Calcitonin Treatment Research Articles

Effects of parathyroid hormone and calcitonin on carbonic anhydrase location in osteoclasts of cultured embryonic chick bone.

The ultrastructural location of carbonic anhydrase has been examined in osteoclasts of cultured embryonic chick metatarsi. In untreated cultures and in those to which parathyroid hormone (PTH) was added, the enzyme was found in close association with the plasma membrane of the ruffled border. After brief calcitonin treatment (10 min) the ruffled border disappeared and the association of carbonic anhydrase with the plasma membrane was diminished. The results indicate that the hormones employed act directly on embryonic bone to alter osteoclast structure and the intracellular location of carbonic anhydrase.

Pulp response after calcitonin treatment of direct exposures in the dog

The hypocalcemic hormone, calcitonin, was used in directly pulp-capped teeth to determine whether or not calcitonin promoted healing. Two dogs were used. Twelve teeth received the calcitonin; nine control teeth were prepared, and five were treated with calcium hydroxide. Calcitonin did not increase either the rate of healing or the amount of secondary dentin formed. Calcitonin reduced the degree of inflammation in the treated tooth pulps.

Hormonal regulation of protein synthesis in cultured kidney cells

Calcitonin-induced changes in gene expression at the level of protein synthesis were examined in cultured porcine kidney cells (LLC-PK 1) using two-dimensional gel electrophoresis of [ 35S]methionine-labeled polypeptides. Twelve intracellular polypetides showed reproducible changes in the relative intensity of labeling. From that set of polypeptides ten showed an increase and two a decrease in the labeling intensity after calcitonin treatment. One of the induced polypeptides was identified as plasminogen activator and two others were shown to be related to cytokeratins. The labeling of two induced and well-separated polypeptides of 70K and 95K M r was quantitated and correlated with an increase in secretion of plasminogen activator.

Decreased responsiveness to chronic salmon calcitonin treatment in rat kidney and calvaria studied using quantitative enzyme cytochemistry.

Growing rats were treated with daily im doses of salmon calcitonin (sCT) (2, 15 and 100 IU/kg) for various times (1, 4 and 24 weeks). The effects on intracellular enzyme activities in bone and kidney were monitored using quantitative cytochemical methods previously developed for the identification of specific target tissue responses to calcitonins. The basal alkaline phosphatase activities in both kidney and bone were decreased by long-term treatment at all time periods and doses tested. No change was noted in basal Ca ATPase activities in kidney after treatment. The capacity of target tissues in chronically treated and control rats to respond to an acute iv dose of sCT was also compared. Acute provocation tests in treated and control rats showed that the renal alkaline phosphatase response was decreased in the rats receiving long-term treatment. Moreover, the direction of response was reversed in chronically treated rats when bone alkaline phosphatase and renal Ca-dependent ATPase activity was measured after acute provocation with sCT, i.e. bone alkaline phosphatase was stimulated instead of being inhibited and renal Ca ATPase was inhibited instead of being stimulated. The application of quantitative cytochemical techniques has demonstrated intracellular changes in enzyme activities in both kidney and bone. The impaired sCT responsiveness can be detected at shorter times of treatment (1 week) and lower doses (2 IU/kg) than has previously been possible by measurement of indices of mineral metabolism in plasma or urine.

Treatment of osteoporosis with calcitonin, with and without growth hormone

A 24 month randomized parallel study of the treatment of postmenopausal osteoporosis with calcitonin alone v calcitonin alternating with growth hormone (combined treatment) was conducted. Each group received 1000 mg daily of oral calcium supplements. The rate of change in total body calcium for the combined and calcitonin groups was +1.68%/yr and +1.33/yr, respectively ( P < .05). However, the difference in the two groups was not statistically significant. Further, the total body calcium level did not increase after 12 to 18 months of treatment. There was a significant difference in the rates of change of bone mineral content (BMC) of the radius for the two groups, with a loss of BMC in the combined treatment group ( F = 4.80, P < .05). Calcitonin treatment is effective in producing an increment in bone mass. The addition of growth hormone to this regimen appears to have a deleterious effect on cortical bone mass.

The effects of calcitonin, parathyroid hormone and prostaglandin E 2 on cyclic AMP levels of isolated osteoclasts

1. 1. Cyclic AMP (cAMP) levels were measured in both isolated and attached osteoclasts. 2. 2. The level of cAMP was 0.1 pmol/10 5 osteoclasts. 3. 3. No change in cAMP level of osteoclasts could be detected following calcitonin treatment. 4. 4. Parathyroid hormone (PTH) and prostaglandin E 2(PGE 2) treatment stimulated cAMP production in proportion to alkaline phosphatase levels and divergent to acid phosphatase levels. This indicates that osteoblasts, not osteoclasts, were responsive to PTH and PGE 2.

