A review of the thoracic splanchnic nerves and celiac ganglia

Anatomical variation of the thoracic splanchnic nerves is as diverse as any structure in the body. Thoracic splanchnic nerves are derived from medial branches of the lower seven thoracic sympathetic ganglia, with the greater splanchnic nerve comprising the more cranial contributions, the lesser the middle branches, and the least splanchnic nerve usually T11 and/or T12. Much of the early anatomical research of the thoracic splanchnic nerves revolved around elucidating the nerve root level contributing to each of these nerves. The celiac plexus is a major interchange for autonomic fibers, receiving many of the thoracic splanchnic nerve fibers as they course toward the organs of the abdomen. The location of the celiac ganglia are usually described in relation to surrounding structures, and also show variation in size and general morphology. Clinically, the thoracic splanchnic nerves and celiac ganglia play a major role in pain management for upper abdominal disorders, particularly chronic pancreatitis and pancreatic cancer. Splanchnicectomy has been a treatment option since Mallet‐Guy became a major proponent of the procedure in the 1940s. Splanchnic nerve dissection and thermocoagulation are two common derivatives of splanchnicectomy that are commonly used today. Celiac plexus block is also a treatment option to compliment splanchnicectomy in pain management. Endoscopic ultrasonography (EUS)‐guided celiac injection and percutaneous methods of celiac plexus block have been heavily studied and are two important methods used today. For both splanchnicectomies and celiac plexus block, the innovation of ultrasonographic imaging technology has improved efficacy and accuracy of these procedures and continues to make pain management for these diseases more successful. Clin. Anat. 23:512–522, 2010. © 2010 Wiley‐Liss, Inc.     

Association fibers of cortical representation zones 1 and 2 of the splanchnic nerve in the cat

Summary The presence of bilateral anatomical relation between the 1 and 2 cortical zones of the splanchnic nerve was established by the method of terminal degeneration. There is a difference in the reciprocal interchange of fibers between the cortical zones of the splanchnic nerve: a much greater number of fibers enters the 2 zone from the 1. A considerable part of the fibers belongs to horizontal systems, whereas the fibers coming from the 2 zone to the 1 zone belong mainly to radial fibers. Thus, the interrelations between the connecting systems of the 1 and 2 splanchnic nerve zones are such that the number of fibers coming from one zone into another one are different.(Presented by Academician V. N. Chernigovskii) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 55, No. 3, pp. 114–117, March, 1963.     

Hypoxia and hypercapnia increase the sympathoadrenal medullary functions in anesthetized, artificially ventilated rats

Graded hypoxia (FETO2 14-6%) and hypercapnia (FETCO2 6-10%), which were applied for 45s and 2 min, respectively, to urethane anesthetized and artificially ventilated rats produced an increase in adrenal sympathetic efferent nerve activity in parallel with increases in adrenaline and noradrenaline secretion measured in the adrenal venous effluent. Percentage increases in adrenaline and noradrenaline were almost equal. In rats whose carotid sinus nerves (CSN) were bilaterally cut, hypoxia did not produce any effect on adrenal sympathetic nerve activity or catecholamine secretion. In contrast, excitatory adrenal nerve and catecholamine secretory responses to hypercapnia remained unchanged in CSN denervated rats. After severing a splanchnic nerve whose branches innervated the adrenal gland, while maintaining the resting level of catecholamine secretion by low-frequency stimulation of the peripheral end of the splanchnic nerve, hypoxia did not produce any increase in catecholamine secretion. Hypercapnia (FETCO2 8 and 10%), however, induced catecholamine secretion from denervated adrenal medulla, although the magnitude of the response was significantly lower than that in animals with adrenal nerve intact. It is concluded that hypoxia stimulates the adrenal medulla via the carotid chemoreceptor reflex whereas hypercapnia acts mainly via mechanisms besides carotid chemoreceptors such as central chemoreceptors with some direct stimulatory effect on the adrenal medulla. The functional significance of these dual mechanisms of sympathoadrenal excitation during hypoxia and hypercapnia is discussed.     

