Adrenergic and cholinergic innervation of rat cerebral arteries

Summary A consecutive demonstration of both aminergic and cholinergic nerves of rat cerebral arteries was carried out on whole mount preparations. For demonstration of aminergic nerves the glyoxylic acid method was used, while for cholinergic nerves Karnovsky's technique was utilized consecutively. This procedure provided a highly sensitive and reproducible demonstration of the two systems on the same specimen. The results obtained were as follows: 1) Aminergic and cholinergic nerves were distributed densely in the proximal portions of the major cerebral arteries examined. They were dense in the arteries of the anterior circulation and sparse in the posterior circulation. Each nerve had two different patterns, i.e. circular and longitudinal. Both circular and longitudinal patterns were observed in the proximal portions of the arteries, while in the distal portions, longitudinal fibres were predominantly present. 2) Superior cervical ganglionectomy produced no change in cholinergic nerve distribution, while it caused decreased density of aminergic nerves on the ipsilateral side on the arteries of the anterior circulation. The contralateral anterior cerebral arteries were partially affected. Bilateral sympathectomies abolished aminergic nerves in all arteries except the vertebral artery.     

Histochemical study of the postnatal development of autonomic nerves in the mouse iris,using a whole-mount preparation method

Summary Postnatal development of autonomic nerves in the mouse iris was studied histochemically from one day to five months of age. For the demonstration of aminergic nerves the glyoxylic acid method was used, while for cholinergic nerves, Karnovsky and Roots' method was utilized on the whole-mount preparations of irises. The results obtained were as follows. In one-day-old mice, many aminergic nerves could already be seen, while cholinergic nerves were scarcely observable. Both types of nerve increased rapidly in the first 2 weeks. Both completed development between 3 and 4 weeks, although aminergic nerves were observed to develop earlier than the cholinergic.     

Chronic hypoxia alters prejunctional alpha(2)-receptor function in vascular adrenergic nerves of adult and fetal sheep

The impact of development and chronic high-altitude hypoxia on the function of prejunctional alpha(2)-adrenoceptors was studied by measuring norepinephrine release in vitro from fetal and adult sheep middle cerebral and facial arteries. Blockade of prejunctional alpha(2)-adrenoceptors with idazoxan significantly increased stimulation-evoked norepinephrine release in normoxic arteries. This effect was eliminated after chronic hypoxia in cerebral arteries, with a tendency to decline in fetal facial arteries. After chronic hypoxia, the capacity to release norepinephrine declined in fetal middle cerebral arteries with a similar trend in facial arteries. Norepinephrine release was maintained in adult arteries. During development, stimulation-evoked norepinephrine release from middle cerebral and facial arteries was higher compared with adult arteries. In fetal arteries, adrenergic nerve function declined after chronic hypoxia. However, in adult arteries, adrenergic nerves adapted to chronic hypoxia by maintaining overall function. This differential adaptation of adrenergic nerves in fetal arteries may reflect differences in fetal distribution of blood flow in response to chronic hypoxic stress.     

Neuropeptide Y and vasoactive intestinal polypeptide in cerebral arteries of the rat: relationships between innervation pattern and mechanical response

Possible relationships between the density of peptide innervation and the contractile response of rat cerebral arteries to exogenously applied neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) were examined. The effects of NPY on membrane potential and reactivity of cerebral arteries to exogenous norepinephrine also were studied. In normally innervated arteries there was no apparent correlation between degree of innervation and response to NPY. Marked, prolonged tachyphylaxis to NPY and VIP was observed following brief exposure to these peptides. Surgical removal of the superior cervical ganglia or the sphenopalatine ganglia greatly reduced and, in some cases, eliminated NPY- or VIP-immunoreactive perivascular nerves from cerebral arteries. However, responses of denervated middle cerebral arteries to exogenous NPY or VIP were not different from responses of innervated arteries. Doses of NPY that induced maximal contraction caused no change in membrane potential of the middle cerebral artery. NPY also did not alter the response of cerebral arteries to exogenous norepinephrine. Finally, electrical stimulation of normal or denervated arteries caused only minor constrictor or dilator responses. These results do not support a substantial role for peptidergic perivascular nerves in regulation of pial arterial contractility in the rat.     

