Ultrastructure of the Parathyroid Gland of Magnesium-Treated Golden Hamster Exposed to a Hypergravity Environment: A Stereological Study

Utsumi, Michiya; Emura, S.; Hayakawa, Daisuke; Yamahira, Tomo; Terasawa, K; Tamada, Akira; Isono, Hideo; Shoumura, Shízuko

doi:10.2535/ofaj1936.70.5_209

Cited by 3 publications

(2 citation statements)

References 36 publications

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“…Several studies have described that the hypoactive chief cells show an increase in lipid droplets (Isono et al, 1980(Isono et al, , 1981(Isono et al, , 1982(Isono et al, , 1983Emura et al, 1988Emura et al, , 1994bEmura et al, , 1995Shoumura et aL, 1990;Utsumi, 1993). The present study likewise demonstrated the higher volume density occupied by the lipid droplets in the immobilized group than the control.…”

Section: Discussionsupporting

confidence: 78%

Effect of Immobilization on the Ultrastructure of the Golden Hamster Parathyroid Gland

Tamada

Emura

Hayakawa

et al. 1998

Okajimas Folia Anatomica Japonica

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To investigate the morphological changes of the parathyroid gland of the immobilized hamsters, we studied the ultrastructure of the parathyroid gland of golden hamsters kept in special small cage (Ballman cage II). All hamsters of the control group were kept in one ordinary cage. Each hamster of the isolated group was kept in ordinary cage individually. Each hamster of the immobilized group was kept in Ballman cage II individually. All hamsters were kept for 5 days. On the first and fifth day of the experiment, bone mineral content (BMC) and bone mineral density (BMD) of whole body were measured by dual energy X-ray absorptiometry (DXA). In the control and isolated groups, BMD of the fifth day was significantly increased as compared to that of the first day. In the immobilized group BMC and body weight were significantly decreased. There was no significant difference among 3 groups concerning the mean serum calcium level. Volume density of the cell organelles and inclusions was estimated and compared among 3 groups. Volume density of the lysosomes and large vacuolar bodies of the isolated and immobilized groups was significantly higher than that of the control group. Much more lipid droplets were observed in the immobilized group than the control and isolated groups. No particular differences were observed as to the Golgi complex in the isolated and the immobilized groups compared to the control group. These findings suggest that the cellular activity of the parathyroid gland is suppressed with immobilization.

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Section: Discussionsupporting

confidence: 78%

Effect of Immobilization on the Ultrastructure of the Golden Hamster Parathyroid Gland

Tamada

Emura

Hayakawa

et al. 1998

Okajimas Folia Anatomica Japonica

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“…In a series of recent morphological studies on the parathyroid glands (PTG) in this laboratory using centrifugation, animals were exposed to simulated increase in body weight by centrifugation at 5.0 G for 1 or 5 hr and these studies have showed acute effects of the high rotation of centrifugation on the PTG (Shoumura et aL, 1988(Shoumura et aL, , 1989a(Shoumura et aL, , 1989b(Shoumura et aL, , 1991a(Shoumura et aL, , 1991b(Shoumura et aL, , 1992a(Shoumura et aL, , 1992b(Shoumura et aL, , 1992cUtsumi et al, 1993). In addition, Sannes and Hayes (1975) have shown the effect of centrifugation at 2.0 G for 60 days on the ultrastructure of the PTG.…”

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confidence: 99%

Effect of Centrifugation on the Ultrastructure of the Parathyroid Gland of the Magnesium-treated Golden Hamster

