Meta-analysis of Randomized Controlled Clinical Studies on Effect of Salmon Calcitonin on Bone Pain in Osteoporosis Patients

[Objectives]To systematically evaluate the efficacy and safety of salmon calcitonin in the treatment of osteoporosis,and to provide reference for clinical salmon calcitonin treatment and improvement of bone pain symptoms of osteoporosis.[Methods]Randomized controlled trials(RCTs)of salmon calcitonin in the treatment of osteoporosis from January 2000 to March 2015 were collected by searching Chinese Biomechanics Literature Database(SinoMed,CBM),China National Knowledge Infrastructure(CNKI),VIP and Wanfang Database.The relevant data of bone pain degree and bone mineral density were extracted to evaluate the methodological quality.Meta-analysis was performed using RevMan 5.1 software.A total of 13 randomized controlled trials involving 1683 patients were included,including 862 patients in the observation group and 821 patients in the control group.[Results]Meta-analysis showed that salmon calcitonin combined with calcium was better than the control group in improving bone pain symptoms in osteoporosis patients,and the difference was statistically significant[RR=1.84,95%CI(1.56,2.18)].[Conclusions]The salmon calcitonin can significantly improve the bone pain symptoms of the osteoporosis patients,and has no serious adverse reaction.However,due to the small number of studies included in this systematic review and the small sample size,it still needs to be confirmed by high-quality,large sample,multi-center randomized controlled trials.

Investigation of Calcitonin and Calcitonin Gene-related Peptide in 88 Cases of Medullary Thyroid Carcinoma

Objective： To investigate the changes of calcitonin （CT） and calcitonin gene-related peptide （CGRP） in patients with medullary thyroid carcinoma （MTC）. Methods： Fifty-eight cases of MTC were selected and the relationship between the CT levels and metastasis was investigated. The immunohistochemical method was used to detect the expression of CT and CGRP in the 58 samples of MTC tissues. The CT and CGRP in 30 newly diagnosed MTC inpatients were measured before operation and in the first few days after operation using a radioimmunoassy. Results： （1） The rate of residual tumor had a significant difference between the normal serum CT group one month after operation and the elevated group at the same period （P〈0.01）. （2） Immunohistochemical study revealed the positive rate of CT was about 98%, and that of the CGRP was 87.8%. （3） Part of the patients had an elevated CGRP levels while CT levels was normal. （4） The serum CT levels were decreased to a stable range one week after operation. Conclusion： CT is a useful index to evaluate the efficacy of surgical treatment. The measurement of serum CGRP is helpful in the diagnosis of MTC, especially for those whose preoperative CT levels are normal.

A HPLC Method for the Determination of Salmon Calcitonin in Injection by Gradient Elution

It was concluded that the described HPLC method could be used for the assayof salmon calcitonin in injection, as it offers qualified selectivity, accuracy and precision ofanalysis.

Effects of rearranged during transfection mutation on calcitonin and procalcitonin expression in sporadic medullary thyroid carcinoma

Objective The aim of this study was to investigate the effects of rearranged during transfection(RET)mutation on the expressions of calcitonin(CTn)and procalcitonin(PCT)in sporadic medullary thyroid carcinoma(SMTC).Methods RET mutation was detected by polymerase chain reaction direct sequencing in 64 cases of SMTC,and the expression levels of CTn and PCT in SMTC tissues were detected using the immunohistochemical streptavidin-perosidase(SP)method.The effect of RET mutations on the expression of CTn and PCT along with its relationship with clinicopathological parameters were analyzed.Results The expression rates of CTn and PCT in SMTC tissues were 90.6%(58/64)and 67.2%(43/64),respectively.CTn and PCT expression were found to be associated with tumor size and lymph node metastasis(P<0.05)but not with gender,age,or tumor capsule invasion(P>0.05).There was a significant correlation between CTn and PCT expression(r=0.269,P=0.041),and the intensity of positive CTn expression was positively correlated with RET mutation(r=0.507,P=0.000).However,PCT expression was not associated with RET mutation(r=0.188,P=0.136).Conclusion High expression of CTn and PCT was associated with the progression of medullary carcinoma,and the intensity of CTn expression was associated with RET mutation.PCT may provide valuable information for the diagnosis and prognosis of SMTC.

