Angiostrongylus cantonensis: Rejection of pulmonary arterial transfers of lung stage worms

Experimental transfer of the lung stage worms of Angiostrongylus cantonensis was performed between permissive hosts (rats) and between permissive (rat) and nonpermissive hosts (guinea pigs and rabbits). These worms from rats were rejected when implanted into nonpermissive hosts. Unexpectedly, similar worms did not survive well even in permissive hosts; the majority of recipient rats did not have first-stage larvae (L₁) in their stools and, even when positive for L₁, the number of the larvae shed was few. These findings contrast with the successful pulmonary arterial transfer of younger, intracranial-stage worms. It was shown that differences in rat strain between donor and recipient had no significant effect on the subsequent worm survival in recipient hosts. The alteration of maintaining conditions of the intrapulmonary worms, prior to transfer, in terms of temperature, media, and maintaining period, also showed no profound effect on the subsequent worm survival. The kinetics of precipitating and reaginic antibody levels in rats implanted with the intrapulmonary worms were analogous to those in rats with intracranial-stage worms. The findings indicate that some qualitative differences may exist between the worms obtained from two different sites.     

Neuropeptide Y in guinea pig, rabbit, rat and man. Identical amino acid sequence and oxidation of methionine-17

Neuropeptide Y (NPY) was isolated and characterised from acid-ethanol extracts of rabbit and guinea pig brain. In both instances the chromatographic purification was a two-step procedure of gel filtration followed by reverse-phase high-performance liquid chromatography. The amino acid sequence of rabbit and guinea pig NPY was found to be identical to human and rat NPY as deduced from the cDNA structures. With the exception of the porcine peptide, all mammalian NPYs characterised to date have a methionine residue in position 17. This methionine residue is readily oxidized as indicated by the high degree of spontaneous oxidation of peptides found in the rabbit and guinea pig brain extracts and in NPY extracted from a rat phaeochromocytoma cell line. It is concluded that NPY is among the most highly conserved peptides and that NPYs containing methionine in position 17 are prone to oxidation.     

电刺激大鼠腓肠神经引起Aδ、 C类传入神经纤维的背根反射

在距脊髓约 15mm处切断大鼠L5背根 ,将中枢端分成 4～ 5条细束 ,电刺激腓肠神经在背根细束上记录背根反射 (dorsalrootreflex ,DRR)。共记录到DRR 5 1例 ,根据引起DRR所兴奋的腓肠神经纤维类别和DRR在背根逆向传出的纤维类别将DRR分为 5类 :Aαβ Aαβ·DRR、Aβδ Aδ·DRR、Aβδ C·DRR、Aαβδδ C·DRR和C C·DRR。结果证明 ,电刺激外周神经激活各类纤维不但能引起A类 (包括Aδ)纤维的DRR ,而且也能引起C类纤维的DRR。记录的Aδ·DRR和C·DRR为细纤维传入终末产生突触前抑制提供了客观指标 ,为DRR逆向传出冲动到达外周组织 ,释放神经肽类递质 ,调节外周效应器的功能提供了证据     

慢性动脉血压监测模型在惊恐条件反射中的应用

目的：探索一种新的、可靠的模型,用于惊恐条件反射的相关研究。方法：通过使用条件刺激(声音)和非条件刺激(足部电击)相结合的方法,可使动物对条件刺激产生惊恐反应。同时对动脉血压进行长期监测并测定利多卡因阻断杏仁基底外侧核群前后的血压变化。结果：该惊恐条件反射建立后(需经4d训练),单独给予动物条件刺激即可引起血压明显升高。我们将它作为条件反射已形成的标志。此时,用利多卡因阻断杏仁基底外侧核群的作用,单独给予动物条件刺激不再引起血压明显升高。结论：慢性动脉血压监测模型在惊恐条件反射的研究中是一种可靠的动物模型。     

The relationship between gastrin cells and bombesin-like immunoreactive nerve fibres in the gastric antral mucosa of guinea-pig,rat, dog and man

