Effects Of Salmon Calcitonin Research Articles

The effect of salmon calcitonin against glutamate-induced cytotoxicity in the C6 cell line and the roles the inflammatory and nitric oxide pathways play.

Recent evidence has shown that salmon calcitonin (sCT) has positive effects on the nervous system. However, its effect and mechanisms on glutamate-induced cytotoxicity are still unclear. The current experiment was designed to examine the effect of sCT on glutamate-induced cytotoxicity in C6 cells, involving the inflammatory and nitric oxide stress pathways. The study used the C6 glioma cell line. Four cell groups were prepared to evaluate the effect of sCT on glutamate-induced cytotoxicity. The control group was without any treatment. Cells in the glutamate group were treated with 10mM glutamate for 24h. Cells in the sCT group were treated with various concentrations (3, 6, 12, 25, and 50µg/mL) of sCT for 24h. Cells in the sCT + glutamate group were pre-treated with various concentrations of sCT for 1h and then exposed to glutamate for 24h. The cell viability was evaluated with an XTT assay. Nuclear factor kappa b (NF-kB), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), neuronal nitric oxide synthase (nNOS), nitric oxide (NO), cyclic guanosine monophosphate (cGMP), caspase-3, and caspase-9 levels in the cells were measured by ELISA kits. Apoptosis was detected by flow cytometry method. sCT at all concentrations significantly improved the cell viability in C6 cells after glutamate-induced cytotoxicity (p < 0.001). Moreover, sCT significantly reduced the levels of NF-kB (p < 0.001), TNF-α, and IL-6 levels (p < 0.001). sCT also decreased nNOS, NO, and cGMP levels (P < 0.001). Furthermore, it decreased the apoptosis rate and increased the live-cell rate in the flow cytometry (P < 0.001). In conclusion, sCT has protective effects on glutamate-induced cytotoxicity in C6 glial cells by inhibiting inflammatory and nitric oxide pathways. sCT could be a useful supportive agent for people with neurodegenerative symptoms.

The effects of salmon calcitonin on epileptic seizures, epileptogenesis, and postseizure hippocampal neuronal damage in pentylenetetrazole-induced epilepsy model in rats

Epilepsy is one of the most common neurological disorders that severely affect the life quality of many people worldwide. Excitatory–inhibitory mechanisms, oxidative stress, and also inflammation systems have been implicated in the pathogenesis of epilepsy. Recent studies have shown that salmon calcitonin (sCT) has positive effects on the nervous system. However, its relation with epilepsy is still unclear. This study aimed to investigate the effect of sCT on epileptic seizures, epileptogenesis, and postseizure hippocampal neuronal damage in pentylenetetrazole (PTZ)-induced epilepsy model in rats. The study was performed in two steps. In the first step, the effect of sCT on epileptic seizures was evaluated by using electroencephalography (EEG) in fully kindled rats. In the second step, the effect of sCT on epileptogenesis was evaluated by using the kindling process. Glutamate and gamma-aminobutyric acid (GABA), thiobarbituric acid reactive substance (TBARS), superoxide dismutase (SOD), catalase (CAT), tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1 β), and interleukin 6 (IL-6) were measured in the second group in the brain and serum. Hippocampal regions were stained with hematoxylin–eosin and toluidine blue to evaluate hippocampal neuronal damage histopathologically. Salmon calcitonin showed an antiepileptic effect in fully kindled rats and also prevented the development of epileptogenesis in the kindling process. Besides, sCT decreased glutamate and increased GABA levels. Furthermore, it reduced TBARS levels and increased SOD and CAT levels. On the other hand, it decreased TNF-α levels, IL-1 β levels, and IL-6 levels. Histopathologically, sCT decreased neuronal damage in all hippocampal regions. Our findings are the first preclinical report to show the positive effect of sCT on epileptic seizures and epileptogenesis. Further investigation is required to answer the questions raised about the probable mechanisms involved.

