Analgesic effect of salmon-calcitonin administered by two routes. Effect on morphine analgesia

Clinical efficacy of calcitonin compared to diclofenac sodium in chronic nonspecific low back pain with type I Modic changes: a retrospective study

Background

The objective of this study was to compare the efficacy of calcitonin with diclofenac sodium in the treatment of patients with nonspecific low back pain (LBP) and type I Modic changes (MC1).

Patients and methods

The study was a retrospective observational study with 109 patients who had nonspecific LBP and MC1 that appeared as bone marrow lesions on magnetic resonance imaging (MRI). Between October 2013 and March 2016, 62 patients were injected intramuscularly with calcitonin 50 IU once daily and 47 patients were treated with diclofenac 75 mg once per day for 4 weeks for the treatment of LBP associated with MC1 on MRI. Visual analog scale (VAS) (0–10) and Oswestry Disability Index (ODI) (0–100) questionnaires were acquired from clinical records to evaluate LBP perception and degree of disability. Imaging data were also collected before and after treatment.

Results

Significant improvements were found in VAS and ODI at posttreatment compared with baseline in both groups (P < 0.05). Meanwhile, there was a significant difference between calcitonin group and diclofenac group at both 4 weeks and 3 months of follow-up (4 weeks: VAS 4.46 ± 1.58 vs 5.08 ± 1.50, ODI 20.32 ± 9.64 vs 24.35 ± 7.95; 3 months: VAS 3.70 ± 1.74 vs 4.51 ± 1.67, ODI 16.67 ± 9.04 vs 21.18 ± 9.56; P < 0.05 for all). Moreover, the proportion of patients with a significant change in LBP scales was higher in the calcitonin group (4 weeks: VAS 50.00% vs 23.40%, ODI 54.83% vs 25.53%; 3 months: VAS 58.06% vs 38.29%, ODI 59.67% vs 38.29%; P < 0.05 for all). According to MRI, 43.54% patients in the calcitonin group showed improvement compared with 21.27% patients in the diclofenac group (P < 0.05).

Conclusion

There was greater short-term efficacy of calcitonin compared with diclofenac in patients with LBP and MC1 on MRI.

Calcitonin for Acute Neuropathic Pain Associated with Spinal Cord Injury

Neuropathic pain associated with spinal cord injury is caused by complex neural mechanisms and is often refractory to standard therapy. Salmon calcitonin was an effective treatment for neuropathic symptoms in this case series of three patients with recent spinal cord injury. Salmon calcitonin is already used to help manage pain after limb amputation and also after vertebral fractures and it is perhaps surprising that it has not been trialled previously for spinal cord injury pain. Calcitonin is thought to exert its effect by modulation of the serotonergic system and is generally well tolerated and convenient to administer. This underutilised drug may be a very useful adjuvant for neuropathic pain associated with spinal cord injury.

A 'reverse' phylogenetic approach for identification of novel osmoregulatory and cardiovascular hormones in vertebrates

Vertebrates expanded their habitats from aquatic to terrestrial environments during the course of evolution. In parallel, osmoregulatory and cardiovascular systems evolved to counter the problems of desiccation and gravity on land. In our physiological studies on body fluid and blood pressure regulation in various vertebrate species, we found that osmoregulatory and cardiovascular hormones have changed their structure and function during the transition from aquatic to terrestrial life. In fact, Na(+)-regulating and vasodepressor hormones play essential roles in fishes, while water-regulating and vasopressor hormones are dominant in tetrapods. Accordingly, Na(+)-regulating and vasodepressor hormones, such as natriuretic peptide (NP) and adrenomedullin (AM), are much diversified in teleost fishes compared with mammals. Based on this finding, new NPs and AMs were identified in mammals and other tetrapods. These hormones have only minor roles in the maintenance of normal blood volume and pressure in mammals, but their importance seems to increase when homeostasis is disrupted. Therefore, such hormones can be used for diagnosis and treatment of body fluid and cardiovascular disorders such as cardiac/renal failure and hypertension. In this review, we introduce a new approach for identification of novel Na(+)-regulating and vasodepressor hormones in mammals based on fish studies. Until recently, new hormones were first discovered in mammals, and then identified and applied in fishes. However, chances are increasing in recent years to identify new hormones first in fishes then in mammals, based on the difference in the regulatory systems between fishes and tetrapods. As the direction is opposite from the traditional phylogenetic approach, we added 'reverse' to its name. The 'reverse' phylogenetic approach offers a typical example of how comparative fish studies can contribute to the general and clinical endocrinology.

