Effect of capsaicin on smooth muscles of rat vas deferens: involvement of calcitonin gene-related peptide?

The effect of capsaicin on the rat vas deferens was examined in relation to the role of endogenous calcitonin gene-related peptide (CGRP) in modifying the contractility of smooth muscles. Capsaicin attenuated the twitch response of the rat vas deferens induced by the transmural nerve stimulation (TNS) in vitro. The effect of capsaicin was transient and developed tachyphylaxis rapidly. Capsaicin inhibited the contraction induced by the direct electrical stimulation of the innervated tissues in the presence of tetrodotoxin but not of the surgically denervated tissues. CGRP-like immunoreactive nerves were demonstrated to be present in the rat vas deferens. Exogenously applied CGRP inhibited both the TNS-induced twitch response and the contraction induced by direct electrical stimulation. Both capsaicin and CGRP slightly hyperpolarized the resting membrane potential of smooth muscle cells but did not affect the amplitude of the excitatory junction potentials. The intensity of CGRP-like immunoreactivity was reduced markedly after the in vitro incubation of the tissue with capsaicin. No CGRP-like immunoreactive nerves were detected in the denervated tissues. Thus, capsaicin inhibited both the TNS-induced twitch response and the contraction induced by direct stimulation of the smooth muscles only when CGRP-like immunoreactive nerves were normally present. These results suggest that capsaicin releases endogenous CGRP and that the released CGRP inhibits the contraction of the rat vas deferens by acting directly on smooth muscle cells but not on the sympathetic nerves.     

Cardiovascular effects of rat calcitonin gene-related peptide in the conscious rat

The role of rat calcitonin gene-related peptide (CGRP), a recently characterized vasoactive neuropeptide, in cardiovascular regulation was studied in the conscious rat. Mean arterial pressure (MAP), heart rate, cardiac output (thermodilution technique) and regional blood flow (directional pulsed Doppler velocimetry) were monitored after i.v. or i.c.v. administration of CGRP. Systemic administration of CGRP (0.1-10 nmol/kg i.v.) decreased MAP and increased heart rate in a dose-related manner. Cardiac output increased (+95 +/- 16 ml/min/kg, P less than .01) after the 1-nmol/kg dose. At the lower or higher doses, CGRP produced no consistent changes in cardiac output. Total peripheral resistance was decreased significantly at the doses of 1 and 10 nmol/kg of CGRP. The CGRP i.v. doses of 1 and 10 nmol/kg increased mesenteric and hindquarter blood flow to a maximum of +23 +/- 7 and +30 +/- 6%, respectively (P less than .01). An increase in renal blood flow (+19 +/- 6%, P less than .05) and a decrease in renal resistance (-15 +/- 4%, P less than .05) were produced by the 0.1-nmol/kg dose of CGRP which had no effect on MAP; higher doses of CGRP tended to decrease renal blood flow. The resistance in all vascular beds was decreased by the CGRP doses of 1 and 10 nmol/kg. The maximum decreases in mesenteric, renal and hindquarter vascular resistance after the 10-nmol/kg dose were -53 +/- 3, -42 +/- 5 and -48 +/- 4%, respectively (P less than .01). The hypotensive and vasodilator responses to CGRP i.v. were significantly magnified, and the tachycardia produced by CGRP was attenuated in the sinoaortic denervated rats. Atropine (muscarinic blockers), propranolol (beta adrenoceptor blocker), cimetidine and pyrilamine (histamine H1 and H2 blockers), indomethacin (prostaglandin synthesis inhibitor), BN52021 (platelet activating factor antagonist) or a substance P antagonist had no effect on the cardiovascular responses elicited by systemic CGRP. CGRP, i.c.v. (0.1-10 nmol/kg), induced a modest tachycardia in both intact and sinoaortic denervated rats, but was devoid of any other cardiovascular effects. The results indicate that CGRP is a potent vasodilator of mesenteric, renal and hindquarter skeletal muscle blood vessels in the conscious rat. The hypotensive and vasodilator actions of circulating CGRP are likely to be mediated by direct peripheral interaction with CGRP receptors on vascular smooth muscle, whereas its tachycardic effect seems to involve reflex activation of the sympathetic nervous system.     

