The influence of the pelvic nerves on anorectal motility in the cat

The influence of the parasympathetic pelvic nerves on anorectal motility was studied in anaesthetized cats. Anal pressure and rectal motility were recorded by a manometric and a volumetric method, respectively. Severing of the pelvic nerves did not cause any pressure change in the anus, indicating that these nerves are not significantly tonically active. Efferent low intensity (0.05-0.5 ms, 8 V at 5 Hz) electrical stimulation of the pelvic nerves (PNS) elicited a contraction of the internal anal sphincter (IAS), while high intensity stimulation (greater than 1 ms, 8 V at 5 Hz) caused a sphincter relaxation. A rectal contraction was noted on both low and high intensity stimulation. After sectioning of the sympathetic nerves, PNS elicited a contraction in both the anus and the rectum irrespective of stimulation intensity. PNS inhibited the anal contraction elicited by simultaneous stimulation of the sympathetic nerves or noradrenaline infusion. The inhibitory anal responses to PNS were unaffected or augmented by atropine, unaffected by propranolol and abolished by hexamethonium. The excitatory anal effects of PNS were reduced or abolished by atropine and abolished by phentolamine. The rectal contraction induced by low intensity PNS was abolished by atropine or converted to a relaxation. In half of the experiments an atropine resistant rectal contraction was observed in response to high intensity PNS. The results are consistent with a pelvic nerve influence on IAS pressure through several mechanisms, including modulation of the activity in the sympathetic nerves and activation of inhibitory non-adrenergic, non-cholinergic neurons. The pelvic nerves convey both cholinergic and non-cholinergic excitatory, as well as non-adrenergic, non-cholinergic inhibitory fibres to the rectum.     

保留直肠肛管移行上皮对预防感觉性大便失禁的意义

目的 :观察保留直肠肛管移行上皮 (ATZ上皮 )对预防感觉性大便失禁的作用。方法 :对 12例切除ATZ上皮患者的排便功能进行随访 ,以同期行同种手术且保留ATZ上皮的患者为对照组。结果 :两组患者无一例发生完全性大便失禁。切除ATZ组发生排便感觉丧失和感觉性大便失禁的发生率明显高于ATZ保留组 (P <0 .0 5 )。但除 2例患者外 ,术后 3个月切除ATZ的 10例患者肛门自制自行恢复。结论 :ATZ上皮在肛门自制 ,特别是预防感觉性大便失禁有着重要作用 ,术中应尽可能保护 ,但如果为了避免直肠粘膜外翻 ,必要时也可以切除 ,不会引起完全性大便失禁和永久性感觉性大便失禁。     

The role of the longitudinal muscle in the anal sphincter complex

Intersphincteric resection (ISR) enables radical sphincter-preserving surgery in a subset of low rectal tumors impinging on the anal sphincter complex (ASC). Excellent anatomical knowledge is essential for optimal ISR. This study describes the role of the longitudinal muscle (LM) in the ASC and implications for ISR and other low rectal and anal pathologies. Six human adult en bloc cadaveric specimens (three males, three females) were obtained from the University of Leeds GIFT Research Tissue Programme. Paraffin-embedded mega blocks containing the ASC were produced and serially sectioned at 250 μm intervals. Whole mount microscopic sections were histologically stained and digitally scanned. The intersphincteric plane was shown to be potentially very variable. In some places adipose tissue is located between the external anal sphincter (EAS) and internal anal sphincter (IAS), whereas in others the LM interdigitates to obliterate the plane. Elsewhere the LM is (partly) absent with the intersphincteric plane lying on the IAS. The LM gave rise to the formation of the submucosae and corrugator ani muscles by penetrating the IAS and EAS. In four of six specimens, striated muscle fibers from the EAS curled around the distal IAS reaching the anal submucosa. The ASC formed a complex structure, varying between individuals with an inconstant LM affecting the potential location of the intersphincteric plane as well as a high degree of intermingling striated and smooth muscle fibers potentially further disrupting the plane. The complexity of identifying the correct pathological staging of low rectal cancer is also demonstrated. Clin. Anat. 33:567–577, 2020. © 2019 Wiley Periodicals, Inc.     

