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  • 1
    Electronic Resource
    Electronic Resource
    Identification of α2-Adrenergic Receptors in Chicken Pineal Gland Using [3H]Rauwolscine (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 51 (1988), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The norepinephrine-induced inhibition of avian pineal N-acetyltransferase activity appears to be mediated by α2--adrenergic receptors. In this study, α2-adrenergic receptors in the chicken pineal gland were directly identified by radioligand binding. Membrane preparations of pineal glands from chickens from 1 to 6 weeks of age were examined using [3H]rauwolscine, a selective α2-adrenergic receptor antagonist, to characterize the binding sites. The results indicate no ontological change in either the affinity (KD) or density of receptor binding sites (Bmax) during the time span examined. The binding was saturable and of high affinity with a mean KD of 0.27 ± 0.01 nM and a mean Bmax of 242 ± 12 fmol/mg protein. Further characterization of these binding sites indicated that the α2-adrenergic receptor is of the α2A subtype, since prazosin and ARC-239 bound with low affinities and oxymetazoline bound with high affinity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1988.tb04838.x
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  • 2
    Electronic Resource
    Electronic Resource
    Relationship of Daylength to Reproduction in the White-Footed Mouse (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 453 (1985), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1985.tb11835.x
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of Daily Afternoon Melatonin Administration on Body Weight and Thyroid Hormones in Female Hamsters (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 6 (1989), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Female hamsters were treated each afternoon for 8 weeks with subcutaneous injections of 25 μg of either melatonin or vehicle solution. Animals were sacrificed in either the morning or afternoon of diestrus and proestrus, along with their respective melatonin-induced acyclic pairs. Melatonin-treated hamsters had significantly greater mean body weights than did the vehicle-treated hamsters (P 〈 0.05). Terminal mean serum T4 levels and free thyroxine index (FT41) were significantly reduced (P 〈 0.05) in melatonin-treated hamsters compared with values obtained from animals subjected to the vehicle alone. In addition, T4 levels, FT41, T3 levels, and FT31 were significantly influenced by day and time of sacrifice independently of the melatonin treatment. T3 uptake was significantly lower on the morning of proestrus in melatonin-treated animals. These results demonstrate that chronic afternoon melatonin administration in female hamsters results in the loss of estrous cyclicity, a significant gain in body weight, and the reduction of T4 levels and T3 uptake. Changes in serum T3 levels are a function of the time of sample collection and are not influenced by melatonin treatment. In addition, these data indicate that thyroid function in general changes during the estrous cycle in these animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1989.tb00433.x
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  • 4
    Electronic Resource
    Electronic Resource
    Ontogeny of Light-Induced Decrease of N-Acetyltransferase Activity in Explanted Chick Pineal Glands (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 8 (1990), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The ontogeny of chick pineal serotonin N-acetyltransferase (NAT) activity was investigated in explanted chick pineal glands at 4, 10 and 21 d of age. Nocturnal levels of the enzyme and the response of the enzyme to light exposure were determined in pineal glands maintained in short-term culture at each age. The results indicate that nocturnal NAT activity was increased in the glands from older birds. Nocturnal levels of NAT activity at the time of the initiation of the experiment were threefold greater in glands from 21-d-old birds as compared to that in glands from 4-day-old chicks. The response to light was similar in all three ages examined; light induced a significant decrease in NAT activity within 60 min in explanted glands from 4-d-old chicks and within 180 min in the glands from the 10- and 21 -d-old chicks. A paradoxical transient increase in enzyme activity occurred immediately (within 5 min) following light exposure which was significant in the glands from the youngest chicks, and present, but more variable, in the older chicks. These data indicate that the nocturnal enzyme activity is greater in glands from older birds, but that light exposure of explanted glands initiates a transient rise followed by a decrease in NAT activity at all three ages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1990.tb00675.x
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  • 5
    Electronic Resource
    Electronic Resource