Utsumi

Emura

Isono

et al. 1997

Okajimas Folia Anatomica Japonica

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Summary: The ultrastructure of the parathyroid glands (PIG) of magnesium (Mg)-treated golden hamsters exposed to centrifugation at 1.2 G for 7 days was compared to that of the control, Mg-treated or centrifuged groups. In the PTG of the Mg-treated group exposed to centrifugation, the Golgi apparatus increased compared with that of the Mg-treated group, but was similar to that of the control and centrifuged groups. The cisternae of the rough endoplasmic reticulum (rER) increased compared with that of the Mg-treated group and decreased compared with that of the centrifuged group, but was the same as that of the control group. There were no significant differences among the 4 groups with regard to lysosomes, large vacuolar bodies, lipid droplets and secretory granules. These observations suggest that the rER is sensitive to centrifugation compared with the Golgi apparatus and more importantly the inhibitive effect of Mg on the synthesis of the hamster parathyroid hormone is enfeebled by centrifugation at 1.2 G.In a series of recent morphological studies on the parathyroid glands (PTG) in this laboratory using centrifugation, animals were exposed to simulated increase in body weight by centrifugation at 5.0 G for 1 or 5 hr and these studies have showed acute effects of the high rotation of centrifugation on the PTG (Shoumura et

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Stimulative Effect of High-level Hypergravity on Differentiated Functions of Osteoblast-like Cells.

Kawashima

Shibata

Negishi

et al. 1998

Cell Struct. Funct.

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Keywords: mechanical stress/hypergravity/osteoblasts/alkaline phosphatase/osteocalcin/CAMP ABSTRA CT. The exposure of freshly isolated osteoblasts and osteoblast-like cells to high-level hypergravity caused the inhibition of cell growth, elevation of CAMPcontent, and the stimulation of differentiated functions such as alkaline phosphatase activity, collagen synthesis, and osteocalcin synthesis. Blockage of elevation of CAMPby SQ22536, an inhibitor of adenylate cyclase, resulted in the inhibition of the hypergravity-stimulated alkaline phosphatase activity, indicating that CAMPis the intracellular mediator of this action of hypergravity. H89, an inhibitor of CAMP-dependent protein kinase (PKA), further inhibited the cell growth that was already inhibited by the hypergravity, and further stimulated the alkaline phosphatase activity that was already stimulated by hypergravity.If CAMPacts through the PKAsystem, H89 should have blocked the changes in cell function effected by the exposure to hypergravity. Therefore the elevated intracellular CAMP by the exposure of hypergravity caused the changes in cell function by a PKA-independent pathway.Observations indicate that mechanical stresses exert profound effects on cell growth and differentiation (34).The loading of shear stress (5, 26) or stretching force (ll, 14, 19) induces a number of morphological, physiological, and biological changes in many kinds of cells. Gravitational alteration also influences the metabolism ofavarietyofcells (8,15, 17, 21, 22, 28, 32, 33). Bone is one of the organs that is sensitive to gravitational alteration. Microgravity generated by space flight is knownto decrease the bone density of astronauts (18).Morphological study has shown that microgravity caused a reduction in bone formation without affecting bone resorption (7). In cell culture experiments, the growth of osteoblasts was inhibited under the microgravitational condition of space flight (12). In addition, microgravity generated by parabolic flight also brought about a decrease in the cell area of osteoblasts (9). These results suggest that microgravity affects the growth and differentiation of osteoblasts. However, few investigations have been done on the effect of hypergravity on osteoblasts. Some reports have shown that the exposure of osteoblasts to a low level of hypergravity stimulates cell growth and inhibits alkaline phosphatase activity (20)

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Ultrastructure of the Parathyroid Gland of Magnesium-Treated Golden Hamster Exposed to a Hypergravity Environment: A Stereological Study

Cited by 3 publications

References 36 publications

Effect of Immobilization on the Ultrastructure of the Golden Hamster Parathyroid Gland

Effect of Immobilization on the Ultrastructure of the Golden Hamster Parathyroid Gland

Effect of Centrifugation on the Ultrastructure of the Parathyroid Gland of the Magnesium-treated Golden Hamster

Stimulative Effect of High-level Hypergravity on Differentiated Functions of Osteoblast-like Cells.

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