Morphologies of the interfaces between the levator ani muscle and pelvic viscera,with special reference to muscle insertion into the anorectum in elderly Japanese

A specific, smooth muscle-mediated interface between the levator ani muscle (LA) and the pelvic viscera has been reported. Using 110 sagittally trimmed anorectal tissue strips (80 lateral, 15 anterior and 15 dorsal specimens) obtained from the donated cadavers of 46 elderly subjects, we examined variations in the interface between the LA and the rectal muscularis propria, including the so-called conjoined longitudinal muscles. In type A (9/46), little or no tissue connected the LA to the external rectal muscularis propria, but the LA and external sphincteric mass formed a definite complex. In type B (26/46), the covering fascia of the LA changed abruptly into smooth muscles, which merged into the external rectal muscularis propria. In type C (11/46), most of the LA-associated connective tissues, composed of smooth muscles, were tightly connected to the internal and external rectal muscularis propria. These variations seemed to depend on the morphology of the recto-urethralis, the lateral extension of which reinforced the LA-associated smooth muscles sufficiently to form type B and C insertions. We also demonstrated differences in the interfacial tissues between the LA and other pelvic viscera. We hypothesize that, to avoid injury of the LA and its interfaces during strong movement of the pelvic viscera, for example during childbirth, coitus or squeezed evacuation, the pelvic connective tissue-like smooth muscles play an important role as an autonomic buffer and/or modulator of pelvic floor function. Digital examination and transrectal or transvaginal sonography may be useful for evaluating interindividual variation in these interfacial tissues in elderly patients.     

Control of the internal anal sphincter (manometric study with human subjects)

Summary Manometric studies of the functions of the internal anal sphincter were performed in 73 children. Twenty-one out of these patients were normal subjects, the others had neurological lesions either central (sacral meningocele, dorsal cord transections) or peripheral (Hirschsprung's disease). It was found that the functions of the internal sphincter do not depend upon mechanical factors and are subject to nervous control. The pathways for control of the basal sphincteric tone are discussed. It is likely that this tone depends not only of the sympathetic pathways, but also of fibers of the sacral outflow. It is shown that the recto-anal inhibitory reflex is specific and independent of peristalsis. Arguments are given to prove that this reflex is an activity proper to the intra-mural plexus which is, however, subject to and regulated by the sacral cord.     

幽门螺杆菌感染对消化性溃疡患者胃肠动力及胃肠激素的影响

为探讨幽门螺杆菌（Hp)感染对消化性溃疡患者胃肠动力及胃肠激素的影响,对85例消化性溃疡患者进行了胃肠测压和血浆胃动素（MTL）及血浆生长抑素（SS）的测定,结果显示消化性溃疡患者与正常对照组相比消化间期胃肠动力明显减低,主要表现为消化间期移行性复合运动（MMC）Ⅲ期缺失和收缩波振幅减低,血中SS水平也明显低于正常对照组;在Hp阳性和Hp阴性的两组之间胃肠动力和SS水平均无显著差异,在血中MTL水平,Hp阳性组明显高于Hp阴性组,也高于正常对照组,结果表明消化性溃疡患者存在胃肠动力障碍和胃肠激素的异常改变。Hp感染对胃肠动力和SS水平无明显影响,但可促进MTL的分泌或释放。     

Adrenergic,cholinergic and VIP-ergic influence on gastric phasic motility in the rat

