Number Of Secretory Granules Research Articles

P16Ink4a-induced senescence in cultured mast cells as a model for ageing reveals significant morphological and functional changes.

Mast cells (MCs) are tissue resident cells of the immune system, mainly known for their role in allergy. However, mounting evidence indicates their involvement in the pathology of age-related diseases, such as Alzheimer's disease, Parkinson's disease, and cancer. MC numbers increase in aged tissues, but how ageing affects MCs is poorly understood. We show that MC ageing is associated with the increased expression of the cell cycle inhibitor p16 Ink4a, a marker and inducer of cellular senescence. Relying on this observation and the tight association of ageing with senescence, we developed a model of inducible senescence based on doxycycline-induced expression of p16Ink4a in cultured bone marrow derived MCs (BMMCs). Using this model, we show that senescent MCs upregulate IL-1β, TNF-α and VEGF-A. We also demonstrate that senescence causes marked morphological changes that impact MC function. Senescent MCs are larger, contain a larger number of secretory granules (SGs) and have less membrane protrusions. Particularly striking are the changes in their SGs, reflected in a significant reduction in the number of electron dense SGs with a concomitant increase in lucent SGs containing intraluminal vesicles. The changes in SG morphology are accompanied by changes in MC degranulation, including a significant increase in receptor-triggered release of CD63-positive extracellular vesicles (EVs) and the exteriorisation of proteoglycans, as opposed to a gradual inhibition of the release of β-hexosaminidase. The inducible expression of p16Ink4a imposes MC senescence, providing a model for tracking the autonomous changes that occur in MCs during ageing. These changes include both morphological and functional alterations. In particular, the increased release of small EVs by senescent MCs suggests an enhanced ability to modulate neighbouring cells.

Proteomic characterization of secretory granules in dopaminergic neurons indicates chromogranin/secretogranin-mediated protein processing impairment in Parkinson's disease.

Parkinson’s disease (PD) is an aging disorder related to vesicle transport dysfunctions and neurotransmitter secretion. Secretory granules (SGs) are large dense-core vesicles for the biosynthesis of neuropeptides and hormones. At present, the involvement of SGs impairment in PD remains unclear. In the current study, we found that the number of SGs in tyrosine hydroxylase-positive neurons and the marker proteins secretogranin III (Scg3) significantly decreased in the substantia nigra and striatum regions of 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) exposed mice. Proteomic study of SGs purified from the dopaminergic SH-sy5Y cells under 1-methyl-4-phenylpyridinium (MPP+) treatments (ProteomeXchange PXD023937) identified 536 significantly differentially expressed proteins. The result indicated that disabled lysosome and peroxisome, lipid and energy metabolism disorders are three characteristic features. Protein-protein interaction analysis of 56 secretory proteins and 140 secreted proteins suggested that the peptide processing mediated by chromogranin/secretogranin in SGs was remarkably compromised, accompanied by decreased candidate proteins and peptides neurosecretory protein (VGF), neuropeptide Y, apolipoprotein E, and an increased level of proenkephalin. The current study provided an extensive proteinogram of SGs in PD. It is helpful to understand the molecular mechanisms in the disease.

Atypical Antipsychotic Lumateperone Effects on the Adrenal Gland With Possible Beneficial Effect of Quercetin Co-administration.

