The low doses effect of experimental zearalenone (ZEN) intoxication on the presence of Ca2+ in selected ovarian cells from pre-pubertal bitches

The objective of this study was to determine the effect of 42-day ZEN intoxication on the presence of Ca2+ in selected ovarian cells from beagle bitches, using the potassium pyroantimonate (PPA) method. Samples were collected from 30 clinically healthy, pre-pubertal, genetically homogeneous animals. The bitches were divided into three groups of 10 animals each: experimental group I - 50 μg ZEN/kg BW (100% NOAEL) administered once daily per os; experimental group II - 75 μg ZEN/kg BW (150% NOAEL) administered once daily per os; control group - placebo containing no ZEN administered per os. An electron microscopic analysis revealed that cells died due to apoptosis, depending on the ZEN dose and the type of cells exposed to intoxication. Lower ZEN doses led to apoptosis-like changes in the cells. Cell death was a consequence of excess Ca2+ accumulation in the mitochondria, followed by cell dysfunction and a decrease in or the absence of mitochondrial metabolic activity in oocytes, follicle cells and interstitial cells in experimental bitches

Neuropeptide Y as a presynaptic modulator of norepinephrine release from the sympathetic nerve fibers in the pig pineal gland

Norepinephrine (NE) released from the sympathetic nerve endings is the main neurotransmitter controlling melatonin synthesis in the mammalian pineal gland. Although neuropeptide Y (NPY) co-exists with NE in the pineal sympathetic nerve fibers it also occurs in a population of non-adrenergic nerve fibers located in this gland. The role of NPY in pineal physiology is still enigmatic. The present study characterizes the effect of NPY on the depolarization-evoked 3H-NE release from the pig pineal explants. The explants of the pig pineal gland were loaded with 3H-NE in the presence of pargyline and superfused with Tyrode medium. They were exposed twice to the modified Tyrode medium containing 60 mM of K+ to evoke the 3H-NE release via depolarization. NPY, specific agonists of Y1- and Y2-receptors and pharmacologically active ligands of a2-adrenoceptors were added to the medium before and during the second depolarization. The radioactivity was measured in medium fractions collected every 2 minutes during the superfusion. NPY (0.1 - 10 μM) significantly decreased the depolarization-induced 3H-NE release. Similar effect was observed after the treatment with Y2-agonist: NPY13-36, but not with Y1-agonist: [Leu31,Pro34]-NPY. The tritium overflow was lower in the explants exposed to the 5 μM NPY and 1 μM rauwolscine than to rauwolscine only. The effects of 5 μM NPY and 0.05 μM UK 14,304 on the depolarization-evoked 3H-NE release were additive. The results show that NPY is involved in the regulation of NE release from the sympathetic terminals in the pig pineal gland, inhibiting this process via Y2-receptors

Ultracytochemiczna lokalizacja jonów wapniowych w szyszynce indyka

Calcium ions are involved in several processes occurring in the avian pineal, including the regulation of melatonin secretion. The aim of study was to investigate distribution of calcium ions in the pineal organ of domestic turkey at the level of electron microscopy. The study was performed on 12 female turkeys housed in a cycle of 12L : 12 D (light intensity 300 lux; 07:00 – 19:00), starting from the third week of life. At the age of 12 weeks, the birds were anesthetized with halothane and sacrificed by decapitation at 14:00 and at 02:00 (in darkness). The pineals were fixed using the potassium pyroantimonate method, which enables visualization of calcium ions in the form of electron dense precipitates. Extremely numerous, large precipitates of calcium pyroantimonate were observed between collagen fibres of the connective tissue surrounding the pineal follicles. The number of precipitates in the follicles was much lower than in the neighbouring stroma. Precipitates were numerous in intercellular spaces between cells forming the follicular wall. In contrast, they were infrequently observed in the follicular lumen. In pinealocytes, large amounts of precipitates were present in the nucleus, mitochondria and short, wide cisterns of the smooth endoplasmic reticulum. Precipitates were sparse in the apical prolongations of rudimentary-receptor pinealocytes. The content of precipitates did not differ prominently between individual pinealocytes. Precipitates in the cytosol of both rudimentary-receptor pinealocytes and secretory pinealocytes were much more numerous in the organs taken ex vivo during nighttime than during daytime. Supporting cells contained much fewer precipitates than pinealocytes