The adrenergic nervous control of fluid transport in the small intestine of normotensive and spontaneously hypertensive rats

Intestinal net fluid transport in normotensive Wistar Kyoto rats (WKR) and spontaneously hypertensive rats of the Okamoto strain (SHR) were studied during 'rest', during electrical stimulation of the regional sympathetic fibres as well as after acute denervation and alpha-adrenergic receptor blockade (phentolamine). During 'rest' no statistically significant difference in fluid transport rate could be demonstrated between WKR and SHR. Cutting the left splanchnic nerve, severing the periarterial nerves or giving phentolamine turned net fluid absorption to net fluid secretion in most SHR, whereas fluid absorption was little influenced in WKR by these procedures. Stimulating the left splanchnic nerve (2, 4, 8 Hz) markedly increased net fluid uptake or decreased net fluid secretion in SHR in a frequency-dependent manner. A small effect was seen in WKR at a stimulation rate of 4 Hz. The 'spontaneous' fluid secretion in denervated intestinal segments of SHR was accompanied by a net chloride secretion. Giving hexamethonium i.v. turned net fluid and chloride secretion into water and ion absorption, suggesting that the secretion was evoked by secretory nervous pathways in the enteric nervous system. It is concluded that the 'spontaneous' fluid and electrolyte secretion seen in denervated intestines of SHR is normally 'concealed' by an augmented rate of firing in the regional adrenergic nerve fibres controlling fluid and electrolyte transport. The possible importance of the 'spontaneous' intestinal secretion in SHR in the pathophysiology of arterial hypertension is tentatively discussed.     

Patterns of reinnervation of denervated cerebral arteries by sympathetic nerve fibers after unilateral ganglionectomy in rats

Summary In order to clarify the manner in which previously denervated cerebral arteries become reinnervated after unilateral excision of the superior cervical ganglion (SCG), we observed directly the reinnervating sympathetic nerve fibers originating in the contralateral SCG by using anterograde labeling with wheat germ aggulutinin-horseradish peroxidase in rats. The nerve fibers sprouted from the nerve fibers in the contralateral anterior cerebral artery and reinnervated the arterial wall of the anterior cerebral artery of the denervated side as early as one week after ganglionectomy. In addition to this sprouting route, three other reinnervating nerve fiber routes were observed in the circle of Willis of the denervated side two weeks after ganglionectomy: the proximal portion of the internal carotid artery, the route passing between bilateral ethmodial arteries, and the posterior communicating artery. Eight weeks after ganglionectomy, these reinnervating nerve fibers formed a fairly dense plexus in a circular pattern in the circle of Willis. However, the reinnervation could not be observed in the arterial branches derived from the circle of Willis (middle cerebral artery and posterior cerebral artery) even 16 weeks after ganglionectomy. The present results clearly demonstrated the time course, distribution pattern and limitation of the reinnervation from the contralateral SCG following unilateral ganglionectomy. The fact that reinnervation could be observed only in the main cerebral arteries of the circle of Willis, in which the nerve plexus appeared to have a circular pattern, suggests a difference between the qualities of sympathetic innervation controlling the cerebral circulation in these arteries and the other arterial branches related to these differences in reinnervation capacity.     

The effect of denervation on ligandin levels and glutathione S-transferase activity in the rat liver

The authors studied the effect of liver denervation (transection of the hepatic branch of the vagus nerve and/or both splanchnic nerves) on the content of the marker of highly-differentiated hepatocytes--ligandin and the activity of glutathione S-transferase (GT) in rat liver homogenate. The immunodiffusion method demonstrated a decrease in the ligandin level by 21-22% as compared to the value in intact rats 2 weeks after the operation. GT activity was reduced in rats with denervation of the liver but remained unchanged in sham-operated on animals. The results are evidence of diminished biochemical specialization of the tissue of a denervated liver and confirm the role of the peripheral nervous system, the afferent link in particular, in its regulation.     

