Synthetic Calcitonin Research Articles

Efficacy of calcitonin for treating acute pain associated with osteoporotic vertebral compression fracture: an updated systematic review.

Acutely painful osteoporotic vertebral compression fractures are associated with hospitalization and mortality in older adults. Calcitonin may be an alternative to opioid or nonopioid analgesia for treating acute compression fracture pain in emergency and primary care settings. This review summarizes pain, function, and adverse events associated with calcitonin. We searched MEDLINE, EMBASE, The Cochrane Library, clinical trials registries, and reference lists of included studies. Eligible studies evaluated the effect of synthetic calcitonins (salmon, eel, and human) on pain scores in adults ≥60 years old with a recent atraumatic compression fracture. Two reviewers screened studies, extracted data, and allocated bias in duplicate. A random effects meta-analysis evaluated standard mean difference (SMD) and heterogeneity (I2). Of 1,198 articles screened, 11 were included (9 in the meta-analysis). Treatment lasted from 14 days to 6 months. Pain was lower in the salmon calcitonin group (100-200 IU IM or NAS, daily) than the control group with high certainty of evidence at week 1 (SMD, -1.54; 95% confidence interval [CI], -2.02 - -1.06; I2 = 52%), representing a number needed to treat of two. The analgesic efficacy of salmon calcitonin at 4 weeks was unclear due to substantial heterogeneity. There was low certainty evidence that calcitonin did not increase the overall risk of adverse events, including nausea and vomiting (risk ratio, 2.10; 95% CI, 0.87-5.08; I2 = 47%). Calcitonin is beneficial and appears safe for treating acute pain associated with compression fractures. Further studies may improve the certainty of evidence.

Development of a system for measuring calcitonin in the stingray Dasyatis akajei (a cartilaginous fish): the possible involvement of stingray calcitonin in gonadal development

To elucidate the physiological role of calcitonin (CT) in stingrays (cartilaginous fish), an enzyme-linked immunosorbent assay (ELISA) system using a specific antibody against stingray CT has been developed. Synthetic stingray CT was subcutaneously injected into mice four times—once every 2 weeks—together with an adjuvant. We purified the IgG antibody fraction using the protein A affinity chromatography from collected antiserum. Evaluating the antibody titer, we found the antibody’s optimum dilution ratio to be 600 times. Competitive ELISA has been developed using the antibody diluted 600 times. Our antibody did not cross-react with teleost CTs and muscle extraction, but cross-reacted with stingray plasma and the extract of the ultimobranchial gland, the secretary organ of stingray CT. Using this ELISA, we measured the plasma CT level in stingrays and examined its correlation with several mineral concentrations. Plasma CT did not show significant correlation to calcium, magnesium, inorganic phosphorus, sodium, chlorine, or urea, although there was a correlation among the factors involved in osmoregulation, such as sodium, chlorine, and urea. On the other hand, plasma CT was significantly correlated to body weight and length. Furthermore, there was a significant correlation between plasma CT and gonad weight. Since plasma CT was correlated with the weight of liver, which is involved in the synthesis of egg yolk protein, we examined the influence of 17β-estradiol (E2) on CT secretion. After E2 injection, the plasma CT level increased significantly. This is the first study to demonstrate that E2 induced plasma CT secretion in cartilaginous fish.

Response of trabecular bone, thyroid C and follicular cells to synthetic salmon calcitonin in middle-aged orchidectomized male rats.