Bojö , L., Cassuto , J., Nellgård , P. & Jönsson , A. 1994. Adrenergic, cholinergic and VIP-ergic influence on gastric phasic motility in the rat. Acta Physiol Scand 150, 67–73. Received 30 December 1992, accepted 23 July 1993. ISSN 0001–6772. Department of Clinical Physiology, Central Hospital Karlstad, Department of Physiology, University of Goteborg and Department of Anaesthesiology, Central Hospital, Molndal, Sweden. We investigated the effects of adrenergic, cholinergic and vasoactive intestinal polypeptide (VlP)-ergic agonists and antagonists on the amplitude of gastric phasic contractions in the anaesthetized rat using a volumetric model. The amplitude of the phasic contractions was reduced significantly by atropine, hexamethonium or bilateral cervical vagotomy indicating that cholinergic neural activity involving both muscarinic and nicotinic receptors and intact vagal nerve function are integral parts of the control of basal gastric phasic motility. In contrast, neither selective α₁-, α₂- or non-selective β-blockers had any significant influence on the amplitude of the gastric contractions suggesting that adrenergic neurones are not tonically active in the maintenance of basal phasic motility in the stomach. The amplitude of the gastric phasic contractions was, however, significantly reduced by the α₁-agonist L-phenylephrine, the α₂-agonist clonidine and a close intraarterial injection of VIP (3 μkg^-1) but not be the selective β₁-agonist, prenalterol, or the β₂-agonist, salbutamol. These data suggest the presence of superimposed inhibitory control of phasic activity by VIP-ergic stimulation and by adrenergic neurones via α-receptor stimulation.     

Morphological analysis of the external anal sphincter motor nerve and its motoneurons in the cat

To investigate the spinal neural circuitry that controls the tonus of the external anal sphincter (EAS) in the cat, the size distribution of EAS motor fibers and their motoneurons (MN) was examined, and the presence of muscle spindles in EAS musculature was also tested for. The size distribution of EAS motor fibers was examined after degeneration of afferent fibers and that of their MN was measured, after labeling the cells with horseradish peroxidase. Both distributions were unimodal, thereby demonstrating the difficulty of distinguishing between alpha and potential gamma MN; but muscle spindles were not found in the musculature. Mechanisms underlying the spinally controlled tonus of the EAS remain unclear, including the nature and role of spinal reflexes. It is argued that non-spindle sensory receptors in the anal canal may provide the sensory component of a reflex circuit that contributes to this tonus.     

盆底超声及盆底肌力评估分析分娩对女性肛门括约肌复合体的影响*

目的：探讨盆底超声及盆底肌力评估分析分娩对女性肛门括约肌复合体（ASC）的影响。方法：选取2018 年1 月～ 2019 年1 月于本院妇科门诊进行产后复查的患者,包括阴道分娩产妇（ 阴道分娩组）和剖宫产产妇（ 剖 宫产组）,2 组均进行妇科检查、盆底超声及盆底肌力评估,比较2 组肛门内括约肌（ IAS）近端平面、中部平面、 远端平面及肛门外括约肌（ EAS）远端平面3、6、9、12 点钟方向的厚度,耻骨直肠肌（ PRM）中部平面4、8 点钟方向的厚度,盆底肌力评估指标。结果：与剖宫产组IAS 近端6 点、12 点,IAS 中部12 点厚度测量值比较, 阴道分娩组显著降低;与剖宫产组EAS远端12 点厚度测量值比较,阴道分娩组显著降低;与剖宫产组Ⅱ类肌最 大收缩力和Ⅰ类肌持续收缩力比较,阴道分娩组显著降低,差异具有统计学意义。结论：盆底超声能够对顺产及 剖宫产产妇的ASC进行有效评估,与剖宫产产妇比较,顺产产妇产后IAS、EAS均发生较大改变,且顺产产妇产 后盆底Ⅱ类肌最大收缩力及Ⅰ类肌持续收缩力均降低。     

Interactive three-dimensional teaching models of the female and male pelvic floor