Pathway of nerves with vasoactive intestinal polypeptide-like immunoreactivity to the major cerebral arteries of the rat

Summary The pathway of nerves with vasoactive intestinal polypeptide(VIP)-like immunoreactivity to the major cerebral arteries was studied in rats by means of the indirect immunofluorescent method. The fibers are densely distributed in the ethmoidal nerves and in the adventitia of both the external and internal ethmoidal arteries. Section of both ethmoidal nerves and external ethmoidal arteries before they enter the cranial cavity induced a marked reduction of VIP-like immunoreactive fibers in the walls of the vessels of the circle of Willis and its major branches. However, section of the external ethmoidal artery alone did not result in visible changes of the nerves around major cerebral arteries. The present study suggests that VIP-like immunoreactive fibers surrounding major cerebral arteries of the rat arise from fibers in the ethmoidal nerve showing immunoreactivity to VIP.     

Incorporation of axonally transported glycoproteins into axolemma during nerve regeneration

The insertion of axonally transported fucosyl glycoproteins into the axolemma of regenerating nerve sprouts was examined in rat sciatic motor axons at intervals after nerve crush. [(3)H]Fucose was injected into the lumbar ventral horns and the nerves were removed at intervals between 1 and 14 d after labeling. To follow the fate of the “pulse- labeled” glycoproteins, we examined the nerves by correlative radiometric and EM radioautographic approaches. The results showed, first, that rapidly transported [(3)H]fucosyl glycoproteins were inserted into the axolemma of regenerating sprouts as well as parent axons. At 1 d after delivery, in addition to the substantial mobile fraction of radioactivity still undergoing bidirectional transport within the axon, a fraction of label was already associated with the axolemma. Insertion of labeled glycoproteins into the sprout axolemma appeared to occur all along the length of the regenerating sprouts, not just in sprout terminals. Once inserted, labeled glycoproteins did not undergo extensive redistribution, nor did they appear in sprout regions that formed (as a result of continued outgrowth) after their insertion. The amount of radioactivity in the regenerating nerves decreased with time, in part as a result of removal of transported label by retrograde transport. By 7-14 d after labeling, radioautography showed that almost all the remaining radioactivity was associated with axolemma. The regenerating sprouts retained increased amounts of labeled glycoproteins; 7 or 14 d after labeling, the regenerating sprouts had over twice as much of radioactivity as comparable lengths of control nerves or parent axons. One role of fast axonal transport in nerve regeneration is the contribution to the regenerating sprout of glycoproteins inserted into the axolemma; these membrane elements are added both during longitudinal outgrowth and during lateral growth and maturation of the sprout.     

RETROGRADE AXONAL TRANSPORT OF RAPIDLY MIGRATING LABELLED PROTEINS AND GLYCOPROTEINS IN REGENERATING PERIPHERAL NERVES

Abstract— The redistribution of rapidly migrating [³H]leucine-labelled proteins and [³H]fucose-labelled glycoproteins was studied in ligated regenerating hypoglossal and vagus nerves of the rabbit. When regenerating and contralateral hypoglossal nerves were ligated 16 h after labelling of the nerve cell bodies, rapidly migrating proteins and glycoproteins accumulated distal to the ligatures indicating a rapid retrograde transport from the peripheral parts of the nerves within 6 h. The retrograde accumulation of both proteins and glycoproteins was greater on the regenerating side than on the contralateral side at both 1 and 5 weeks after a nerve crush. Labelled proteins and glycoproteins also accumulated proximal to the ligatures, indicating a delayed rapid anterograde phase of axonal transport. The accumulation of this phase was also greater on the regenerating side 1 week after a nerve crush for both labelled proteins and glycoproteins. One week after a crush of the cervical vagus nerve, rapidly migrating proteins and glycoproteins redistributed between he crush zone and a proximal ligature applied 16 h after labelling of the nerve cell bodies. A retrograde accumulation occurred distal to the ligature within 6 h, indicating a rapid retrograde transport from the crush zone.     

