A HORMONAL ASSESSMENT OF BOVINE PARTURIENT PARESIS: EVIDENCE FOR A ROLE OF OESTROGEN

1981 ◽  
Vol 88 (2) ◽  
pp. 161-171 ◽  
Author(s):  
B. W. HOLLIS ◽  
H. H. DRAPER ◽  
J. H. BURTON ◽  
R. J. ETCHES
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Plasma Levels ◽  
Post Partum ◽  
Comparative Assessment ◽  
Hormonal Control ◽  
Elevated Plasma ◽  
Calcium Phosphorus ◽  
Parturient Paresis

A comparative assessment was made of the hormonal control of calcium homeostasis in eight dairy cows which developed parturient paresis and in seven normal animals from the same herd. Plasma levels of calcium, phosphorus, magnesium, free hydroxyproline, 25-hydroxycholecalciferol (25-OHD), 1,25-dihydroxycholecalciferol (1,25-(OH)2D), parathyroid hormone, calcitonin, prolactin and oestrogen were monitored from 30 days prepartum to 15 days post partum. Prepartum levels of plasma calcium, hydroxyproline and calcitonin were depressed in the paretic animals, and plasma levels of phosphorus and oestrogen were elevated. Plasma levels of 25-OHD remained stable in both groups, whereas levels of 1,25-(OH)2D, parathyroid hormone and prolactin rose sharply at parturition. Plasma hydroxyproline, an index of bone resorption, began to rise 2 days prepartum in the control cows but not until 2 days post partum in the paretic cows. The data indicate that bone resorption was inhibited in the paretic group at the onset of lactation, and that a decreased capacity for bone resorption is a major factor in the susceptibility of some cows to this disease. The failure of the paretic animals to resorb bone was not associated with an inability to synthesize the calcium-mobilizing hormones parathyroid hormone or 1,25-(OH)2D, or to regulate the production of calcitonin. However, hypocalcaemia in the affected animals was associated with a significantly higher plasma level of oestrogen (a known inhibitor of bone resorption) in the immediate prepartum period. Following parturition, plasma levels of oestrogen fell rapidly and active bone resorption ensued in the paretic animals.

Role of osteoblasts in hormonal control of bone resorption—A hypothesis

1981 ◽  
Vol 33 (1) ◽  
pp. 349-351 ◽  
Author(s):  
Gideon A. Rodan ◽  
T. Jack Martin
Keyword(s):  
Bone Resorption ◽  
Hormonal Control

Role of parathyroid hormone in regulation of main calcium fluxes in rats.

1977 ◽  
Vol 232 (6) ◽  
pp. E535
Author(s):  
B Haldimann ◽  
J P Bonjour ◽  
H Fleisch
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Bone Formation ◽  
Bone Turnover ◽  
Linear Correlation ◽  
Constant Amount ◽  
Calcium Fluxes ◽  
Growing Rats

The effect of calcium deprivation on the various calcium fluxes was studied in growing rats either sham-operated (SHAM), thyroparathyroidectomized (TPTX), or thyroparathyroidectomized and supplemented with parathyroid hormone (PTH) (TPTX + PTH). In SHAM rats a decrease in the net absorption of calcium (Vna) has no influence on calcemia or on bone formation (Vo+), but leads to an increase in bone resorption (Vo-). In TPTX rats a decrease in Vna induces a decrease in calcemia and in Vo+ but still causes an increase in Vo-. The same is true in TPTX + PTH rats although all the variables measured are increased. In TPTX rats, both without and with PTH, a linear correlation exists between calcemia and Vo+ suggesting that calcemia influences bone formation. Furthermore, it appears that PTH is important in regulating bone turnover, but that the adaptation of Vo- to a change in Vna can occur in the absence or in the presence of a constant amount of this hormone. The mechanism of regulating this adaptation of bone resorption is still unknown.

Role of prolactin in vitamin D metabolism and calcium absorption during lactation in the rat

1982 ◽  
Vol 94 (3) ◽  
pp. 443-453 ◽  
Author(s):  
C. J. Robinson ◽  
E. Spanos ◽  
M. F. James ◽  
J. W. Pike ◽  
M. R. Haussler ◽  
...  
Keyword(s):  
Vitamin D ◽  
Alkaline Phosphatase ◽  
Parathyroid Hormone ◽  
Alkaline Phosphatase Activity ◽  
Plasma Levels ◽  
Calcium Absorption ◽  
High Plasma ◽  
Intestinal Calcium Absorption ◽  
Vitamin D Metabolism

Intestinal calcium absorption and plasma levels of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) were measured in lactating and non-lactating rats and the effects of bromocriptine and exogenous prolactin treatment were evaluated. In lactating rats calcium absorption and plasma levels of parathyroid hormone, 1,25(OH)2D3 and alkaline phosphatase activity were significantly increased. Bromocriptine treatment significantly reduced the enhanced calcium absorption and levels of plasma 1,25(OH)2D3 and alkaline phosphatase but had no significant effect on plasma levels of parathyroid hormone. Prolactin administered with bromocriptine to lactating animals prevented all the changes observed with bromocriptine treatment alone. It was concluded that the increased plasma levels of prolactin during lactation lead to high plasma levels of 1,25(OH)2D3 which are responsible for the enhanced intestinal calcium absorption.

scholarly journals Direct extraction and assay of bone tissue collagenase and its relation to parathyroid-hormone-induced bone resorption

1986 ◽  
Vol 239 (3) ◽  
pp. 793-796 ◽  
Author(s):  
Y Eeckhout ◽  
J M Delaissé ◽  
G Vaes
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Bone Tissue ◽  
Direct Extraction ◽  
Latent Form ◽  
Fetal Mouse ◽  
Quantitative Extraction

A method has been developed for the quantitative extraction of collagenase from as little as one 19-day-fetal-mouse calvarium. About 20-40 munits of collagenase are extracted per mg of tissue, all in a latent form that, after proper activation, shows the typical properties of mammalian collagenase. Culturing the calvaria for 2 days with parathyroid hormone (PTH) increases their procollagenase content up to 3-fold and induces bone resorption. Both PTH effects are prevented by cycloheximide, but not by indomethacin. Calcitonin inhibits resorption without affecting the PTH-induced procollagenase synthesis. The role of this synthesis is discussed in relation to the mechanisms of bone resorption.