Synthesis and analgesic activity of a series of new azaalkane bis-guanidinium and bis(2-aminoimidazolinium) compounds

In the present paper, we wish to report the synthesis and antinociceptive activity of a series of new azaalkane bis(2-aminoimidazolinium) compounds from which, N,N'-di(4,5-dihydro-1H-imidazol-2-yl)-3-aza-1,6-hexanediamine 2a has shown the best analgesic properties in vivo in two different assays (i.e., acetic acid-induced writhing test and hot-plate test in mice), as well as oral bioavailability.

Synthesis and opioid activity of new fentanyl analogs

Three new fentanyl analogs (compounds 3-4-5) have been synthesized and evaluated for antinociceptive properties using the writhing test. The analgesic property of the active compound, N-[1-phenylpyrazol-3-yl]-N-[1-(2-phenethyl)-4-piperidyl)] propenamide (compound 4), was tested using the hot plate test in mice. Its opioid agonistic activity was characterized using three isolated tissues: guinea pig ileum, mouse vas deferens, and rabbit vas deferens. Compound 4 was as effective as fentanyl or morphine and it showed less antinociceptive potency than fentanyl but it was more potent than morphine. The duration of the antinociception was similar to that of fentanyl. This compound inhibited the electrically evoked contractions of myenteric plexus-longitudinal muscle strips of guinea pig ileum and of mouse vas deferens but not those of rabbit vas deferens. These effects could be reversed by micro selective antagonists (naloxone and/or CTOP) but not by the delta selective antagonist naltrindole, thus indicating that the compound acted as a micro opioid agonist. Finally, the binding data confirmed that compound 4 had high affinity and selectivity for the micro-receptor.

Analgesic effect of calcitonin in osteoporosis

Bone pain is the most common symptom in osteoporotic patients. To date, there is mounting evidence that calcitonin significantly reduces bone pain in osteoporosis, and that the analgesic effect can be evident as soon as the second week of treatment. The limitations to the use of calcitonin, which are parenteral administration and side effects, can now be overcome by the availability of the nasal spray preparation. At present, controlled studies have demonstrated the analgesic activity of calcitonin given by nasal spray in patients with vertebral crush fractures and bone pain. The mechanism for the analgesic effect of calcitonin is yet to be clarified. In humans, similarities between calcitonin and morphine-induced analgesia, and reports of calcitonin-induced elevation of plasma beta-endorphin levels, suggest the possible involvement of the endogenous opiate system in mediating the analgesic action of calcitonin. However, the demonstration of calcitonin binding sites in areas of the brain involved in pain perception and a series of animal studies have raised the possibility that calcitonin may directly modulate nociception in the central nervous system. In support of this hypothesis are some observations of an analgesic effect obtained by direct epidural or subaracnoidal injection of calcitonin in humans.

Guanidinium and aminoimidazolinium derivatives of N-(4-piperidyl)propanamides as potential ligands for mu opioid and I2-imidazoline receptors: synthesis and pharmacological screening

Derivatives of N-(1-phenethyl-4-piperidyl)propanamides incorporating guanidinium and 2-aminoimidazolinium groups have been prepared by a synthetic approach involving first introduction of a spacer between the piperidine and the functional group by reductive amination of piperidinone. The formation of each of these functional groups was carried out using N-N'-di(tert-butoxycarbonyl)thiourea and 2-methylthioimidazolinium iodide, respectively. These structures have been designed to incorporate two pharmacologic goals into one entity. Radioligand binding assays have been used to study their affinity for opioid (mu, delta and kappa) and I2-imidazoline receptors. Two of them, 10 and 16, showed high affinity for mu opioid receptors and functionally they had moderate analgesic properties in the hot plate and writhing tests. The in vitro studies on guinea pig ileum (GPI) indicated that both compounds are mu opioid agonists. In what concerns I2-imidazoline receptor activity, these derivatives showed low affinity around 6 to 7 times less than idazoxan.