Reinnervation of regenerating smooth muscle cells in minced vas deferens of the guinea-pig

Summary In adult guinea-pigs, a portion of the wall of the vas deferens was removed, minced and replaced. This caused muscle cells to dedifferentiate, divide and redifferentiate. Reinnervation of redifferentiating cells was followed using electron microscopy and histochemistry. Adrenergic nerves were first observed to re-enter the regenerating area 5 days after operation, and close contacts (within 20 nm) with muscle cells were first seen at 10 days. The total number of adrenergic nerves per 100 muscle cells reached control values by 5 weeks, and by 15 weeks was higher than control levels. Cholinergic nerves first appeared in the regenerating area about 3–4 weeks after the operation. The total number of cholinergic nerves present had not reached control values even at 15 weeks, and no nerve muscle contacts within 20 nm were observed. The ratio of adrenergic to cholinergic nerves in the regenerating area was higher at 15 weeks than in control tissue.This work was supported by grants from the Wellcome Trust and the Medial Research Council     

The interaction of nerves of opposite regenerating polarity in fused newt forelimbs

Previous studies involving nerve interactions and limb regenerative processes were carried out on adult newts after their forelimbs were amputated through the distal radius and ulna and fused end-to-end. On the basis of limb regeneration results at the junction of the fused limbs, it was postulated that regenerating nerves from each limb (i.e., nerves of opposite polarity) would not invade the foreign territory of the contralateral limb if it were already normally innervated. A direct study of this nerve interaction, however, was not made in this earlier study. The present investigation was designed to obtain direct histological and electrophysiological evidence for the interaction of nerves of opposite regenerating polarity in fused newt forelimbs. The primary objective was to determine how the regenerating nerves would interact in the establishment of innervation territories-first, at the fusion zone, which represents the junction of the normal innervation territories of the nerves of each limb; and secondly, half way up one of the limbs, where interaction would occur in a territory normally innervated by only one of the regenerating nerves. The results showed that when nerves of opposite regenerating polarity approached one another at the junction of the fused limbs a discontinuation of axonal growth occurred; no indication of overlap of nerves into foreign territory was seen. When the nerves were allowed to interact within one of the fused limbs, however, an overlap of nerve fibers and a functional "double innervation" of that limb was demonstrated. These results are discussed in terms of possible mechanisms for the establishment of innervation territories in salamander limbs. The question of nerve-muscle reinnervation specificity is also raised.     

Axonal Transport of Polyamines in Intact and Regenerating Axons of the Rat Sciatic Nerve

The axonal transport of putrescine or its polyamine derivatives spermidine or spermine is a subject of some debate. We investigated this question by injecting [3H]putrescine into the lumbar spinal cord of the rat and measuring the accumulation of radioactivity central to ligatures placed on intact and regenerating sciatic nerves. In normal nerves, approximately twice as much radioactivity built up proximal to these ligatures 2 or 3 days after injection than at more distal ligatures used to control for accumulation of radioactivity which might be due to tissue damage alone. In regenerating nerves the amount of radioactivity accumulating at the ligature was approximately five times that at the distal ligature and two to three times greater than in intact nerves. The identity of the radioactivity in regenerating nerves, determined on an amino acid analyzer, was found to be primarily spermidine and an unknown compound that migrated as a frontal elution peak. Autoradiographic analysis showed that the radioactivity was largely confined to axons, but a significant amount of the silver grains was associated with Schwann cells and myelin sheaths surrounding labeled axons in both intact and regenerating nerves. The data indicate that polyamine derivatives of putrescine are transported axonally in rat sciatic nerves, and some of this transported material accumulates in Schwann cells surrounding the labeled axons. These processes are apparently augmented during regeneration of the injured axons.     