Dual effect of ouabain on the palytoxin-induced contraction and norepinephrine release in the guinea-pig vas deferens

Palytoxin (PTX), C129H223N3O54, isolated from marine coelenterates of Palythoa tuberculosa, caused a first rapid contraction followed by the slow phasic contraction of guinea-pig vas deferens. In the presence of ouabain (10(-5) M), PTX (10(-8) M) failed to cause the first contraction; however, the second contraction was potentiated. In the presence of phentolamine (10(-6) M), the second contraction was inhibited selectively. When ouabain was applied to the muscle in the presence of phentolamine, both first and second contractile responses to PTX were abolished. When the muscle was exposed to the potassium-depleted solution, the first contractile response to PTX was rather potentiated. PTX caused the release of norepinephrine from the muscle. Exposure of the muscle to ouabain (10(-5) M) markedly increased the PTX-induced release. It is indicated that the first and second contractile responses to PTX have entirely different properties. The second response is due to a release of norepinephrine from nerves and was potentiated by ouabain through the increase in the norepinephrine release, whereas the first response was not due to the norepinephrine release but presumably to a direct action on smooth muscle cell and was inhibited by ouabain. The mechanism of the action of PTX was discussed in the relation with Na,K-ATPase.     

大鼠降钙素基因相关肽重组腺病毒的构建与鉴定

目的利用AdMaxTM腺病毒载体系统,构建大鼠降钙素基因相关肽（CGRP）基因重组腺病毒载体,包装重组腺病毒并鉴定。方法根据Genbank提供的大鼠CGRP序列信息（NM₀01033956.1）,合成序列全长,PCR方法扩增目的基因,将CGRP/His基因片段亚克隆至穿梭质粒pDC316,形成重组质粒pDC316-CGRP/His,挑选测序正确的质粒与骨架质粒pBHGloxdelE13cre共转染293A细胞,包装出重组腺病毒Ad-CGRP/His,利用PCR和Western鉴定基因的表达。结果 （1）成功构建pDC316-rCGRP/His重组质粒。（2）包装出表达rCGRP/His的重组腺病毒。结论成功构建携带大鼠CGRP基因的重组腺病毒载体,并获得表达rCGRP/His的重组腺病毒,为深入研究CGRP基因并开展相关的基因治疗研究奠定基础。     

Tyr0]-calcitonin gene-related peptide 28-37 (rat) as a putative antagonist of calcitonin gene-related peptide responses on opossum internal anal sphincter smooth muscle

The effects of calcitonin gene-related peptide (CGRP) I(alpha) (human), CGRP II(beta) (human), CGRP (rat), and [Tyr0]-CGRP (rat) on the resting tone of opossum internal anal sphincter (IAS) were studied. Different CGRPs identified above produced a concentration-dependent fall in the resting tension of the IAS. CGRP II (human) was most potent, while [Tyr0]-CGRP (rat) was the least. The fall in IAS tension caused by CGRP II (human) was not modified by the neurotoxin tetrodotoxin, beta adrenoceptor antagonist propranolol and prostaglandin synthesis inhibitor indomethacin. In contrast to the other CGRP analogs, [Tyr0]-CGRP 28-37 (rat) produced no significant effects on the resting tension of the IAS. However, the fragment caused significant rightward shifts in the concentration-effect curves of different CGRP analogs examined on the IAS. [Tyr0]-CGRP 28-37 (rat) was found to be almost equipotent in antagonizing the inhibitory effects of CGRP (rat) and [Tyr0]-CGRP (rat), but was approximately 12 and 4 times more potent in antagonizing the responses of CGRP I (human) and CGRP II (human), respectively, as compared to that of CGRP (rat) and [Tyr0]-CGRP (rat). Calcitonin, on the other hand, caused a rise in the IAS tension by its action directly at the smooth muscle and this was not modified by [Tyr0]-CGRP 28-37. Thus, we conclude that: 1) CGRP causes a fall in the resting tension of IAS by its action directly at the smooth muscle; 2) [Tyr0]-CGRP 28-37 (rat) may serve as an antagonist of CGRP responses and 3) CGRP and calcitonin produce opposite actions on the resting IAS tension by the activation of their own receptors at the smooth muscle cells.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative affinities and antagonistic potencies of various human calcitonin gene-related peptide fragments on calcitonin gene-related peptide receptors in brain and periphery.