Jony wapniowe w szyszynce swini - badania ultracytochemiczne

The aim of the study was to analyze the distribution of calcium ions in the pig pineal gland at the level of electron microscopy. The investigations were performed on the pineals obtained immediately after slaughter (performed between 11:30 and 12:00 a.m.) from 4-month-old gilts. The fixation procedures were conducted with the use of pyroantimonate, which reacted with calcium ions and formed electron dense precipitates. The precipitates were found both in the intercellular spaces and in cells - pinealocytes, gial cells, endothelial cells and fibroblasts. The precipitates were much more numerous in the intercellular spaces than in the cells. Amount and distribution of precipitates differed significantly between pinealocytes, therefore two types of cells were distinguished. The first type of pinealocytes included cells containing a small or moderate amount of precipitates. They were usually characterized by light or dark cytoplasm and large variability in number and structure of dense bodies. Pinealocytes classified to the second type possessed large or very large content of precipitates. These cells were characterized by electron dense cytoplasm and showed the presence of numerous dense bodies. In both types of pinealocytes, precipitates were present in the nucleus and in the cytoplasm. In nuclei, precipitates were numerous in nucleoplasma and rather infrequently noted between membranes of the nuclear envelope. In the cytoplasm deposits were found in mitochondria, vesicles and cisterns of smooth endoplasmic reticulum, in the Golgi apparatus and in cytosol. The amount of precipitates in glial cells, endothelial cells and fibrocytes was lower than in pinealocytes.Celem pracy była analiza ultracytochemiczna rozmieszczenia jonów wapniowych w szyszynce świni domowej. Badano szyszynki pobrane bezpośrednio po uboju (wykonanym między godz. 11:30 a 12:00) od loszek w wieku ok. 4 miesięcy. Do utrwalania gruczołów zastosowano pyroantymonian potasu, co umożliwiło związanie jonów wapniowych w postaci elektronowo gęstych precypitatów, których rozmieszczenie określono za pomocą mikroskopu elektronowego. Precypitaty występowały w przestrzeni międzykomórkowej oraz w komórkach: pinealocytach, komórkach glejowych, komórkach śródbłonka naczyń włosowatych i fibrocytach. Zawartość złogów pyroantymonianu wapnia była znacznie większa w przestrzeni zewnątrzkomórkowej niż wewnątrz komórek. Ze względu na ilość i lokalizację precypitatów możliwe było wyróżnienie dwóch typów pinealocytów. Pierwszy z nich stanowiły komórki zawierające małą lub średnią ilość precypitatów. Komórki te charakteryzowały się elektronowo jasną lub elektronowo gęstą cytoplazmą, a skład ciałek gęstych był zróżnicowany pod względem ilościowym i jakościowym. Drugi typ pinealocytów stanowiły komórki z dużą lub bardzo dużą zawartością precypitatów. Najczęściej charakteryzowały się one elektronowo gęstą cytoplazmą oraz obecnością bardzo licznych ciałek gęstych. W obu typach pinealocytów precypitaty występowały zarówno w jądrze komórkowym, jak i w cytoplazmie. W jądrze stosunkowo liczne precypitaty o zróżnicowanych wymiarach stwierdzono w obrębie chromatyny, natomiast jedynie sporadycznie obserwowano je w przestrzeni między błonami otoczki jądrowej. W cytoplazmie precypitaty występowały w mitochondriach, pęcherzykach i cysternach siateczki śródplazmatycznej gładkiej, strukturach aparatu Golgiego oraz w cytoplazmie podstawowej. Zawartość precypitatów w komórkach glejowych, komórkach środbłonka oraz fibrocytach była znacznie mniejsza niż w pinealocytach

Regulation of melatonin secretion in the pineal organ of the domestic duck - an in vitro study