Neural influence on the action of insulin in the adrenomedullary catecholamine content in the pigeon

Insulin-induced (4 IU/100 g b.wt.) changes of adrenomedullary catecholamines (CA) were investigated in unilaterally splanchnic denervated pigeons 0.5, 4, 12, 24, 72, 144 and 216 h after injection. Insulin caused depletion of more norepinephrine (NE) from the denervated glands 0.5 h after treatment. This indicates that the splanchnic nerve prevents early phase of insulin-induced depletion of NE. Accelerated resynthesis of NE exceeding the control value was more in the innervated glands 24 h after administration. Insulin brought about augmented synthesis of epinephrine (E) surpassing the control value in the innervated glands 72 h after treatment. The findings point out that the splanchnic nerve stimulates resynthesis of NE and synthesis of E induced by insulin.     

骨髓间充质干细胞移植治疗失神经肌萎缩

背景:外科显微镜手术和一些辅助治疗方法均无法通过修复损伤的神经细胞来有效延缓或治疗失神经肌萎缩。研究发现骨髓间充质干细胞具有定向分化潜能,并且在一定环境因素下能对损伤的组织进行修复,由此推测其可以对失神经萎缩肌肉起到一定的修复作用。目的:探讨移植骨髓间充质干细胞是否能够减轻和延缓失神经肌肉组织萎缩。方法:分离培养SD大鼠骨髓间充质干细胞,取第3代骨髓间充质干细胞经BrdU标记后用于移植治疗。将30只SD大鼠分为3组,每组10只,对每只大鼠左后肢进行手术。假手术组只暴露坐骨神经主干,不钳夹神经,移植治疗组、模型对照组钳夹坐骨神经主干后,向其支配的腓肠肌注射骨髓间充质干细胞悬液和不含胎牛血清的DMEM培养液。骨髓间充质干细胞移植后1,2周,采用BBB评分评价各组大鼠左后肢运动功能;骨髓间充质干细胞移植后14 d,取腓肠肌组织进行苏木精-伊红染色和BrdU免疫组化染色。结果与结论:第3代骨髓间充质干细胞BrdU标记为阳性;标记的骨髓间充质干细胞能在移植治疗组失神经损伤的肌肉组织中存活并起修复作用;相对于模型对照组,移植治疗组失神经肌纤维由相互融合重新恢复规整。结果表明移植骨髓间充质干细胞能够减轻和延缓失神经肌肉组织萎缩。     

Adrenergic structures, M-cholino- and β-adrenoception in thyroid gland of desympathized rats during postnatal ontogenesis

The density of adrenergic nerve terminals in thyroid gland decreases with age, and this decrease is more pronounced in parafollicular terminals. Density of³H-dihydroalprenolol binding sites increases in 1-month-old rats and decreases in senescent rats. In comparison with control rats, in sympathetically denervated rats the density of nerve fibers increases at the age of 1–6 months and decreases at the age of 12 months. Binding of³H-dihydroalprenolol is considerably higher in immature sympathetically denervated rats. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 3, pp. 340–343, March, 1999     

The immunophilin ligand FK506, but not the P38 kinase inhibitor SB203580, improves function of adult rat muscle reinnervated from transplants of embryonic neurons

