The psychotomimetic drugs D-amphetamine and phencyclidine release calcitonin gene-related peptide in the limbic forebrain of the rat

Calcitonin gene-related peptide (CGRP) is the major product of the calcitonin gene in brain and exerts a number of actions in the central nervous system (CNS). In particular the finding that CGRP affects dopamine (DA) release and metabolism has raised the possibility that it may play a role in several neuropsychiatric disorders. Consequently, we have here studied the effects of two psychotomimetic drugs, namely, d-amphetamine (AMPH) and phencyclidine (PCP), on CGRP concentrations in brain microdialysates from freely moving rats. The animals were stereotaxically implanted with vertical concentric probes in the medial prefrontal cortex (mPFC), the ventral striatum (vSTR), or the hippocampus; and the experiments were performed 48 hr after surgery. The dialysis probes were perfused with a modified Ringer's solution at the rate of 5 μl/min. AMPH 1.5 mg/kg, PCP 2.5 mg/kg, or NaCl 0.9% were injected s.c.; and the perfusates were collected at 60 min intervals before and after the injections and used for CGRP-like immunoreactivity (-LI) determination by radioimmunoassay (RIA). In separate experiments, KCl (100 mM), veratridine (50 μM), or tetrodotoxin (2 μM), were added to the perfusate and infused in the vSTR. Baseline levels of CGRP-LI were detected in dialysates from all three regions. Both AMPH and PCP caused a significant and sustained increase (maximum about 300%) in CGRP-LI concentrations, in particular from the mPFC and vSTR, while saline had no effect. KCl and veratridine also increased CGRP-LI in dialysates during the first posttreatment period, while tetrodotoxin induced a significant but delayed decrease in CGRP-LI levels. Finally, cervical dislocation also elevated CGRP-LI in dialysates from the mPFC and the vSTR. Our findings demonstrate that 1) CGRP-LI can be measured in vivo in microdialysates from mPFC, vSTR, and hippocampus; 2) the release in vSTR is action potential-dependent; and 3) systemic administration of AMPH or PCP results in a long-lasting release of CGRP-LI in the mPFC and vSTR, thus demonstrating a novel action of these drugs in the brain. Since other studies have shown that major antipsychotic drugs appear to reduce CGRP release in brain, our study provides, in principle, support for a role of CGRP in psychotic disorders. © 1996 Wiley-Liss, Inc.     

大鼠生后脑下垂体前叶CGRP免疫反应阳性神经纤维的发育

应用免疫组织化学方法观察了大鼠生后其脑下垂体前叶 CGRP免疫反应阳性神经纤维的发育变化。 SD大鼠按生后天数分为 P1～ 2、P8、P15、P30、P45等五个实验组。结果证明 ,P1～ 2 d,从周围脑膜中来的 CGRP阳性神经纤维进入前叶浅表 ,形态较短直 ,前叶中央部未见阳性纤维。P8d,CGRP阳性纤维的数量较 P1～ 2 d者显著增多 ,CGRP阳性纤维细而弯曲 ,富含膨体 ,呈网状或簇状分布于前叶背侧中央部及吻侧部。P15 d,CGRP阳性纤维可分为粗直类纤维和弯曲的膨体型细纤维 ,前者分布于前叶大部分 ,后者主要呈网状或簇状分布于前叶吻端近腹侧部及背尾部。 P30 d,CGRP阳性纤维也分为粗直类纤维和弯曲的膨体型细纤维 ,粗直类纤维分布于整个垂体前叶 ;弯曲的膨体型细纤维较 P15 d者分布广泛。P45 d CGRP阳性纤维类型和分布接近成年大鼠。本研究结果表明 ,大鼠垂体前叶的 CGRP阳性神经纤维随出生后年龄的增长 ,其类型、数量、分布逐渐由少到多 ,由分布于浅表到广泛分布于整个垂体前叶 ,呈现一种动态变化 ,说明出生后大鼠垂体前叶中 CGRP阳性纤维发育迅速     

