首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The experiments were designed to detect somatopetal transport of [14C]noradrenaline in the postganglionic sympathetic nerves supplying the cat spleen and sheep eye. The animals were treated with nialamide to protect the radioactive noradrenaline, after uptake into the nerve terminals, from monoamine oxidase. In the spleen, the transmitter stores were labelled by infusion of [14C]noradrenaline into a branch of the splenic artery. The branches of the nerves to the infused and non-infused sides of the spleen were ligated in an attempt to arrest, distal to the constriction, any noradrenaline transported somatopetally in the axons from their terminals. After 24 hr, however, there was less radioactivity in the nerves distal compared to proximal to the constriction, despite heavier labelling of the terminal transmitter stores in the infused portion of the spleen. The proximal accumulation of radioactivity could be attributed to a somatofugal transport of [14C]noradrenaline. Experiments were also done on the intact sympathetic nerve supply of the sheep eye. The sympathetic nerve terminals in the smooth muscle of the left eye were heavily labelled 5 days after the injection of [14C]noradrenaline into the left vitreous humour. However, both superior cervical ganglia were only lightly labelled, and there was no significant difference in the radioactivity present in the two ganglia. The results provide no support for a bidirectional transport of noradrenaline in sympathetic nerves but are consistent with a somatofugal transport of the amine storage vesicles from their site of synthesis in the soma to the axon terminals.  相似文献   

2.
Summary The pineal gland of the rat receives a rich nervous supply originating from the superior cervical ganglia. These fibers contain serotonin in addition to their neurotransmitter, noradrenaline. Cytochemical studies at the ultrastructural level have shown that both amines are present in the cores of the granular vesicles that are characteristic of these nerves. It is presently shown that the bilateral electrical stimulation of the preganglionic fibers innervating the ganglia markedly reduces the number of small sites reacting cytochemically for both noradrenaline and serotonin, these sites corresponding to the cores of small granular vesicles, while the larger reactive sites (cores of large vesicles) remain unaltered. The vesicles are retained in nerve terminals after stimulation, as observed in conventionally processed tissues, although with altered sizes and shapes. Apart from these cytochemical and structural changes, nerve stimulation also reduces the endogenous noradrenaline content of the pineal gland. Thus, both noradrenaline and serotonin are released from their storage sites in pineal sympathetic nerves after electrical stimulation in vivo. This suggests the possibility that several substances with presumed transmitter or modulatory functions might be simultaneously released by nerve impulses from a given nerve terminal.  相似文献   

3.
Abstract— —Both [14C]noradrenaline and [14C]leucine were injected into the coeliac ganglia of cats in an attempt to label the noradrenaline and protein of the granular vesicles, so that their movement in the splenic nerves could be followed.
When a constriction was placed on the nerves, labelled noradrenaline and protein accumulated just proximal to it, but there was no such accumulation below it, nor above a second, more distal constriction placed on the same nerve. This indicated that a neural transport mechanism, rather than uptake from the circulation, was responsible for the accumulation.
Peaks of labelled noradrenaline and protein were observed to move down the axon at about 5 mm/hr. In addition a slow moving component of axonal protein, advancing at about 1 mm/day, was detected.
The results demonstrate a rapid proximo-distal movement of noradrenaline and protein which could represent the transport of granular synaptic vesicles from their site of manufacture in the cell body to their site of storage in the nerve terminals within the spleen.  相似文献   

4.
Abstract: The acetylcholine (ACh) content of sympathetic ganglia increases above its normal level following a period of preganglionic nerve stimulation. In the present experiments, this extra ACh that accumulates following activity was labeled radioactively from [3H]choline and its specific activity was compared with that of ACh subsequently released during preganglionic nerve stimulation. The specific activity of the released ACh was similar to that of the total tissue ACh, suggesting that the extra ACh mixes fully with endogenous stores. The present experiments also show that transmitter release during neuronal stimulation is necessary for the poststimulation increase in transmitter store. However, the increase was not evident when transmitter release was induced by K+. It is concluded that both transmitter release and impulse invasion of the nerve terminals are necessary for the adaptive phenomenon to manifest itself. The role of choline delivery and choline acetyltransferase activity in generating the poststimulation increase in transmitter store was tested. When choline transport activity measured as choline analogue (homocholine) accumulation increased, ACh synthesis was increased and when transport activity was not increased, neither was ACh synthesis. There was no poststimulation increase in measured choline acetyltransferase activity.  相似文献   