Effects of Salmon Calcitonin on the Concentrations of Monoamines in Periaqueductal Gray in Formalin Test

Background:The receptors of salmon calcitonin, located on certain areas of the brain such as the periaqueductal gray matter, are responsible for pain modulation.Aims:The effects of intracerebroventricular injection of salmon calcitonin on the behavioral response to pain and on the levels of monoamines in the periaqueductal gray were explored using a biphasic animal model of pain.Study Design:Animal experiment.Methods:A total of 45 male rats were divided into four groups (n=6). Salmon calcitonin was injected into the lateral ventricle of the brain (1.5 nmol, with a volume of 5 μL). After 20 min, 2.5% formalin was subcutaneously injected into the right leg claw, and pain behavior was recorded on a numerical basis. At the time of the formalin test, the periaqueductal gray area was microdialized. High-performance liquid chromatography method was used to gauge the levels of monoamines and their metabolites.Results:Intracerebroventricular injections of salmon calcitonin resulted in pain reduction in the formalin test (p<0.05). The dialysate concentrations of serotonin, dopamine, norepinephrine, 5-hydroxyindoleacetic acid, 3,4-dihydroxyphenylacetic, and 4-hydroxy-3-methoxyphenylglycol increased in the periaqueductal gray area in different phases of the formalin pain test (p<0.05).Conclusion:Salmon calcitonin reduced pain by increasing the concentrations of monoamines and the metabolites derived from them in the periaqueductal gray area.

Effect of salmon calcitonin on postoperative humeral head replacement in elderly patients

To observe the effect of anti-osteoporosis drugs on the curative effect of femoral head replacement in the elderly patients with proximal humerus fracture. From November 2012 to June 2016, 38 patients with proximal humeral fractures received humeral head replacement were divided into the treatment group and the control group according to whether the anti-osteoporosis drugs were used after the operation. The treatment group included 19 cases, of which 11 cases were three part fractures, 18 cases were four part fractures, and bone density was(0.58±0.14) g/cm²; the control group involved 19 cases, of which 10 cases were the three part fractures, 9 cases were four part fractures, and bone density was(0.58±0.11) g/cm². Periprosthetic bone mineral density(BMD) was measured at 4, 8, 12, 24 and 48 weeks after operation, and visual analogue scale(VAS) was used to evaluate the pain and Neer score was used to evaluate the function of the shoulder joint. The incisions of all patients were healed with grade A and no complications occurred. Thirty-five patients were followed up for 1 year. The bone density around the prosthesis of treatment group was higher than that of control group, the difference was statistically significant(P<0.05);VAS in two groups had no statistical significance(P>0.05). The total score and functional score of Neer in the treatment group were better than those in the control group, the difference was statistically significant(P<0.05), and there was no significant difference in pain and activity score between the two groups(P>0.05). According to the Neer score, the results of treatment group was excellent in 10 cases, good in 5 cases, fair in 3 cases;in the control group, 3 cases were excellent, 9 cases were good, and 5 cases were fair;the difference between the two groups was statistically significant(P<0.05). Artificial humeral head replacement combined with anti-osteoporosis drugs in the treatment of proximal humeral fractures in elderly patients can effectively improve the bone density around the prosthesis and restore shoulder function. The early clinical effect is satisfactory.

Effect of salmon calcitonin on RANK/RANKL/OPG osteolysis pathway in human macrophages after particle induction