Injury to the adult CNS often involves death of motoneurons, resulting in the paralysis and progressive atrophy of muscle. There is no effective therapy to replace motoneurons in the CNS. Our strategy to replace neurons and to rescue denervated muscles is to transplant dissociated embryonic day 14-15 (E14-15) ventral spinal cord cells into the distal stump of a peripheral nerve near the denervated muscles. Here, we test whether long-term delivery of two pharmacological inhibitors to denervated muscle, FK506 or SB203580, enhances reinnervation of muscle from embryonic cells transplanted in the tibial nerve of adult Fischer rats. FK506, SB203580 (2.5 mg/kg) or saline was delivered under the fascia of the medial gastrocnemius muscle for 4 weeks, beginning when muscles were denervated by section of the sciatic nerve. After 1 week of nerve degeneration, one million E14-15 ventral spinal cord cells were transplanted into the distal tibial nerve stump of each rat in the three treatment groups. Ten weeks later, all cell transplants had neuron-specific nuclear protein (NeuN) positive neurons. Neuron survival and axon regeneration were similar across treatments. An average (+/-S.E.) of 210+/-66, 100+/-36 and 176+/-58 myelinated axons grew distally from the cell transplants of rats with muscles treated with FK506, SB203580 or saline, respectively. Regenerating axons in muscles of all three treatments groups were detected with antibodies against phosphorylated neurofilaments and synaptophysin, and motor end plates were labeled with alpha-bungarotoxin. Muscles of rats that received transplants of media only had no axon growth, indicating that the muscles were denervated. The mean muscle fiber areas of rats that received cell transplants and had long-term delivery of FK506, SB203580 or saline to muscles were significantly larger than those of denervated muscle fibers. Thus, cell transplantation reduced muscle atrophy. Transplantation of embryonic cells also resulted in functional muscle reinnervation. Electromyographic activity and force were evoked from >90% of the muscles of rats with cell transplants, but not from denervated muscles. FK506-treated muscles were significantly more fatigue resistant than naive control muscles. FK506-treated muscles also had significantly stronger motor units than those in SB203580 or saline-treated muscles. These data suggest that a pathway regulated by FK506 improves the function of muscles reinnervated by embryonic neurons placed in peripheral nerve.     

Nerve contributions to the pelvic plexus and the umbilical cord

Serial sections of human embryos and fetuses reveal that the sacral nerves which contribute fibers to the pelvic plexus often have dorsal, ventral, and oblique communicating rami. The ventral rami resemble the white rami of upper thoracic nerves and some of their fibers pass close by or through the chain ganglia and into the pelvic plexus. The sizes of the ventral rami are often in inverse proportion to that of the pelvic splanchnic nerves. That is, when the pelvic splanchnic nerves are poorly developed, the ventral rami are large, and conversely, when the pelvic splanchnic nevers are well developed, these rami are small. The pelvic plexus was found to receive fibers from the sympathetic trunk and its ganglia in addition to those from the hypogastric plexus and the pelvic splanchnic nerves. Analysis of the observations made in this study together with a review of the literature in light of the present day classification of nerve fibers raises serious doubts concerning the limits set for the outflow of preganglionic nerve fibers from the spinal cord and the distribution of gray and white rami as described in recent textbooks in terms of their histological and physiological significance. Nerve fibers from the pelvic plexus can be traced along the walls of the bladder and the urachus and along the umbilical arteries into the umbilical cord. In embryos, only a few scattered nerve fibers were found distal to the umbilicus, but in fetuses at term, distinct nerve bundles were identified in the cord. These bundles sent branches to the walls of the umbilical arteries; other branches terminated as “end-nets” in Wharton's jelly. These nets appeared as fine fibers with nodular swellings at irregular intervals. Innervation of the umbilical arteries was richest within the first few inches of the cord. Beyond this region, the nerves rapidly decreased in number. “End-nets” were present as far as four inches from the umbilicus. Granular cells resembling Langerhans' cells were found in the cord. Often these cells were closely associated with fine nerve fibers.     

盆腔内筋膜的解剖结构及神经走形：避免修复中的损伤

背景：盆腔内走行着大量支配泌尿生殖等系统脏器的神经,包括内脏神经和脊神经两种,每一种均由运动神经和感觉神经两种成分组成。其中内脏神经的核心为盆丛。1982年,Heald提出的全直肠系膜切除已经成为直肠癌诊疗的“金标准”。但术中极易损伤神经,导致术后出现尿潴留、性功能障碍等并发症。目的：综述前人的研究,以明确盆腔内筋膜的解剖结构和神经走形。方法：以“splanchnic nerves,superior hypogastric plexus,pelvic plexus,pelvic splanchnic nerve,total mesorectal excision(TME),clinical anatomy”为关键词,检索2000年1月至2015年1月PubMed数据库中关于盆腔内神经及相关脊神经的走形和成分、盆腔内神经节及相关脏器反射等研究,以盆腔内的神经为主。结果与结论：盆腔内的主要内脏神经丛为：①上腹下丛：主体位于由左、右髂总动脉和骶岬围成的髂间三角内,左髂总静脉和第5腰椎前面。②盆丛：腹下神经、盆内脏神经、骶内脏神经在直肠侧面的后下方1/3处汇合形成神经丛,也称下腹下丛,位于输尿管后下方、膀胱及精囊腺的背侧。由内脏神经丛发出的神经包含交感神经、副交感神经及感觉神经3种成分,走行分布在盆腔各脏器表面,支配其运动与感觉功能。明确的盆腔内筋膜的解剖结构和神经走形是全直肠系膜切除成功的关键,可在手术中最大程度避免神经损伤,提高患者预后及生活质量。中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Differential effects of neonatal denervation on intrafusal muscle fibers in the rat