Recent data have suggested that N-truncated human calcitonin gene-related peptide (hCGRP) fragments such as hCGRP8-37 and hCGRP12-37 behave as competitive antagonists in certain bioassays. The present study was undertaken to determine which amino acid residues between positions 8 to 12 are directly involved in ensuring high affinity and antagonist properties at CGRP receptors. In brain, atrium and vas deferens membrane preparations, hCGRP8-37 and hCGRP9-37 demonstrated affinities similar to or much higher than that of the native peptide hCGRP alpha. Shorter fragments such as hCGRP 10-37 and hCGRP 11-37 possessed less than 20% of the affinity of hCGRP alpha in these various assays demonstrating the critical importance of the Thr residue in position 9 for maintenance of adequate receptor affinity. In the in vitro guinea pig left and right atria bioassays, both hCGRP8-37 and hCGRP9-37 behaved as potent and competitive antagonists (pA2:7.0-7.7) of positive chronotropic and inotropic effects induced by hCGRP alpha. hCGRP 10-37 and hCGRP 11-37 were at least 10 times less potent (pA2: 6.1-6.6). Interestingly, both hCGRP 8-37 and hCGRP9-37 were much less potent (pA2: 6.2-6.3) in blocking the effects of hCGRP alpha in the rat vas deferens whereas only slight inhibition was observed at 1.0 microM with hCGRP10-37 and no blocking activity was detected with hCGRP11-37 at a low micromolar concentration. These results are in accordance with binding data and demonstrate further the importance of residues in positions 9 (Thr) and 10 (His) to ensure potent antagonistic properties of N-truncated hCGRP fragments.(ABSTRACT TRUNCATED AT 250 WORDS)     

骨折愈合过程中降钙素基因相关肽表达与脑损伤的影响

背景:临床观察及实验研究发现合并中枢神经损伤的骨折愈合加速,但其具体机制尚未明确.目的:观察股骨骨折合并脑损伤大鼠骨痂中降钙素基因相关肽及其mRNA的表达变化,探讨脑损伤对骨折愈合的影响及作用机制.设计、时间及地点:随机对照动物实验,于2007-01/10在华北煤炭医学院骨科实验室完成.材料:健康12周龄雌性SD大鼠64只,建立大鼠开放骨折模型.方法:骨折造模后64只SD大鼠随机数字法分为骨折合并脑损伤组和单纯骨折组,每组32只,骨折合并脑损伤组接着制备脑损伤模型.造模后7,14,21,28 d分批麻醉并处死动物,苏木精-伊红染色观察骨折愈合情况,免疫组织化学染色及原位杂交检测降钙素基因相关肽及其mRNA的表达变化.主要观察指标:①造模后28 d大鼠右侧股骨X射线平片表现.②造模后不同时间点两组大鼠骨痂苏木精一伊红染色、免疫组织化学染色及原位杂交结果.结果:64只SD大鼠均进入结果分析.①X射线平片显示与单纯骨折组相比,骨折合并脑损伤组骨折端骨痂形成早,骨痂量多.②苏木精一伊红染色示单纯骨折组呈典型骨折愈合过程,而骨折合并脑损伤组骨痂形成及改造提前,骨折愈合加速.免疫组织化学染色显示骨折愈合过程中内皮细胞、骨祖细胞、软骨细胞及成骨细胞表达降钙素基因相关肽.骨折合并脑损伤组造模后各时间点阳性细胞数均高于单纯骨折组,差异有显著性意义(P<0.05).原位杂交检测示骨折合并脑损伤组造模后7,14,21 d表达降钙素基因相关肽mRNA的成骨细胞数均高于单纯骨折组,差异有显著性意义(P<0.05).结论:脑损伤对骨折愈合有促进作用,可能与合并脑损伤后降钙素基因相关肽及其mRNA表达水平升高有关.     