Objective To explore the effect of salmon calcitonin on the receptor activator of NF-κB/receptor activator of NF-κB ligand/osteoprotegerin (RANK/RANKL/OPG) osteolysis pathway in human macrophages after particles induction. Methods The polyethylene wear particles were extracted from the periacetabular boundary membrane tissue of a patient with hip prosthesis loosening. The optimal reaction cell concentration of human macrophages to polyethylene wear particles (with a concentration of 0.1 mg/ml) was measured by methyl thiazolyl tetrazolium (MTT) assay. Particles were used to stimulate human macrophages, while salmon calcitonin with different drug concentrations was used for intervention. They were randomly divided into five groups, with six parts in each group: Group A, control group; Group B, particle group; Group C, particle+ salmon calcitonin (10-8 mol/L) group; Group D, particle+ salmon calcitonin (10-10 mol/L) group; Group E, particle+ salmon calcitonin (10-12 mol/L) group. After cocultured for 48 hours, quantitative polymerase chain reaction (qPCR) assay was used to detect the mRNA expression of RANK, RANKL and OPG in macrophages. Results After induction with particles, Group B had a higher expression in RANK and RANKL, and lower OPG expression than Group A. After salmon calcitonin intervention, the expression of RANK and RANKL were significantly decreased, and OPG expression was significantly increased. Group B had the highest RANKL/OPG rate. After drug intervention, the RANKL/OPG rate in C, D, E group were reduced. Conclusions The particles can induce the transformation of macrophages into osteoclasts. In addition to directly inhibiting osteoclast activity, salmon calcitonin prevents macrophage from differentiating into osteoclasts through modulating RANKL/RANK/OPG signaling pathway. Key words: Calcitonin; Macrophages; Receptor activator of nuclear factor-kappa B; RANK ligand; Osteoprotegerin; Osteolysis; In vitro

P032 The analgesic effect of salmon calcitonin on acute rib fractures in cystic fibrosis

P032 The analgesic effect of salmon calcitonin on acute rib fractures in cystic fibrosis

Effect of calcitonin on analgesia and expression of calcitonin receptor in periaqueductal gray

Objective To investigate the analgesic effect of salmon calcitonin(sCT)and its effect on expression of calcitonin receptor(CT-R)in periaqueductal gray(PAG). Methods Rat models of neuropathic pain were prepared by chronic constriction injury(CCI). Thermal withdrawal latency(TWL)and mechanical nociceptive threshold(MNT)were measured using hot plate test and yon Frey monofilaments test. The distribution of CT-R in PAG was detected by immunohistochemical method. CT-R protein was quantitatively determined by western blotting. Fourty male SD rats were randomized into 5 groups: normal group, sham-CCI group, CCI group, CCI plussubcutaneous sCT group, and CCI plus microinjection of sCT into PAG group. Results TWL, MNT, andexpression of CT-R in PAG showed no difference between normal group and sham-CCI group(P＞0. 05). TWL and MNT in CCI group were significantly lower than those in normal group(P＜0.05), and expression of CT-R in CCI group was significantly higher than that in normal group(P＜0.05). TWL, MNT and expression of CT-R in CCI rats increased significantly after sCT therapy(P＜0. 05), and the effect was more marked in PAG injection group than subcutaneous injection group(P＜0.05). Conclusions sCT raises the pain threshold and increase the expression of CT-R in PAG of CCI rats, while PAG injection showed more marked effect than subcutaneous injection. Key words: Calcitonin; Analgesia; Chronic constriction injury; Periaqueductal gray; Calcitonin receptor

Effects of salmon calcitonin and calcitonin gene related peptide (CGRP) on gastric mucosal barrier in stress induced rats

The aim of this investigation was to examine and compare the effects of calcitonin gene related peptide (CGRP) and salmon calcitonin (sCT) on gastric lesions and mucosal barrier components such as mucus and phospholipids in rats exposed to cold + restraint stress (CRS). Twenty-eight Wistar albino rats (150 – 200 g) used for this study were provided by the Animal Health and Research Center of Dicle University Diyarbakir/Turkey (DUSAM). The rats were withheld from feeds for 24 h; then, they were divided into four groups - each of which consisted of seven rats such as: control, stress, and CGRP +CRS and sCT + CRS groups. CGRP and sCT were administered 10 ig/kg intravenously 30 min prior to stress induction. After scarification of the rats, stomachs were examined macroscopically for ulcerative lesions. The amounts of mucus and phospholipids, which are important components of the gastric mucosal barrier, were then measured according to Corne and Baur methods. It was found that cold + restraining stress caused gastric lesions to increase, and that the application of CGRP and sCT decreased the lesions (P = 0.002, P = 0.001 respectively). Moreover, at the same time, it was determined that the decrease in the amount of mucus and phospholipids, due to the stress, was prevented significantly by administration of CGRP and sCT; for mucus as P = 0.002 and P = 0.002 respectively, for phospholipids as P = 0.002 and P = 0.002, respectively. According to our findings, CGRP and sCT were found to be effective in preventing acute hemorrhagic gastric lesions caused by stress, and in maintaining gastric mucosal barrier parameters.