Calcitonin treatment and plasma prolactin levels in pregnant and lactating ewes.

The intravenous injection of a physiological dose of salmon calcitonin (0.5 microgram/kg bw) in 5 ewes on day 125 of gestation induced a slight but significant hypocalcaemia. It had no significant effect on plasma prolactin levels. Ten days after parturition the same dose of salmon calcitonin given in a similar manner to 5 ewes has no effect on suckling-induced prolactin release, although it significantly decreased plasma calcium concentration. This demonstrates that short-term changes in plasma calcitonin concentration have no effect on basal plasma prolactin concentration or on suckling-induced prolactin surge in ewes.

Effect of calcitonin treatment on the natural course of bone demineralization in Paget's disease.

Numerous studies have been done to determine the effects of long term calcitonin (CT) treatment on Paget's disease of bone, but very few studies have been undertaken to determine the long term CT effect on nonpagetic bone in man. Because of conflicting results of the CT effect on osteoporosis and also for further understanding of the role of CT on normal bone, we conducted a longitudinal prospective study on the effect of CT treatment on nonpagetic bone in patients with Paget's disease using monoenergetic photon absorptionmetry method. Patients with Paget's disease were given salmon CT daily for a period of 3 yr, the bone mineral content (BMC) in the nonpagetic distal radius was measured periodically for 3 yr, and the data were compared with those of the control group of patients with Paget's disease not receiving CT treatment. It was found that the control group showed a persistent gradual decrease in BMC during the study period of 3 yr, but the CT-treated group showed no decrease in BMC during the 3-yr period of treatment. Our study suggests that CT treatment may delay the natural course of bone demineralization with aging in patients with Paget's disease.

Effects of salmon calcitonin on synthesis and mineralization of collagen in rats.

The effects of salmon calcitonin (CT) on collagen metabolism and mineral deposition in fractures and intact femora, and on collagen metabolism in healing skin wounds and intact skin have been studied in young male rats. Serum calcium and serum phosphorus were reduced 3 h after the daily subcutaneous CT injection (3 MRC-U/kg body weight), whereas a rebound increase in the serum levels of both minerals was observed at 24 hours after the injection. CT had an early transient inhibitory influence on the collagen synthesis, and this resulted in a reduced total content of collagen in bones and skin specimens from treated rats compared to controls. The concentration of collagen in bone and skin was, however, increased in treated animals compared to controls after prolonged CT administration. Following an early transient increase, the incorporation of strontium-85 into the fractured bones was impaired after 30 days of CT treatment. This resulted in a reduced mineral concentration in the fractures of treated rats compared to controls in the last part of the experiment. The recorded effects of CT treatment, which were most pronounced in healing fractures and intact skin specimens, may be interpreted as an inhibitory influence of CT both on synthesis, mineralization and degradation of collagen.

Ultrastructural immunocytochemical localization of carbonic anhydrase in normal and calcitonin-treated chick osteoclasts.

Carbonic anhydrase was localized in osteoclasts by light and electron microscopy using a preembedding peroxidase-antiperoxidase staining method. Osteoclasts on the endosteal surface of the metatarsi of calcitonin-treated and untreated (control) chicks were studied. A positive staining reaction was seen in the cytosol, in the Golgi apparatus, in and on vesicles, on the plasma membrane of the ruffled border, and on the bone surface beneath control osteoclasts. After calcitonin treatment, positive staining reactions were seen at the same sites except that staining was absent on the plasma membrane and endosteal bone surface. The morphology of osteoclasts from calcitonin-treated chicks was indicative of cell inactivity. The carbonic anhydrase which was bound to the plasma membrane of the ruffled border is appropriately arrayed for hydrogen ion secretion and subsequent mineral dissolution. The presence of the enzyme within lysosomelike vesicles and on the endosteal surface beneath active cells suggests that it may be released into the resorbing zone along with the lysosomal hydrolases. The function of the extracellular enzyme is also unknown.

Calcitonin stimulates bone formation when administered prior to initiation of osteogenesis.