Incidental diagnosis of medullary thyroid carcinoma due to persistently elevated procalcitonin in a patient with COVID-19 pneumonia:A case report

BACKGROUND Procalcitonin(Pct)is a common biomarker in clinical practice,especially in the era of coronavirus disease 2019(COVID-19)infection.Although it is frequently used for the diagnosis and prognostication of bacterial infections or sepsis,it is also elevated in a few other conditions,including medullary thyroid carcinoma(MTC).CASE SUMMARY A 43-year-old female presented with moderately severe COVID-19 pneumonia in April 2021.She gradually recovered clinically;however,despite normalization of other inflammatory markers,Pct levels remained persistently elevated.Further workup identified the cause as left lobe MTC with locoregional metastasis.Calcitonin levels were high,and carcinoembryonic antigen levels were normal.The patient underwent total thyroidectomy and neck dissection,which was followed by another radical neck dissection due to residual disease.Currently,she is doing well,nearly having completed her course of external beam radiotherapy with no recurrence.Pct is well documented as a screening tool for MTC,especially because of its stable nature compared to calcitonin in the community settings.It is important to keep in mind the differential diagnosis of MTC in patients with persistently elevated Pct levels despite normal levels of other acute phase reactants.To the best of our knowledge,this is the first report from Asia of such an incidental diagnosis of MTC due to persistently elevated Pct levels in a patient with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection.CONCLUSION Persistently elevated Pct levels can occur in any pro-inflammatory state including infections,sepsis,or acute respiratory distress syndrome.In the current setting,SARS-CoV-2 infection is one such clinical scenario,and in rare situations of persistent elevation,MTC may need to be ruled out.

Electroacupuncture at Fengchi(GB20) inhibits calcitonin gene-related peptide expression in the trigeminovascular system of a rat model of migraine

Most migraine patients suffer from cutaneous allodynia; however, the underlying mechanisms are unclear. Calcitonin gene-related peptide（CGRP） plays an important role in the pathophysiology of migraine, and it is therefore, a potential therapeutic target for treating the pain. In the present study, a rat model of conscious migraine, induced by repeated electrical stimulation of the superior sagittal sinus, was established and treated with electroacupuncture at Fengchi（GB20）（depth of 2–3 mm, frequency of 2/15 Hz, intensity of 0.5–1.0 m A, 15 minutes/day, for 7 consecutive days）. Electroacupuncture at GB20 significantly alleviated the decrease in hind paw and facial withdrawal thresholds and significantly lessened the increase in the levels of CGRP in the trigeminal ganglion, trigeminal nucleus caudalis and ventroposterior medial thalamic nucleus in rats with migraine. No CGRP-positive cells were detected in the trigeminal nucleus caudalis or ventroposterior medial thalamic nucleus by immunofluorescence. Our findings suggest that electroacupuncture treatment ameliorates migraine pain and associated cutaneous allodynia by modulating the trigeminovascular system ascending pathway, at least in part by inhibiting CGRP expression in the trigeminal ganglion.

Relationship of calcitonin gene-related peptide with disease progression and prognosis of patients with severe traumatic brain injury

Calcitonin gene-related peptide（CGRP） has been implicated in multiple functions across many bioprocesses; however, whether CGRP is associated with severe traumatic brain injury（TBI） remains poorly understood. In this study, 96 adult patients with TBI（enrolled from September 2015 to December 2016） were divided into a mild/moderate TBI group（36 males and 25 females, aged 38 ± 13 years） and severe TBI group（22 males and 13 females, aged 38 ± 11 years） according to Glasgow Coma Scale scores. In addition, 25 healthy individuals were selected as controls（15 males and 10 females, aged 39 ± 13 years）. Radioimmunoassay was used to detect serum levels of CGRP and endothelin-1 at admission and at 12, 24, 48, 72 hours, and 7 days after admission. CGRP levels were remarkably lower, but endothelin-1 levels were obviously higher in the severe TBI group compared with mild/moderate TBI and control groups. Levels of CGRP were remarkably lower, but endothelin-1 levels were obviously higher in deceased patients compared with patients who survived. Survival analysis and logistic regression showed that both CGRP and endothelin-1 levels were associated with patient mortality, with each serving as an independent risk factor for 6-month mortality of severe TBI patients. Moreover, TBI patients with lower serum CGRP levels had a higher risk of death. Thus, our retrospective analysis demonstrates the potential utility of CGRP as a new biomarker, monitoring method, and therapeutic target for TBI.