Alendronate induces antinociception in mice, not related with its effects in bone

The antinociceptive effect of alendronate was studied. The bisphosphonate was i.p. administered and two tests were carried out: acetic acid in mice and formalin test in rats. In the acetic acid test, alendronate induced a dose-dependent antinociceptive effect that was statistically significant for the doses of 10, 20 and 40 mg/kg, and could be detected 48 hr after its administration. In the formalin test, however, alendronate, at the doses of 10 and 20 mg/kg, did not modify the pain score nor the number of flinches, when it was administered either 30 or 60 min before the test. However it must be noted that doses inducing analgesic effect are close to those inducing toxicity.

Effect of salmon-calcitonin on the analgesic effect of selective mu, delta and kappa opioid agonists in mice

The analgesic effect of three different opioid agonists, DAMGO ([D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin), U-50,488H (trans-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidynyl)cyclohexyl] benzene-aceramide methane sulphonate), and [D,Pen2-D,Pen5]-enkephalin, which act upon mu, delta and kappa 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 delta and kappa-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.

Serotonergic mechanisms involved in calcitonin potentiation of kappa-opioid receptor-mediated effects on adrenal secretion

Calcitonin can selectively modulate the effects of opioids on the rat hypothalamic-pituitary-adrenal axis and increase the release of corticosterone induced by a kappa-opioid receptor agonist. Considerable evidence supports the involvement of opioid and serotonergic systems in the analgesic effect of calcitonin. In this study, the involvement of hypothalamic serotonergic pathways in the calcitonin potentiation of the effect of (trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl]-benzeneacetamide methane sulphonate (U-50,488H) on the secretion of corticosterone was examined. The correlation between the calcitonin-induced potentiation of the pituitary adrenal response to U-50,488H and changes in serotonin turnover was evaluated. Our results show that the increase in the release of corticosterone induced by treatment with calcitonin + U-50,488H was not evident when the turnover of serotonin was decreased by inhibition of its synthesis with m-hydroxybenzylhydrazine (NSD 1015) or by blockade of its metabolism with trans-2-phenylcyclopropylamine (tranylcypromine). Although other factors can not be discarded, from the present data it can be suggested that the serotonergic system plays an important role in the interaction calcitonin-kappa-opioid receptor agonist in the hypothalamic-pituitary-adrenal axis.

Production of bioactive salmon calcitonin from the nonendocrine cell lines COS-7 and CHO

To produce bioactive salmon calcitonin from the conventional nonendocrine cell lines, COS-7 and CHO, we devised a salmon calcitonin expression vector by combining the amino-terminus of human calcitonin precursor with a salmon calcitonin sequence, inserting the efficient furin-cleavable processing sequence Arg-X-Arg-X-Lys-Arg before salmon calcitonin, and deleting the carboxyl-terminal extension peptide. This chimeric calcitonin precursor terminates at glycine to easily receive an amidation reaction. COS-7 and CHO produced a high level of bioactive calcitonin by the resorption pit formation assay. Although amidating activity is highly expressed in CHO, but only a little in COS-7 cells, both cells produced a similar level of bioactive calcitonin. Thus, the engineered salmon calcitonin expression vector enables nonendocrine cells even with low amidation activity to produce bioactive calcitonin.

Influence of pertussis toxin on the calcitonin-opioid interaction in isolated tissues

1. In order to clarify one of the mechanisms involved in the analgesic effect of calcitonin, we have tested the in vitro modifications induced by calcitonin on the effect of opioids. 2. The inhibition of the contractions induced by opioids or clonidine, in guinea-pig ileum or in mouse vas deferens, were significantly reduced in tissues incubated with pertussis toxin (PTX). When tissues were incubated with PTX and calcitonin, the inhibitory effect was restored. 3. These results suggest that calcitonin is able to potentiate a non-PTX-sensitive mechanism of transduction and support the possibility of involvement of similar G-proteins in the effects of opioid and alpha 2-adrenoceptor agonists.