The influence of calcitonin (CT) on various stages of bone formation was investigated. A demineralized collagenous bone matrix-induced bone forming system in rats was used to temporally segregate chondrogenesis and osteogenesis. Administration of CT (15 Medical Research Council Units [MRCU]) daily) at the initiation of matrix-induced bone formation (BF) resulted in a 76% stimulation of BF as measured by 45Ca incorporation and alkaline phosphatase activity. This increase was due, in part, to a stimulation of cartilage and bone precursor cell proliferation monitored by the rate of [3H]thymidine incorporation and ornithine decarboxylase activity. Chondrogenesis on day 7 as measured by 35SO4 incorporation was increased by 52% with CT treatment. To rule out the possibility of a secondary response due to parathyroid hormone, similar studies were done in parathyroidectomized animals and CT stimulation of BF was still observed. However, when CT injections were started after cartilage formation (day 8) there was no stimulation of BF but a significant decrease in 45Ca incorporation was observed. These results indicate CT has two actions: (a) when CT is administered during the initial phases of bone formation, it increases BF due to a stimulation of proliferation of cartilage and bone precursor cells; and (b) when CT is administered after bone formation has been initiated, subsequent bone formation is suppressed.

Calcitonin receptors in a cloned human breast cancer cell line (MCF 7)

A human breast cancer cell line, MCF 7, is shown to possess a specific calcitonin receptor and calcitonin responsive adenylate cyclase, and calcitonin treatment results in activation of cyclic AMP-dependent protein kinase. Studies with several analogues of calcitonin show that the receptor and adenylate cyclase response preserve the ability to discriminate among the structure-function relationships of the calcitonin molecule. The same cell line has been shown recently to possess a receptor for the steroid hormone, 1,25(OH) 2-vitamin D. Coexistence in MCF 7 cells of receptors for two calcium-regulating hormones may be related to the osteoclast-like properties of these cells.

SPINAL-CORD SYNDROME DUE TO NON-COMPRESSIVE PAGET'S DISEASE OF BONE: A SPINAL-ARTERY STEAL PHENOMENON REVERSIBLE WITH CALCITONIN

A 76-year-old man had progressive low back pain, leg weakness, and sensory loss. Radiology showed changes consistent with widespread Paget's disease, but no cord compression or involvement of nerve roots was detected by myelography or computerised axial tomography. His symptoms were relieved within 12 days of starting 100 MRC units of subcutaneous salmon calcitonin and recurred when calcitonin was discontinued for 5 days. The improvement continued on calcitonin treatment for 1 year, with falls in serum alkaline phosphatase and urinary hydroxyproline excretion. It is suggested that calcitonin treatment, in reducing the abnormally high metabolic activity of the diseased bone, and hence its vascular perfusion, allows more blood to reach the spinal cord.

Effects of calcitonin in a case of congenital hypophosphatasia: 42

A female infant with congenital limb deformities developed craniotabes and x-ray revealed rachitic metaphyses. Initial biochemistry showed serum calcium 11.6 mg%, phosphate 7.8 mg%, alkaline phosphatase 6 King Armstrong units. Subsequent alkaline phosphatase values were persistently low (range 0.9-2.7 K.A.Units) and a diagnosis of the severe form of congenital hypophosphatasia was made supported by levels of alkaline phosphatase in cultured cells and tissues. Family studies showed a pattern consistent with autosomal recessive inheritance. At the age of three months she was irritable, feeding poorly and failing to thrive. Porcine calcitonin 50 M.R.C. Units/day was given intramuscularly for three weeks. Within two weeks hardening of the skull bones was noted with disappearance of craniotabes which recurred, however, six weeks later. X-rays over the following months showed increased mineralisation and periosteal new bone. Metabolic balance studies for calcium, phosphorus and magnesium before, during and after calcitonin therapy showed an alteration from an average positive calcium balance of 15 mg/day to 103 mg/day with treatment. No consistent change in phosphate or magnesium balance was evident. At the time of calcitonin treatment evidence of craniosynostosis developed. The child died of chest infection at 14 months of age. In this case of severe congenital hypophosphatasia there is evidence of clinical, radiological and biochemical response to calcitonin. Treatment may have precipitated craniosynostosis and failed to alter the grave prognosis. It is possible that smaller doses of calcitonin over a longer period of time would be safer and more effective.

The influence of calcitonin on the plasma and urine phosphate changes produced by parathyroid hormone.