Schizophrenia remains one of the most chronic and highly disabling mental disorders. Lumateperone is a recent FDA-approved atypical antipsychotic drug for the treatment of schizophrenia. However, the internal FDA pathologist raised concerns regarding pigment deposition associated with degeneration in different tissue in animal studies with lumateperone treatment. The adrenal gland may be implicated in lumateperone side effects, and quercetin may have the ability to fulfill this treatment gap. To prove this hypothesis, 40 male guinea pigs were used and divided into four groups; control, quercetin-treated, lumateperone-treated, and quercetin/lumateperone cotreated orally for 28 consecutive days. Behavioral forced swim (FST) and open field (OF) tests were done at the end of treatment. Retro-orbital blood samples were taken to assess hormones: adrenocorticotropic hormone (ACTH), cortisol, dehydroepiandrosterone acetate (DHEA), and aldosterone, along with an assessment of oxidative stress parameters: malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD). Adrenal glands were extracted for histopathological assessment with H&E, Mallory trichome staining, immunostaining, and electron microscopy studies. Lumateperone-treated group showed a significant reduction in the activity in FST and OF with histopathological deterioration in adrenal secretory function and structure and increased expression of interleukin-6 (IL-6), CASPASE-3, collagen deposition, and decreased proliferating cell nuclear antigen (PCNA). Cytoplasmic vacuolation, pyknosis of the nuclei, increase in the lysosome, lipofuscin pigment, and cellular infiltration with diminishing in the number of secretory granules could all be observed in lumateperone-treated group. Coadministration of quercetin and lumateperone showed improvement of the previously deteriorated parameters. Quercetin had a prophylactic effect against lumateperone depressive-like effect on animal behavior and its possible adrenal damage.Graphical Conceptual framework for the proposed mechanism of action of coadministration of quercetin and lumateperone.

In pancreatic β-cells myosin 1b regulates glucose-stimulated insulin secretion by modulating an early step in insulin granule trafficking from the Golgi.

Pancreatic β-cells secrete insulin, which controls blood glucose levels, and defects in insulin secretion are responsible for diabetes mellitus. The actin cytoskeleton and some myosins support insulin granule trafficking and release, although a role for the class I myosin Myo1b, an actin- and membrane-associated load-sensitive motor, in insulin biology is unknown. We found by immunohistochemistry that Myo1b is expressed in islet cells of the rat pancreas. In cultured rat insulinoma 832/13 cells, Myo1b localized near actin patches, the trans-Golgi network (TGN) marker TGN38, and insulin granules in the perinuclear region. Myo1b depletion by small interfering RNA in 832/13 cells reduced intracellular proinsulin and insulin content and glucose-stimulated insulin secretion (GSIS) and led to the accumulation of (pro)insulin secretory granules (SGs) at the TGN. Using an in situ fluorescent pulse-chase strategy to track nascent proinsulin, Myo1b depletion in insulinoma cells reduced the number of (pro)insulin-containing SGs budding from the TGN. The studies indicate for the first time that in pancreatic β-cells Myo1b controls GSIS at least in part by mediating an early stage in insulin granule trafficking from the TGN.

Ultrastructural characteristics of the anterior pituitary gland of cattle in the definitive period of postnatal ontogenesis

Today much attention is paid to the study of the pituitary ultrastructure of laboratory animals and humans. But there is not enough available literature to study the most important organ of internal secretion of productive animal. The aim of our work is to study the structure of the ultrastructure of cells of the anterior pituitary gland of cattle in the definitive period of postnatal ontogenesis. Histological, morphometric, and electron microscopic techniques were used to study the cellular composition of the anterior pituitary gland of cattle. It was revealed that the anterior lobe of the pituitary gland occupies 64 % of the entire pituitary parenchyma, while the posterior and middle lobes occupy 27% and 9%, respectively. After using general histological methods there are detected the functionally inactive chromophobes (41%) and chromophilic cells, which include acidophils (38%) and basophils (21%) in the anterior lobe of the pituitary gland. The electron microscopic studies in the parenchyma of the anterior pituitary gland let find Somatotropes that differ in the presence of a large number of secretory granules in the cytoplasm. Lactotropes are less common than somatotropes and differ from them in larger secretory granules. Corticotropes, gonadotropes and thyrotropes with a minimum content of secretory granules are the least detected. All identified endocrine cells are at different stages of functional activity.

Pancreatic β-Cell-Specific Deletion of VPS41 Causes Diabetes Due to Defects in Insulin Secretion.