Calcitonin promotes osteoclast survival in vitro

Inactivation of resorbing osteoclasts by calcitonin is associated with typical morphological changes and alteration of the specific organization of osteoclast cytoskeleton. Here we show that calcitonin also promotes the survival of rat osteoclasts in vitro, cultured either on glass or bone, by delaying the onset of apoptosis. Parathyroid hormone had no effect on osteoclasts cultured on glass but it slightly increased apoptosis index of osteoclasts cultured on bone. Calcitonin was also able to rescue osteoclasts in calvarial explant cultures. The survival effect of calcitonin was mimicked by dibutyryl cAMP and could not be blocked by various metabolic inhibitors known to affect the apoptotic pathway. However, clodronate-induced apoptosis of osteoclasts could not be reversed by calcitonin and neither could calcitonin rescue osteoclasts already committed to apoptosis. It did not alter the distribution of Bcl-2 in osteoclasts. Our results show that at least in vitro calcitonin protects osteoclasts from apoptosis and suggest that it regulates the onset of apoptosis.

Antinociceptive effects of repeated systemic injections of calcitonin in formalin-induced hyperalgesic rats

Calcitonin (CT) produces long-lasting analgesia in patients suffering from painful diseases following repeated systemic injections, but there have been only a few contradictory reports on the antinociceptive action of systemic injections of CTs in animal experiments. This study was conducted to elucidate an antinociceptive action of systemic CT in rats. An injection of dilute formalin induced hyperalgesia for about 2 h. Single topical injections of 0.12 and 1.2 U, but not 0.012 U, of [Asu1.7] eel CT (eCT) into the same site of formalin injection inhibited the hyperalgesia. Repeated systemic injections of eCT (4 and 40, but not 0.4, U kg-1 day-1) for 7 days inhibited the hyperalgesia, while the single injection was without effects at doses tested. Although the highest dose of eCT (40 U kg-1 day-1) inhibited an increase in body weight following repeated injections, lower doses (0.4 and 4 U kg-1 day-1) were without effects. The suppression of hyperalgesia following repeated systemic injections of eCT (4 U kg-1 day-1) lasted for at least 24 h, and subsided by 3 days following the last eCT injection. These results indicate that the repeated systemic injections of eCT produce a long-lasting inhibition of formalin-induced hyperalgesia in rats. This inhibitory effect is similar to CT analgesia in human subjects in terms of a necessity for repeated administration, effective dose and long-lasting effects.

Intranasal salcatonin (salmon calcitonin). A review of its pharmacological properties and role in the management of postmenopausal osteoporosis

Osteoporosis is a common problem among postmenopausal women and is associated with significant morbidity, mortality and costs primarily resulting from osteoporotic fractures. Salcatonin (salmon calcitonin) inhibits osteoclastic bone resorption and is approximately 40 to 50 times more potent than human calcitonin. In most randomised trials in which intranasal salcatonin (usually 50 to 200 IU/day plus oral calcium supplements) was administered for 1 to 5 years to postmenopausal women for prevention of osteoporosis, bone mineral density or content of the lumbar spine increased by approximately 1 to 3% from baseline. In contrast, postmenopausal women receiving only oral calcium supplements typically had reductions in bone mineral density or content of about 3 to 6%. The difference between treatment groups was statistically significant in essentially all studies. Although changes in bone mineral density or content were broadly similar in studies of postmenopausal women with established osteoporosis to those in postmenopausal women receiving therapy for prevention of the disease, studies in women with established osteoporosis did not usually demonstrate statistically significant differences between treatment groups. Also in postmenopausal women with established osteoporosis, intranasal salcatonin reduced pain and/or analgesic consumption in some trials and, in a limited number of studies of relatively short duration (i.e. < or = 2 years), the incidence of osteoporotic fractures. A large multicentre 5-year study with adequate statistical power to confirm the effect of intranasal salcatonin on reducing osteoporotic fracture rates in postmenopausal women is currently under way. The intranasal formulation of salcatonin offers a more convenient and better tolerated alternative to the parenteral formulation of the drug which is administered by regular subcutaneous or intramuscular injections. Adverse events associated with the intranasal formulation are generally mild and transient, usually involving local reactions such as nasal discomfort, rhinorrhoea or rhinitis. Thus, for postmenopausal women unable or unwilling to tolerate long term hormone replacement therapy, intranasal salcatonin is an attractive alternative for the management of osteoporosis.