The influence of calcitonin (CT) on parathyroid hormone-induced changes in plasma phosphate, urine phosphate, plasma32P and32P specific activity (32P-S.A.) was studied using thyroparathyroidectomized rats. Radiophosphorus was injected at either 10 h (32P-10 h) or 8 days (32P-8 d) before commencing hormonal treatment. In order to produce consistent plasma32P-S.A. changes in rats treated with parathyroid hormone (PTH) alone, we maintained all animals for 48 h prior to hormone injection on a closely regulated carbohydrate intake (both quantity of food and time of feeding). Rats were then fasted 10 h prior to injection of PTH (0.01 U/g body weight/h), or CT (0.1 mU/g body weight/h), or both hormones injected simultaneously. Under these conditions, PTH produced a rise (relative to controls) in plasma32P-S.A. (-8 d) during an 8-h experimental period, while plasma32P-S.A. (-10 h) fell. Calcitonin treatment alone did not affect plasma32P-S.A., regardless of when32P was administered. When both hormones were injected concurrently, CT augmented the PTH-induced hypophosphatemia and magnified the fall in plasma32P levels, but the addition of CT did not affect PTH-induced changes in either renal calcium or phosphate excretion. However, the PTH-induced changes in plasma32P-S.A. were abolished. These data could not be explained by the opposing effects of the two hormones on rates of bone resorption. We interpret the results as adding support to the postulate that calcitonin moves phosphate into and prevents its loss from bone and bone fluid.

Divalent cation-phospholipid complexes and tumor growth inhibition.

Growth inhibition of DS sarcomas provoked by calcitonin treatment is accompanied by an increase of calcium and magnesium in the phospholipid fraction. Changes in tumor cell membrane characteristics reflected in ionic or molecular transport modifications seem to be involved in the growth impairment phenomenon.

CALCITONIN TREATMENT OF PAGET'S DISEASE

CALCITONIN TREATMENT OF PAGET'S DISEASE

Calcitonin and prostaglandin system

It has been repeatedly reported that calcitonin treatment in various diseases with high levels of bone resorption is associated with an antalgic effect, the mechanism of which is far from been clarified. The involvment of prostaglandins and thromboxane in hyperalgesia prompted us to consider the possibility that calcitonin induces its antalgic effect through on interference with prostaglandin and thromboxane synthesis. Guinea pig lung which, perfused with arachidonic acid releases in the perfusate a mixture of thromboxane and prostaglandins, each measurable on a separate smooth muscle tissue (rabbit aorta and rat stomach strip), was used as a test system. Calcitonin added to the perfusion fluid was shown to inhibit the synthesis both of prostaglandins and thromboxane. The concentration of calcitonin (salmon) which decreased the activity of arachidonic acid by 50% (KB) was 0.27 and 0.40 nmoles for prostaglandins and thromboxane respectively. In the experiments carried out using Ca ++ concentration in the perfusion fluid 50% higher than normal (0.28 g/l), calcitonin inhibition of prostaglandins and thromboxane was unchanged (KB = 0.23 and 0.36 nmoles respectively). The reported results by indicating that calcitonin has an influence on cyclooxygenase as indomethacin (used as reference standard) whose it is well known the activity at this level, support the interesting possibility that the antalgic effect consequent to the treatment with the hormone is due, at least in part, to a mechanism involving the prostaglandin synthetase system.

The effect of porcine calcitonin on plasma calcium in Channa punctatm Bloch

The effect of porcine calcitonin on the plasma calcium of the freshwater Indian murrel, Channa punctatus Bloch has been studied. An injection of 200 MRC mU of porcine calcitonin was given intraperitoneally, while control fish received the gelatin carrier. A significant hypocalcaemia was noted I h after calcitonin treatment (P &lt; 0.001). The plasma calcium had returned to the normal level by the 6th h.

Bone matrix studies Influences of parathyroid extract, calcitonin, and cholecalciferol and of rickets and its treatment

Bones from young rats were incubated with radioactive glucosamine and proline. The concentrations and specific activities of matrix glycosaminoglycan fractions, prepared by a cetylpyridinium chloride method, and the specific activity of insoluble collagen hydroxyproline were determined. Acute parathyroid extract treatment increased labelling of hyaluronic acid and a glycopeptide fraction. These effects were partially blocked by calcitonin treatment which had no effect by itself. Parathyroid extract inhibited collagen synthesis and this effect was not blocked by calcitonin. Effects of these two hormones on labelling of chondroitin sulfate fractions were more variable. Vitamin D-3 caused an increase in labelling of all matrix fractions measured in bone from thyroparathyroidectomized rats, but its stimulating effect upon collagen synthesis was blocked by paratyroid extract. Bones from rats made rachitic on a phosphorus and vitamin D-deficient diet were incubated in vitro with radioactive glucosamine and proline. Over a three-week period rachitic bone exhibited a progressive fall in concentration and labelling of a glycopeptide-hyaluronic acid fraction, while pair-fed animals supplemented either with phosphorus alone or with phosphorus and vitamine D-3 not only remineralized their bones, but the bones showed a pronounced increment in concentration and labelling of this fraction. Both treatment regimens also enhanced chondroitin sulfate and collagen labelling.