conditions.Material and methods: forty adult male albino rats were divided into four subgroups. Group I (GI):the rats were kept under normal diurnal conditions, group II (GII): the rats were confined to constantdarkness, group III (GIII): the rats were exposed to constant red light (long wavelength; 670nm) andgroup IV (GIV): the rats were subjected to constant blue light (short wavelength, 450nm); for four weekscontinuously.Results: morphological findings of pinealocytes type I (PI) were analyzed statistically and revealed anincrease in the nuclear number of PI in GII, decrease in the nuclear number of PI in GIV and nonsignificantdifference in nuclear number of PI in GIII as compared to the control group. In addition,rats of GIV reported a statistically significant increase in the amount of collagen fibers between looselypacked parenchymal cells. Electron microscopic results of the cytoplasm of PI in GII showed abundantcell organelles such as mitochondria, numerous ribosomes and multiple lipid droplets together withwell-developed Golgi bodies, scarce dense core vesicles (DCV), few cisternae of smooth endoplasmicreticulum (SER) and rough endoplasmic reticulum (RER). GIII demonstrated similar results to that ofGI. On the other hand, GIV showed scarce cytoplasmic organelles such as few mitochondria; mostlydistended with disturbed cristae, scattered lipid droplets with abundant DVC and numerous cisternaeof SER. Ultrastructurally, PI nuclei of GII exhibited infolded nuclear envelope with heterochromatickaryoplasm and prominent nucleoli while GIV revealed reduction of the nuclear chromatin with ruptureof nuclear envelope at certain sites. However, GIII nuclei demonstrated results similar to that of GI. Noobservable changes were detected by light and electron microscopy of PII in the different experimentalgroups apart from the presence of statistically significant increase in the nuclear number of PII in GII.Moreover, the PII cytoplasm showed scarce mitochondria in GI, II and RER in GIV. The glial cellsdemonstrated statistically significant increase in GIV but non-significant differences were noticed in theother groups as compared to GI.Conclusion: it could be concluded that the morphological and electron microscopic changes ofpinealocyte type I indicate decrease in the activity of pinealocytes type I on exposure to constant shortwavelength blue light and increase in the activity of PI confined to constant darkness. While the exposureto constant long wavelength red light demonstrates results similar to the control group. There were nochanges in the structure of pinealocytes type II in the different experimental groups, exposed to differentlight wavelengths or confined to darkness.

Daily variation in antioxidant enzymes lipid peroxidation in thyroid and plasma level thyroxine and triiodothyronine levels of a tropical bird Perdicula asiatica during reproductively active and inactive phases

The aim of this work was to study the variations in the interference of neuroendocrine pineal gland and metabolically active thyroid gland in a tropical bird, Perdicula asiatica. Maximum pineal gland activity (pineal weight and melatonin level), minimum thyroid gland activity (weight, T3/T4 and thymidine kinase activity) along with less oxidative load (MDA level, SOD, CAT and ABTS activity) were observed during reproductively inactive phase (RIP) was observed. Further, a robust and significant rhythmicity was noted in melatonin levels during RIP and RAP, but no significant rhythmicity was noted in T4/T3 level by cosinor analysis. Overall, melatonin and thyroid circadian profile suggested that melatonin might be acting as an antioxidant molecule with time of the day effect in rescuing thyroid gland from free radical load in birds.