Insulin secretory granules (SGs) mediate the regulated secretion of insulin, which is essential for glucose homeostasis. The basic machinery responsible for this regulated exocytosis consists of specific proteins present both at the plasma membrane and on insulin SGs. The protein composition of insulin SGs thus dictates their release properties, yet the mechanisms controlling insulin SG formation, which determine this molecular composition, remain poorly understood. VPS41, a component of the endolysosomal tethering homotypic fusion and vacuole protein sorting (HOPS) complex, was recently identified as a cytosolic factor involved in the formation of neuroendocrine and neuronal granules. We now find that VPS41 is required for insulin SG biogenesis and regulated insulin secretion. Loss of VPS41 in pancreatic β-cells leads to a reduction in insulin SG number, changes in their transmembrane protein composition, and defects in granule-regulated exocytosis. Exploring a human point mutation, identified in patients with neurological but no endocrine defects, we show that the effect on SG formation is independent of HOPS complex formation. Finally, we report that mice with a deletion of VPS41 specifically in β-cells develop diabetes due to severe depletion of insulin SG content and a defect in insulin secretion. In sum, our data demonstrate that VPS41 contributes to glucose homeostasis and metabolism.

The health status of children born to mothers with persistent galactorrhea syndrome - amenorrhea treated with parlodel

A dopamine agonist - bromo-a-ergocriptine (parlodel) is traditionally used in the treatment of persistent galactorrhea-amenorrhea syndrome (SGA) [11, 13, 19]. Parlodel reduces the frequency of mitoses and the number of secretory granules in the lactotrophs of the adenohypophysis [50], and is capable of slowing the growth of prolactin-secreting pituitary adenomas [1, 40].
 According to a number of authors [5, 11, 13, 56], the dosage and timing of the use of the drug depend on the form of LNG. According to most researchers [6, 17, 19, 24, 29], the effectiveness of its use correlates with the form of the disease. However, the effectiveness of parlodel therapy is apparently also influenced by the functioning of the dopaminergic system (DAS) of a particular patient [15].

Morphological changes of parathyroid glands and thymus of rats after correction of induced immunosupression

The aim of the research was to investigate the features of the electron microscopic structure of rats' parathyroid glands and thymus after correction of cyclophosphamide-induced immunosuppression with imunofan.Material and methods. The study was performed on 24 male rats weighing 180±10 g. The animals of the experimental series were injected cyclophosphamide once intramuscularly at a dosage of 200 mg/kg. Immunocorrection was achieved by administering imunofan once a day at 50 mcg/kg for 1, 3, 5, 7, 9 days. The second group consisted of intact rats. The animals were withdrawn from the experiment on 3rd and 30th day after the drugs administration. We studied the ultrastructure of organs in the rats of the control group and after immunostimulation.Results. It was established that on the 3rd day after correction of induced immunosuppression imunofan parathyroid nuclei characterized by uneven surface due to numerous invaginations of nuclear membranes. In separate cells sporadic pyknosis of nuclei is determined. The number of secretory granules decreases, the amount of glycogen and lipid droplets increases. In the thymus characteristic signs of an accidental involution occur. After 30 days after the administration of immunotropic drugs, the number of active dark parathyrocytes increased. In the nucleoli, the predominance of the granular component over the fibrillar component is revealed. Well-developed organelles of protein synthesis were found in the cytoplasm of cells. In the cortex of the thymus, an increased number of plasma cells is observed, a recovery of the population of both lymphoid cells and microenvironment cells, in particular macrophages, is noted. Conclusions. On the 3rd day after the administration of immunotropic drugs, a decrease in the number of secretory granules, pyknosis of nuclei and multiple invaginations of nuclear membranes are revealed in segregated cells. The use of an immunocorrector leads to the development of organelles of protein synthesis and an increase in the number of secretory granules in the cytoplasm of cells on the 30th day after administration of the drugs. In the cortical zone of the thymus there is an active cells proliferation. The dynamics of changes in the electron microscopic structure of rats' parathyroid glands and thymus indicates a high degree of reactivity of the organs in response to the administration of immunotropic drugs.