Effects of salmon calcitonin in treatment of osteoporosis in patients undergoing dialysis

To investigate the prevalence of osteoporosis in patients undergoing maintenance dialysis and explore the safety and efficacy of salmon calcitonin in maintenance dialysis patients underwent with osteoporosis. Double-energy X-ray bone density meter was used on 256 patients undergoing maintenance dialysis, 126 males and 130 females, aged 60 +/- 14 (22 -79), to measure the bone mineral density (BMD) at the lumbar spine and femoral neck. 108 of them with the T values < -2.5 s were diagnosed as with osteoporosis, and then were randomly divided into 2 equal groups matched in baseline age, sex, mode of dialysis, and levels of iPTH, ALP, and BMD: control group receiving oral administration of calcium carbonate 1500 mg tid and rocaltrol 0.25 microg qn for 18 months, and experimental group, received subcutaneous injection of salmon calcitonin (50 U) three times a week in addition. The BMD levels of lumbar spine and femoral neck, and serum intact parathyroid hormone (iPTH), calcium, phosphorus, and alkaline phosphatase (ALP) were assessed before treatment and 3, 6, 12, and 18 months after treatment. (1) The osteoporosis rate of the 256 maintenance dialysis patients was 42.19%. (2) The osteoporosis rate of the 201 patients undergoing maintenance hemodialysis (MHD) was 47.76%, significantly higher than that of the 55 patients undergoing maintenance peritoneal dialysis (21.82%, P < 0.01). (3) At the end of the trial, there was a significant increase of BMD of lumbar spine and femoral neck in the experiment group compared with the control group. (4) Compared with the control group, the serum ALP, iPTH, and BGP levels 3, 6, 12, and 18 months after treatment were all significantly lower than the baseline level and those of the corresponding control groups (all P < 0.01). The serum calcium of the control group at the end of experiment increased significantly in comparison with baseline level (P < 0.05). (5) No adverse events were found after the treatment of salmon calcitonin. Salmon calcitonin effectively increases the BMD of the maintenance dialysis patients and is well tolerated.

Stimulation of salmon calcitonin on secretion of 17β-estradiol by the ovarian follicles of common carp, Cyprinus carpio

The effects of salmon calcitonin (sCT) on the secretion of 17beta-estradiol (E(2)) were examined in female common carp, Cyprinus carpio. Vitellogenic stage fish adapted to high-Ca water were i.p. injected with vehicle, sCT, human chorionic gonadotropin (hCG), or hCG plus sCT. To determine whether ovarian follicles are equipped with CT receptors, a CT binding assay was conducted. In the in vitro experiments, vitellogenic follicles were incubated with stimulators and inhibitors. Administration of sCT increased the basal and hCG-stimulated E(2) release in vivo and in vitro. Binding characteristics of [(125)I]sCT to plasma membrane preparation of carp ovarian follicles showed saturability with high-affinity (K(d)=48.48 pmol/l and B(max)=1.2 pmol/mg protein). To clarify the mechanism of E(2) production by sCT, in vitro effect of sCT and hCG on aromatase activity (conversion of testosterone to E(2)) and cytochrome P450 aromatase (P450arom) gene expression in carp ovarian follicles were investigated. Salmon CT-stimulated both aromatase activity and P450arom gene expression in ovarian follicles of carp. sCT-stimulated E(2) release by the ovarian follicles in vitro was augmented in the presence of dibutyryl cAMP. Inhibitor of protein kinase A (PKA), SQ 22536 inhibited sCT-stimulated steroid production in a dose-dependent manner. Specific inhibitor of protein kinase C (PKC), NPC-15437 dihydrochloride had no inhibitory effects on sCT-induced E(2) release. The present study indicates that sCT binds specifically to carp ovary and stimulates E(2) production by increasing the activity of cytochrome P450 aromatase and P450arom gene expression. The results further suggest that stimulatory action of sCT on E(2) production is mediated through cAMP pathway.

