Showing papers on "Pinealocyte published in 1980"

Circadian rhythms of melatonin release from individual superfused chicken pineal glands in vitro.

Abstract: The pineal gland of birds contains one or more circadian oscillators that play a major role in overall temporal organization. We have developed a flow-through culture system for the isolated pineal by which we can measure the release of melatonin continuously from superfused glands over long periods of time. Chicken pineals release melatonin rhythmically, and these rhythms persist in vitro with a circadian oscillation. In light cycles the release of melatonin is strongly rhythmic; however, in constant conditions the amplitude of the rhythm is lower and appears to be damping. Light has at least two effects upon the isolated pineal: cyclic light input synchronizes the rhythm, and acute light exposure at night rapidly inhibits melatonin release. The cultured avian pineal clearly offers great potential as a model system for the study of vertebrate circadian oscillators and may open the way for an analysis of mechanism.

N-acetyltransferase in the chick retina: I. Circadian rhythms controlled by environmental lighting are similar to those in the pineal gland

Abstract: SummaryN-acetyltransferase activity (NAT) was measured in tissues of chicks exposed to light-dark treatments and to injections. The results support hypotheses of similar circadian rhythms in retinal and pineal NAT, regulation of retinal and pineal NAT by environmental lighting, and inhibition of retinal and pineal NAT by cycloheximide and isoproterenol.1.NAT was measured in 20 tissues dissected from chicks kept in LD12∶12. NAT fluctuated from 0.5 to 2.3-fold in the tissues except for the pineal gland and retinas (6.9 and 4.2-fold, respectively).2.Retinal and pineal NAT were high in the dark and low in the light in LD12∶12; the change was usually larger in the pineal gland (7 to 12-fold) than in the retina (3 to 6-fold), but the NAT of the two eyes taken together was at least 2/3 of that of the pineal gland.3.The NAT daily change persisted in both the eyes and the pineal gland for at least 3 days of constant dark which is evidence that NAT has a circadian rhythm in both these tissues.4.Unexpected dark-to-light transitions resulted in a plummet (in 1 h) of NAT in the retina (51%) and in the pineal gland (77%). Extension of the light into the dark-time likewise suppressed NAT in the retina (78%) and in the pineal gland (83%). NAT in the retina was refractory to stimulation by dark in the early light-time, similar to the pineal gland.5.Isoproterenol injections lowered pineal (53%), but not retinal, NAT when the injection was subcutaneous; the injection lowered retinal (52%), but not pineal, NAT, when the injection was intraocular. Cycloheximide injections lowered both pineal (48%) and retinal (68%) NAT when the injection was intraocular, but only pineal NAT (70%) when the injection was subcutaneous.

Preliminary investigations on melatonin and 5-methoxytryptophol synthesis in the pineal, retina, and Harderian gland of the mole rat and in the pineal of the mouse “eyeless”

Abstract: Hydroxyindole-O-methyltransferase (HIOMT) activity for the synthesis of melatonin and 5-methoxytryptophol, both 5-methoxyindoles, was measured in the pineal, the Harderian gland and the retina of the mole rat and in the pineal of the mouse “eyeless”. In the pineal and the Harderian gland of the mole rat a larger amount of 5-methoxytryptophol than of melatonin is synthesized. 5-Methoxyindole synthesis is extremely high in the Harderian gland, whereas in the retina HIOMT activity is low and variable. In the pineal of the mouse “eyeless”, a low 5-methoxyindole synthesis showing no circadian rhythm is demonstrated. It is concluded that, besides the generally accepted regulation of the indole metabolism by light, in species with atrophied eyes having Harderian glands (mole rat) and in species without eyes other factors than light might be responsible for the indole metabolism in the pineal gland.

Neonatal development of circadian rhythm in 'synaptic' ribbon numbers in the rat pinealocyte

Abstract: Populations of “synaptic” ribbons (SR) in pinealocytes of the rat pineal gland at various ages from the neonatal period through early adulthood were analyzed morphometrically. Diurnal and nocturnal numbers of SR were small on day one but had increased dramatically by the end of the first week and beginning of the second week. By day 10, numbers of SR had peaked. Thereafter nocturnal numbers of SR demonstrated no significant increases or decreases. However, between days 10 and 19, diurnal numbers of SR decreased precipitously, appearing to have leveled off at the onset of puberty to levels observed in adults. SR were never scarce or absent in any age group studied. The neonatal appearance of large numbers of SR coincides developmentally with the initial sympathetic innervation of pineal parenchyma. Circadian rhythm in numbers of SR begins shortly thereafter. It is suggested (1) that circadian rhythm in numbers of SR is initiated and regulated or modified by sympathetic innervation of pinealocytes containing SR, and (2) that SR formation may be related to the intracellular flow of membrane relative to the transport and release of specific pineal products.