5.
—Dopamine β-hydroxylase was used as a marker enzyme for sympathetic nerve vesicles which were studied by density gradient technique in bovine splenic nerves. The enzyme analyses were complicated by the occurrence of inhibitors which had to be carefully neutralized with copper. The inhibitor was mainly found in the soluble fraction and no evidence for the occurrence of endogenous inhibitors in the nerve vesicles was obtained. A great variation in density of the dopamine β-hydroxylase containing particles was observed. This was probably mainly due to the variation in vesicle maturation since dopamine β-hydroxylase was distributed more towards the lighter gradient fractions in the proximal nerve segment preparations compared with intrasplenic nerve segment preparations. Noradrenaline/protein and noradrenaline/dopaminc β-hydroxylase ratios were found to be increased about 1·7-fold in the vesicle fraction isolated from the proximal nerve segments to those from the intrasplenic segments. A further increase of the noradrenaline/dopamine β-hydroxylase ratio was observed in a fraction with the same density isolated from the spleen. On the basis of these findings the noradrenaline/protein ratio was calculated to be about 500-600 nmol/mg in the nerve terminal vesicles.  相似文献   

6.
Summary The subcellular distribution of noradrenaline (NA), neuropeptide Y (NPY), Met and Leu-enkephalin (ENK), substance P (SP), somatostatin (SOM), and vasoactive intestinal polypeptide (VIP) was investigated in homogenates of bovine splenic nerve. The distribution of noradrenergic peptide-containing nerves in the bovine celiac ganglion, splenic nerve and terminal areas in spleen was studied by indirect immunofluorescence histochemistry using antisera to tyrosine hydroxylase (TH), dopamine--hydroxylase (DBH), NPY, enkephalin peptides, SP, SOM, VIP and peptide HI (PHI).After density gradient centrifugation, high levels of NPY and ENK-like immunoreactivity (LI) were found in high-density gradient fractions, coinciding with the main NA peak. SP, SOM and VIP were found in fractions with a lower density, VIP being also enriched in a heavy fraction; the latter three peptides were present in low concentrations.Immunohistochemistry revealed that staining for NPYLI and ENK-LI partly overlapped that for TH and DBH in celiac ganglia, splenic nerve axons and terminal areas of spleen. Almost all principal ganglion cells were TH- and DBH-immunoreactive. Many were also NPY-immunoreactive, whereas a smaller number were ENK-positive. In the celiac ganglion patches of dense SP-positive networks and some VIP/PHI- and ENK-immunoreactive fibers were seen around cell bodies.The results indicate that NPY and ENK are stored with NA in large dense-cored vesicles in unmyelinated axons of bovine splenic nerve. SP, SOM and VIP appear in different organelles in axon populations separate from sympathetic noradrenergic nerves.  相似文献   

7.
在46只麻醉兔,记录了经冠脉内注射尼古丁诱发Bezold-Jarisch反射时不同区域交感神经传出放电的变化。肾神经、心脏神经、脾神经、星状神经节-颈神经交通支和颈前神经节的颈外动脉支五个部位的交感性传出放电,在冠脉内注射尼古丁后均减少,其中以肾神经、心脏神经和脾神经的减少更为显著。此结果表明,交感神经传出放电减少所致的总外周阻力降低,在Bezold-Jarisch反射诱发的低血压中起着重要作用。  相似文献   

8.
用液氮骤冻造成大白鼠交感节前神经变性后,通过神经末梢乙酰胆碱含量、胆碱酯酶活性测定以及电刺激交感干时外周反应等研究其再生规律。结果表明冻伤后3周内再生过程进展迅速,神经结构与功能均有相当程度的恢复;3周后再生过程转慢,直至一年时各指标仍远未达到正常。这证明交感节前神经的再生过程不同于中枢及其它外周神经而独具特征。  相似文献   

9.
Afferent stimulation of one canine thoracic cardiopulmonary nerve can generate compound action potentials in another ipsilateral cardiopulmonary nerve. These compound action potentials persist after acute decentralization of the middle cervical ganglion, indicating that they result from neural activity in the middle cervical ganglion and thoracic nerves. Changing the frequency of stimulation can alter the compound action potentials, suggesting that temporal facilitation or inhibition occurs in this middle cervical ganglion preparation. The compound action potentials can be modified by stimulation of sympathetic preganglionic fibers and by hexamethonium, atropine, phentolamine, propranolol, and (or) manganese. It thus appears that afferent cardiopulmonary nerves can activate efferent cardiopulmonary nerves via synaptic mechanisms in the stellate and middle cervical ganglia. It also appears that these mechanisms involve adrenergic and cholinergic receptors and are influenced by preganglionic sympathetic fibers arising from the cord.  相似文献   