Ultramicroscopic changes of rat parathyroid glands after immunosuppression

Background . Parathyroid glands actively respond to exogenous and endogenous factors that confirmed by a number of fundamental researches. Currently there are no comprehensive morphological works devoted to the study of ultramicroscopic features of parathyroid glands during immune status changing. Cyclophosphamide is widely used in the clinical practice. It’s belongs to a class of drugs known as alkylating agents, which have been used to treat some types of cancer. Objective. The objective of the work was to study features of electron-microscopic structure of the rat parathyroid glands under immunosuppression caused by the administration of cyclophosphamide. Methods . The study was conducted on 24 outbred male mature rats with the weight 180±10g. Maintenance and care of animals were conducted in according to the norms of bioethics. The animals received an intramuscular injection of cyclophosphamide in a dose of 200 mg/kg body weight. The animals were withdrawn from the experiment on the 7 th and 30 th day after the injection. The ultrastructure of rat parathyroid glands in normal condition as well as after immunosuppression was studied. Results. The parenchyma of the parathyroid glands of intact animals is composed of two cell types: chief cells and oxyphil cells. Principal (chief) cells are the most numerous type of the gland’s parenchyma. They are small, polygonal cells, with a centrally located nucleus. The cytoplasm of the chief cells contains well-developed rough endoplasmic reticulum and Golgi apparatus. There are numerous dense secretory vesicles, large accumulations of glycogen, and lipid droplets in the cytoplasm. Oxyphil cells constitute a minor portion of the parenchymal cells. The cells are more rounded, considerably larger than the principal cells. Mitochondria, often with bizarre shapes and sizes, almost fill the cytoplasm and are responsible for the strong acidophilia of these cells. No secretory vesicles and little if any rough endoplasmic reticulum are present. Cytoplasmic inclusion bodies consist of occasional lysosomes, lipid droplets, and glycogen distributed among the mitochondria. Conclusion. The introduction of cyclophosphamide to rats in high doses caused marked changes in the ultrastructure of the organ. Polymorphism of cell nuclei, reducing the amount of the organelles that are participate in the protein synthesis, reducing the number of secretory granules, increasing the number of lipid and colloid droplets in the cell cytoplasm were observed in the early period of observation (7th day). On the 30th day after the administration of cyclophosphamide tendency to normalization of morphological structure of the organ revealed.

ОСОБЛИВОСТІ СЕКРЕТОРНОЇ АКТИВНОСТІ МІОЕНДОКРИННИХ КЛІТИН ПЕРЕДСЕРДЬ ЛЕГЕНЕВОГО СЕРЦЯ ПРИ РІЗНИХ ТИПАХ КРОВОПОСТАЧАННЯ

В останні роки дослідники все частіше звертають увагу на міоендокринні клітини передсердь, що продукують натрійуретичний гормон, який бере активну участь у водно-сольовому гомеостазі організму. Крім діуретичної та натрійуретичної функцій даний гормон є антагоністом системи ренін-ангіотензин-альдостерон і, ремоделюючи стінку артерій, регулює судинний опір. Варто зазначити, що при гіпертензіях у великому та малому колах кровообігу і легеневому серці структуру й функцію міоендокринних клітин передсердь досліджено недостатньо.Мета дослідження – вивчення особливостей секреторної активності міоендокринних клітин передсердь легеневого серця при різних типах кровопостачання.Матеріали і методи. Досліджено міоендокринні клітини передсердь 22 статевозрілих свиней-самців в’єтнамської породи, яких поділили на 6 груп. Перша група нараховувала 4 неушкоджених серця (18,2 %) з правовінцевим типом кровопостачання, друга – 3 аналогічних органи (13,6 %) із лівовінцевим типом кровопостачання, третя – 3 неушкоджених серця (13,6 %) з рівномірним розподілом вінцевих артерій, четверта – 5 легеневих сердець (22,8 %) із правовінцевим типом кровопостачання, п’ята – 4 легеневих серця (18,2 %) з лівовінцевим типом кровопостачання, шоста – 3 легеневих серця (13,6 %) із рівномірним розподілом вінцевих артерій. Артеріальну гіпертензію у малому колі кровообігу та легеневе серце моделювали шляхом виконання у тварин правосторонньої пульмонектомії. Через місяць від початку досліду здійснювали евтаназію тварин кровопусканням в умовах тіопентал-натрієвого наркозу. Виймали серця з грудної клітки, розрізали за Г. Г. Автанділовим і проводили окреме зважування камер серця і планіметрію їх ендокардіальних поверхонь. З лівого та правого передсердь після відповідної фіксації та проведення виготовляли ультратонкі зрізи, які досліджували на електронному мікроскопі ПЕМ-125К. Стереометричними методами в міоендокринних клітинах лівого та правого передсердь визначали відносні об’єми секреторних гранул, а також відсотки молодих, зрілих та дифундуючих секреторних гранул. Отримані кількісні показники обробляли статистично.Результати досліджень та їх обговорення. Окремим зважуванням та планіметрією камер серця встановлено, що через місяць після правосторонньої пульмонектомії зростала маса частин серця та їхні просторові характеристики з домінуванням гіпертрофії та дилатації правого шлуночка. Отримані результати свідчили про розвиток легеневого серця. Всестороннім аналізом отриманих даних виявлено, що у змодельованих експериментальних умовах кількісні морфологічні характеристики секреторних гранул міоендокринних клітин передсердь істотно змінювалися. Встановлено, що при пострезекційній артеріальній легеневій гіпертензії та легеневому серці суттєво змінюється секреторна активність міоендокринних клітин передсердь. При цьому в міоендокриноцитах передсердь виражено зменшувалася кількість секреторних гранул, спостерігалося зниження серед них молодих і зрілих структур та збільшення дифундуючих, що свідчило про посилене виділення натрійуретичного гормону для підтримки порушеного гомеостазу. Найвираженішими кількісні зміни секреторних гранул були у правому передсерді легеневого серця та при право- і лівовінцевому типах кровопостачання.Висновки. Результати проведених досліджень свідчать, що в умовах тривалої пострезекційної артеріальної гіпертензії у малому колі кровообігу та легеневому серці суттєво погіршується секреторна активність міоендокринних клітин передсердь, порушується співвідношення між типами секреторних гранул. Найбільш виражене зниження секреторної активності вказаних структур у досліджуваних експериментальних умовах виявлено у правому передсерді та при домінуванні правовінцевого і лівовінцевого типів кровопостачання серця.