In contrast to studies in women, male osteoporosis is poorly understood and strictly related to advancing age. Among the first antiresorptive substances used in the prevention and treatment of osteoporosis is calcitonin (CT), a hypocalcemic hormone that potently inhibits osteoclastic bone resorption. Natural CT is produced and secreted by thyroid C-cells. The other endocrine population of thyroid cells produces thyroid hormones (TH), which also affect bone turnover. The aim of this study was to evaluate the influence of salmon CT on trabecular bone microarchitecture with special reference to effects on the structure and function of both CT- and TH-producing thyroid cells in orchidectomized (Orx) middle-aged rats. Twenty-four male Wistar rats aged 15months were randomly divided into Orx and sham-operated (SO) groups. One group of Orx animals received (s.c.) synthetic salmon CT (Orx+CT; 100IUkg-1 b.w.) subcutaneously every second day for 6 weeks. The second Orx group and SO rats were given the same volume of vehicle alone by the same schedule. Trabecular bone histomorphometrical parameters were: cancellous bone area (B.Ar), trabecular thickness (Tb.Th), trabecular number (Tb.N) and trabecular separation (Tb.Sp) were obtained with an ImageJ public-domain image-processing program. The peroxidase-antiperoxidase method was applied for localization of CT in C-cells. Anti-human CT antisera served as the primary antibodies. For immunohistochemical characterization of vascular endothelial growth factor (VEGF) in thyroid tissue, rabbit antisera against human VEGF, served as primary antibodies. CT-immunopositive thyroid C-cells, thyroid follicular epithelium, interstitium and colloid were evaluated morphometrically. Blood serum samples were analyzed for CT, osteocalcin (OC), and thyroxine (T4 ), and calcium (Ca2+ ) concentration was determined in urine samples. Salmon CT application significantly increased B.Ar, TbTh and TbN, but markedly decreased Tb.Sp. Administration of exogenous CT significantly decreased mean volume (Vc) and relative volume density (Vv) of thyroid C-cells in relation to both SO and Orx groups. The Vv of the colloid was higher, whereas the VV of the follicular epithelium was lower after CT treatment compared with Orx alone. CT treatment markedly elevated serum CT, whereas serum OC, T4 and urinary Ca2+ concentrations were lower than in the Orx group. These results indicate that salmon CT stimulates trabecular bone microarchitecture, strongly inhibits thyroid C-cells and changes the structure of the thyroid gland, indicating hypoactivity.

Assessment of Changes in Mineral Components in Bone Repair After Laser Therapy and Pharmacotherapy by μ-EDX: A New Potential Tool in Medical Diagnostics

Energy-dispersive microspectroscopy X-ray fluorescence (μ-EDX) is a non-destructive, multi-element analytical method. This technique is able to quickly perform a qualitative and semiquantitative evaluation of several sorts of samples with minimal or no previous sample preparation. Low-level laser therapy (LLLT) and synthetic calcitonin have been used to promote osteogenesis and to accelerate the repair process in bone lesions. The aim of this study was to evaluate qualitatively and semiquantitatively biochemical changes in the composition of the bone tissue during the repair process in rats by the analytical measurement tool, μ-EDX. We created a surgical bone defect in 60 Wistar rats with induced osteoporosis treated with calcitonin, LLLT, and a combination of both. The animals were divided into four groups. In groups Ca and CaLa, calcitonin, 2 UI/kg, i.m., was administered on alternate days. LLLT (20 J/cm(2), 10 mW, 830 nm, 6 sec, every 48 hours) was applied to the La and CaLa groups. The experimental times were 7, 14, and 21 days. After euthanasia, the specimens were measured for inorganic chemical compounds with μ-EDX. This study showed that it was possible to perform qualitative and semiquantitative analysis of inorganic components of biological samples with this technique during the bone repair process using different experimental treatment protocols. CaLa specimens showed the relation between calcium and phosphorus (Ca/P) closest to stoichiometric hydroxyapatite.