    An Immunocytochemical Study of the Luteinizing Hormone-Releasing Hormone (LHRH) System in the White-Footed Mouse: Effect of Blinding and Melatonin (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 1 (1984), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Previous studies have provided evidence that pineal-mediated gonadal atrophy involves the luteinizing hormone-releasing hormone (LHRH) system in some rodents. The purpose of the present study was to visualize the LHRH system in the brain of the white-footed mouse by immunocytochemical methods and to assess the influence of blinding or melatonin on the LHRH immunostaining characteristics of the median eminence. Six intact adult female mice and six adult males (two intact, two blinded, and two with subcutaneous melatonin-beeswax implants) treated for 6 wk were sacrificed by perfusion of fixative, and their brains were removed, cut into 60-μm sections and stained for LHRH by the peroxidase-antiperoxidase (PAP) method. Since the tissues were batch-processed in separate wells in a common chamber, semiquantitive comparisons may be made between similar sections from animals subjected to different treatments. The testes were also collected and prepared for microscopic examination. The distribution of LHRH-stained cell bodies and fibers was found to be essentially the same as has been described in other rodents, i.e., predominantly confined to the preoptic area and hypothalamus. The perikarya appear as unipolar and bipolar fusiform cells with “beaded fiber” type processes. In sections that included the median eminence of the blinded and melatonin-treated males, the degree of immunopositive staining appears to be greater than in the median eminence of untreated mice. The histological appearance of the testes from the treated animals revealed a profound inhibition of gametogenesis. These observations support the suggestion that pineal-mediated gonadal atrophy is the result of an inhibition of LHRH release from the median eminence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1984.tb00227.x
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  • 6
    Electronic Resource
    Electronic Resource
    Morphological and morphometric changes in the ovaries of white-footed mice (Peromyscus leucopus) following exposure to long or short photoperiod (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 205 (1983), S. 13-19 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Two experiments were carried out with a total of 36 white-footed mice (Peromyscus leucopus) exposed to either long (LP) or short (SP) photoperiod for six weeks. Ovaries and uteri were weighed. Serial sections of the ovaries were processed for light microscopy. The total number of the interstitial gland cells, preantral and antral follicles with early and advanced stages of atresia as well as corpora lutea, was determined.Uteri from LP mice weighed significantly more than those from SP mice in both experiments. In contrast, the weight of ovaries from LP and SP animals only differed significantly in one experiment; this experiment also produced no obvious changes in the total number of corpora lutea. While interstitial gland cells of LP ovaries were hypertrophic and appeared mature, the interstitial gland cells of SP ovaries were of the degenerating cell type. The total number of follicles as well as their mean follicular diameters were higher in LP animals in comparison with SP animals. In addition, the percentage of antral follicles were increased and there were fewer signs of advanced stages of atresia in the LP group. It is suggested that the changes of the interstitial gland cell morphology combined with alterations of follicular growth during LP or SP appear to support intensified follicular growth.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092050103
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  • 7
    Electronic Resource
    Electronic Resource
    Inverse correlation between “Synaptic” ribbon number and the density of adrenergic nerve endings in the pineal gland of various mammals (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 205 (1983), S. 93-99 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The number of “synaptic” ribbons was inversely correlated with the density of the adrenergic nerve endings of the pineal gland compared among a diverse group of species including the fox, cat, rat, cotton rat, white-footed mouse, Djungarian hamster, ground squirrel, and chipmunk. The concentration of norepinephrine paralleled the number of adrenergic nerve terminals in the pineal glands of the cotton rat, rat, and ground squirrel, the only species in which norepinephrine concentrations were measured. The number of ribbon fields paralleled numbers of “synaptic” ribbons in all species examined. Adrenergic nerve endings were observed primarily within the perivascular spaces, although some endings also were found among parenchymal cells. Adrenergic nerve endings forming synaptic junctions with pinealocytes were not observed in any of these species, nor was there any physical association between these nerve endings and “synaptic” ribbons.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092050112