Controversies regarding structure and function of the pelvic floor persist because of its poor accessibility and complex anatomical architecture. Most data are based on dissection. This “surgical” approach requires profound prior knowledge, because applying the scalpel precludes a “second look.” The “sectional” approach does not entail these limitations, but requires segmentation of structures and three-dimensional reconstruction. This approach has produced several “Visible Human Projects.” We dealt with limited spatial resolution and difficult-to-segment structures by proceeding from clear-cut to more fuzzy boundaries and comparing segmentation between investigators. We observed that the bicipital levator ani muscle consisted of pubovisceral and puborectal portions; that the pubovisceral muscle formed, together with rectococcygeal and rectoperineal muscles, a rectal diaphragm; that the external anal sphincter consisted of its subcutaneous portion and the puborectal muscle only; that the striated urethral sphincter had three parts, of which the middle (urethral compressor) was best developed in females and the circular lower (“membranous”) best in males; that the rectourethral muscle, an anterior extension of the rectal longitudinal smooth muscle, developed a fibrous node in its center (perineal body); that the perineal body was much better developed in females than males, so that the rectourethral subdivision into posterior rectoperineal and anterior deep perineal muscles was more obvious in females; that the superficial transverse perineal muscle attached to the fibrous septa of the ischioanal fat; and that the uterosacral ligaments and mesorectal fascia colocalized. To facilitate comprehension of the modified topography we provide interactive 3D-PDFs that are freely available for teaching purposes. Clin. Anat. 33:275–285, 2020. © 2019 Wiley Periodicals, Inc.     

Nerves in the intersphincteric space of the human anal canal with special reference to their continuation to the enteric nerve plexus of the rectum

In the intersphincteric space of the anal canal, nerves are thought to “change” from autonomic to somatic at the level of the squamous‐columnar epithelial junction of the anal canal. To compare the nerve configuration in the intersphincteric space with the configuration in adjacent areas of the human rectum, we immunohistochemically assessed tissue samples from 12 donated cadavers, using antibodies to S100, neuronal nitric oxide synthase (nNOS), and tyrosine hydroxylase (TH). Antibody to S100 revealed a clear difference in intramuscular nerve distribution patterns between the circular and longitudinal muscle layers of the most inferior part of the rectum, with the former having a plexus‐like configuration, while the latter contained short, longitudinally running nerves. Most of the intramural ganglion cells in the anal canal were restricted to above the epithelial junction, but some were located just below that level. Near or at the level of the epithelial junction, the nerves along the rectal adventitia and Auerbach's nerve plexus joined to form intersphincteric nerves, with all these nerves containing both nNOS‐positive parasympathetic and TH‐positive sympathetic nerve fibers. Thus, it was histologically difficult to distinguish somatic intersphincteric nerves from the autonomic Auerbach's plexus. In the intersphincteric space, the autonomic nerve elements with intrapelvic courses seemed to “borrow” a nerve pathway in the peripheral branches of the pudendal nerve. Injury to the intersphincteric nerve during surgery may result in loss of innervation in the major part of the internal anal sphincter. Clin. Anat. 26:843–854, 2013. © 2013 Wiley Periodicals, Inc.     

Pain-induced inhibition of gastric motility is mediated by adrenergic and vagal non-adrenergic reflexes in the rat

Painful stimuli have been shown to inhibit gastric motility in animal experiments and delay gastric emptying in humans. The aim of the present study was to investigate in detail mechanisms involved in pain-induced gastric inhibition. Pain stimulation by exerting pressure on a testicle induced a prompt gastric relaxation which lasted throughout the period of stimulation. Pain-induced gastric relaxation was significantly reduced by the selective α-1 blocker, prazosin, and by the non-selective β-blocker, propranolol. Similarly pain-induced inhibition of gastric tone was significantly reduced by bilateral cervical vagotomy. In contrast, gastric relaxation following pain stimulation was significantly potentiated by the selective adrenergic α-2 blocker, yohimbine. Combined administration of prazosin and propranol followed by bilateral cervical vagotomy abolished gastric relaxation in response to pain stimulation. In conclusion, gastric relaxation in response to painful stimulation was found to be reflex-mediated via sympathetic neurons acting on α-1 and β receptors and possibly also via vagal non-adrenergic fibres. Pain-induced inhibition of gastric tone was significantly increased by yohimbine. It is suggested that yohimbine by blocking presynaptic inhibitory receptors on adrenergic neurons facilitates the release of noradrenaline in response to pain stimulation.     