Antinociceptive activity of calcitonin and central cholinergic system: behavioural and neurochemical analyses

Behavioural and neurochemical analyses were carried out to investigate the relationship between the antinociceptive activity of porcine calcitonin (pCT) and central cholinergic system in mice and rats. Behavioural studies revealed that the antinociceptive activity of pCT encapsulated in sulphatide-containing liposomes injected intravenously into mice was significantly inhibited by atropine sulphate, but not by atropine methylnitrate, and potentiated by physostigmine, but not by neostigmine. Neurochemical studies using rat brain synaptosomes showed that pCT stimulated synaptosomal sodium-dependent high-affinity choline uptake, which was found to be closely associated with acetylcholine (ACh) synthesis (50-60%). This effect was concentration-dependent. In addition, pCT elicited a biphasic effect on ACh release from synaptosomes with an initial brief period of stimulation and subsequent prolonged inhibition. This stimulation was not affected by atropine sulphate, but markedly reduced by incubation in the presence of diltiazem or in a calcium-free medium, indicating that the modulation of ACh release by the peptide may be mediated by calcium fluxes across the synaptosomal membrane independent of cholinergic receptor activation. However, pCT does not affect the activity of synaptosomal acetylcholinesterase. Therefore, the behavioural study in vivo with the neurochemical analysis in vitro suggests that the central cholinergic system may be involved in the antinociceptive activity of calcitonin.

Involvement of kappa-opioid receptor mechanisms in the calcitonin-induced potentiation of opioid effects at the hypothalamus-pituitary-adrenocortical axis

The present study was conducted to evaluate the influence of calcitonin on the neuroendocrine effects of both the mu-opioid receptor agonist, morphine, and the selective kappa-opioid receptor agonist, U-50,488H (trans-3,4-dichloro-N-methyl-N-[2-(1- pyrrolidynyl)cyclohexyl]benzeneacetamide methane sulphonate), at the hypothalamus-pituitary-adrenocortical axis in rats. Calcitonin given alone (2.5, 5 or 10 UI/kg i.p.) induced no changes or a slight reduction (20 UI/kg i.p.) in plasma corticosterone, 45 min after its administration. Morphine did not produce any modification in plasma corticosterone at doses of 3 or 10 mg/kg i.p., whereas it produced a significant increase in corticosterone secretion at doses of 20 or 30 mg/kg i.p., 30 min after its administration. Pretreatment with calcitonin (2.5 UI/kg i.p.) 15 min before morphine (3 or 10 mg/kg i.p.) did not modify the effect of the opioid on plasma corticosterone. U-50,488H (0.5, 1, 5 or 15 mg/kg i.p.) induced an increase in the release of corticosterone only at the higher dose, 30 min after injection. Significantly higher plasma corticosterone levels after U-50,488H administration at doses of 0.5, 1 or 5 mg/kg i.p. were observed when calcitonin was administered 15 min before the kappa-opioid receptor agonist. The enhanced responsiveness of the hypothalamus-pituitary-adrenocortical axis to U-50,488H (1 mg/kg i.p.) in animals pretreated with calcitonin, was completely blocked by the selective kappa-opioid receptor antagonist, nor-binaltorphimine, suggesting a role of kappa-opioid receptors in mediating the calcitonin-induced supersensitivity to U-50,488H.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary calcium and blood pressure in experimental models of hypertension. A review