10.
Summary Neuropeptide Y (NPY)-immunoreactive (IR) nerve fibres were found around both arteries and veins and in smooth muscle trabeculae of the cat spleen with the highest density on the arterial side. Considerably more tyrosine hydroxylase (TH)- and dopamine--hydroxylase (DBH)-positive than NPY-IR nerves were seen in the trabeculae and splenic capsule. The NPY-IR nerves in the spleen most likely originated in the coeliac ganglion, since (1) splanchnic nerve sectioning did not change the splenic NPY-IR nerves, (2) most neurones in the coeliac ganglion were NPY-IR, as well as DBH- and TH-positive, and (3) NPY-IR was transported axonally from the coeliac ganglion towards the spleen via the splenic nerve. Local NPY infusion in the isolated, blood-perfused cat spleen caused a marked increase in splenic vascular resistance and a small volume reduction. NA caused a comparatively larger reduction in splenic volume than NPY in addition to vasoconstriction. VIP-IR cell bodies in the coeliac ganglion were NPY- and TH-negative. VIP-IR nerves were seen both around the splenic artery and vein as well as around arterioles and within venous trabeculae of the spleen. VIP infusion caused reduction of splenic perfusion pressure (i.e. vasodilation) as well as an increase in splenic volume. Substance P-IR nerves, most likely of splanchnic afferent origin, were present in the coeliac ganglion around the splenic artery and arterioles of the spleen. Infusion of substance P induced marked reduction in perfusion pressure and a reduction in splenic volume. Enkephalin-immunoreactive nerves of splanchnic origin surrounded some TH- and NPY-positive, coeliac ganglion cells.It is concluded that several vasoactive peptides are located in splenic nerves. NPY is present in noradrenergic neurones and causes mainly increased vascular resistance. VIP occurs in non-adrenergic neurones of sympathetic origin and induces vasodilation and relaxation of the capsule. Finally, substance P is present in peripheral branches of spinal afferent nerves and causes vasodilation and capsule contraction. Stimulation of the splenic nerves may thus release several vasoactive substances in addition to noradrenaline, exerting a variety of actions.  相似文献   

11.
Since hexamethonium and surgical section have been used to prevent reflex splanchnic capacitance responses, we examined the effectiveness of these procedures in blocking responses to direct stimulation of preganglionic fibres in the splanchnic nerves. Liver blood volume was measured by plethysmography and splenic blood volume by weighing in cats anesthetized by pentobarbital. The cats were adrenalectomized to prevent adrenal catecholamine secretion in response to splanchnic nerve stimulation. Hexamethonium (10 and 20 mg/kg) alone or atropine (1 mg/kg) alone caused only a small variable block of the responses to preganglionic nerve stimulation. A combination of the two drugs essentially produced a complete block of the liver capacitance response, but a significant response still persisted in the spleen. Surgical section of the postganglionic nerve bundles around the hepatic and splenic arteries completely abolished the responses to preganglionic stimulation. It is concluded that a relatively complete block of reflex splanchnic capacitance responses requires either a combination of hexamethonium and atropine or surgical section of the postganglionic nerves.  相似文献   

12.
Renal efferent sympathetic activity and its changes due to stimulation of the central stump of the vagal, sciatic and ulnar nerves were investigated. In addition, the effect on basal activity and sympathetic reflexes of drugs with well defined site of action was studied (diazepam, tofizopam, phentolamine, dihydroergotamine, chlorpromazine, reserpine, clonidine, atropine, methysergide and phenindamine). The sympathetic efferent activity and the changes in sympathetic reflexes allowed conclusions to be drawn as to the functional state of the vasomotor centre. Neither methysergide nor phenindamine inhibited efferent sympathetic activity or influenced sympathetic reflexes. These findings exclude the possibility of serotonin or histamine being the transmitter substance in the vasomotor neurone. Experiments with atropine revealed that the muscarinic action of acetylcholine does not figure in the sympathetic inhibitory or excitatory reflex processes. Of the drugs investigated only diazepam and clonidine inhibited efferent sympathetic activity. Clonidine was more selective and acted in much lower doses (20 micrograms/kg) than diazepam (0.5--1 mg/kg). The alpha blocking agents inhibited the viscero-sympathetic inhibitory reflex arch more intensely than the somato-sympathetic inhibitory one. The transmitter is presumably noradrenaline. The sympathetic excitatory reflexes were decreased by diazepam and tofizopam and increased by clonidine and phentolamine. The other substances were ineffective. As to the transmitter substance figuring in the sympathetic excitatory reflexes no unequivocal answer could be obtained in the present experiments.  相似文献   