Pools of serotonin in the pineal gland of the mouse: the mammalian pinealocyte as a component of the diffuse neuroendocrine system.

Abstract: In the pineal gland of the mouse the distribution of serotonin (5-HT) and its eventual relationships to a protein secretion were examined by means of fluorescence histochemical (Falck-Hillarp) and ultracytochemical (chromaffin and argentaffin) methods. Taking into account the specificity and sensitivity of these three complementary methods, previous biochemical data in mammals and ultracytochemical data in submammalian vertebrates, synthesis, storage, catabolism and release of 5-HT in the mouse and hamster pineals are discussed at the cellular level. Different pools of 5-HT are present: agranular and granular in pinealocytes and sympathetic nerve endings; agranular in interstitial cells. In the mouse, only a small portion of the total 5-HT content appears to be secondarily taken up by the DCV. Within the DCV, 5-HT is possibly bound to a protein secretion of unknown significance (peptidergic neurohormone?). In the pinealocytes, which are sensitive to a large variety of inputs, processes of indole and protein secretion are found. These cells apparently are the recepto-secretory elements of the mammalian pineal gland. They can thus be classified as a member of the diffuse neuroendocrine system of the paraneuron group.

The role of the pineal gland in stress.

Abstract: A short survey of the results of our previous research into the protective role of the pineal gland against stress is given. The neuroendocrine aspect of a chronic auditory stress and the neuroendocrine aspect of ulcer disease in man were studied. Auditory stress: hypertrophy and hyperplasia of pinealocytes, hyperplasia of the STH, FSH, LTH and TSH cells, hypertrophy of the nuclei and nucleoli of the neuroglandular cells of the supraoptic and paraventricular nuclei, pronounced hyperplasia of the cells of the reticular zone of the adrenal gland, involution of the seminal epithelium, hyperplasia of the Leydig cells. Ulcer disease: numerous glial plates, cavities and acervuli in the pineal gland, numerous granules and vacuoles in the FSH cells, large and eccentrical nuclei in the LH cells, hyperplasia of the cells of the reticular zone of the adrenal gland, presence of the seminal tubules marked by signs of involution, hyperplasia of the Leydig cells. The results obtained point to the secretion of androgens and the insufficiency of the antiandrogenic function of the pineal gland both in auditory stress and ulcer disease. The anticancerogenic effect of the pineal gland would be based on its antiandrogenic function.

Ultrastructure of serotonin-containing cells in the pineal organ of Lampetra planeri (Petromyzontidae).

Abstract: The ultrastructure of the “cells containing residual bodies” (Collin, 1969) was investigated in the pineal organ of Lampetra planeri. These cells are characterized by their indoleamine metabolism (Meiniel, 1978; Meiniel and Hartwig, 1980). Morphologically, they belong mainly to two types: (1) a photoreceptor cell type, and (2) a pinealocyte cell type. The first type is present in the pineal sensory epithelium and in the atrium, while the second is observed in the deep part of the atrium. Intermediate cell types are rare. All these cells are characterized by the presence of voluminous dense bodies, the 5-HT-storing structures, in their cytoplasm.

Fine structural alterations in the aging rat pineal gland.

Abstract: The pineal glands of 1 mo to 28 mo old male and female rats were examined by electron microscopy. With increasing age the following observations were made: (1) the capsule thickness increases; (2) there is an increase in collagen infiltration; (3) increased amounts of granular deposits are seen between cells; (4) there is a greater variability in the number of light pinealocytes; (5) pinealocytes with nuclear invaginations and pinealocytes with nuclear inclusions increase in number; (6) more cytoplasmic dense bodies are seen in pinealocytes and gliocytes; (7) the maximum diameter of pinealocyte lipid droplets tends to increase; (8) no definite change is observed in granular endoplasmic reticulum; (9) occasional cells are found to contain reticulated mitochondria, and a few cell processes have an appearance similar to neuroaxonal dystrophy. Besides illustrating age-related changes, the present study proves the existence of pinealocyte nuclear inclusions, suggests the possibility of pineal concreti...

The pineal gland of the mole (Talpa europaea L.)

Abstract: The ultrastructure of the pinealocytes in the fetal mole (Talpa europaea) was examined and compared with that in the adult mole. The parenchyma of the fetal pineal gland consists primarily of pinealocytes with very few dispersed “glial” cells. Three different morphological types of pinealocytes (I, II and III) were observed. Pinealocytes of types I and II, homologous to the rudimentary photoreceptor cells of lacertilians and birds, were commonly found, especially around the pineal lumen, which is still present in the fetus. These results support the concept of the phylogenetic origin of mammalian pinealocytes from the pineal photoreceptor cells of the non-mammalian vertebrates.