Effects of Salmon Calcitonin on Trabecular Microarchitecture as Determined by Magnetic Resonance Imaging: Results From the QUEST Study

The unique noninvasive MRI technique was used to assess trabecular microarchitecture at multiple skeletal sites in 91 postmenopausal osteoporotic women receiving nasal spray salmon calcitonin (CT-NS) or placebo over 2 years. In the distal radius and lower trochanter of the hip, individuals treated with CT-NS exhibited significant preservation of trabecular bone microarchitecture compared with placebo, where significant deterioration was shown. MRI analyses of os calcis or microCT/histomorphometric analyses of bone biopsies did not reveal consistent differences in architecture between CT-NS and placebo. It is postulated that the reduction in osteoporotic fracture risk in response to certain antiresorptive osteoporosis therapies is caused less by effects on bone quantity than on bone quality (specifically trabecular microarchitecture). To test this hypothesis, the QUEST study was conducted to assess the effects of nasal spray salmon calcitonin (CT-NS) or placebo on parameters of trabecular microarchitecture at multiple skeletal sites using noninvasive MRI technology and iliac crest bone biopsies by microCT/histomorphometry. Ninety-one postmenopausal osteoporotic women were followed for 2 years (n = 46 for CT-NS, n = 45 for placebo); all women received 500 mg calcium daily. MRI measurements at distal radius, hip (T2 relaxation time [T2*]), and os calcis (obtained yearly), iliac crest bone biopsies with 2D histomorphometry and 3D microCT (obtained at study onset and conclusion), DXA-BMD at spine/hip/wrist/os calcis (obtained yearly), and markers of bone turnover (obtained at 2-week to 12-month intervals) were analyzed, with an analysis of covariance model used to assess treatment effect for parameters of interest. MRI assessment of trabecular microarchitecture at individual regions of the distal radius revealed significant improvement, or preservation (no significant loss), in the CT-NS-treated group compared with significant deterioration in the placebo control group, as reflected in apparent BV/TV (p < 0.03), apparent trabecular number (p < 0.01), and apparent trabecular spacing (p < 0.01). Also, at the hip, the CT-NS group exhibited preservation of trabecular microarchitecture at the lower trochanter (p < 0.05) as determined by T2* MRI technology. Significant deterioration of trabecular bone architecture was noted in the placebo group at the femoral neck, Ward's triangle, and lower trochanteric sites. Apart from a significant increase in apparent trabecular number in the CT-NS group, significant changes within or between groups were not noted at the os calcis. Combined microCT/histomorphometric analysis of iliac crest bone biopsies did not reveal significant differences between treated and placebo groups. In the CT-NS group, regardless of the change in BMD (gain or loss) at the spine, hip, or distal radius, preservation of parameters of trabecular microarchitecture was noted, whereas in the placebo group, regardless of the change in BMD (gain or loss) at the spine, hip, or distal radius, loss or preservation was noted; however, changes in DXA/BMD (of the spine, hip, wrist, os calcis) between CT-NS and placebo groups were not significant. Serum C-telopeptide (S-CTx), a specific bone resorption marker, was reduced by 22.5% at 24 months (p = 0.056). The results of the QUEST study suggest therapeutic benefit of CT-NS compared with placebo in maintaining trabecular microarchitecture at multiple skeletal sites and support the use of MRI technology for assessment of trabecular microarchitecture in clinical research trials. However, the results also highlight site specific differences in response to antiresorptive therapies and the importance of sufficiently large sampling volumes (areas) to obtain reliable assessment of bone architecture.

Calcitonin administration in a rabbit distraction osteogenesis model.