13.
The role of the celiac plexus in maintenance of temperature homeostasis in rats exposed to cold stress was studied by histochemical, ultrastructural, and electrophysiological methods. Inhibition of efferent impulsation was found in the preganglionic (splanchnic) nerves and potentiation in postganglionic (superior mesenteric) nerves under the influence of short-term cold stress, leading to a state of mild hypothermia. During cooling of the animals after decentralization of the celiac plexus an increase was observed in the intensity of fluorescence, in the activity of enzymes of energy metabolism, and in hyperplasia of the ultrastructural formations responsible for protein synthesis and the energy supply of the cell. It is suggested that during cold stress, when the flow of efferent impulses along preganglionic nerves is considerably reduced the celiac plexus becomes the center regulating autonomic functions that are involved in the maintenance of temperature homeostasis.Institute of Physiology, Belorussian Academy of Sciences, Minsk. Translated from Neirofiziologiya, Vol. 24, No. 6, pp. 659–667, November–December, 1992.  相似文献   

14.
The influence of sodium oxybutyrate on the adrenergic neurotransmitter content in the nerve fibers and the synaptic vesicles and the uptake of exogenous noradrenaline (NA) by the sympathetic nerves of rat Vas deferens was studied by spectrofluorimetry, fluorescent-histochemistry and cytochemical electron microscopy. Sodium oxybutirate failed to influence the stores of the adrenergic mediator, but was capable of blocking the uptake and accumulation of the exogenous NA.  相似文献   

15.
The augmentation of ventricular inotropism induced by electrical stimulation of acutely decentralized efferent sympathetic preganglionic axons was reduced, but still present, following administration of hexamethonium (10 mg/kg i.v.). While hexamethonium continued to be administered, the cardiac augmentations so induced were enhanced significantly following administration of the alpha-adrenergic receptor blocking agent, phentolamine myselate (1 mg/kg i.v.). Stimulation of the sympathetic efferent postganglionic axons in cardiopulmonary nerves induced cardiac augmentations that were unchanged following administration of these agents singly or together. The cardiac augmentations induced by stimulation of efferent preganglionic sympathetic axons were unchanged when phentolamine was administered alone. The augmentations of cardiac inotropism induced by efferent postganglionic sympathetic axonal stimulation were decreased following local administration of the beta-adrenergic antagonist timolol into the ipsilateral stellate and middle cervical ganglia. Thereafter, these augmentations were unchanged following the subsequent intravenous administration of phentolamine. It is concluded that the activation of cardiac neurons in the stellate and middle cervical ganglia by stimulation of efferent preganglionic sympathetic axons can be modified by alpha-adrenergic receptors and that these effects are dependent upon beta-adrenergic receptors, not nicotinic ones, in intrathoracic ganglia.  相似文献   

16.
An increase in 32P labelling of phosphatidylinositol, associated with synaptic activity, has previously been reported in excised sympathetic ganglia excited by preganglionic nerve impulses. In the present experiments a similar effect occurred in naturally-stimulated ganglia. It occurred when the preganglionic impulses were either evoked by electrical stimulation of the preganglionic nerve or were discharged spontaneously from the central nervous system. Thus increased turnover of phosphatidylinositol appears to be a normal accompaniment of synaptic transmission in these ganglia.  相似文献   