Effect of warm acupuncture on nitric oxide synthase and calcitonin gene-related peptide in a rat model of lumbar nerve root compression

BACKGROUND： Varying degrees of inflammatory responses occur during lumbar nerve root compression. Studies have shown that nitric oxide synthase （NOS） and calcitonin gene-related peptide （CGRP） are involved in secondary disc inflammation. OBJECTIVE： To observe the effects of warm acupuncture on the ultrastructure of inflammatory mediators in a rat model of lumbar nerve root compression, including NOS and CGRP contents. DESIGN, TIME AND SETTING： Randomized, controlled study, with molecular biological analysis, was performed at the Experimental Center, Sixth People＇s Hospital Affiliated to Shanghai Jiao Tong University, between September 2006 and April 2007. MATERIALS： Acupuncture needles and refined Moxa grains were purchased from Shanghai Taicheng Technology Development Co., Ltd., China; Mobic tablets were purchased from Shanghai Boehringer Ingelheim Pharmaceuticals Co., Ltd., China; enzyme linked immunosorbent assay （ELISA） kits for NOS and CGRP were purchased from ADL Biotechnology, Inc., USA. METHODS： A total of 50, healthy, adult Sprague-Dawley rats, were randomly divided into five groups normal, model, warm acupuncture, acupuncture, and drug, with 10 rats in each group. Rats in the four groups, excluding the normal group, were used to establish models of lumbar nerve root compression. After 3 days, Jiaji points were set using reinforcing-reducing manipulation in the warm acupuncture group. Moxa grains were burned on each needle, with 2 grains each daily. The acupuncture group was the same as the warm acupuncture group, with the exception of non-moxibustion. Mobic suspension （3.75 mg/kg） was used in the oral drug group, once a day. Treatment of each group lasted for 14 consecutive days. Modeling and medication were not performed in the normal group. MAIN OUTCOME MEASURES： The ultrastructure of damaged nerve roots was observed with transmission electron microscopy; NOS and CGRP contents were measured using ELISA. RESULTS： The changes of the radicular ultramicrostructure were characterized by Wallerian degeneration; nerve fibers were clearly demyelinated; axons collapsed or degenerated; outer Schwann cell cytoplasm was swollen and its nucleus was compacted. Compared with the normal group, NOS and CGRP contents in the nerve root compression zone in the model group were significantly increased （P 〈 0.01）. Nerve root edema was improved in the drug, acupuncture and the warm acupuncture groups over the model group. NOS and CGRP expressions were also decreased with the warm acupuncture group having the lowest concentration （P 〈 0.01）. CONCLUSION： In comparison to the known effects of Mobic drug and acupuncture treatments, the warm acupuncture significantly decreased NOS and CGRP expression which helped improve the ultrastructure of the compressed nerve root.

The Experimental Study on the Effect Calcitonin Gene related Peptide on Bone Resorption Mediated by Interleukin-1

To investigate the effect of calcitonin gene related peptide (CGRP) on bone resorption mediated by interleukin 1β(IL 1β) in vitro , the osteoclasts isolated from the long bones of newborn SD rats were co cultured with osteoblasts on ivory slices placed in 24 well plates . 24 h later, conditioned media containing CGRP and/or IL 1β were added to the wells respectively, and continued culturing for 48 h. After the cells were stripped off by ultrasonication, the ivory slices were stained in toludine blue. The number and the total area of resorption lacunae on each slice were measured by computer imaging analysis system. Our results showed that IL 1β significantly stimulated bone resorption, but CGRP inhibited the effect mediated by IL 1β in a dose dependent manner. It is suggested that CGRP may inhibit osteoclastic bone resorption through two ways: One is that CGRP functions directly on osteoclasts to block their activation; the other is that CGRP regulates the release of cytokines by osteoblasts and indirectly affects the function of osteoclasts.

Substance P and calcitonin gene-related peptide expression in dorsal root ganglia in sciatic nerve injury rats

The neuropeptides, substance P and calcitonin gene-related peptide, have been shown to be involved in pain transmission and repair of sciatic nerve injury. A model of sciatic nerve defect was prepared by dissecting the sciatic nerve at the middle, left femur in female Sprague Dawley rats. The two ends of the nerve were encased in a silica gel tube. L5 dorsal root ganglia were harvested 7, 14 and 28 days post sciatic nerve injury for immunohistochemical staining. Results showed that substance P and cal- citonin gene-related peptide expression increased significantly in dorsal root ganglion of rats with sci- atic nerve injury. This increase peaked at 7 days, declined at 14 days, and reduced to normal levels by 28 days post injury. The findings indicate that the neuropeptides, substance P and calcitonin gene- related peptide, mainly increased in the early stages after sciatic nerve injury.