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  • 8
    Electronic Resource
    Electronic Resource
    On the occurrence of a myeloid body in pinealocytes of the white-footed mouse, Peromyscus leucopus (1983)
    Springer
    Cell & tissue research 228 (1983), S. 649-659 
    Details
    ISSN: 1432-0878
    Keywords: Pinealocyte ; Myeloid body ; White-footed mouse ; Peromyscus leucopus ; Retinal pigment epithelial cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine-structural features of pinealocytes of the white-footed mouse, Peromyscus leucopus, were examined. A single population of pineaocytes was observed in both superficial and deep components of the gland. Cells in both locations are characterized by the presence of an indented nucleus exhibiting a prominent nucleolus. The usual organelles in the perikaryon are the Golgi complexes, mitochondria, endoplasmic reticulum, polysemes, microtubules and dense-core vesicles. In addition the perikaryonal cytoplasm often contains a single myeloid body. These bodies are usually lenticular in shape, are formed of an array of flattened membranous cisternae, and are not bounded by a limiting membrane. This organelle usually lies in the vicinity of the nucleus and is infrequently associated with lipid bodies. Complex forms were also observed. The cisternae are continuous with elements of the endoplasmic reticulum at points along their expanded rims. The outer surface of the cisternal membrane exhibits a granularity or fuzziness. The cisternae may be fenestrated. Pinealocyte processes with an abundance of clear vesicles, and some dense-core vesicles and vesicle-crowned rodlets are present in the parenchyma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00211481
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  • 9
    Electronic Resource
    Electronic Resource
    Ultrastructure of pinealocytes of the cotton rat, Sigmodon hispidus (1979)
    Springer
    Cell & tissue research 204 (1979), S. 407-416 
    Details
    ISSN: 1432-0878
    Keywords: Pineal gland ; Ultrastructure ; Cotton rat (Sigmodon hispidus)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fine structural features of pinealocytes of cotton rats (Sigmodon hispidus) were examined. Golgi complexes, mitochondria, endoplasmic reticulum and polysomes are usual organelles seen in the perikaryonal cytoplasm of pinealocytes. Many non-granulated vesicles (40 to 80 nm in diameter) and a few granulated vesicles (about 100 nm in diameter) are associated with the Golgi cisternae. Occasionally, the cisternae contain granular materials. The perikaryonal cytoplasm of pinealocytes is characterized by the presence of inclusion bodies. These bodies are usually round in shape, not bounded by a limiting membrane and composed of fine granular or filamentous materials of high electron-opacity, which are similar in appearance to the substance seen in the nucleolonema. Pinealocyte processes, filled with abundant non-granulated vesicles and some granulated vesicles, are mainly found within the parenchyma and occasionally in perivascular spaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233652
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  • 10
    Electronic Resource
    Electronic Resource
    Inclusion bodies in pinealocytes of the cotton rat (Sigmodon hispidus) (1983)
    Springer
    Cell & tissue research 232 (1983), S. 413-420 
    Details
    ISSN: 1432-0878
    Keywords: Pinealocytes ; Cotton rat ; X-ray microanalysis ; Protein digestion ; Inclusion bodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pinealocytes of the cotton rat (Sigmodon hispidus) often contain large (2–6 μm diameter) intracytoplasmic inclusions, the function of which is not known. These inclusions may represent nucleolus-like bodies, mineral deposits, secretory products or viral inclusions. In this study these inclusions were classified as type A, B or C inclusions based on the amount of electron-dense material interspersed within the finely granular material comprising the bulk of these inclusions. Each type of inclusion was analyzed by X-ray microanalysis and enzymatic protein-aceous digestion. X-ray microanalysis of these inclusions differed both quantitatively and semiquantitatively from that of human or gerbil pineal concretions, the latter two of which are extracellular deposits. Pronase, a proteolytic enzyme, digested the electron-dense material only after longer times of tissue exposure to this enzyme in contrast to the easily digested, finely granular matrix-like material of these inclusions. Such intrapinealocytic inclusions have only been observed in the cotton rat. Their functional significance remains unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213796
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