Posttranslational Protein Modification by Amino Acid Addition in Regenerating Optic Nerves of Goldfish

Previous experiments have demonstrated that 4S RNA, (tRNA), is transported axonally during the reconnection and maturation of regenerating optic nerves of goldfish. The present experiments were performed to determine if tRNA is transported axonally during elongation of these regenerating nerves and whether, as has been demonstrated in other systems, it participates in posttranslational protein modification (PTPM). [3H]Uridine was injected into both eyes of fish with intact optic nerves and 0, 2, 4, or 8 days after bilateral optic nerve cut. Fish were killed 2 days after injection, and [3H]RNA was isolated from retinae and nerves by phenol extraction and ethanol precipitation. [3H]RNA was fractionated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Although the percentage of [3H]4S RNA remained constant in all retinal and control nerve samples, regenerating nerves showed a twofold increase by 6 days after injury, suggesting that [3H]4S RNA is transported axonally in regenerating nerves as early as 6 days after injury. In other experiments, the 150,000-g supernatant of optic nerves was analyzed for incorporation of 3H-amino acids into proteins. No incorporation of 3H-amino acid was found in the soluble supernatant, but when the supernatant was passed through a Sephacryl S-200 column (removing molecules less than 20,000 daltons), [3H]Arg, [3H]Lys, and [3H]Leu were incorporated into proteins. This posttranslational addition of amino acids was greater (1.4-5 times for Lys and 2-13 times for Leu) in regenerating optic nerves than nonregenerating nerves, and the growing tips of regenerating nerves incorporated 5-15 times more [3H]Lys and [3H]Leu into proteins than did the shafts.(ABSTRACT TRUNCATED AT 250 WORDS)     

ET-1神经分布异常与高血压鼠脑动脉神经源性调节的关系

目的探讨ET-1（Endothelin-1,ET-1）能神经纤维分布与高血压鼠脑血管的神经源性调节的关系,探讨ET-1神经是否参与高血压时期脑血流的调节。方法应用免疫组织化学技术观察自发性高血压鼠和Wistar正常血压鼠脑底动脉（包括大脑前动脉、大脑中动脉、大脑后动脉和基底动脉）ET-1能神经纤维的分布密度和走行方式。结果自发性高血压鼠和Wistar正常血压鼠脑底动脉均可见棕褐色的ET-1能免疫反应阳性纤维,似细线状,攀附于血管壁上,自发性高血压鼠脑底动脉各主要分支ET-1能免疫反应阳性纤维密度较Wistar正常血压鼠明显增加,纤维走行大多呈网状。结论实验结果提示自发性高血压鼠脑底动脉增加的ET-1能免疫反应阳性纤维可能与脑血管的神经源性调节有关;高密度的ET-1能神经纤维可能涉及高血压时期脑血流的调节。     

Recovery of breathing pattern after 15 min of cerebral ischemia in rabbits

The study was undertaken to ascertain the neural control of breathing and vagal reflexes during and after cerebral ischemia. The experiments were performed on anesthetized, paralyzed, and artificially ventilated rabbits. Cerebral ischemia was induced by reversible intrathoracic occlusion of the brachiocephalic trunk and the left subclavian and both internal thoracic arteries for 15 min. The effect of cerebral ischemia on breathing pattern was assessed by monitoring the integrated activities of phrenic and recurrent laryngeal nerves. Ischemia produced enhancement of breathing followed by apnea and gasping. During enhanced breathing as well as during gasping, the inspiratory-inhibiting effect of lung inflation (Breuer-Hering reflex) was abolished. When brain circulation was restored, respiratory activity started with gasps, which later were intermingled with eupneic type of inspirations. During the onset of a eupneic breath, lung inflation produced inspiratory facilitation but never an inhibition. However, after 30 min of recovery from cerebral ischemia, the Breuer-Hering reflex was restored. Results show that precise analysis of vagal reflexes and respiratory pattern during ischemia and resuscitation may be used as an indicator of resumption of autonomic activity in the brain stem.     