Protection of Calcitonin Gene-Related Peptide-Induced Preconditioning against Myocardial Injury due to Adriamycin in the Isolated Rat Heart *

The protective effect of calcitonin gene-related peptide (CGRP)-induced preconditioning on myocardial injury due to adriamycin was studied in the isolated perfused rat heart. Adriamycin (100 and 200 (mol / L) caused a gradual decrease in coronary flow (CF) and cardiac function (LVP and LV dp/dtmax), and an increase in the level of MDA. Pretreatment with CGRP at the concentration of 5 nmol/L for 5 min markedly reduced the attenuation of CF and cardiac function and inhibited the elevation of MDA content induced by adriamycin. The findings suggest that the pretreatment with CGRP possesses a protection against myocardial injury elicited by adriamycin. The present results also suggest that the protection of CGRP may be related to a reduction in lipid peroxidation.

Preliminary study on androgen dependence of calcitonin gene-related peptide in rat penis

Aim: To study the androgen dependence of the neurotransmitter, calcitonin gene-related peptide (CGRP) in rat penis. Methods: Forty-four Sprague-Dawley rats were randomly divided into Group A (intact controls), Group B (castrated) and Group C (gavaged with finasteride 4.5 mg·kg^(-1).day^(-1)). Four and ten weeks later respectively, half of rats in each group were anaesthetized. Blood samples were taken for the measurement of serum testosterone and dihydrotestosterone (DHT) by means of radioimmunoassay. Penile samples were harvested for the investigation of calcitonin gene related peptide (CGRP)-immunoreactive nerve fibers with immunohistochemistry. The computer-assisted imaging analysis system was applied to calculate the area proportion of the CGRP-positive nerve fibers (CGRP-PNF) in each group. Results: 1) Both 4 and 10 weeks later, testosterone and DHT levels in Group B decreased significantly compared with those in Group A, (P < 0.05, P < 0.01, respectively); DHT level in Group C was also significantly decreased in comparison with that in Group A for both 4- and 10- week animals (P < 0.05); 2) There was no significant differences in area proportion of CGRP-PNF among Groups A, B and C 4 weeks after treatments (P > 0.05); However, 10 weeks later, the proportion of CGRP-PNF in Groups B and C was significantly less than that in Group A (P < 0.01);3) The proportion of CGRP-PNF of 4-week animals in Groups B and C was significantly higher than that of 10-week animals (P < 0.05). Conclusion: The expression of neurotransmitter, CGRP may depend on androgens, including testosterone and DHT in rat penis.

C-reactive protein,procalcitonin,interleukin-6,vascular endothelial growth factor and oxidative metabolites in diagnosis of infection and staging in patients with gastric cancer

AIM:The current study was to determine the serum/pLasma levels of VEGF,IL-6,malondialdehyde (MDA),nitric oxide (NO),PCT and CRP in gastric carcinoma and correlation with the stages of the disease and accompanying infection. METHODS:We examined the levels of serum VEGF,IL-6, PCT,CRP and plasma MDA,NO in 42 preoperative gastric cancer patients and 23 healthy subjects.There were infection anamneses that had no definite origin in 19 cancer patients. RESULTS:The VEGF levels (mean±SD; pg/mL) were 478.05±178.29 and 473.85±131.24 in gastric cancer patients with and without infection,respectively,and these values were not significantly different (P>0.05).The levels of VEGF, CRP,PCT,It-6,MDA and NO in cancer patients were significantly higher than those in healthy controls and the levels of CRP,PCT,It-6,MDA and NO were statistically increased in infection group when compared with non- infection group (P<0.001). CONCLUSION:Although serum VEGF concentrations were increased in gastric cancer,this increase might not be related to infection.CRP,PCT,IL-6,MDA and NO have obvious drawbacks in the diagnosis of infections in cancer patients. These markers may not help to identify infections in the primary evaluation of cancer patients and hence to avoid unnecessary antibiotic treatments as well as hospitalization. According to the results of this study,IL-6,MDA,NO and especially VEGF can be used as useful parameters to diagnose and grade gastric cancer.