降钙素基因相关肽通过抑制Nod样受体蛋白3表达促进小鼠成骨细胞分化的研究

目的 研究降钙素基因相关肽（CGRP）作用下相关炎症体和信号因子的表达变化,探讨CGRP对成骨细胞分化的作用机制。方法 将不同浓度的CGRP（0、10、30、100 ng•mL-1）加入到成骨细胞中,采用实时聚合酶链反应技术检测细胞内Nod样受体蛋白3（NLRP3）及白细胞介素-1β（IL-1β）mRNA的表达水平,蛋白质印迹法检测NLRP3的蛋白表达,酶联免疫吸附测定检测IL-1β的蛋白表达,流式细胞仪检测细胞内活性氧（ROS）含量,茜素红染色显示成骨细胞分化情况。结果 随着CGRP浓度的增加,NLRP3和IL-1β的蛋白表达及mRNA表达均呈降低趋势（P<0.05）,而且细胞内ROS浓度逐渐下降（P<0.05）。100 ng•mL-1CGRP实验组较0 ng•mL-1CGRP对照组显著促进成骨细胞分化。结论 CGRP在一定条件下,可通过抑制细胞内炎症因子的表达促进成骨细胞分化。     

Plasticity of autonomic nerves: Differential effects of long-term guanethidine sympathectomy on the sensory innervation of the rat uterus during maturation

The sensory nerves, containing substance P and calcitonin gene-related peptide, and noradrenaline-containing sympathetic nerves of the rat uterus were analyzed following long-term sympathectomy with guanethidine in prepubertal (four weeks), young adult (eight weeks) and fully adult animals (18 weeks). Immunohistochemical and histochemical methods were used in association with nerve density measurements and biochemical assays. The main findings were as follows:

1. (1) long-term guanethidine treatment completely abolished the noradrenergic innervation of the uterine horn and parametrial tissue and markedly reduced the tissue levels of noradrenaline in both regions at the three ages analysed;

2. (2) in the uterine hom guanethidine treatment had no effect on the tissue levels of either calcitonin gene-related peptide or substance P or on the density of calcitonin gene-related peptide-containing nerves, at any of the three ages studied;

3. (3) in the parametrial tissue increased levels of calcitonin gene-related peptide were observed at 8 and 18 weeks of age, together with a significant increase in the density of calcitonin gene-related peptide-containing nerves.

Substance P levels showed a transient increase in this tissue at eight weeks. In conclusion, long-term sympathectomy with guanethidine resulted in an increase in calcitonin gene-related peptide and substance P in sensory nerves in the parametrial tissue, but not in the uterine horn. The changes in the parametrial tissue only occurred after puberty. It is suggested that sensory nerves in the uterine horn may be less responsive to sympathetic denervation since loss of sympathetic nerves occurs as part of a normal physiological process during pregnancy in this region.

Effects of Synthetic Salmon Calcitonin on C Cells of the Thyroid

The effects of long term administration of synthetic salmon calcitonin (TZ-CT) on thyroid C cells of rats were evaluated immunohistochemically and electron microscopically. Low dose (0.075, 0.75 and 7.5 IU/kg/day) administration caused no significant changes in the C cell population, whereas high doses (30 and 120 IU kg day) caused C cell suppression. The area ratio of C cells to total cells in the thyroid was measured on sections immunoperoxidase stained for calcitonin. The average C cell ratio was compared among the experimental groups. This mor-phometric analysis of the high-dose and control groups confirmed the differences in C cell populations statistically (30 IU/kg vs. control, pgO.05; 120 IU/kg vs. control, p ≦ 0.05). The suppressive effect of TZ CT on C cells was reversible after cessation of administration for one month. Electron microscopic examination on the C cells in the high dose groups revealed no particular ultrastructural differences. These results may suggest a negative feedback mechanism on C cells by exogenous CT. Acta Pathol Jpn 39: 545-550, 1989.     

Distribution and morphology of sensory and autonomic fibres in the subendocardial plexus of the rat heart

Cardiac reflexes originating from sensory receptors in the heart ensure blood supply to vital tissues and organs in the face of constantly changing demands. Atrial volume receptors are mechanically sensitive vagal afferents which relay to the medulla and hypothalamus, affecting vasopressin release and renal sympathetic activity. To date, two anatomically distinct sensory endings have been identified which may subserve cardiac mechanosensation: end-nets and flower-spray endings. To map the distribution of atrial receptors in the subendocardial space, we have double-labelled rat right atrial whole mounts for neurofilament heavy chain (NFH) and synaptic vesicle protein 2 (SV2) and generated high-resolution maps of the rat subendocardial neural plexus at the cavo-atrial region. In order to elucidate the nature of these fibres, double labelling with synaptophysin (SYN) and either NFH, calcitonin gene-related peptide (CGRP), choline acetyltransferase (ChAT) or tyrosine hydroxylase (TH) was performed. The findings show that subendocardial nerve nets are denser at the superior cavo-atrial junction than the mid-atrial region. Adluminal plexuses had the finest diameters and stained positively for synaptic vesicles (SV2 and SYN), CGRP and TH. These plexuses may represent sympathetic post-ganglionic fibres and/or sensory afferents. The latter are candidate substrates for type B volume receptors which are excited by stretch during atrial filling. Deeper nerve fibres appeared coarser and may be cholinergic (positive staining for ChAT). Flower-spray endings were never observed using immunohistochemistry but were delineated clearly with the intravital stain methylene blue. We suggest that differing nerve fibre structures form the basis by which atrial deformation and hence atrial filling is reflected to the brain.     