Distribution and origin of vasoactive intestinal polypeptide (VIP)-immunoreactive,acetylcholinesterase-positive and adrenergic nerves of the cerebral arteries in the bent-winged bat (Mammalia: Chiroptera)

Summary The overall distribution and origins of vasoactive intestinal polypeptide (VIP)-immunoreactive (IR), acetylcholinesterase (AChE)-positive and adrenergic nerves in the walls of the cerebral arteries were investigated in the bent-winged bat. VIP-IR and AChE-positive nerves innervating the bat cerebral vasculature appear to arise mainly from VIP-IR and AChE-positive cell bodies within microganglia found in the nerve bundle accompanying the sympathetic nerve bundle within the tympanic cavity. These microganglia, as well as the nerve bundle containing them, do not emit catecholamine fluorescence, suggesting that they are of the cranial parasympathetic outflow, probably the facial or glossopharyngeal one. The axons from VIP-IR and AChE-positive microganglia run intermingled with sympathetic adrenergic nerves in the same thick fiber bundles, and reach the cranial cavity through the carotid canal. In addition, some of the VIP-IR fibers innervating the vertebro-basilar system, at least the basilar artery, originate from VIP-IR nerve cells located in the wall of this artery.The supply of VIP-IR fibers to the bat major cerebral arteries is the richest among mammals that have been studied, and differs from other mammals in that it is much greater in the vertebro-basilar system than in the internal carotid system: plexuses of VIP-IR nerves are particularly dense along the walls from the posterior ramus to posterior cerebral and basilar arteries. Small pial and intracerebral arteries of the vertebro-basilar system, especially those of the posterior cerebral artery which supply most parts of the diencephalon and cerebrum, are also richly innervated by peripheral VIP-IR fibers. This pattern corresponds well with the innervation pattern of adrenergic and AChE-positive nerves.     

Distribution and origins of VIP-immunoreactive nerves in the cephalic circulation of the cat

VIP-immunoreactive (IR) nerves were visualized in whole mounts and sections of cephalic arteries and cranial nerves of cats with indirect immunofluorescence. Perivascular VIP-IR nerves were very widely distributed in arteries and arterioles supplying glands, muscles and mucous membranes of the face. Within the cerebral circulation, perivascular VIP-IR nerves were most abundant in the Circle of Willis and the proximal portions of the major cerebral arteries and their proximal branches supplying the rostral brain stem and ventral areas of the cerebral cortex. VIP-IR nerves were absent from arterial branches supplying the posterior brain stem, cerebellum and dorsal cerebral cortex. Cerebral perivascular VIP-IR nerves probably arise from VIP-IR perikarya within microganglia found in the cavernous plexus and external rete. Extracerebral perivascular VIP-IR nerves probably arise from VIP-IR perikarya in microganglia associated with the tympanic plexus, chorda tympani, lingual nerve and Vidian nerve as well as from cells in the otic, sphenopalatine, submandibular and sublingual ganglia. It seems likely, therefore, that each major segment of the cephalic circulation is supplied by local VIP-IR neurons.     

双侧迷走神经和颈总动脉联合切断法建立急性脑缺血大鼠模型

目的建立一种操作简单的急性脑缺血动物模型。方法取雄性Wistar大鼠40只,体重200～230g,手术前禁食12 h,自由饮水,随机分为对照组A、B、C组及模型D组,共4组,每组10只。即A组:假手术组,仅切开颈部两侧皮肤,分离双侧颈总动脉和迷走神经,不切断,然后缝合;B组:仅切断双侧颈部迷走神经;C组:结扎并切断双侧颈总动脉(CCA);D组:联合组,即结扎并切断双侧颈总动脉,同时切断双侧颈部迷走神经。观察各组大鼠手术后的脑缺血症状,记录各组大鼠在8h内的死亡情况,超过8h死亡的动物按8h计,计算死亡率和死亡时间。结果 A组大鼠没有脑缺血症状,无死亡;B组大鼠无脑缺血症状,呼吸变慢变深,心率血压上升,但无死亡;C组大鼠部分出现脑缺血症状,眼睑下垂,活动能力低下,自发运动减少,有些大鼠术后自发运动增加,在8 h内无死亡;D组大鼠大多数出现较为明显的脑缺血症状,在8 h内全部死亡。结论采取同时结扎并切断大鼠双侧颈总动脉和双侧颈部迷走神经的方法,可以建立急性脑缺血大鼠动物模型,此方法具有手术简单,成功率高,术后动物缓慢死亡的特点。     