The response of developing muscle spindles to denervation was studied by sectioning the nerve to the medial gastrocnemius muscle of rats at birth. The denervated spindles were examined daily throughout the first postnatal week for changes in ultrastructure and expression of several isoforms of myosin heavy chain (MHC). Each of the three different types of intrafusal muscle fiber exhibited a different response to denervation. Within 5 days after the nerve section nuclear bag₂ fibers degenerated completely; nuclear bag₁ fibers persisted, but ceased to express the spindle-specific slow-tonic MHC isoform and thereby could not be differentiated from extrafusal fibers; nuclear chain fibers did not form. The capsules of spindles disassembled, hence spindles or their remnants could no longer be identified 1 week after denervation. Neonatal deefferentation has little effect on these features of developing spindles, so removal of afferent innervation is presumably the factor that induces the loss of spindles in denervated muscles. Degeneration of the bag₂ fiber, but not bag₁ or extrafusal fibers, reflects a greater dependence of the bag₂ fiber than the bag₁ fiber on afferent innervation for maintenance of its structural integrity. This difference in response of the two types of immature bag fiber to denervation might reflect an origin of the bag₂ fibers from a lineage of myogenic cells distinct from that giving rise to bag₁ or extrafusal fibers, or a difference in the length of contact with afferents between the two types of bag fiber prior to nerve section.     

Delayed muscle fiber transformation after foreign-reinnervation of excessive muscle tissue

Following partial denervation motor units can increase (by self-reinnervation) as much as four to five times their normal size. To investigate the still unknown quantitative reinnervation capacity of a motor nerve in the case of foreign-reinnervation, in adult male rats the denervated sternomastoid muscle was either self-reinnervated by its original nerve or foreign-reinnervation by the omohyoid nerve, which had to reinnervate the three times the amount of muscle fibers and six times the amount of muscle mass. After survival times of 7, 8, 9, or 10 months, nerves and muscles were investigated histochemically and immunohistochemically. The omohyoid nerve could fully reinnervate the sternomastoid muscle, but at 7 and 8 months this muscle still revealed nearly the same proportions of IIA and IIB fibers as were seen in the self-reinnervated sternomastoid at all stages. However, in the following 2 months a shift of the fiber pattern toward that of the normal omohyoid was observed, as evidenced by a strong increase in type IIB fibers (from 24% to 62%), at the expense of type IIA fibers. These findings are in contrast to those after foreign (cross) reinnervation of leg muscles where the fiber transformation (according to the foreign motor input) occurs in parallel with the reinnervation process during the first 2-3 months. The delayed fiber transformation observed could be the consequence of the highly enlarged peripheral field of the omohyoid motoneuron pool or could merely reflect a general difference between limb and neck muscles.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hepatic portal vein infusion of glucose on sodium excretion in the rat.

Anesthetized rats were prepared with catheters in the hepatic portal (HPV) and femoral (FEM) veins and in the bladder or ureters. In some experiments the left kidney was denervated. HPV infusion of 1 M glucose at 2 ml/h for 20 min increased Na excretion by the kidney when given as a second infusion. Bilateral cervical vagotomy eliminated the increase in Na excretion during glucose infusion and uncovered a delayed decrease in Na and K excretion. Renal denervation attenuated the increase in Na excretion to HPV glucose. FEM infusion of glucose had variable effects, increasing Na excretion only after vagotomy. The results are interpreted to suggest that central and vagal receptors tend to enhance Na excretionwhereas splanchnic nerve afferents and humoral mediator(s) have the opposite effect.     