New Roles of Syntaxin-1A in Insulin Granule Exocytosis and Replenishment

In type-2 diabetes (T2D), severely reduced islet syntaxin-1A (Syn-1A) levels contribute to insulin secretory deficiency. We generated β-cell-specific Syn-1A-KO (Syn-1A-βKO) mice to mimic β-cell Syn-1A deficiency in T2D. Glucose tolerance tests showed that Syn-1A-βKO mice exhibited blood glucose elevation corresponding to reduced blood insulin levels. Perifusion of Syn-1A-βKO islets showed impaired first- and second-phase glucose-stimulated insulin secretion (GSIS) resulting from reduction in readily releasable pool and granule pool refilling. To unequivocally determine the β-cell exocytotic defects caused by Syn-1A deletion, EM and total internal reflection fluorescence microscopy showed that Syn-1A-KO β-cells had a severe reduction in the number of secretory granules (SGs) docked onto the plasma membrane (PM) at rest and reduced SG recruitment to the PM after glucose stimulation, the latter indicating defects in replenishment of releasable pools required to sustain second-phase GSIS. Whereas reduced predocked SG fusion accounted for reduced first-phase GSIS, selective reduction of exocytosis of short-dock (but not no-dock) newcomer SGs accounted for the reduced second-phase GSIS. These Syn-1A actions on newcomer SGs were partly mediated by Syn-1A interactions with newcomer SG VAMP8.