Calcitonin delays the progress of early-stage mechanically induced osteoarthritis. In vivo, prospective study

Introducing new or testing existing drugs in an attempt to modify the progress of osteoarthritis (OA) is of paramount importance. This study aims to determine the effect exerted by Calcitonin on the progress of early-stage osteoarthritic lesions. We used 18, skeletally mature, white, female, New Zealand rabbits. OA was operatively induced in the right knee of each animal by the complete dissection of the anterior cruciate ligament, complete medial meniscectomy and partial dissection of the medial collateral ligament. Postoperatively, animals were divided into two groups. Starting on the ninth postoperative day and daily thereafter, group A animals (n=9) received 10IU oculus dexter (o.d.) of synthetic Calcitonin IntraMuscularly (I.M.); group B animals (n=9) received equal volume of saline o.d. Three animals from each group were sacrificed at 1, 2 and 3 months following treatment's initiation. The extent and the grade of OA were assessed macroscopically, histologically and by radiographs, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI)-scans. The Osteoarthritis Research Society International (OARSI) score, incorporating histological and macroscopic information, was calculated for each knee. Osteoarthritic changes in group A animals were less severe and progressed less rapidly when compared with those of group B animals (sham). This difference was statistically significant in the first and second month (P=0.05), but not in the third month (P=0.513). I.M. administration of Calcitonin seems to delay the progress of early-stage osteoarthritic lesions induced by mechanical instability in a rabbit experimental model.

Calcitonin treatment for calcifying tendinitis of the shoulder

In an open, uncontrolled trial, the clinical and radiological responses to calcitonin therapy in the treatment of acute calcifying tendinitis of the shoulder were investigated. A total of 35 patients (38 shoulders) were enrolled. Each patient was injected with 10 U synthetic calcitonin intramuscularly twice a week. The mean number of injections was 6.0 (range, 1–16). At the end of the treatment period, 33 shoulders (87%) were pain-free. In 28 shoulders (74%), the localized pain disappeared within 2 weeks of the start of treatment. In 25 shoulders (66%), the clinical results were rated as good, with complete pain relief and sufficient recovery in the activities of daily living (ADL) and active range of shoulder joint motion (ROM). On the contrary, in 4 shoulders (10%) pain persisted, requiring alternative treatment. In 28 shoulders (74%), the pre-existing calcific deposits were remarkably reduced or had disappeared. Radiologically, the shoulders with fluffy-type deposits had greater pain relief and ROM recovery than those with defined-type deposits. However, there was no correlation between the clinical results and localized region or size of deposits. In 19 cases (50%) where the calcified deposits had completely disappeared, the shoulder had become pain-free, and in all of them except two cases there was complete recovery of ROM. No patient developed clinical complications. These results suggest that calcitonin treatment may be useful for calcifying tendinitis of the shoulder, and that this therapy results in both clinical and radiological improvement in this condition.

Comparison of the analgesic efficacy of pamidronate and synthetic human calcitonin in osteoporotic vertebral fractures: a double-blind controlled study

Our aim was to compare the analgesic efficacy of pamidronate (PAM) and synthetic human calcitonin (CT) in intravenous infusion for recent painful benign vertebral compression in a randomised prospective double-blind study. Twenty-seven patients aged 49-85 years with painful benign non-traumatic vertebral compression were included in the study. They received either PAM (1 mg/kg) or synthetic human CT (1.5 mg) as an intravenous infusion. Pain and functional disability were evaluated before infusion, and 4 and 30 days afterwards. The pain score assessed on a visual analogue scale at day 0 was 5.94+/-2.47 in patients treated with PAM and 6.27+/-2.50 in patients treated with CT (p=0.74); at day 4, 4.8+/-2.80 with PAM vs 3.9+/-2.68 with CT (p=0.37); and at day 30, 3.6+/-3.13 with PAM vs 3.10+/-2.76 with CT (p=0.70). Spinal function scores were 18.21+/-3.17 at day 0 in patients treated with PAM vs 17.23+/-4.42 in patients treated with CT (p=0.69) and at day 30, 13.7+/-5.36 with PAM vs 12.33+/-3.22 with CT (p=0.68). We found no advantage of PAM over CT in a single intravenous infusion for the treatment of painful recent benign vertebral compression. Since CT is ten times less costly, its use should be preferred.