Regeneration of phasic synapses on a crayfish slow muscle following allotransplantation of a mixed phasic-tonic nerve

Separate phasic or tonic nerves allotransplanted to reinnervate a denervated slow superficial flexor muscle (SFM) in the abdomen of adult crayfish regenerate synaptic nerve terminals with phasic or tonic properties. To test competitive interactions between tonic and phasic axons, we allotransplanted the sixth abdominal ganglion with its third nerve root containing a mixture of phasic and tonic axons onto the denervated SFM. The resulting reinnervation of the SFM was compared to the normal innervation on the contralateral intact SFM, which receives innervation only from tonic motoneurons. Variable sizes of excitatory postsynaptic potentials indicated that 2–3 axons innervated each muscle fiber of the SFM in both the allotransplant and normal preparations. Compared to the normal tonic terminals on the intact contralateral side, the allotransplanted synaptic terminals had more phasic-like properties; specificially, they gave rise to larger synaptic potentials, had a lower mitochondrial content and contained a higher density of active zone dense bars per synapse. Moreover, prolific sprouting of the axons in the regenerated nerve, typical of phasic axons, points to more vigorous regeneration of phasic rather than tonic axons to the denervated SFM. In keeping with this prolific axon sprouting, there was both a much higher density of innervation in the allotransplanted SFM compared to the normal SFM, and a higher frequency of extrasynaptic active zones in regenerated terminals of the mixed nerve compared to those of the tonic nerve. Thus, an allotransplanted mixed nerve regenerates mainly phasic axons and synapses on the slow denervated SFM, demonstrating the instructive nature of the neuron in synapse specification, as well as the permissive nature of the target muscle.     

Hepatic portal vein infusion of glucose on sodium excretion in the rat

Anesthetized rats were prepared with catheters in the hepatic portal (HPV) and femoral (FEM) veins and in the bladder or ureters. In some experiments the left kidney was denervated. HPV infusion of 1 M glucose at 2 ml/h for 20 min increased Na excretion by the kidney when given as a second infusion. Bilateral cervical vagotomy eliminated the increase in Na excretion during glucose infusion and uncovered a delayed decrease in Na and K excretion. Renal denervation attenuated the increase in Na excretion to HPV glucose. FEM infusion of glucose had variable effects, increasing Na excretion only after vagotomy. The results are interpreted to suggest that central and vagal receptors tend to enhance Na excretion whereas splanchnic nerve afferents and humoral mediator(s) have the opposite effect.     

Remodeling of the vascular bed and progressive loss of capillaries in denervated skeletal muscle