Apoptosis Might Contribute to the Thrombocytopenia in Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a prothrombotic autoimmune complication of heparin therapy. Thrombocytopenia and thrombosis in HIT patients are caused by immune complexes containing pathogenic antibodies against platelet factor 4 (PF4)/glycosaminoglycan complexes. Mechanisms of platelet activation and/or destruction in HIT are not fully understood. Phosphatidylserine expression is a marker of platelet activation that contributes to the procoagulant function. On the other hand, phosphatidylserine expression is generally an early marker of cell apoptosis, which, similarly to other cells, controls platelet life span. The aim of this study was to investigate if apoptosis might play a role in HIT.Gel-filtered normal platelets were incubated for 15 or 60 min with recombinant PF4 (10 µg/ml) and KKO antibodies (50 µg/ml) and studied by electron microscopy and flow cytometry using fluorescently labeled markers of cell activation and apoptosis, such as annexin V, antibodies to CD62P (P-selectin) and MitoTracker DeepRed FM. Platelets and platelet-derived microparticles were identified by flow cytometry using labeled antibodies to CD41 and electron microscopy. Calcium ionophore A23187 (10 µM) was used as a positive control.Incubation of platelets with PF4+KKO caused fast expression of P-selectin on platelets comparable with calcium ionophore A23187 stimulation, suggesting that platelets were fully activated by PF4+KKO within 15 min, when they also started to produce CD41 and annexin-positive microparticles. Activation of platelets with PF4+KKO for 60 minutes led to a further increase in phosphatidylserine expression on their surface, with a time-dependent reduction of mitochondrial membrane potential, which reflects a disturbance of energy metabolism and is characteristic of cell apoptosis. Scanning electron microscopy showed that platelets treated with PF4+KKO or A23187, unlike untreated cells, displayed dramatic morphological changes with a loss of discoid shape, formation of filopodia, and microvesiculation. By transmission electron microscopy, the PF4+KKO-treated platelets had an irregular shape due to formation of plasma membrane invaginations and pseudopodia. Formation of an increasing number of intracellular vacuoles and enlargement of the lumen of the open canalicular system were observed. Some vacuoles contained various inclusions, such as secretory granules, membrane components, and grainy particles. The number of secretory granules in the PF4+KKO-treated cells was dramatically reduced. In all cases, formation of microparticles of various shapes and sizes was observed.These results indicate that the PF4-containing pathogenic immune complexes induce strong and time-dependent platelet activation leading to procoagulant microparticle formation that may contribute to thrombosis. At the same time, the results strongly suggest that the HIT-like immune complexes likely induce platelet apoptosis that can be an important mechanism of thrombocytopenia. DisclosuresNo relevant conflicts of interest to declare.

Ultrastructure of the oviductal mucosa of Leptodactylus chaquensis. Analysis of the preovulatory and postovulatory periods.

In the present study we analysed the ultrastructural characteristics of the oviductal mucosa of Leptodactylus chaquensis during the preovulatory period and immediately after ovulation. Epithelial secretory cells, ciliated cells, basal cells and glandular secretory cells are described. During the preovulatory period, the oviduct exhibits its maximum degree of development at both the epithelial and the glandular levels, with numerous secretory cells that contain a large number of secretory granules whose contents are released into the oviductal lumen by apocrine and exocytotic secretory processes. The secretory cells present throughout the oviduct display considerable variability in the characteristics of their secretory granules, which show different shapes, sizes, organization of the material contained and electron density. The different cell types are distributed following a characteristic pattern for each oviductal zone, thus creating an ultrastructural mosaic along the oviduct. During the postovulatory period, the number of secretory cells decreases and the remaining ones exhibit a marked reduction in secretory granules. Ciliated cells show a typical ultrastructural organization that is not modified throughout the reproductive cycle. Basal cells, located at the basal region of the epithelium, are characterized by their heterochromatic nuclei and electron-lucent cytoplasm, while glandular secretory cells exhibit oval, round or polyhedric granules, most of them with a prominent core. Our results, which indicate a high heterogeneity of secretory cell contents, allow us to suggest differential synthesis and secretion of specific products in each oviductal zone.

THE PROTECTIVE EFFECT OF CAMEL’S MILK, IN COMPARISON TO THYMOQUINONE, ON STREPTOZOTOCIN-INDUCED DAMAGE IN THE PANCREAS OF ALBINO RATS