More than 80 studies have reported lowered blood pressure after dietary calcium enrichment in experimental models of hypertension. The evidence presented here suggests that dietary calcium may act concurrently through a number of physiological mechanisms to influence blood pressure. The importance of any given mechanism may vary depending on the experimental model under consideration. Supplemental dietary calcium is associated with reduced membrane permeability, increased Ca(2+)-ATPase and Na,K-ATPase, and reduced intracellular calcium. These results suggest that supplemental calcium may limit calcium influx into the cell and improve the ability of the VSMC to extrude calcium. This could be a direct effect of calcium on the VSMC or an indirect effect mediated hormonally. The calcium-regulating hormones have all been found to have vasoactive properties and therefore may influence blood pressure. Furthermore, CGRP and the proposed parathyroid hypertensive factor are both vasoactive substances that are responsive to dietary calcium. Therefore, diet-induced variations in calcium-regulating hormones may influence blood pressure. Modulation of the sympathetic nervous system is another important way that dietary calcium can influence blood pressure. There is evidence of altered norepinephrine levels in the hypothalamus as a consequence of manipulations of dietary calcium as well as changes in central sympathetic nervous system outflow. Dietary calcium has also been shown to specifically modify alpha 1-adrenergic receptor activity in the periphery. In some experimental models of hypertension, dietary calcium may alter blood pressure by changing the metabolism of other electrolytes. For example, the ability of calcium to prevent sodium chloride-induced elevations in blood pressure may be attributed to natriuresis. However, natriuresis does not account for all of the interactive effects of calcium and sodium chloride on blood pressure. Sodium chloride-induced hypertension may be due in part to calcium wasting and subsequent elevation of calcium-regulating hormones. Chloride is an important mediator of this effect because it appears that sodium does not cause calcium wasting when it is not combined with chloride. More attention to the central nervous system effects of dietary calcium is needed. Not only can calcium itself influence neural function, but many of the calcium-regulating hormones appear to affect the central nervous system. The influence of calcium and calcium-regulating hormones on central nervous system activity may have important implications for blood pressure regulation and also may extend to other aspects of physiology and behavior.

Involvement of central serotonergic pathways in analgesia elicited by salmon calcitonin in the mouse

The contribution of central serotonergic pathways to the analgesic activity induced by salmon calcitonin in the writhing test was investigated. Salmon calcitonin was administered to mice after lesioning of the ascending and descending serotonergic pathways by means of i.p. administration of p-chloroamphetamine (40 mg/kg, for 2 days) or p-chlorophenylalanine (300 mg/kg, for 3 days). The analgesic effect induced by salmon calcitonin at the doses of 10 and 20 IU/kg was not evident in mice previously treated with p-chloroamphetamine or p-chlorophenylalanine. However, the analgesic effect of salmon calcitonin 40 IU/kg was not significantly modified by p-chloroamphetamine or p-chlorophenylalanine pretreatment. Salmon calcitonin did not alter the depletion of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid after p-chloroamphetamine or p-chlorophenylalanine administration. Similarly, this hormone did not change the NSD 1015-induced accumulation of 5-hydroxytryptophan or the tranylcypromine-induced accumulation of 5-HT. These results indicate that although salmon calcitonin does not influence the synthesis and metabolism of 5-HT, it does require the integrity of the serotonergic system in order to cause analgesia.

Biodistribution of calcitonin encapsulated in liposomes in mice with particular reference to the central nervous system

The biodistribution of [125I]porcine calcitonin (pCT) encapsulated in reverse-phase evaporation vesicles (REVs) in mice upon the intravenous administration was examined. It was found that sulfatide significantly improved the stability of REVs in vivo, and altered the relative distribution of [125I]pCT encapsulated in liposomes in mice. These sulfatide-containing REVs were able to target [125I]pCT into the liver and central nervous system (CNS) reasonably well, with the maximal effect of about 40% and 2% of the injected doses occurring at 30 min and 90 min, respectively, after injection. Neither free [125I]pCT, nor sulfatide-free liposome-encapsulated [125I]pCT, nor a mixture of free [125I]pCT and empty sulfatide liposomes was effective. [125I]pCT was widely distributed in the CNS, with predominance in hypothalamus, brainstem, striatum and spinal cord. The results indicate that pCT encapsulated in sulfatide-containing liposomes is able to pass through the blood-brain barrier (BBB), and calcitonin, thus encapsulated, may be applicable to studies on its functions in the CNS.