The effect of salmon calcitonin on the maturation of the regenerate bone was assessed in an experimental model in rabbits. Twenty-six New Zealand White male rabbits, approximately 5 months old and weighing 3 to 3.5 kg, were subjected to a mid-diaphyseal tibial osteotomy. After 5 days, the right tibia was lengthened gradually at a rate of 0.375 mm every 12 hours, for 10 days. Ten international units of salmon calcitonin were administered daily subcutaneously to the study group (14 animals), whereas the animals of the control group (12 animals) were injected with a placebo, for the duration of the experiment. The bone mineral density of the regenerate bone was assessed on Days 20, 35, 45, and 55 of the experiment, in both groups, using dual energy xray absorptiometry. No statistical significant difference was found in the dual energy xray absorptiometry measurements between the study and control groups regarding the change of the bone mineral density of the new bone relative to a preoperative baseline measurement. Characteristic time-related changes were observed in the bone mineral density of the regenerate bone during its maturation, which proved to be identical in both groups. It seems that the administration of calcitonin does not enhance regenerate bone mineralization rate and tendency during bone lengthening.

Histomorphometric effects of calcitonin on pharyngeal bone in fed and starved goldfish Carassius auratus

: The effects of salmon calcitonin (sCT) on osteoblasts and osteoclasts were histologically and histomorphometrically investigated in the pharyngeal bone of fed and starved goldfish Carassius auratus. The thickness of the osteoid and the height of osteoblasts were also measured. Fish were given sCT intraperitoneally at a dose of 10 ng/g bodyweight four times every other day under either fed or starved conditions. The sCT treatment induced the retraction of osteoclasts and their disengagement from the bone surface. Salmon calcitonin had no effect on the histomorphometric parameters of bone formation activity, but suppressed the parameter (OcP/EP) that showed osteoclast activity. Salmon calcitonin did not affect the thickness of the osteoid, but increased the height of osteoblasts in starved fish. Histological and histomorphometric results demonstrated that osteoclast activity was suppressed when sCT was given to starved estrogenized goldfish five times for 10 days. Overall, results suggest that calcitonin is involved in bone assimilation by suppressing osteoclast activity and by enhancing osteoblast activity in the pharyngeal bone of goldfish.

Calcitonin Potentiates Oxygen–Glucose Deprivation-Induced Neuronal Death

Calcitonin is a hormone that decreases plasma calcium through inhibition of osteolysis. It is used in the treatment of osteoporosis and other bone disorders. Salmon calcitonin is typically utilized in individuals for whom use of estrogen is contraindicated, for example, women at high risk for breast cancer. In addition to actions on bone, calcitonin may have effects on the central nervous system. Receptors for calcitonin are present on central neurons, and salmon calcitonin has been shown to alter neuronal activity. Since salmon calcitonin is used clinically, and it can have actions on neurons, the present studies were designed to determine whether salmon calcitonin could alter death of cortical neurons. The effects of salmon calcitonin on neuronal death induced by exposure of murine cortical cultures to serum deprivation, staurosporine, oxygen–glucose deprivation, kainate, and NMDA were tested. Salmon calcitonin had no effect on apoptotic cell death in cortical cultures. However, acute treatment with salmon calcitonin (1–1000 nM) caused significant potentiation of neuronal death induced by oxygen–glucose deprivation. Similarly, salmon calcitonin potentiated cell death induced by exposure to kainate. In contrast, it did not potentiate cell death induced by exposure to NMDA. In fact, addition of a high concentration (1000 nM) of salmon calcitonin attenuated NMDA toxicity. These results indicate that calcitonin is not a survival factor for cortical neurons; however, it can alter excitotoxic cell death. The most interesting, and disturbing, effect is the ability of low concentrations of salmon calcitonin to potentiate oxygen–glucose deprivation-induced cell death.