Ultrastructural evidence for seasonal changes in pinealocytes of the 13-lined ground squirrel, spermophilus tridecemlineatus: A qualitative and quantitative study

Abstract: The fine structure of pinealocytes in the hibernating ground squirrel, Spermophilus tridecemlineatus, was found to vary both qualitatively and quantitatively according to the season in which the animals were sacrificed. Ultrastructural features of pinealocytes from fall (prehibernation) and winter (hibernation) periods, when the animals were sexually quiescent, included: 1) arrangement of the endoplasmic reticulum into flattened stacks or concentric rings (formations which have been implicated in antigonadotropic activity of the pineal); 2) condensations of a fine granular material; and 3) dilation of the cisternae of the endoplasmic reticulum and Golgi bodies with an increased number of Golgi associated vesicles. Moreover, there was an apparent increase in the number of dense-cored vesicles and microtubules in pinealocytes of winter animals. These findings indicate that a circannual rhythm in pinealocyte ultrastructure occurs in this species and further suggest that cellular activity is seasonal.

Cerebrospinal fluid-contacting area in the pineal recess of the vole (Microtus agrestis), guinea pig (Cavia cobaya), and rhesus monkey (Macaca mulatta).

Abstract: The ventricular lining in the pineal recess of the vole (Microtus agrestis), guinea pig (Cavia cobaya) and Rhesus monkey (Macaca mulatta) was investigated light and electron microscopically. Deep in the pineal recess of all three species the ependymal lining exhibits interruptions. A varying proportion of pinealocytes penetrates through this ependymal area, so that the surface of the protruding cells is directly exposed to the cerebrospinal fluid (CSF). At their base, these cells are anchored in the hypependymal tissue by means of processes. It is conjectured that these pinealocytes are engaged in secreting pineal substances into the CSF, as various physiological findings appear to indicate.

Phylogenetic Aspects of the Sensory Neurons of the Wall of the Diencephalon

Abstract: Physiological investigations suggest the presence of light receptors, thermoreceptors, as well as sodium and glucose receptors in the wall of the diencephalon (22). Morphological data likewise indicate the occurrence of sensory cells in the hypothalamus (12); for instance, the so-called liquor-contacting neurons (13, 14, 19) and the coronet cells of the vascular sac of fishes (16). The photoreceptor cells of the retina and the similarly built pinealocytes develop from the diencephalon as well.

The ultrastructure of pinealocytes in the pig.

Abstract: Pinealocytes of female pigs were studied electron-microscopically and compared with those of other mammals. A prominent Golgi apparatus forming dense-cored vesicles was widely dispersed in the cytoplasm of the cell body. A very characteristic feature of the pig pinealocytes was the presence of membrane-bounded bodies showing wide variations in internal structure. Possible roles of the dense-cored vesicles and membrane-bounded bodies in secretory processes of pinealocytes are discussed.

The pineal gland of equatorial mammals. I. The pinealocytes of the Malaysian Rat (Rattus sabanus).

Abstract: The ultrastructure of the pinealocytes of the Malaysian rat (Rattus sabanus), a mammal inhabiting a zone near the equator where the annual variations of daylength are inconspicuous, was examined and compared with that of pinealocytes of other mammals. On the basis of the presence of granular vesicles, only one population of pinealocytes was found. A large number of granular vesicles and vesicle-crowned rodlets is characteristic of the pinealocytes of this equatorial species. Vesicle-crowned rodlets are especially numerous in the endings of the pinealocyte processes and; they most often found in direct topographical connection with the perivascular spaces. The physiological significance of the presence of such large amounts of vesicle-crowned rodlets and of the secretory process characterized by the formation of granular vesicles is discussed.

Evidence for a serotonin uptake system in isolated bovine pinealocyte suspensions.

Abstract: Serotonin uptake was investigated in bovine pinealocyte suspensions. Pinealocytes were disaggregated from calf pineal glands by enzymatic treatment with papain followed by mechanical disruption of the tissue fragments. Cells were resuspended in Hank’s balanced salt solution which contained 12.5 µM nialamide to inhibit monoamine oxidase activity present in the pinealocytes. The uptake of radiolabeled serotonin as a function of concentration exhibited saturation phenomena when high (10 µM-5 mM) concentrations of serotonin were used. Estimates of the fraction of serotonin bound to the cell membrane were attempted by three methods: (1) lysing cells by exposing them to a hypotonic medium after incorporation of radiolabeled serotonin in standard medium; (2) exposing cells to media of increasing osmolarity in the presence of radiolabeled serotonin; and (3) displacing radiolabeled serotonin from nonspecific binding sites on the cell membrane by cold serotonin. Estimates of the fraction of uptake of serotonin contributed by simple diffusion were made by adding an excess of unlabeled serotonin to 0.76µM radiolabeled serotonin to saturate specific carrier sites and nonspecific membrane binding sites. Tissue-to-medium ratios exceeded 1 with all concentrations of serotonin used.