17.
Summary The physiological, pharmacological and morphological characteristics of guinea-pig vas deferens supplied by hypogastric nerves rendered inactive by decentralisation were compared with those of vas deferens in which the nerve supply had been chronically stimulated for 3–9 days using implanted electrodes. No change was seen in decentralised preparations prior to 7 days, but from 8–15 days, increased sensitivity to application of noradrenaline in vitro was observed, which was shown to be related to reduced transmitter uptake by nerve terminals as well as to an increase in postjunctional sensitivity; there was also increased fatigability 7–14 days following decentralisation. Continuous stimulation of hypogastric nerves at 2 Hz for 4–8 h daily for 4–8 days resulted in enhanced transmitter uptake and reduced responses to noradrenaline; this was associated with a slight increase in noradrenaline content and a faster adrenergic neuromuscular response with a shorter latency. No appreciable changes in nerve or muscle structure studied by electron microscopy were observed following decentralisation, but there was an increase of between 12.5 and 29.6% in the number of close (< 100 nm) neuromuscular junctions following chronic stimulation for 8 days.  相似文献   

18.
The adrenergic innervation of structures in the gills of brown and rainbow trout was studied with catecholamine fluorescence histochemistry. In the arterio-arterial vascular pathway, there was an innervation of the afferent and efferent lamellar arterioles, but the afferent and efferent filamental arteries and the secondary lamellae were devoid of any fluorescent nerve fibres. In S. trutta only, there was an additional innervation of the afferent and efferent branchial arteries and the base of the efferent filamental artery. The innervation of the arterio-venous vascular pathway was similar in both trout species. Many fluorescent nerve fibres were found on nutritive arterioles in the gill arch and interbranchial septum, and in the core of each filament between the surface epithelium and the wall of the filament venous sinus. No fluorescent nerve fibres were observed at the origins of the capillaries arising from the efferent filamental artery. The sympathetic nerve supply is provided to the gills mainly through the posttrematic nerve, with an occasional small contribution through the pretrematic nerve. The presence of adrenergic nerves in the gills is discussed in relation to the regulation of blood flow through the arterio-arterial and arterio-venous pathways.  相似文献   

19.
We investigated the relationship between the membrane potential of frog taste cells in the fungiform papillae and the tonic discharge of parasympathetic efferent fibers in the glossopharyngeal (GP) nerve. When the parasympathetic preganglionic fibers in the GP nerve were kept intact, the mean membrane potential of Ringer-adapted taste cells was -40 mV but decreased to -31 mV after transecting the preganglionic fibers in the GP nerve and crushing the postganglionic fibers in the papillary nerve. The same result occurred after blocking the nicotinic acetylcholine receptors on parasympathetic ganglion cells in the tongue and blocking the substance P neurokinin-1 (NK-1) receptors in the gustatory efferent synapses. This indicates that the parasympathetic nerve (PSN) hyperpolarizes the membrane potential of frog taste cells by -9 mV. Repetitive stimulation of a transected GP nerve revealed that a -9-mV hyperpolarization of taste cells maintained under the intact GP nerve derives from an approximately 10-Hz discharge of the PSN efferent fibers. The mean frequency of tonic discharges extracellularly recorded from PSN efferent fibers of the taste disks was 9.1 impulses/s. We conclude that the resting membrane potential of frog taste cells is continuously hyperpolarized by on average -9 mV by an approximately 10-Hz tonic discharge from the parasympathetic preganglionic neurons in the medulla oblongata.  相似文献   

20.
Summary The presence of neurofilament (NF)-like and glial fibrillary acidic protein (GFAP)-like immunoreactivities was studied in sympathetic ganglia of adult rats and guinea pigs during normal conditions and after perturbation. In the superior cervical ganglion (SCG) of normal rats, many ganglion cells and nerve fibers show NF immunoreactivity. Some of these nerve fibers disappear after preganglionic decentralization of SCG; this indicates the presence of a mixture of preand postganglionic NF-positive nerves in the ganglion. Cuts in both preand postganglionic nerves result in a marked increase in GFAP immunoreactivity in SCG, whereas NF immunoreactivity increases in nerve cell bodies after preganglionic cuts. Only a few ganglion cells show NF immunoreactivity in the normal SCG of guinea pig. All intraganglionic NF-positive nerves are of preganglionic origin; decentralization abolishes NF immunoreactivity in these nerve fibers. The inferior mesenteric ganglion, the hypogastric nerves and colonic nerves in guinea pigs contain large numbers of strongly NF-immunoreactive nerve fibers.When the SCG of adult rat is grafted to the anterior eye chamber of adult rat recipients, both ganglionic cell bodies and nerve fibers, forming on the host iris from the grafted ganglion, are NF-positive. As only the perikarya of these neurons normally exhibit NF immunoreactivity, and the terminal iris arborizations are NF-negative, it appears that the grafting procedure causes NF immunoreactivity to become more widespread in growing SCG neurons.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号