Role of parathyroid hormone in mediating age-related changes in bone resorption in men

2003 ◽  
Vol 14 (8) ◽  
pp. 631-636 ◽  
Author(s):  
Kurt A. Kennel ◽  
B. Lawrence Riggs ◽  
Sara J. Achenbach ◽  
Ann L. Oberg ◽  
Sundeep Khosla
Keyword(s):  
Parathyroid Hormone ◽  
Bone Resorption ◽  
Age Related ◽  
Age Related Changes

Effects of somatostatin on parathyroid hormone levels and on responses of parathyroid hormone to β-adrenergic agonists and hypocalcaemia

1982 ◽  
Vol 100 (4) ◽  
pp. 534-538 ◽  
Author(s):  
J. W. Blum ◽  
J. A. Fischer
Keyword(s):  
Parathyroid Hormone ◽  
Plasma Levels ◽  
The Other ◽  
Immunoreactive Insulin ◽  
Adrenergic Agonists ◽  
Hormone Levels ◽  
Other Hand

Abstract. Experiments were designed to study the effect of exogenous somatostatin (S) on basal levels or parathyroid hormone (PTH) and on PTH responses to isoproterenol (ISO), adrenaline (A) or ethyleneglycol-bis (β-aminoethylether) N,N'-tetraacetate (EGTA) in cattle. During S infusions (6.11 nmol injected iv as a bolus and 0.82 nmol/kg/min infused iv for 30 or 60 min) plasma levels of PTH and calcium (Ca) did not change, whereas concentrations of immunoreactive insulin (IRI) decreased significantly (P < 0.01). In response to ISO (0.09 nmol/kg/min) or EGTA (5.6 μmol/kg/min, depressing plasma Ca by 0.27 nmol/l) PTH levels were similarly increased (P < 0.05) both in the absence and presence of S. On the other hand, S supressed IRI responses to ISO. During 60-min infusions of EGTA (3.15 μmol/kg/min) plasma Ca fell to significantly lower levels (P < 0.01) during simultaneous infusions of S than in the absence of exogenous S, while the magnitude of PTH responses was similar. The results do not support a role of somatostatin on basal PTH levels and on PTH responses to β-adrenergic agonists or hypocalcaemia under conditions, in which S markedly lowers IRI levels and IRI responses to ISO. However, S apparently reduces Ca mobilisation during abrupt hypocalcaemia.

EFFECTS OF NEONATAL TREATMENT WITH OESTROGEN AFTER OVARIECTOMY ON DIURNAL PERIODICITIES IN PLASMA LEVELS OF PROLACTIN, THYROTROPHIN AND CORTICOSTERONE IN ADULT RATS

1980 ◽  
Vol 86 (2) ◽  
pp. 319-327 ◽  
Author(s):  
E. R. KÜHN ◽  
E. J. NOUWEN ◽  
L. NIEUWBORG ◽  
W. HEYNS ◽  
F. BERTIAU
Keyword(s):  
Plasma Levels ◽  
Post Partum ◽  
Later Life ◽  
Significant Negative Correlation ◽  
High Plasma ◽  
Plasma Prolactin ◽  
Adult Rats ◽  
High Incidence ◽  
Increased Susceptibility

Rats were ovariectomized 2–4 h post partum and injected with oil or 100 μg oestradiol benzoate (OB). At 65 days of age, they were decapitated at various times and circadian plasma levels of prolactin, TSH and corticosterone were measured. Rats injected with OB had a significantly raised mean concentration of plasma prolactin, whereas levels of TSH and corticosterone did not differ from those of control rats. Plasma levels of corticosterone and prolactin were positively correlated both in oil-treated controls and oestrogenized rats. A small but not significant negative correlation existed between the levels of TSH and corticosterone in oil-treated control rats. This correlation became positive in rats neonatally injected with OB. Prolactin and TSH were positively correlated in oestrogenized rats but no correlation was found in control animals. It was possible to fit the diurnal variations of all hormones in oil-treated control and OB-injected rats to a significant sinusoidal curve. The acrophase for prolactin, but not for TSH and corticosterone, shifted significantly from 22·30 h in control rats to 14·69 h in oestrogenized rats. In oil-treated control rats, the acrophases of prolactin and corticosterone differed significantly by about 12 h from the TSH peak. In rats injected neonatally with OB, however, no difference between the acrophases of the hormones was seen. It was, therefore, possible that the shift in prolactin release and the high plasma levels were both mediated by mechanisms which are common to TSH and prolactin and whose increased susceptibility is oestrogen-dependent. The role of this abnormal phasing relationship between prolactin, corticosterone and TSH which occurred in the oestrogenized rats is discussed in relation to the high incidence of various spontaneous or induced tumours which occur during later life in these rats.

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