Effects of salmon calcitonin on calcium deposition on and release from calcified tissues in fed and starved goldfish Carassius auratus

SUMMARY: Effects of salmon calcitonin on calcium physiology of the otolith, rib bone, pharyngeal bone, and scale were examined in fed and starved goldfish Carassius auratus. Fish were intraperitoneally given salmon calcitonin at a dose of 10 ng/g body weight four times every other day. They were then incubated in 45Ca-containing water for 24 h to examine the effect of the hormone on calcium deposition on these tissues. Another group of goldfish was incubated in 45Ca-bone water for 2 days to prelabel the tissues with 45Ca. Then they were kept in 45Ca-free water for 8 days, during which they were given calcitonin four times every other day. The effect of calcitonin on calcium release from the tissues was examined by analyzing the prelabeled radioactivity. Calcitonin had no effect on plasma calcium concentrations or on calcium deposition in any of the tissues in fed fish. In starved fish, however, calcitonin increased calcium deposition on the rib bone, pharyngeal bone, and scale. In the starved fish, plasma calcium levels were not affected by the hormone, but plasma 45Ca activity was lower in the calcitonin-treated group than in the control group. Calcitonin had no effect on calcium release from the bone and the scale, but reduced radioactivity in the otoliths of fed fish. These results suggest that calcitonin functions as an accelerator for calcium deposition on the bone and the scale in starved goldfish.

Effect of salmon calcitonin on experimental osteoporosis induced by ovariectomy and low-calcium diet in the rat.

To investigate the action and effect of calcitonin on osteoporosis, this study was performed in osteoporotic rats that had been ovariectomized and maintained on a low-calcium diet. Significant bone loss was noted in ovariectomized rats compared with those that underwent sham surgeries, and histological findings proved bone turnover to be increased. In comparison with this osteoporotic rat group, those given calcitonin showed less bone loss; the reduction in bone loss was obvious in the vertebral body, and rats given a high dose of calcitonin over a long duration showed even less bone loss, but this was hardly seen in the proximal tibial metaphysis. Histological findings proved that calcitonin inhibited the bone resorption that was stimulated by the ovariectomy. Values for osteoblast surfaces were relatively higher while those of reversal surfaces were lower. The results confirm that salmon calcitonin has an inhibitory action on bone resorption as well as being effective in maintaining and stimulating bone formation in vivo. These effects of calcitonin prevented progress of the osteoporosis that had been induced by ovariectomy, and the effects appeared differently in each region.

Inhibition of salmon calcitonin on secretion of progesterone and GnRH-stimulated pituitary luteinizing hormone.

The effects of salmon calcitonin (sCT) on the production of progesterone and secretion of luteinizing hormone (LH) were examined in female rats. Diestrous rats were intravenously injected with saline, sCT, human chorionic gonadotropin (hCG), or hCG plus sCT. Ovariectomized (Ovx) rats were injected with saline or sCT. In the in vitro experiments, granulosa cells and anterior pituitary glands (APs) were incubated with the tested drugs. Plasma LH levels of Ovx rats were reduced by sCT injection. Administration of sCT decreased the basal and hCG-stimulated progesterone release in vivo and in vitro. 8-Bromo-cAMP dose dependently increased progesterone production but did not alter the inhibitory effect of sCT. H-89 did not potentiate the inhibitory effect of sCT. Higher doses of 25-hydroxycholesterol and pregnenolone stimulated progesterone production and diminished the inhibitory effects of sCT. sCT did not decrease basal release of LH by APs, but pretreatment of sCT decreased gonadotropin-releasing hormone (GnRH)-stimulated LH secretion. These results suggested that sCT inhibits progesterone production in rats by preventing the stimulatory effect of GnRH on LH release in rat APs and acting directly on ovarian granulosa cells to decrease the activities of post-cAMP pathway and steroidogenic enzymes.

3,5 cyclic adenosine monophosphate mediates the salmon calcitonin-induced increase in hypothalamic tyrosine hydroxylase activity.