Exogenous Calcitonin Suppresses Growth Fraction of Thyroid C Cells

Calcitonin (CT) is a peptide hormone synthesized and secreted by the para-follicular (C) cells of the thyroid. Little is known about the mechanisms controlling proliferation of C cells by other humoral factors including CT, and there is no report that CT suppresses C cell proliferation. The effects of short-term administration of CT on C cell growth fraction were analyzed using BrdU and CT double immunohistochemical method in the rat thyroid. Continuous administration of 0.4 IU/kg and 40 IU/kg synthetic salmon CT for 14 days induced dose-dependent suppression of BrdU labeling number of C cells without decrease of C cell to the total thyroid follicular cell ratio. These results suggest that exogenous CT may induce negative feedback to C cell proliferation in the thyroid.

A new therapeutic approach in medullary thyroid cancer treatment: Inhibition of oncogenic RET signaling by adenoviral vector-mediated expression of a dominant-negative RET mutant

Background. Mutations in the RET proto-oncogene that result in constitutive tyrosine kinase activity are the underlying cause for the development of medullary thyroid cancer (MTC). To investigate an alternative strategy in MTC treatment, we took advantage of a dominant-negative RET (dn-RET) mutant, Ret51HSCR32, which inhibits oncogenic signal transduction by retaining the oncogenic RET protein in the endoplasmic reticulum, thereby reducing the amount of oncogenic RET protein from the cell surface. Methods. We constructed an adenoviral (Ad) vector expressing dn-RET under control of the C-cell specific synthetic calcitonin promoter TSE2.CP1 (AdTSE2.CP1-RET51HSCR32) and investigated the effect of dn-RET on cell growth of MTC-derived TT cells. Results. Analysis of the subcellular localization of endogenous oncogenic RET protein showed a significant dominant-negative effect of Ad vector-delivered dn-RET in TT cells, resulting in a strong inhibition of cell viability. The observed effect is partially dependent on growth inhibition and possibly apoptosis induction. Conclusions. In the present study, growth of human MTC cells was successfully inhibited by Ad vector-mediated delivery of RET51HSCR32, suggesting that inhibition of oncogenic RET receptor tyrosine kinase expression by a dn-RET mutant might be a powerful approach for in vivo therapy of MTC. (Surgery 2002;132:991-7.)

Multicenter collaborative study to calibrate salmon calcitonin by bioassay and high-performance liquid chromatography: establishment of the third international standard

Salmon calcitonin (sCT) is widely used therapeutically in the treatment of patients with postmenopausal osteoporosis, Paget’s disease, and some forms of hypercalcemia. Preparations of synthetic calcitonin peptides of high purity and reproducibility are now routinely produced and physicochemical methods, particularly reverse-phase high-performance liquid chromatography (RP-HPLC), are replacing the in vivo biological assay for monitoring and calibration. Although the bioassay is no longer required for routine batch control in Europe, calcitonin bioassays are still required in some countries and in the development of new products. Stocks of the Second International Standard (IS) for salmon calcitonin are now depleted and, to replace it with a new calibrant, an international collaborative study was organized in which the aims were to: determine the activity of the candidate sCT by in vivo bioassay in terms of the second IS; assess the stability of the preparation after accelerated thermal degradation; estimate the purity of the ampouled candidate preparation; and determine the sCT content in gravimetric units by HPLC. The HPLC data in terms of ampoule content were in good agreement giving an estimate of 23.1 (coefficient of variation [CV] 3.8%) μg per ampoule. The HPLC chromatograms revealed a small, but detectable, degree of heterogeneity, which possibly occurred during the formulating or ampouling procedures, resulting in a reduction in monocomponent content (purity) from 96% to 92%. The biological activity of the ampoule contents in international units (IU) was calculated from the mass value and the internationally agreed-upon figure of 6000 IU/per mg for the specific activity of salmon calcitonin. This gave a value of 138 IU per ampoule, which was in good agreement with the biological assay estimate (140 IU per ampoule). The preparation of sCT was subsequently adopted as the Third International Standard by the World Health Organization with an assigned content of 138 IU per ampoule.