男性老年骨质疏松症患者血清IL-8、CT、BGP和T含量变化及临床意义

目的:探讨男性老年骨质疏松症患者血清IL-8、降钙素(CT)、骨钙素(BGP)和睾酮(T)含量的变化及临床意义.方法:应用放射免疫分析对33例男性老年骨质疏松症患者进行了血清IL-8、CT、BGP和T检测,并与35名正常人组作比较.结果:男性老年骨质疏松症患者血清IL-8水平非常显著地高于正常人组(P＜0.01),而C...     

大鼠脑底动脉降钙素基因相关肽能神经纤维分布的形态学观察

目的　探讨 14只成年鼠和 14只老年鼠脑底主要动脉降钙素基因相关肽能神经纤维的分布特征。方法　应用免疫组织化学ABC法、神经交点计数法。结果　成年鼠脑底各主要动脉壁上均含有呈线状黑色的CGRP能免疫反应阳性神经纤维 ,分布密度以大脑前动脉最高 ,其次是大脑中动脉、大脑后动脉、基底动脉。各动脉间CGRP能神经纤维密度比较具有统计学意义 (P <0 .0 1) ,成年鼠脑底动脉壁CGRP能神经纤维以环行分布为主 ;老年鼠脑底动脉壁CGRP能神经纤维密度以大脑前动脉最高 ,走行方式以网状分布为主 ;老年鼠脑底各主要动脉壁CGRP能神经纤维分布密度低于成年鼠相应脑底动脉。结论　不同脑底动脉CGRP能神经纤维分布特征各异 ,老年鼠较成年鼠脑底动脉CGRP能神经纤维的分布密度为低     

Stimulus-evoked release of neuropeptides is enhanced in sensory neurons from mice with a heterozygous mutation of the Nf1 gene

Neurofibromatosis type I is a common autosomal dominant disease characterized by formation of multiple benign and malignant tumors. People with this disorder also experience chronic pain, which can be disabling. Neurofibrinomin, the protein product of the NF1 gene (neurofibromin gene (human)), is a guanosine triphosphate activating protein for p21(ras). Loss of NF1 results in an increase in activity of the p21(ras) transduction cascade. Because of the growing evidence suggesting involvement of downstream components of the p21(ras) transduction cascade in the sensitization of nociceptive sensory neurons, we examined the stimulus-evoked release of the neuropeptides, substance P and calcitonin gene-related peptide, from primary sensory neurons of mice with a mutation of the Nf1 gene (neurofibromin gene (mouse)) (Nf1+/-). Measuring immunoreactive substance P and immunoreactive calcitonin gene-related peptide by radioimmunoassay, we demonstrated that capsaicin-stimulated release of neuropeptides is three to five-fold higher in spinal cord slices from Nf1+/- mice than from wildtype mouse tissue. In addition, the potassium and capsaicin-stimulated release of immunoreactive calcitonin gene-related peptide from cultures of sensory neurons isolated from Nf1+/- mice was more than double that from cultures of wildtype neurons. Treatment of wildtype sensory neurons with nerve growth factor for 5-7 days mimicked the enhanced stimulus-evoked release observed from the Nf1+/- neurons. When nerve growth factor was removed 48 h before conducting release experiments, nerve growth factor-induced augmentation of immunoreactive calcitonin gene-related peptide release from Nf1+/- neurons was more pronounced than in Nf1+/- sensory neurons that were treated with nerve growth factor continuously for 5-7 days. Thus, sensory neurons from mice with a heterozygous mutation of the Nf1 gene that is analogous to the human disease neurofibromatosis type I, exhibit increased sensitivity to chemical stimulation. This augmented responsiveness may explain the abnormal pain sensations experienced by people with neurofibromatosis type I and suggests an important role for guanosine triphosphate activating proteins, in the regulation of nociceptive sensory neuron sensitization.