辣椒素对大鼠面部皮肤CGRP免疫反应性神经影响的实验研究

目的:研究辣椒素(CAP)对大鼠面部皮肤降钙素基因相关肽(CGRP)免疫反应性神经纤维(IRF)的影响,探讨CAP治疗三叉神经的镇痛机制。方法:把CAP配成30mM浓度溶液备用,按用量分成四组(A组20μl、B组30μl、C组50μl和D组100μl),分别皮下注射大鼠三叉神经眶下支,24h取材,切片,免疫组化染色,镜检,计算机图像分析。结果:经方差分析,除CGRP平均光度的对照组和A组,无显著性差异外(P>0.05),其它各组之间,有非常显著性差异(P<0.01)。并且随着用药量的增加其差值也更大。结论:CAP对大鼠面部皮肤CGRP免疫反应性神经有明显的影响,CGRP参与口面部的痛与镇痛。     

降钙素基因相关肽神经生长因子与失神经支配兔骨折愈合

背景:骨折不愈合严重影响患者生活质量,神经生长因子用于骨不连的防治是重建外科领域研究的重点和方向.目的:观察神经生长因子降钙素基因相关肽对失神经支配兔骨折愈合的影响.方法:构建大白兔失神经支配腓骨骨折模型后,实验组骨折端局部注射降钙素基因相关肽10μg,每2 d一次;对照组骨折端局部注射等量生理盐水.术后2,4,6周分别测定静脉血中肾上腺素和去甲肾上腺素的水平,并进行生物力学和组织学分析.结果与结论:术后两组血清肾上腺素和去甲肾上腺素水平均有显著增高,在术后第4周达到最高峰,比术前高出1倍以上,第6周时出现下降,但仍然显著高于术前;术后2,4,6周,实验组肾上腺素和去甲肾上腺素血清水平较对照组显著增高,差异具有显著性意义(P<0.05～0.01).在三点弯曲实验中,实验组骨痂的抗弯强度明显高于对照组(P<0.05～0.001);术后第6周时苏木精-伊红染色可见实验组骨痂中的透明软骨细胞已被成骨细胞替代,对照组骨痂中的软骨细胞仍没有完全成骨细胞化.提示神经生长因子降钙素基因相关肽对失神经支配兔骨折愈合具有明显的促进作用.     

低频脉冲磁刺激对大鼠牙髓组织内降钙素基因相关肽免疫阳性神经纤维的影响

目的探讨低频脉冲磁刺激对大鼠牙髓组织内降钙素基因相关肽（CGRP）免疫阳性的神经纤维的影响。方法选择健康Sprague—Dawley大鼠15只，随机分为对照组、多次磁刺激组和单次磁刺激组，每组5只。后两组采用低频脉冲磁刺激大鼠颌面部，频率为2Hz，强度峰值为2T。多次磁刺激组每日给予1次连续30个脉冲的磁刺激，连续刺激6d；单次磁刺激组仅给予1次30个脉冲的磁刺激。取上颌磨牙制备标本，CGRP免疫组织化学染色，显微镜观察阳性神经纤维密度并进行统计学分析。结果多次磁刺激组大鼠牙根髓上段和髓角处CGRP阳性神经纤维明显增多，染色增强，与对照组比较，差异有统计学意义（P〈0．05）；而单次磁刺激组大鼠牙根髓上段和髓角处CGRP阳性神经纤维明显减少，染色变淡，与对照组比较，差异有统计学意义（P〈0．01）。结论多次连续低频脉冲磁刺激可促进牙髓组织内CGRP的表达，单次低频脉冲磁刺激可促进组织中部分CGRP释放，使其在组织中表达减少，其机制及生物学意义尚需深入探讨。     

Characterization of erenumab and rimegepant on calcitonin gene-related peptide induced responses in Xenopus Laevis oocytes expressing the calcitonin gene-related peptide receptor and the amylin-1 receptor

BackgroundThe clinical use of calcitonin gene-related peptide receptor (CGRP-R) antagonists and monoclonal antibodies against CGRP and CGRP-R has offered new treatment possibilities for migraine patients. CGRP activates both the CGRP-R and structurally related amylin 1 receptor (AMY₁-R). The relative effect of erenumab and the small-molecule CGRP-R antagonist, rimegepant, towards the CGRP-R and AMY-R needs to be further characterized.MethodsThe effect of CGRP and two CGRP-R antagonists were examined in Xenopus laevis oocytes expressing human CGRP-R, human AMY₁-R and their subunits.ResultsCGRP administered to receptor expressing oocytes induced a concentration-dependent increase in current with the order of potency CGRP-R> > AMY₁-R > calcitonin receptor (CTR). There was no effect on single components of the CGRP-R; calcitonin receptor-like receptor and receptor activity-modifying protein 1. Amylin was only effective on AMY₁-R and CTR. Inhibition potencies (pIC₅₀ values) for erenumab on CGRP induced currents were 10.86 and 9.35 for CGRP-R and AMY₁-R, respectively. Rimegepant inhibited CGRP induced currents with pIC₅₀ values of 11.30 and 9.91 for CGRP-R and AMY₁-R, respectively.ConclusionOur results demonstrate that erenumab and rimegepant are potent antagonists of CGRP-R and AMY₁-R with 32- and 25-times preference for the CGRP-R over the AMY₁-R, respectively. It is discussed if this difference in affinity between the two receptors is the likely reason why constipation is a common and serious adverse effect during CGRP-R antagonism but less so with CGRP binding antibodies.Supplementary InformationThe online version contains supplementary material available at 10.1186/s10194-022-01425-9.     