Effects of indoleamines on sperm motility in vitro.

Indoleamines are products of the pineal gland and are postulated to play an antigonadotrophic role in the reproductive system of mammals. In humans, indoleamines have been localized in tissue fluids such as plasma, serum and cerebrospinal fluid. Because indoleamines exhibit antigonadotrophic properties, the authors examined whether these agents cause inhibitory effects on sperm motility. In this study, time and dose-dependent inhibition of sperm motility by indoleamines was observed. Furthermore, the presence of indoles in incubation medium decreased sperm velocity. These data suggest that the presence of high doses of indoles in reproductive fluids may inhibit sperm motility and velocity.     

The influence of the cerebellum and peripheral somatic nerves on the activity of Deiters' cells in the cat

Summary The influence of the cerebellum on the activity of Deiters' cells has been studied by comparing the extracellularly recorded activity of single cells in decerebellate cats and in those with an intact cerebellum. The tonic inhibitory influence of the cerebellum is reflected in three ways: a smaller proportion of those cells projecting to the spinal cord is spontaneously active; fewer cells are found which do not project to the spinal cord, indicating that activity in this population of cells is depressed; among those cells that are spontaneously active, the rates of discharge are lower.In the decerebellate cat, stimulation of either ipsior contralateral limb nerves facilitates many cells, whereas in the presence of the cerebellum, peripheral stimulation evokes facilitation followed by inhibition. The inhibition is ascribed to activation by peripheral stimulation of Purkinje cells projecting to Deiters' nucleus from the cerebellum. The thresholds for facilitation and inhibition are similar but longer stimulus trains are required to evoke inhibition. Inputs from many different nerves converge upon the same cell. Among the nerves to muscles, quadriceps was the only nerve effective at stimulus strengths below the group III range.Three populations of cells are found in Deiters' nucleus: cells receiving somatic inputs but not labyrinthine inputs; cells receiving inputs from both the labyrinth and ascending somatic systems; cells activated from the labyrinth but free of somatic influences.This work was supported in part by Grants 5R01-NS-02619 and 5T01-NS-05463 from the National Institute of Neurological Diseases and Stroke, USPHS.Public Health Service Training Fellow.     

Comparison of the contractile properties, oxidative capacities and fibre type profiles of the voluntary sphincters of continence in the rat

The external urethral sphincter (EUS) and external anal sphincter (EAS) are the principal voluntary striated muscles that sustain continence of urine and faeces. In light of their common embryological origin, shared tonic sphincteric action and synchronized electrical activity in vivo, it was expected that they would exhibit similar physiological and structural properties. However, the findings of this study using paired observations of both sphincters isolated from the rat show clearly that this is not the case. The anal sphincter is much more fatigable than the urethral sphincter. On completion of a fatigue protocol, the amplitude of the last twitch of the EAS had declined to 42 ± 3% of the first twitch, whereas the last twitch of the EUS was almost identical to that of the first (95 ± 3%). Immunocytochemical detection of myosin heavy‐chain isoforms showed that this difference was not due to the presence of more slow‐twitch oxidative type 1 fibres in the EUS compared with the EAS (areal densities 4 ± 1% and 5 ± 1%, respectively; P = 0.35). In addition, the fatigue difference was not explained by a greater contribution to force production by fast oxidative type 2A fibres in the urethral sphincter. In fact, the anal sphincter contained a higher areal density of type 2A fibres (56 ± 5% vs. 37 ± 4% in the EUS, P = 0.017). The higher oxidative capacity of the EUS, measured histochemically, explained its fatigue resistance. These results were surprising because the fatigue‐resistant urethral muscle exhibited faster single‐twitch contraction times compared with the anal sphincter (56 ± 0.87 ms vs. 72.5 ± 1.16 ms, P < 0.001). Neither sphincter expressed the type 2X myosin isoform but the fast‐twitch isoform type 2B was found exclusively in the EUS (areal density 16 ± 2%). The type 2B fibres of the EUS were small (diameter 19.5 ± 0.4 μm) in comparison to typical type 2B fibres of other muscles. As a whole the EUS is a more oxidative than glycolytic muscle. In conclusion, analysis of the twitch mechanics and fatigue of two sphincters showed that the EUS contained more fatigue‐resistant muscle fibres compared with the EAS.     