This study examined the effect of salmon calcitonin (sCT) on hypothalamic tyrosine hydroxylase (TH) activity and evaluated the cellular signaling mechanisms involved in the response. Fetal hypothalamic cells were cultured in a defined medium and treated with sCT and/or specific protein kinase inhibitors on day 14 in vitro. sCT (0.1-10 nM) increased both TH activity and cellular cAMP content in a concentration-dependent manner. sCT (10 nM) increased TH activity to 150-175% of control values and resulted in a 10-fold increase in cellular cAMP content. Both the C1a and C1b CT receptor isoforms were present in the cultures, as assessed by RT-PCR. Rp-adenosine 3',5'-cyclic monophosphothioate (Rp-cAMPS), a cAMP antagonist, and H-8, a cyclic nucleotide kinase inhibitor, blocked the sCT-induced increase in TH activity, with complete abolition of the response observed at concentrations of 1 mM and 5 microM, respectively. sCT (10 nM) increased radiolabeled phosphate incorporation into TH protein to 169% of control values and 1 mM Rp-cAMPS completely blocked this effect. In contrast, neither Calphostin C, a protein kinase C inhibitor, nor U-73122, a phospholipase C inhibitor, significantly altered the ability of sCT to increase TH activity. Likewise, the sCT-induced increase in TH activity was observed after pretreating the cells with either BAPTA/AM, an intracellular calcium chelator, or thapsigargin, an inhibitor of the endoplasmic reticulum calcium pump. These data indicate that sCT has a profound stimulatory effect on TH activity in fetal hypothalamic cells and that enhanced phosphorylation of TH coincides with the sCT-induced increase in enzyme activity. Moreover, CT receptors, which are linked to cAMP production, are expressed in the hypothalamic cells and a cAMP-dependent mechanism mediates the sCT-induced activation and phosphorylation of TH.

Effects of salmon calcitonin and anti-salmon calcitonin antibody on plasma calcium concentrations in the goldfish,Carassius auratus

The role of calcitonin (CT) in plasma calcium regulation was studied by the administration of exogenous CT and anti-salmon(s) CT antibody using goldfish,Carasius auratus, loaded or otherwise with calcium. CT elicited a decrease in plasma calcium concentrations at a dose of 10 ng/g body weight 1 h after administration. However, no effects were observed following doses of 30 ng and 50 ng/g 1 h, nor for the three doses 3 h after administration. In calcium-loaded fish, the effect of CT was different depending on the dosage of CT. Ten ng and 50 ng/g induced a decrease and an increase in plasma calcium concentrations, respectively, 3 h after administration. Anti-sCT antibody (0.02 μg or 0.1 μg/g) did not affect plasma calcium concentrations. In calcium-loaded fish, neither dose of anti-sCT antibody changed plasma calcium concentrations 1 h after administration. However, following a dose of 0.1 μg/g, plasma calcium concentrations decreased after 3 h. A positive correlation between plasma calcium concentrations and the gonad somatic index (GSI) in females was no longer apparent after administration of anti-sCT antibody. There was no relationship between plasma calcium concentrations and GSI in control and anti-sCT antibody-treated males. These results suggested that CT regulates plasma calcium concentrations in different ways depending on the dosage with CT having a role in calcium physiology during vitellogenesis.

Effect of salmon-calcitonin on the analgesic effect of selective μ, δ and κ opioid agonists in mice

The analgesic effect of three different opioid agonists, DAMGO ([ d-Ala 2, N-Me-Phe 4,Gly 5-ol]enkephalin), U-50,488H ( trans-3,4-dichloro- N-methyl- N-[2-(1-pyrrolidynyl)cyclohexyl] benzene-aceramide methane sulphonate), and [ d,Pen 2- d,Pen 5]-enkephalin, which act upon μ, δ and κ opioid receptors, respectively, was compared in the presence and absence of salmon-calcitonin (s-CT). The analgesic test used was the writhing test in mice. The analgesic effect of the opioids was significantly enhanced by pretreatment of the animals with s-CT intraperitoneally (i.p.) administered. This effect was more evident for the δ and κ-agonists. The present result suggests that the joint administration of s-CT and opioids may be a useful and interesting alternative in the treatment of painful diseases resistant to other treatments.