A seasonal study of pinealocytes in the 13-lined ground squirrel, Spermophilus tridecemlineatus.

Abstract: A quantitative histological study of pinealocytes in the 13-lined ground squirrel, Spermophilus tridecemlineatus, was conducted over a period of one year. Consistent and statistically significant seasonal differences were found in nuclear and nucleolar dimensions suggesting a circannual rhythm in the metabolism of these cells. Annual peaks occurred during hibernation, whereas the nadirs occurred during the period of sexual activity. Differences between sexes in any season were not statistically significant. An inverse relationship between nuclear and nucleolar size and the normal sexual cycle suggests that reproduction in this species may be mediated by the pineal gland. The question of what role, if any, the pineal gland plays in hibernation awaits further experimental evidence.

Experimental and spontaneous pineal tumors: findings relating to endocrine and oncogenic factors and mechanisms.

Abstract: Pineocytomas have been induced in a high percentage of hamsters inoculated intracerebrally within 24 hours after birth with particular strains of a human papovavirus. Studies on biochemical and ultrastructural characteristics and transformations of such experimentally induced pineal tumors have led to important conclusions and implications: (1) Many of the differentiated pineocytoma cells contained organelles and related structures that are characteristic of hamster pineocytes, and others that are reminiscent of possible phylogenetic precursors, including pineal photoreceptor cells. (2) An inverse relationship was noted between degree of cytological differentiation and level of hydroxyindole-O-methyltransferase (HIOMT) activity in the pineocytomas. (3) It is therefore apparent that even when pineal tumor formation leads to great increase in pinealocyte-like cells, their enzymatic capacity for synthesis of melatonin, and possibly of other humoral products, may be only 4 to 7% of that of normal pinealocytes if they are of a relatively less differentiated type.

Characterization of serotonin uptake in isolated bovine pinealocyte suspensions.

Abstract: The uptake of radiolabeled serotonin as a function of concentration exhibited saturation when low (0.005-2 µM) concentrations of serotonin were used. Kinetics of the initial rate (30 s) of entry of radiolabeled serotonin into pinealocytes were examined using various concentrations of the substrate. The effects of temperature, changes in external ion concentrations, drugs, metabolic inhibitors, and other compounds on the uptake of serotonin were investigated. High concentrations (10 µM-5 mM) of serotonin appear to use amino acid transport systems, e.g., L-lysine, L-leucine, and L-alanine. Uptake is partially sodium dependent, temperature dependent, sensitive to metabolic inhibitors, and inhibited by various amino acids. Low concentrations (0.005-1 µM) of serotonin appear to use a highly specific, allosteric carrier for transport. Uptake is sodium dependent, temperature dependent, and sensitive to a variety of metabolic inhibitors.

Mechanism involved in the response of granulated vesicles in the mouse pinealocyte to acute cold exposure.

Abstract: Quantitative electron microscopic studies on the mouse pineal gland were done to elucidate the mechanism of the response of the granulated vesicles in pinealocytes to acute cold exposure An increase in the number of the granulated vesicles in the mouse pinealocytes occurs following administration of isoproterenol and this increase is prevented by pretreatment with the beta-adrenergic blocking agent, propranolol In addition, a numerical increase of the granulated vesicles in response to acute cold exposure is abolished in mice pretreated with propranolol or in adrenalectomized animals The results suggest that catecholamines released from the adrenal medulla, but not from sympathetic nerve endings, may cause the response of the granulated vesicles to cold by way of beta-receptors

The ependyma of the saccular pineal gland in the non-eutherian mammal Trichosurus vulpecula. A scanning electron microscopic study.