Progression of steroid-associated osteoporosis after heart transplantation

Background. Osteoporosis has been recognized as an important side effect of long-term and of pulsed steroid application after heart transplantation. Methods. In June 1989 a prospective clinical trial was started to study bone demineralization by quantitative computed tomographic scan. All patients received vitamin D and calcium. In group I (n = 30) synthetic calcitonin (40 Medical Research Council Standard Units subcutaneously per day was administered in 14-day cycles, whereas group II patients (n = 31) received a placebo preparation. Repeat trabecular and cortical quantitative computed tomographic scans of the thoracic (T12) and lumbar spine (L1, L2, L3) were obtained within 48 weeks after heart transplantation. Results. Expressed as the means of T12, L1, L2, and L3, trabecular bone density decreased significantly from 100 ± 24 to 79 ± 29 mg/mL within 3 weeks after heart transplantation, followed by a further reduction to 67 ± 29 mg/mL after 3 months in the calcitonin group. The values for cortical bone density decreased significantly from 229 ± 37 to 202 ± 40 mg/mL (calcitonin) 3 weeks after heart transplantation. Comparable results were obtained in the placebo group. In both groups bone density remained stable thereafter. Intergroup differences were not of statistical significance. Conclusions. In heart transplant recipients progressive trabecular bone demineralization is limited to the first 3 postoperative months. Thereafter, bone density remained stable. A positive effect of synthetic calcitonin in addition to prophylactic calcium and vitamin D application could not be proved by repeat quantitative computed tomography.

Effects of calcitonin and parathyroid hormone on calcification of primary cultures of chicken growth plate chondrocytes.

Few studies have been directed toward elucidating the action of calcitonin (CT) and parathyroid hormone (PTH) on growth plate chondrocytes, cells directly involved in longitudinal bone growth and provisional calcification. In this study, primary cultures of avian growth plate chondrocytes that calcify without the supplement of beta-glycerophosphate were used to investigate the effects of synthetic human CT and 1-34 bovine PTH on (1) cell division and growth; (2) the deposition of Ca2+ and inorganic phosphate (Pi); (3) the activity of alkaline phosphatase (AP), an enzyme long associated with the mineralization process; (4) the levels of proteoglycans; and (5) the synthesis of collagens. Added continually to preconfluent cultures from day 6 until harvest, CT (1-30 nM) and PTH (0.1-1.0 nM) increased mineral deposition; the maximal increase was seen between days 18-21 at 10 nM CT (175-260%) and 0.5 nM PTH (approximately 170-280%), both p < 0.001. CT had no significant effect on cellular protein, or AP-specific activity, whereas PTH increased cellular protein, DNA, proteoglycan, and collagen content of the cultures in a dosage-dependent manner. AP activity and levels of Type II and X collagens and fibronectin in the culture medium showed a biphasic response to PTH; maximal increases were seen at 0.5 nM between days 15-18. Longer exposure (days 21-27) to PTH at higher levels (5-10 nM) caused a marked decreased in AP activity but a lesser decrease in the collagens. These results indicate that CT and PTH can act directly on chondrocytes to stimulate mineralization, but that PTH specifically stimulated cell division and synthesis of cellular and extracellular proteins by growth plate chondrocytes. The implications of these findings with regard to Ca2+ homeostasis and bone formation are discussed.