hCGRP8-37, a calcitonin gene-related peptide antagonist revealing calcitonin gene-related peptide receptor heterogeneity in brain and periphery

The C-terminal fragment of human calcitonin gene-related peptide (CGRP), hCGRP8-37, fails to induce any biological activity in a variety of isolated tissues and behavioral assays even though it possesses nanomolar affinity for [125I]hCGRP alpha binding sites in the central nervous system and peripheral membrane preparations. However, hCGRP8-37 displays relatively potent, competitive antagonist properties toward the action of native hCGRP alpha in guinea pig atrial and ileal preparations and on the central nervous system-mediated inhibition of CGRP on food intake. On the contrary, in the rat vas deferens the antagonistic potency of hCGRP8-37 was much weaker and was ineffective against CGRP-induced hyperthermia after i.c.v. injection. Such evidence suggests the existence of at least two classes of CGRP receptors, the first (CGRP1) being sensitive to the antagonist properties of hCGRP8-37, whereas the second (CGRP2) is not. The use of hCGRP8-37 should greatly facilitate the characterization of the physiological roles of CGRP-like peptides, especially those which are mediated via the activation of CGRP1 receptors.     

The effect of calcitonin gene-related peptide (CGRP) on human forearm blood flow

Summary. The effect of intravenous and intra-arterially administered calcitonin generelated peptide (CGRP) on the human forearm blood flow and cutaneous blood flow were investigated by means of venous occlusion plethysmography and laser-Doppler flowmetry, respectively. Infusion of CGRP (11–216 pmol min^-1) into the brachial artery resulted in a dose-dependent increase in forearm blood flow and cutaneous blood flow which persisted for up to 90 min after the infusion was stopped. Repeated infusions resulted in an identical response. Systemic intravenous infusion of CGRP (104–520 pmol min^-1) resulted in a dose-dependent flush in the face, neck, upper trunck and upper arms, and an increase in the forearm blood flow. The cutaneous blood flow was dramatically increased on the forehead, whereas on the hand only a slight increase was noted. By intravenous infusions a significant drop in blood pressure and increase in heart rate were seen at 520 pmol min^-1. Thus, it is possible to give CGRP in doses that increase the blood flow in muscle and skin without resulting in a fall in systemic arterial blood pressure and tachycardia, suggesting that CGRP may be used as a tool for the treatment of various conditions in man with compromised blood flow.     

迷走神经切断对鼠肺降钙素基因相关肽的影响

目的:探讨切断左侧迷走神经对大鼠血清降钙素基因相关肽含量和降钙素基因相关肽(CGRP)基因表达及调控机制的影响.方法:30只SD大鼠切断左侧迷走神经并按术后取样时间随机分为术后1周组、术后1个月组、术后3个月组,每组10只;另设10只SD大鼠作为正常对照组.采用放射免疫分析法测定血清中CGRP浓度,RT.PCR法测定肺内CGRP mRNA表达.结果:迷走神经切断术后1周和1个月血清CGRP含量比正常对照组显著降低(P＜0.01),随着时间延长,血清中CGRP含量逐渐增加,至3个月时接近正常对照组(P＞0.05):而肺组织CGRP mRNA表达在术后1周和1个月均明显高于对照组(P＜0.01),随着时间的延长,其表达量逐渐减少,至术后3个月时接近正常对照组(P＞0.05).结论:迷走神经切断后血清内CGRP浓度下降及肺内CGRP mRNA表达量增加,表明迷走神经对CGRP基因的表达和神经活性物质CGRP的分泌具有调节作用.     