Structure and sympathetic innervation of the intracranial arteries in the giraffe (Giraffa camelopardalis)

Fluorescence histochemistry discloses that the carotid rete mirabile in the giraffe has a poor sympathetic innervation. In contrast, the efferent artery of the rete (internal carotid artery) and the cerebral arteries show moderate sympathetic innervation. A certain degree of regional variability was noted in which the rostral arteries (anterior and middle cerebral) receive more sympathetic nerves than the caudal (posterior communicating and basilar) arteries. The sympathetic nerves on the giraffe cerebral vessels may constitute part of a host of mechanisms by which regional blood flow to the brain is regulated. Conversely, the paucity of sympathetic innervation of the carotid rete mirabile may indicate that this structure does not play an active role in vasoconstrictor responses during postural changes of the head.     

Vasoactive-intestinal-polypeptide (VIP)-like immunoreactive cells in the skull base of rats. A combined study using acetylcholinesterase histochemistry

We investigated the distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactive cell bodies in relation to the major cerebral and internal carotid arteries at the skull base in rats. Acetylcholinesterase (AChE) histochemistry was also applied to investigate the localization of this enzyme. VIP staining revealed a few positive cell bodies in nerves close to the internal carotid artery at the base of the skull as well as in the cerebral arterial wall. Ganglion-like cell bodies were detectable within the greater superficial petrosal (GSP) nerve. AChE activity was observed in VIP-like immunoreactive cell bodies along the whole of the GSP nerve. These cell bodies in the GSP nerve may give rise to at least some of the perivascular VIP- and AChE-containing nerves of the internal carotid arteries at the base of the skull.     

Vasoactive-intestinal-polypeptide (VIP)-like immunoreactive cells in the skull base of rats

Summary We investigated the distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactive cell bodies in relation to the major cerebral and internal carotid arteries at the skull base in rats. Acetylcholinesterase (AChE) histochemistry was also applied to investigate the localization of this enzyme. VIP staining revealed a few positive cell bodies in nerves close to the internal carotid artery at the base of the skull as well as in the cerebral arterial wall. Ganglion-like cell bodies were detectable within the greater superficial petrosal (GSP) nerve. AChE activity was observed in VIP-like immunoreactive cell bodies along the whole of the GSP nerve. These cell bodies in the GSP nerve may give rise to at least some of the perivascular VIP-and AChE-containing nerves of the internal carotid arteries at the base of the skull.     

Cerebral Vulnerability Is Associated with Selective Increase in Extracellular Glutamate Concentration in Experimental Thiamine Deficiency

Abstract: The concentration of apolipoprotein E (apoE), a high-affinity ligand for the low-density lipoprotein receptor, increases dramatically in peripheral nerve following injury. This endoneurial apoE is thought to play an important role in the redistribution of lipids from the degenerating axonal and myelin membranes to the regenerating axons and myelin sheaths. The importance of apoE in nerve repair was examined using mutant mice that lack apoE. We show that at 2 and 4 weeks following sciatic nerve crush, regenerating nerves in apoE-deficient mice were morphologically similar to regenerating nerves in control animals, indicating that apoE is not essential for peripheral nerve repair. Moreover, cholesterol synthesis was reduced in regenerating nerves of apoE-deficient mice as much as in regenerating nerves of control animals. These results suggest that the intraneural conservation and reutilization of cholesterol following nerve injury do not require apoE.