Streptozotocin has been used extensively to produce an experimental animal model for diabetes mellitus. The present study was undertaken to investigate the protective effect of camel milk, in comparison to thymoquinone, against streptozotocin-induced damage in the pancreas. The rats were divided into four groups as follows. (1) Control group, (2) Diabetic group with a single intraperitoneal injection of streptozotocin (50 mg/kg body weight), (3) Diabetic group treated with camel’s milk (CM) orally and daily at a dose of 2 ml/rat, (4) Diabetic group treated with thymoquinone (TQ) orally and daily at a dose of 50 mg/kg body weight. After 2 months, the animals were sacrificed and blood samples were collected for the detection of serum glucose levels. The pancreas was prepared for histopathological, immunohistochemical and ultrastructural studies. The histological examination of diabetic pancreas showed vacuolation and shrinkage of the islets of Langerhans. The exocrine part of the gland showed vacuolization and flattening of the lining epithelium of the acini. Dense collagen fibres around the acini, blood vessels and pancreatic ducts were also detected. The immunoreactivity or anti-insulin antibodies was markedly decreased. Electron microscopic examination of the diabetic group showed marked changes in pancreatic acini represented by dilatation of the rough endoplasmic reticulum, decrease of secretory granules, vacuolization of the cytoplasm, damage of the mitochondria, and dilatation of the perinuclear space. The β-cells of the diabetic rats showed decrease in the number of secretory granules, heterochromatic nuclei and cytoplasmic vacuolation. CM and TQ improved the histological and ultrastructural changes of the β-cells and exocrine acini epithelium, which almost reverted to their normal structure. These factors increased insulin immunoreactivity and decreased the elevated glucose concentrations. However, insulin immunoreactivity was found in the majority of the pancreatic islets in diabetic rats treated with CM or TQ.

Secretagogue Stimulation of Neurosecretory Cells Elicits Filopodial Extensions Uncovering New Functional Release Sites

Regulated exocytosis in neurosecretory cells relies on the timely fusion of secretory granules (SGs) with the plasma membrane. Secretagogue stimulation leads to an enlargement of the cell footprint (surface area in contact with the coverslip), an effect previously attributed to exocytic fusion of SGs with the plasma membrane. Using total internal reflection fluorescence microscopy, we reveal the formation of filopodia-like structures in bovine chromaffin and PC12 cells driving the footprint expansion, suggesting the involvement of cortical actin network remodeling in this process. Using exocytosis-incompetent PC12 cells, we demonstrate that footprint enlargement is largely independent of SG fusion, suggesting that vesicular exocytic fusion plays a relatively minor role in filopodial expansion. The footprint periphery, including filopodia, undergoes extensive F-actin remodeling, an effect abolished by the actomyosin inhibitors cytochalasin D and blebbistatin. Imaging of both Lifeact-GFP and the SG marker protein neuropeptide Y-mCherry reveals that SGs actively translocate along newly forming actin tracks before undergoing fusion. Together, these data demonstrate that neurosecretory cells regulate the number of SGs undergoing exocytosis during sustained stimulation by controlling vesicular mobilization and translocation to the plasma membrane through actin remodeling. Such remodeling facilitates the de novo formation of fusion sites.

Morphogenesis and reaction to hypoxia of atrial myoendocrine cells in chick embryos (Gallus gallus)

The ultrastructural and stereomorphometrical study of the right atrium of chick embryos at the 14th day of incubation has shown the cardiomyocytes to divide by mitosis and to be at different stages of differentiation. In the cytoplasm of some muscle cells we detected secretory granules that by their sizes and morphology can be classified into the forming, mature, and dissolved forms. By the 18th day of incubation most cardiomyocytes are already differentiated, and the number of secretory granules in them rises. Under conditions of hypoxia, after 3 days, in myoendocrine cells there are noted signs of accelerated release of the peptides synthesized earlier and accumulated in granules, while after one week - of enhancement of their synthesis. It can be concluded that in chick embryos, beginning from at least the 14th incubation day, the system of natriuretic heart peptides takes part in regulation of hemodynamics and of water-salt balance and responds to hypoxia.

The Absence of Somatotroph Proliferation During Continuous Stress is a Result of the Lack of Extracellular Signal‐Regulated Kinase 1/2 Activation