Very little is known regarding structural and functional responses of the vascular bed of skeletal muscle to denervation and about the role of microcirculatory changes in the pathogenesis of post-denervation muscle atrophy. The purpose of the present study was to investigate the changes of the anatomical pattern of vascularization of the extensor digitorum longus muscle in WI/HicksCar rats 1, 2, 4, 7, 12, and 18 months following denervation of the limb. We found that the number of capillaries related to the number of muscle fibers, i.e. the capillary-to-fiber ratio (CFR), decreased by 88%, from 1.55 +/- 0.35 to 0.19 +/- 0.04, during the first 7 months after denervation and then slightly declined at a much lower rate during the next 11 months of observation to 10% of the CFR in normal muscle. Between months 2 and 4 after denervation, the CRF decreased by 2.4 times, from 58% to 24% of the control value. The loss of capillaries during the first 4 months following nerve transection was nearly linear and progressed with an average decrement of 4.16% per week. Electron microscopy demonstrated progressive degeneration of capillaries following nerve transection. In muscle cells close to degenerating capillaries, the loss of subsarcolemmal and intermyofibrillar mitochondria, local disassembly of myofibrils and other manifestations of progressive atrophy were frequently observed. The levels of devascularization and the degree of degenerative changes varied greatly within different topographical areas, resulting in significant heterogeneity of intercapillary distances and local capillary densities within each sample of denervated muscle. Perivascular and interstitial fibrosis that rapidly developed after denervation resulted in the spatial separation of blood vessels from muscle cells and their embedment in a dense lattice of collagen. As a result of this process, diffusion distances between capillaries and the surfaces of muscle fibers increased 10-400 times. Eighteen months after denervation most of the capillaries were heavily cushioned with collagen, and on the average 40% of the muscle cells were completely avascular. Devascularization of the tissue was accompanied by degeneration and death of muscle cells that had become embedded in a dense lattice of collagen. Immunofluorescent staining for the vascular isoform of alpha-actin revealed preservation of major blood vessels and a greater variability in thickness of their medial layer. Hyperplastic growth of the medial layer in some blood vessels resulted in narrowing of their lumens. By the end of month 7 after denervation, large deposits of collagen around arterioles often exceeded their diameters. Identification of oxidative muscle fibers after immunostaining for slow-twitch myosin, as well as using ultrastructural criteria, has shown that after 2 months of denervation oxidative muscle fibers were less susceptible to atrophy than glycolytic fibers. The lower rate of atrophy of type I muscle fibers at early stages of denervation may be explained by their initially better vascularization in normal muscle and their higher capacity to retain capillaries shortly after denervation. Thus, degeneration and loss of capillaries after denervation occurs more rapidly than the loss of muscle fibers, which results in progressive decrease of the CFR in denervated muscle. The change of capillary number in denervated muscle is biphasic: the phase of a rapid decrease of the CFR during the first 7 months after nerve transection is followed by the phase of stabilization. The presence of areas completely devoid of capillaries in denervated muscle and the virtual absence of such areas in normal muscle indicate the development of foci of regional hypoxia during long-term denervation. The anatomical pattern of muscle microvascularization changes dramatically after nerve transection. Each muscle fiber in normal muscle directly contacts on average 3-5 capillaries. (ABSTRACT TRUNCATED)     

Enkephalin-like immunoreactivity in gland cells and nerve terminals of the adrenal medulla.

Met-enkephalin-like immunoreactivity has been observed in adrenal medullary gland cells of the rat, guinea-pig and cat. There were marked quantitative differences in untreated animals. Most medullary gland cells were positive in the cat, a large proportion in the guinea-pig but only a few in the rat. After sectioning of the splanchnic nerve, however, a large proportion of the gland cells were met-enkephalin positive also in the rat. Occasionally the met-enkephalin-like immunoreactivity had a granular appearance suggesting that the storage sites could be vesicular.In the guinea-pig a moderate number of met-enkephalin immunoreactive nerve fibers were observed in the adrenal medulla. They disappeared to a large extent after sectioning of the splanchnic nerve. A few fibers were also seen in the rat adrenal medulla, and in the cat some fibers could be seen in areas with few immunoreactive cells.The present findings suggest that in the adrenal medulla an enkephalin-like peptide(s) is present both in gland cells and in nerve terminals arising mainly from fibers in the splanchnic nerve. Thus, the possibility exists that in the adrenal medulla opioid peptides may be released from the gland cells into the blood as hormones as well as from nerve terminals to act as a modulator or transmitter. It should, however, be emphasized that the well-documented metabolic instability of met-enkephalin may be somewhat difficult to reconcile with a hormonal role of this peptide.     

Lipophilic nerve sprouting factor(s) isolated from denervated muscle

This report confirmed earlier studies by other workers which suggested that collateral nerve sprouting in mammalian skeletal muscle is induced by factors released from denervated or atrophic muscle fibers. Crude lipid extracts of denervated but not of normal muscle were found to bring about histological evidence of significantly increased collateral nerve outgrowth when injected into normal muscles. Additional experiments indicated that separated non-polar and polar lipid fractions of muscle were less active. The injection of a chemically pure lipid, monlaurin, also caused significant sprouting.