Calcitonin gene-related peptide and traumatic brain injury

Dear editor,It is with great interest that we read the article“Relationship of calcitonin gene-related peptide with disease progression and prognosis of patients with severe traumatic brain injury”(Chen et al.,2018).In this study,the authors evaluated 121 patients who were divided into mild/moderate traumatic brain injury(TBI)(n=61),severe TBI(n=35)and control(n=25)groups,and measured serum levels of calcitonin gene-related peptide(CGRP)and serum endothelin-1(ET-1).They found that low levels of CGRP and high levels of ET-1 were associated with high mortality at 6 months.Identification of morphological abnormalities on CT scans is very important for evaluating patients with TBI because different diagnoses are made based on different imaging findings(Maas et al.,2005).

Expression and role of calcitonin gene-related peptide in mouse Aspergillus fumigatus keratitis

AIM: To investigate the expression and role of calcitonin gene-related peptide(CGRP) in the mouse models induced by Aspergillus fumigatus(A. fumigatus). METHODS: C57 BL/6 mice were randomized into a control group and A. fumigatus keratitis group. The cornea photography was assessed under the slit lamp and the clinical score was recorded after infection. Western blot, real-time polymerase chain reaction(PCR) and immunohistofluorescence analysis were applied to detect CGRP expression in cornea of both groups. In vitro, tests were conducted with C57 BL/6 mice macrophages to investigate CGRP expression after interaction with A. fumigatus. Cytokines expression induced by exogenous CGRP and the antagonist CGRP8-37 in A. fumigatus-exposed macrophages was evaluated by real-time PCR and ELISA.RESULTS: The cornea expression of CGRP was significantly elevated in C57 BL/6 mice corneas and macrophages after A. fumigatus infection. After treatment with exogenous CGRP, the levels of interleukin-1β(IL-1β), tumor necrosis factor-α(TNF-α) and IL-6 were reduced, and IL-10 level was increased in the A. fumigatus stimulatedmacrophages. However, IL-1β, TNF-α and IL-6 levels were upregulated after pretreatment of CGRP8-37. But the m RNA levels of MIP-2, TGF-β and IL-10 were not changed. CONCLUSION: This study provides evidence that A. fumigatus increased CGRP expression. CGRP may play a protective role against inflammation in A. fumigatus keratitis.

Transient receptor potential channel A1 involved in calcitonin gene-related peptide release in neurons

Transient receptor potential channel A1 is one of the important transducers of noxious stimuli in the primary afferents, which may contribute to generation of neurogenic inflammation and hyperalgesia. The present study was designed to investigate if activation of transient receptor potential channel A1 may induce calcitonin gene-related peptide release from the primary afferent neurons. We found that application of allyl isothiocyanate, a transient receptor potential channel A1 activator, caused calcitonin gene-related peptide release from the cultured rat dorsal root ganglion neurons. Knock- down of transient receptor potential channel A1 with an antisense oligodeoxynucleotide prevented calcitonin gene-related peptide release by allyl isothiocyanate application in cultured dorsal root ganglion neurons. Thus, we concluded that transient receptor potential channel A1 activation caused calcitonin gene-related peptide release in sensory neurons.

The anti-inflammatory regulation of calcitonin gene-related peptide in mouse Aspergillus fumigatus keratitis

AIM:To analyze the impact of calcitonin gene-related peptide(CGRP)in mouse keratitis after Aspergillus fumigatus(A.fumigatus)infection.METHODS:C57 BL/6 mice were treated subconjunctivally with different concentrations of exogenous CGRP,and BALB/c mice were treated with CGRP8-37(a CGRP antagonist)before corneas were infected with A.fumigatus.The cornea was assessed under the slit-lamp and the clinical score was recorded.The mRNA levels of IL-1β,TNF-α,IL-6,and MIP-2 were detected by quantitative real-time polymerase chain reaction(PCR),while the protein level of IL-1βwas determined by Western blotting.In vitro,RAW264.7 cells were used to investigate NLRP3 and IL-1βexpression induced by A.fumigatus after the pretreatment of exogenous CGRP or CGRP8-37.Cytokines expression in RAW264.7 cells was evaluated by real-time PCR and Western blotting.RESULTS:Using exogenous CGRP resulted in downregulated synthesis of IL-1βand MIP-2 stimulated by A.fumigatus in C57 BL/6 mice keratitis,and the synthesis of IL-1β,MIP-2 and IL-6 was up-regulated in BALB/c mice corneas after the pretreatment with CGRP8-37.Pretreatment with exogenous CGRP and CGRP8-37 did not influence TNF-αmRNA levels either in BALB/c or C57 BL/6 mice keratitis.The levels of NLRP3 and IL-1βwere both reduced in A.fumigatus stimulated-macrophages after treatment with exogenous CGRP.And CGRP8-37 pretreatment would increase NLRP3 and IL-1βlevels.CONCLUSION:CGRP may alleviate the inflammatory reaction in mice keratitis after infection with A.fumigatus.The anti-inflammatory effect may be related to the inhibition of NLRP3 expression by CGRP.