The integrity of homeostasis can be affected by chronic stress, and hyposomatotropism is evident in chronic stress-associated illnesses. In the present study, we demonstrated that a continuous stress (CS) severely affected somatotrophs among hormone-secreting cells in the anterior lobe (AL) of the pituitary by using a rat CS model. Among AL cells, the proliferation of somatotrophs was almost entirely suppressed in rats that had 3-5 days of CS (5dCS), although other hormone-secreting cells continued to proliferate. The cell size of somatotrophs was reduced at 5dCS (P<0.01), the number of secretory granules was increased at 3dCS (P<0.01) and serum growth hormone (GH) was on declining trend during 1 to 5dCS, suggesting that GH release was inhibited. GH-releasing hormone (GHRH) mRNA level in the arcuate nucleus was transiently decreased, whereas its receptor expression in the AL was significantly increased in CS rats. When 5dCS rats were injected with GHRH, transient GH secretion was observed, whereas proliferation of somatotrophs did not occur. The GHRH administration failed to stimulate extracellular signal-regulated kinase (ERK) 1/2 phosphorylation and the nuclear translocation of ERK in somatotrophs. These results suggest that somatotrophs of 5dCS rats expressed sufficient GHRH receptor, which could transfer a signal for GH release. However, the GHRH-induced proliferation signal was blocked somewhere between the receptor and ERK1/2. Because significant increase of corticosterone in the initial stage (the 1-3dCS) was observed in this model, the corticosterone may affect the signalling. Although the mechanism underlying the blockage of the proliferation signal in somatotrophs under CS remains unclear, these somatotrophic disorder, suggesting that the present animal model may be useful for understanding the molecular mechanisms of chronic stress-associated illnesses.

Mo1779 Interleukin-33 Induces Distinct Gastric Epithelial Alterations and Plays an Important Role in the Pathogenesis of Murine Gastritis

active in CD Paneth cells. TEM high magnification observation revealed that autophagy activation was associated with a significant decrease in the number of secretory granules in CD patients. The granules appeared to be wrapped around autophagolysosomal vacuoles and abnormally degraded. Conclusion: This work describes of a novel selective autophagy pathway, called crinophagy that targets specifically secretory granules of CD Paneth cells. This process consists of the self-digestion of secretory granules by the autophago-lysosomal pathway. Crinophagy may explain the decrease of CD secretory granule observed in our study as well as the disorganization of the secretory granules and the exocytosis defect previously reported in CD.

Abnormal Activation of Autophagy-Induced Crinophagy in Paneth Cells From Patients With Crohn's Disease

Autophagy-related 16 like-1 (ATG16L-1), immunity-related GTPase-M (IRGM), and nucleotide-binding oligomerization domain-containing 2 (NOD2) regulate autophagy, and variants in these genes have been associated with predisposition to Crohn's disease (CD). However, little is known about the role of autophagy in CD. Intestinal biopsies from untreated pediatric patients with CD, celiac disease, or ulcerative colitis were analyzed by immunohistochemistry and electron microscopy. We observed that autophagy was specifically activated in Paneth cells from patients with CD, independently of mucosal inflammation or disease-associated variants of ATG16L1 or IRGM. In these cells, activation of autophagy was associated with a significant decrease in number of secretory granules and features of crinophagy. These observations might account for the disorganization of secretory granules previously reported in Paneth cells from patients with CD.

Progesterone Is a Sperm-Releasing Factor from the Sperm-Storage Tubules in Birds

Because of the presence of sperm-storage tubules (SST) in the utero-vaginal junction (UVJ) in the oviduct, once ejaculated sperm have entered the female reproductive tract, they can survive for a prolonged time in domestic birds, although the specific mechanisms involved in the sperm uptake into, maintenance within, and controlled release from the SST remain to be elucidated. In this report, we provide evidence that progesterone triggers the release of the resident sperm from the SST in the UVJ. The ultrastructural observation of the SST indicated that the resident sperm are released from the SST around 20 h after oviposition. When laying birds were injected with progesterone, most of the sperm were released from the SST within 1 h of injection. In situ hybridization analyses demonstrated the presence of the transcripts of membrane progestin receptor α in the UVJ, and the translated proteins were detected in the UVJ extracts by Western blotting. Moreover, the number of secretory granules in the SST epithelial cells fluctuates during the ovulatory cycle, and the progesterone administration mimics this phenomena. A binding assay using [(3)H]-progesterone indicated the presence of a high affinity, limited capacity, saturable and single binding site for [(3)H]-progesterone in the membrane fraction of the UVJ, and this receptor did not interact with the synthetic antiprogestin RU486. These results demonstrated for the first time that the progesterone stimulates the release of the resident sperm from the SST and that the release of the sperm might occur via membrane progestin receptor α-mediating signal transduction.