Smooth muscle of the male pelvic floor: An anatomic study

Knowledge of the anatomy of the male pelvic floor is important to avoid damaging the pelvic floor muscles during surgery. We set out to explore the structure and innervation of the smooth muscle (SM) of the whole pelvic floor using male fetuses. We removed en-bloc the entire pelvis of three male fetuses. The specimens were serially sectioned before being stained with Masson's trichrome and hematoxylin and eosin, and immunostained for SMs, and somatic, adrenergic, sensory and nitrergic nerve fibers. Slides were digitized for three-dimensional reconstruction. We individualized a middle compartment that contains SM cells. This compartment is in close relation with the levator ani muscle (LAM), rectum, and urethra. We describe a posterior part of the middle compartment posterior to the rectal wall and an anterior part anterior to the rectal wall. The anterior part is split into (1) a centro-levator area of SM cells localized between the right and left LAM, (2) an endo-levator area that upholsters the internal aspect of the LAM, and (3) an infra-levator area below the LAM. All these areas are innervated by autonomic nerves coming from the inferior hypogastric plexus. The core and the infra-levator area receive the cavernous nerve and nerves supplying the urethra. We thus demonstrate that these muscular structures are smooth and under autonomic influence. These findings are relevant for the pelvic surgeon, and especially the urologist, during radical prostatectomy, abdominoperineal resection and intersphincteric resection. Clin. Anat., 2019. © 2019 Wiley Periodicals, Inc.     

Effects of neurotensin and neurotensin analogues on the migrating myoelectrical complexes in the small intestine of rats

The purpose of the present experiments was to study the effect of neurotensin and neurotensin analogues on the migrating myoelectrical complexes in the small intestine of rats. Four bipolar electrodes were implanted into the muscular wall of the small intestine. The electrodes were placed 5, 15, 25 and 35 cm distal to the pylorus. 7–10 days after the operation the animals were fasted for 48 h with free access to water. Some experiments were performed on conscious rats and in others the rats were anesthetized with pentobarbital, 30 mg/kg. I.v. infusion of either neurotensin (NT) or (Gln⁴)-neurotensin at doses of 1.8, 3.6 and 7.1 pmol kg^-1· min^-1abolished the migrating myoelectric complexes, which were replaced by increased spiking activity along the whole length of the small intestine from which activity was recorded. The changes in myoelectrical activity were observed within 2–4 min after commencement of the infusion. The activity returned to control levels within 5–15 min after the end of the infusion period. The neurotensin sequences NT 9–13, NT 8–13, NT 4–13, NT 1–9 and (Gln⁴)-NT 1–11 did not induce any changes in the electrical activity in the small intestine. The effects of NT and (Gln⁴)-neurotensin on the myoelectrical activity in the small intestine were indistinguishable. The changes induced by NT or (Gln⁴)-NT resemble those found after the ingestion of food. The present data indicate that the intact NT sequence, rather than smaller NT fragments, is necessary to induce changes in myoelectrical activity in the small intestine.