Antinociceptive effects of elcatonin, a synthetic eel calcitonin derivative, in ovariectomized animals

Antinociceptive effects of elcatonin, a synthetic eel calcitonin derivative, in ovariectomized animals

Diabetogenic effects of salmon calcitonin are attributable to amylin-like activity

During the development of synthetic calcitonins for therapeutic use in bone disease, a “diabetogenic” (hyperglycemic) effect was observed, particularly with salmon calcitonin. The effect was attributed by some to inhibition of insulin secretion. We have recently reported high-affinity (28 pmol/L) amylin-binding sites in certain areas of rat brain, and found that these sites also bind salmon but not rat calcitonin with comparable high affinity. Rat amylin and salmon calcitonin have been determined to have significant structural homology. In vitro and in vivo studies indicate that rat amylin can exert calcitonin-like effects on osteoclasts and on plasma calcium. Here we report that salmon calcitonin mimics the actions of rat amylin on skeletal muscle glycogen metabolism in vitro; it stimulates glycogenolysis and inhibits incorporation of radiolabeled glucose into glycogen (50% effective concentration [EC 50], 0.4 ± 0.11 nmol/L log and 8.4 ± 0.05 nmol/L log, respectively). In anesthetized rats salmon calcitonin, like rat amylin, rapidly increases plasma lactate concentration, followed by a slower increase in glucose concentration. Like amylin, salmon calcitonin also inhibits the insulin response to 2 mmol infused glucose (insulin increments suppressed by 52% and 57% at 10 minutes for salmon calcitonin and amylin). Other shared actions, such as suppression of appetite, stimulation of renin secretion, inhibition of gastric acid secretion, and inhibition of gastric emptying, further affirm our proposal that the exogenous peptide, salmon calcitonin, is a mimic of endogenous amylin in the rat.

Human synthetic calcitonin therapy for hypercalcemia of immobilization

We studied four children with hypercalcemia of immobilization resulting from quadriplegia. After a trial of conventional therapy, human synthetic calcitonin was given subcutaneously at 0.5 to 2.5 mg per day in divided doses. Serum calcium concentrations returned to normal levels in all patients, decreasing an average of 0.72 mmol/L (2.9 mg/dl) within 4 to 10 days. Calcitonin therapy was effective for periods varying from 3 to 10 months. In one patient a bladder stone developed without nephrocalcinosis. (J P EDIATR 1995;126:825-7)

Molecular characterization of calcitonin gene-related peptide (CGRP) in a rat medullary thyroid carcinoma cell line.

The rat medullary thyroid carcinoma cell line, CA-77, is known to express the calcitonin gene and the cell line has been used for characterization of procalcitonin. The present investigations concentrate on a molecular characterization of the calcitonin gene-related peptide (CGRP) expressed by a subclone of this cell line. The investigations demonstrate that this subclone produces significantly more CGRP compared to calcitonin. Gel chromatography of cell extracts demonstrates heterogeneity for both CGRP and calcitonin, but a significant amount of immunoreactivity elutes corresponding to the elution position for synthetic CGRP and calcitonin, respectively. The gel chromatogram for CGRP demonstrates four immunoreactive peaks with Kd of 0.42, 0.53, 0.68, and 0.85. The immunoreactive peak with Kd 0.42 elutes corresponding to synthetic rat CGRP. The four immunoreactive peaks were characterized by high pressure liquid chromatography followed by sequence analysis and mass spectrometry. The immunoreactive peak with Kd 0.42 was identified as rat alpha-CGRP as was the peak with Kd 0.53. The peak with Kd 0.68 was identified as 19-37 rat alpha-CGRP and the peak with Kd 0.85 as 28-37 rat alpha-CGRP. In summary, we find that the CA-77 cell line expresses large quantities of normally processed amidated alpha-CGRP and specific fragments thereof. However, the cell line does not express detectable levels of rat beta-CGRP. The findings indicate that the CA-77 cell line can be useful for studies of calcitonin/CGRP gene expression.