One-time injection of calcitonin induces glucose intolerance in children with the first degree obesity

The effect of calcitonin on the blood glucose level in glucose-tolerance test of children with the first degree obesity was studied. Initial blood glucose level was normal and glucose-tolerance test per os didn’t expose glucose tolerance impairment in children under control. Calcitonin didn’t change initial glucose concentration but evoked impairment of glucose tolerance. The girls with the first degree obesity were more sensitive to hyperglycemic effect of calcitonin than the boys. Sex specificities must be taken into consideration in calcitonin treatment. Besides one ought mean that the increasing secretion of calcitonin occurs in stress-reactions. In these conditions endogenous calcitonin can make the same effect on the regulation of carbohydrate metabolism as exogenous injections of hormone.

Relationship among plasma endothelin, calcitonin gene-related peptide and blood flow rate of bilateral vertebral arteries in patients with cervical vertigo

Objective： To investigate the relationship among plasma endothelin（ET）, calcitonin gene-related peptide（CGRP） and blood flow rate of bilateral vertebral arteries in patients with cervical vertigo（CV） and to assess the effect of ET and CGRP on the onset of CV. Methods：The concentration of ET and CGRP in 64 patients with CV and 30 controls was determined by radioimmunity method. The average blood flow velocity （Vm） of bilateral vertebral arteries was detected by Transcranial Doppler（TCD）. Results：Plasma concen- tration ofET（91.48 ± 9.08 pg/ml） and ET/CGRP ratio value（2.88 ± 0.52） in vertebrobasilar arteriospasm group were both higher than those in vertebrobasilar non-arteriospasm group and in controls, while CGRP concentration（30.66 ± 6.05 pg/ml） in vertebrobasilar arteriospasm group was lower than that in vertebrobasilar non-arteriospasm group and controls respectively. The Vm of bilateral verte- bral arteries in vertebrobasilar arteriospasm group（67.97 ± 11.64 cm/s ） was higher than that in vertebrobasilar non-arteriospasm group and controls respectively, having a positive correlation with ET concentration and ET/CGRP ratio value（r1=0.52, P 〈 0.05; r2=0.59, P 〈 0.05）, but a negative correlation with CGRP concentration（r3=-0.54, P 〈 0.05）. There was no significant difference in ET and CGRP concentration, ET/CGRP ratio value and the Vm of bilateral vertebral arteries between vertebrobasilar non-arteriospasm group and the control group. Conclusion： All the results indicate that ET and CGRP are possibly the most important substance factors at the onset of CV with vertebrobasilar arteriospasm, and their imbalance of regulating vertebrobasilar arterial contraction and relaxation may play an important role in the onset of CV with vertebrobasilar arteriospasm.

Correlation of calcitonin gene-related peptide and endothelin receptor A with subarachnoid hemorrhage

Numerous studies have demonstrated that endothelin-1 combines with endothelin receptor A, resulting in intense vasoconstriction. Although calcitonin gene-related peptide （CGRP） suppresses endothelin-1, CGRP and endothelin receptor A exhibit direct biological effects on brain tissue. The present study analyzed CGRP and endothelin receptor A expression following subarachnoid hemorrhage in rabbits using immunohistochemistry. CGRP expression was significant at 5 days after model establishment, and endothelin receptor A expression was significant at 3 days after model induction. The perimeter of the basilar artery was measured to determine the amount of cerebral vasospasm. Analytical results revealed a significantly shortened basilar artery perimeter following subarachnoid hemorrhage. Changes in the basilar artery perimeter were negatively associated with endothelin receptor A expression, but positively correlated with CGRP expression in vessels. These results suggest that following subarachnoid hemorrhage, CGRP and endothelin receptor A expressions dynamically changed in brain vessels and tissues, although these changes were not synchronous. Changes in endothelin receptor A expression exhibited a significant effect on the occurrence and development of delayed cerebral vasospasm and delayed neuronal death, while CGRP relaxed vessels and protected nerves.