Abstract: The pineal gland in the possum is represented by a thickening in the wall of the pineal recess A superficial pineal body and a pineal stalk are characteristically lacking The ependyma related to the gland is specialized but differs markedly from the lining in other circumventricular organs in form and in surface morphology Two distinct topographic zones have been recognized In the middle is a mass of cells which form a prominent knobby-surfaced central zone These cells are characterized by the absence of cilia, the paucity of microvilli and blebs and the presence of processes which overlap adjacent cells A surface pattern formed of cell outlines was lacking it is suggested that the central zone is lined by pinealocytes, supporting cells and the processes of both cell types Most of the central zone is surrounded by an intermediate zone of variable width The latter region has been observed to possess a circumventricular organ-type surface morphology It is sparsely ciliated, almost totally covered by a carpet of microvilli and it exhibits a variety of surface specializations Supraependymal cells and various transitory supraependymal cell processes are also present Outside the specialized ependyma is the peripheral zone which like the regular ventricular lining is densely ciliated Supraependymal processes are found among the clusters of cilia, or rarely, on the surface of the ciliary bed Season and sex related differences in surface ultrastructure were not observed

An electron microscopical morphometrical study on pinealocytes of pregnant rats.

Abstract: A morphometrical study was made on the cut-surface of the pinealocytes in electron micrographs of the pineals from pregnant, puerperal and non-pregnant female rats. No significant differences in the cross-sectional area of the pinealocytes and the nuclei or in the nucleo-cytoplasmic ratio were found among the three groups of pregnant, puerperal and non-pregnant rats. The cross-sectional area of the nucleoli was, however, larger in the pinealocytes of the rats in pregnancy and early puerperium. This has been statistically confirmed by the ranking method (the U-test) of Wilcoxon, Mann and Whitney. The enlargement of nucleoli suggests the enhanced function of the pineal in pregnancy and early puerperium.

The pineal region in the opossum, Didelphis virginiana. I. Ultrastructural observations.

Abstract: In the pineal region of the opossum, Didelphis virginiana, two types of cells predominate: 1) pinealocytes, and 2) fibrous astrocytes. Pinealocytes are characterized by the presence of prominent Golgi bodies, numerous clear and dense-cored vesicles, sensory cilia (9+0), vesicle-crowned rods, and condensation of a material that was always associated with the rough endoplasmic reticulum. In addition, two other cell types are occasionally seen. These include 1) neuron-like cells, and 2) darker staining cells of unknown identity. The endoplasmic reticulum of the darker staining cells is typically expanded and filled with an amorphous substance. Although the pineal region is small in size, the present findings suggest that pinealocytes in this species are metabolically active cells displaying a secretory function. Moreover, the presence of sensory cilia (9+0) and vesicle-crowned rods indicates that pinealocytes of the opossum are phylogenetically related to the photoreceptor cells found in the pineal organ of lower vertebrates.

LHRH incorporation in normal and denervated pineal gland, and in pineal gland of rats with constant estrous-anovulatory syndrome: a preliminary study.

Abstract: Pineal gland and superior sympathetic cervical ganglia accumulated intravenously injected 3H-LHRH in an amount significantly higher than anterior and posterior hypothalamus, cerebral cortex and pituitary gland, the latter a specific target for LHRH. The prior administration of unlabelled LHRH significantly decreased the 3H-LHRH incorporation only in pineal and pituitary gland. Autoradiography showed that the radiolabel was localized at the level of the pinealocytes, with a seemingly, prevalent distribution of grains on the cellular contours. Pineal incorporation of LHRH was not significantly modified by either acute or chronic bilateral cervical ganglionectomy, although acute ganglionectomy resulted in a slight decrease in LHRH accumulation by pineal gland. Constant estrous anovulatory syndromes induced by either frontal hypothalamic deafferentation, or continuous illumination, or neonatal androgenization did not appear to modify the LHRH incorporation in either pineal gland or cervical ganglia. On the basis of these results, pineal gland is supposed to be a target organ for LHRH.

Effect of glutaurine on the pineal gland of the rat.

Abstract: Glutaurine (gamma-L-glutamyl-taurine), the recently discovered hormone of the parathyroid enhances the aggregation and subsequent degeneration of mitochondria in the pinealocyte processes of the rat pineal gland. It also stimulates autophagy, probably through its general lysosome activating effect.

Ultrastructural organization of the mammalian pineal gland during postnatal ontogenesis.

Abstract: Ultrastructural organization of the components composing the mammal pineal gland is analyzed on the basis of literature data and personal observations. Variations in the form, size and ultrastructural organization of the cellular elements in the pineal gland--pinealocytes, interstitial and glial cells--are discussed. The problem of dark and light pinealocytes is considered as a part of a general biological problem on the presence of dark and light cells as a reflection of the law on "intermittent activity of functional structures". An attention is paid to the organization of the microcirculatory bed and pericapillary space to the peculiarities of the secretory process in the organ. Dynamic changes in the cytologic organization of pinealocytes and other components of the organ in the postnatal ontogenesis are presented in detales.