The aim of study was to determine the mechanisms regulating melatonin secretion in the pineal organs of 1-day-old and 9-month-old domestic ducks. The pineals were cultured in a superfusion system under different light conditions. Additionally, some explants were treated with norepinephrine. The pineal glands of 1-day-old ducks released melatonin in a well-entrained, regular rhythm during incubation under a 12 hrs light : 12 hrs dark cycle and adjusted their secretory activity to a reversed 12 hrs dark : 12 hrs light cycle within 2 days. In contrast, the diurnal changes in melatonin secretion from the pineals of 9-month-old ducks were largely irregular and the adaptation to a reversed cycle lasted 3 days. The pineal organs of nestling and adult ducks incubated in a continuous light or darkness secreted melatonin in a circadian rhythm. The treatment with norepinephrine during photophases of a light-dark cycle resulted in: 1) a precise adjustment of melatonin secretion rhythm to the presence of this catecholamine in the culture medium, 2) a very high amplitude of the rhythm, 3) a rapid adaptation of the pineal secretory activity to a reversed light-dark cycle. The effects of norepinephrine were similar in the pineal organs of nestlings and adults. In conclusion, melatonin secretion in the duck pineal organ is controlled by three main mechanisms: the direct photoreception, the endogenous generator and the noradrenergic transmission. The efficiency of intra-pineal, photosensitivity-based regulatory mechanism is markedly lower in adult than in nestling individuals

Histology and ultrastructure of the pineal organ in the domestic goose

The pineal organs of 14-week-old domestic geese were investigated with light and electron microscopy. The pineals consisted of a wide distal part and a narrow middle-proximal one. The glands were attached to the intercommissural region via the choroid plexus. The pineal parenchyma was formed by round or elongated follicles. The follicular wall was composed predominantly by cells immunoreactive with antibodies against hydroxyindolo-O-methyltransferase (HIOMT) or glial fibrillary acid protein (GFAP). They formed two or more layers. HIOMT-positive elements were represented by elongated cells bordering the follicular lumen and oval cells located in the external layer of the follicular wall. These cells were identified in ultrastructural studies as rudimentary-receptor pinealocytes and secretory pinealocytes, respectively. Among rudimentary-receptor pinealocytes two types of cells, designed as A and B, were distinguished due to structural differences. Type A cells extended through the whole follicular wall and showed regular stratified distribution of organelles in well-recognizable zones with rough endoplasmic reticulum, the Golgi apparatus and mitochondria. Type B cells, like type A pinealocytes, contacted the pineal lumen and showed polarity of their internal structure. However, they were markedly shorter than the cells of type A and lacked stratified distribution of organelles. Secretory pinealocytes contained irregularly dispersed organelles. A prominent feature of all types of goose pinealocytes was the presence of numerous dense core vesicles. The population of GFAP-positive cells consisted of ependymal-like supporting cells and astrocyte-like cells

Pineal concretions in turkey (Meleagris gallopavo) as a result of collagen-mediated calcification

The intra-pineal calcification is a well-known phenomenon in mammals, however it is almost completely unknown in birds. The aim of the present work was to analyze morphology and genesis of the pineal concretions in the turkey. The studies were performed on the pineals collected from one-year-old turkeys (Meleagris gallopavo). In addition to standard morphological methods, the alizarin red S and potassium pyroantimonate methods were employed for localization of calcium at the light and electron microscopy level. In light microscopy, calcified concretions with diameters from 300 μm to 2 mm and quantities from 3 to 6 per gland were observed in all the examined pineals. They were stained red with alizarin S and showed the presence of collagen in Mallory's staining. Two types of cells were noted inside the concretion: polygonal and elongated ones. Using electron microscopy, three parts were distinguished within the calcification area. The peripheral part contained densely packed collagen fibrils, some elongated cells and numerous pyroantimonate precipitates demonstrating the presence of calcium ions. In the intermediate part, the fibrils were covered by almost continuous sheets of pyroantimonate precipitates and fused side by side. The central part showed an appearance of calcified hard tissue and showed an appearance of calcified hard tissue and contained some polygonal (osteocyte-like) cells. The obtained data demonstrated that the formation of the pineal concretions in the turkey is associated with the mineralization of collagen. This process is completely different from the mechanisms responsible for the formation of the concretions in the mammalian pineal