P2-104 - Gastrointestinal motor action of synthetic calcitonins in conscious dogs

P2-104 - Gastrointestinal motor action of synthetic calcitonins in conscious dogs

Parenteral Calcitonin for Metabolic Bone Disease Associated With Primary Biliary Cirrhosis

No satisfactory treatment is available for metabolic bone disease associated with primary biliary cirrhosis. On the basis of the similarities to postmenopausal osteoporosis, the rationale exists for calcitonin to be tested in clinical studies in patients with primary biliary cirrhosis-associated osteoporosis. We evaluated the effect of calcitonin on bone metabolism and mineral density in 25 women with primary biliary cirrhosis and severe osteopenia. After 6 mo of observation, patients received a synthetic calcitonin or a control treatment consisting of less than one hundredth of the recommended dose of porcine calcitonin. The two treatments were administered in sequence to each patient for two 6-mo periods, with a 3-mo washout between them, according to a crossover design. After the observation period, oral calcium supplementation was started. Bone mineral density was measured by dual-photon absorptiometry of the lumbar spine at study entry and at the beginning and the end of each treatment period. During the observation period bone mineral density fell by 3.5% whereas during the following 6 mo it increased in both the patients who received calcitonin (4.3%) and those who received the control treatment (4.9%). Conversely, after the crossover, bone mineral density decreased during both calcitonin (-2.7%) and control treatment (-2.9%). A significant difference was observed between the two periods but not between the two treatments or between the two sequences of treatment administration. In conclusion, our findings indicate that parenterally administered calcitonin for 6 mo is ineffective in halting bone loss in patients with primary biliary cirrhosis-associated metabolic bone disease, whereas calcium supplementation may have a transient beneficial effect.

Management of postmenopausal osteoporosis

More than 25% of postmenopausal women are at risk of osteoporosis. In order to avoid its consequences, it is necessary to find an appropriate prevention and/or treatment. We studied: (1) 15 postmenopausal women treated with percutaneous estradiol (50 μg/24 h) plus MPA (10 mg/10 days/month); (2) 15 postmenopausal women treated with synthetic calcitonin nasal spray at the daily dose of 100 IU; (3) 10 postmenopausal women treated with nandrolone decanoate (50 mg every 3 weeks); (4) 10 postmenopausal women treated with ipriflavone (600 mg/day); and (5) 10 postmenopausal women treated with sodium fluoride (20 mg) plus calcium (600 mg). Clinical examination, bone mass measurement (total BMD), hematochemical and urinary parameters of bone metabolism (calcium, urinary hydroxyproline, PTH) and growth factors (as IGF-I and TNF-β) were evaluated. After 6 months of therapy, a complete prevention of bone resorption was achieved. In agreement with current literature, we observed that the various therapeutic approaches have all some positive effect on BMD, with different results on pain, blood biochemical parameters and growth factors' concentrations.

Expression of calcium-binding protein regucalcin mRNA in rat liver is stimulated by calcitonin: the hormonal effect is mediated through calcium.

The involvement of a hypocalcemic hormone calcitonin (CT) in the expression of hepatic Ca(2+)-binding protein regucalcin mRNA was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb). A single oral administration of calcium chloride (100 mg Ca/100 g body weight) to rats induced a remarkable increase in the serum calcium concentration and a corresponding elevation of the liver calcium content during 120 min after the administration. Thyroparathyroidectomy (TPTX) did not cause a significant increase in the liver calcium content after calcium administration. Hepatic regucalcin mRNA level was markedly elevated by calcium administration; the level was about 180% of controls at 60 min after the administration. This increase was completely abolished by TPTX. A single subcutaneous administration of CT (synthetic eel CT; 25-100 MRC mU/100 g) to TPTX rats received oral administration of calcium (100 mg/100 g) produced a remarkable increase in hepatic regucalcin mRNA levels; the level was about 280% of controls with the dose of 25 MRC mU CT/100 g. The present finding suggests that the expression of hepatic mRNA is stimulated by CT, and that the hormonal effect is mediated through Ca2+ in rat liver.