Diurnal variation of the rat vas deferens contraction induced by stimulation of presynaptic nicotinic receptors and pineal function.

A rhythmic variation of maximal contraction induced by acetylcholine in the prostatic portion of rat vas deferens was tested. This contraction is due to the release of norepinephrine and ATP from sympathetic nerve terminals. Male Wistar rats (4 months old) were housed on a light/dark cycle (12 hr/12 hr, lights on at 6:00 A.M.). The diurnal variation of acetylcholine-induced contraction was determined on animals sacrificed every 3 hr during the day. The maximal contractile response shows a circadian (24:00 hr) and an ultradian (12:20 hr) rhythm. Otherwise, the sensitivity to acetylcholine (pD2 values) and the maximal contraction or pD2 values to norepinephrine, ATP and K+ did not change throughout the day. The blocking effect of hexamethonium on the contraction induced by field stimulation was higher at 9:00 P.M. than at 3:00 P.M., indicating a diurnal variation of the effect of endogenous released acetylcholine. When melatonin released by the pineal gland is suppressed by constant illumination or superior cervical ganglionectomy, the circadian rhythm was abolished and the period of the ultradian rhythm changed to 6:30 hr. The acetylcholine-induced contraction of vasa deferentia from animals sacrificed at 3:00 P.M. and incubated "in vitro" with melatonin (100 pg/ml) increased reaching nocturnal values. In conclusion, it seems that a functional pineal gland, most probably through the synthesis and release of melatonin, is necessary for expression (circadian) and modulation (ultradian) of the rhythmicity in the maximal acetylcholine-induced contraction in the prostatic portion of the rat vas deferens.     

Pharmacological characterization of purinergic receptors in the rat vas deferens

Using the isolated rat vas deferens, we have confirmed the existence of P1 purinergic receptors whose activation results in an inhibition of the neurogenic twitch of the vas deferens. The observed order of potency for agonists (adenosine ethyl carboxamide greater than 2-chloroadenosine greater than adenosine greater than 5'-AMP greater than 5'-ADP greater than ATP) and antagonism of these effects by theophylline supports a P1-mediated response. Metabolically stable analogs of ATP elicited dose-dependent contractile responses which were quantitatively greater than, but qualitatively comparable to, ATP-induced responses. The order of potency for the eliciting contraction was the following: adenylyl-5-imidodiphosphate = beta-gamma-methylene ATP greater than adenosine tetraphosphate much greater than ATP greater than ADP. Interestingly, these compounds also produced an inhibition of the neurogenic twitch with a similar rank order of potency. This response was not due to the activation of P1 receptors insofar as high concentrations of theophylline failed to attenuate either the inhibition of the neurogenic twitch or the contractile response induced by these agonists. Thus, these data demonstrate the presence of both P1 and P2 purinergic receptors in the rat vas deferens. In addition, the data are consistent with the idea that two distinct classes of P2 receptors exist in this tissue. Furthermore, these data suggest that the rat vas deferens provides a useful tissue for studying compounds which interact with both major subtypes of purinergic receptors.     

辣椒素对大鼠面部皮肤降钙素基因相关肽和一氧化氮合酶阳性神经纤维的影响

背景辣椒素外敷治疗浅表性疼痛已为人们接受,但能否直接作用于皮下或深层组织中的神经末梢或神经治疗三叉神经痛?目的观察皮下注射辣椒素对大鼠面部皮肤降钙素基因相关肽、一氧化氮合酶阳性神经纤维的影响.设计随机对照实验.单位咸宁学院医学院解剖学教研室,华中科技大学同济医学院神经生物学研究室.材料实验于2003-10/12于华中科技大学同济医学院神经生物学研究室完成.健康Wistar大鼠20只,雌雄不拘,体质量120～170 g.方法辣椒素皮下注射处理大鼠三叉神经眶下支,大鼠左侧面区为对照侧,右侧面区为实验侧,按用量将动物分为辣椒素20μL组,辣椒素30μL组,辣椒素50μL组,辣椒素100μL组4组,每组5只.24 h取材后切片镜检,降钙素基因相关肽和一氧化氮合酶免疫组化染色.主要观察指标[1]镜检实验侧各组染色标本中降钙素基因相关肽和一氧化氮合酶阳性神经纤维的变化;图像分析降钙素基因相关肽和一氧化氮合酶的平均吸光度.[2]大鼠的特征性行为和体征改变.结果20只大鼠均进入结果分析.[1]行为变化皮下注射辣椒素溶液数分钟后,大鼠出现一系列特征性的行为和体征改变,但随着用药次数的增加,则逐渐减轻或消失.[2]镜检结果实验侧各组标本中降钙素基因相关肽和一氧化氮合酶阳性神经纤维有明显差别.[3]图像分析各组大鼠面部皮肤降钙素基因相关肽平均吸光度对照侧为0.984±0.056,辣椒素20μL组为0.947±0.025,辣椒素30 μL组为0.852±0.042,辣椒素50 μL组为0.756±0.028,辣椒素100 μL组为0.730±0.016;各组大鼠面部皮肤一氧化氮合酶平均吸光度对照侧为0.151±0.009,辣椒素20μL组为0.148±0.007,辣椒素30μL组为0.132±0.012,辣椒素50μL组为0.111±0.067,辣椒素100μL组为0.107±0.006.方差分析组间差异有显著性意义(P＜0.01).结论降钙素基因相关肽、一氧化氮合酶参与了伤害性信息处理和调控痛与镇痛的过程,辣椒素通过耗竭大量的神经递质而发挥镇痛作用.     

Presence and function of the calcitonin gene-related peptide receptor on rat pial arteries investigated in vitro and in vivo

Calcitonin gene-related peptide (CGRP) and related peptides may be involved in migraine pathogenesis. To understand their vasomotor role in the cerebral circulation, we performed two studies, a pressurized arteriography study of the middle cerebral artery (MCA) and a genuine closed cranial window (gCCW) in vivo study. Using the pressurized arteriography model rat MCAs were mounted on micropipettes, pressurized to 85 mmHg and luminally perfused. The diameter responses to luminally and abluminally applied rat-alphaCGRP, rat-betaCGRP, amylin and adrenomedullin were compared with the resting diameter. Only abluminally applied CGRP induced dilation of the cerebral arteries; E(max) for alphaCGRP and betaCGRP were 35 +/- 0.5% and 10.8 +/- 0.2%. These responses were blocked by CGRP(8-37). The gCCW model allowed videomicroscopic visualization of the pial vessels in anaesthetized rats. Changes in vessel diameter to intravenously administered alphaCGRP and betaCGRP were compared with pre-infusion baseline. Intravenous infusion of alphaCGRP and betaCGRP in the highest dose induced dilation of the cerebral cortical pial arteries/arterioles of 40.3 +/- 7.5% and 49.1 +/- 8.4%, respectively. However, this was probably secondary to a decrease in blood pressure of 44.8 +/- 3.3 mmHg and 49.2 +/- 3.3 mmHg. Our results suggest that CGRP receptors are probably functional on the smooth muscle cells and not on the endothelium of rat cerebral arteries.     

Species differences in sodium-potassium adenosine triphosphatase activity in the smooth muscle of the guinea-pig and rat vas deferens.

The acitvities of sodium-potassium-activated adenosine triphosphatase (Na+,K+-activated ATPase) and ouabain-inhibited, sodium-potassium-activated adensoine triphosphatase (Na+,K+-ATPase) in subcellular fractions of guinea-pig and rat vasa deferentia were compared to determine whether the ineffectiveness of ouabain and reduced extracellular potassium in the rat vas deferens observed in the preceding paper occurs because of a relatively low level of Na+,K+-ATPase and/or an insensitivity to ouabain. The results indicate that the specific and total activities of Na+,K+-activated ATPase and Na+,K+-ATPase (i.e., the transport enzyme) in the individual subcellular fractions and in the tissue were higher in the vas deferens of the rat than in the guinea pig. The percentage of inhibition of Na+,K+-activated activity by ouabain (8 x 10(-5) M) varied in the subcellular fractions; it was higher in the guinea-pig (range 31--87%) than in the rat (nonsignificant effect to 40%). A greater percentage of total Na+K+- activated ATPase activity was inhibited in the vas deferens of the guinea pig (56%) than the rat (30%). Differences in the effects of lowered extracellular potassium concentration or ouabain on resting membrane potential (preceding paper) are apparently unrelated to the amount of transport enzyme in the vasa deferentia or the two species, or to its relative sensitivity to ouabain.