Summary The relationship between bombesin-like immunoreactive (bombesin-LI) nerve fibres and gastrin-LI G-cells was examined in gastric antral mucosa from guineapig, rat, dog and man using a double-labelling fluorescence immunohistochemical technique. The greatest density of bombesin-LI nerve fibres was found within the basal mucosa in all species and the density of innervation decreased towards the luminal surface. Most G-cells were in a band occupying approximately the middle third of the mucosa. The proportion of G-cells found within a distance of 2 m from bombesin-LI nerve fibres was low in all species (6% in the guinea-pig, 22% in the rat, 14% in the dog, and 9% in the human). It is proposed that the neuropeptide released from bombesin-LI antral mucosal nerve fibres traverses distances of greater than several m to reach the target G-cells. This may be achieved by passage through the mucosal microcirculation.     

Species variations in the biliary and urinary excretion of arsenate, arsenite and their metabolites

In most mammalian species, inorganic arsenicals are extensively biotransformed and excreted both in unchanged form and as metabolites. In the bile of rats receiving arsenate (AsV) or arsenite (AsIII) we have identified monomethylarsonous acid (MMAsIII), purportedly the most toxic metabolite of inorganic arsenic. As rats are not commonly accepted for studying arsenic metabolism, we carried out a comparative investigation on the excretion of AsV, AsIII and their metabolites in five animal species in order to determine whether they also form MMAsIII from AsV and AsIII. Anaesthetised bile duct-cannulated rats, mice, hamsters, rabbits, and guinea pigs were injected with AsV or AsIII (50 micromol/kg, i.v.) and their bile and urine was collected for 2 h. Arsenic in bile and urine was speciated by HPLC-hydride generation-atomic fluorescence spectrometry and the excretion rates of AsV, AsIII, monomethylarsonic acid (MMAsV), MMAsIII and dimethylarsinic acid (DMAsV) were quantified. All species injected with AsV excreted arsenic preferentially into urine, whereas all animals receiving AsIII, except rabbits, delivered more arsenic into bile than urine. Bile contained almost exclusively trivalent arsenic (i.e. AsIII and/or MMAsIII), whereas AsV, AsIII and DMAsV appeared in urine. Except for guinea pigs, which do not methylate arsenic, the other species formed MMAsIII and excreted it into bile. Having excreted as much as 8% of the dose of AsIII or AsV in 2 h as MMAsIII, rats were by far the most efficient producers of this supertoxic metabolite. Thus, although the rat is not a good model for studying long-term arsenic disposition, this species appears especially valuable in studies on AsIII methyltransferase and in vivo formation of MMAsIII.     

Sympathetic nerve regulation of cochlear blood flow during increases in blood pressure in humans

The purpose of this work was to show that regulation of the blood flow to the cochlea by the sympathetic nervous system occurs in humans at the level of the cochlear microcirculation during increases in blood pressure and that its involvement depends on the pressure level. Eight anaesthetized patients undergoing tympanoplasty for hearing disease took part in a pharmacological protocol of stimulation and inhibition of the autonomic nervous system (ANS) to provide variations in systolic blood pressure (BP_S) and cochlear blood flow (CBF). The CBF was measured by laser-Doppler flowmetry. Changes in autonomic nerve activity were brought about by changes in baroreceptor activity (BR) initiated by the injection of an α adrenergic agent before and after sympathetic and parasympathetic blockade. The CBF variations (δCBF) were plotted against BP_S increases at each stage of the ANS inhibition. The BR diminished significantly after α blockade, after α and β blockade, and after α and β blockade and atropine, by 50% (P < 0.01), 29% (P < 0.05), and 95% (P < 0.001) respectively. The BP_S increased significantly (P < 0.01) by 36 (SD 9)%, 47 (SD 1)%, and 67 (SD 16)% respectively. The CBF response to an increase in BP_S exhibited two opposing variations in the patients: CBF decreased significantly in one group, and increased significantly in the other group. In both groups, δCBF decrease and δCBF increase, respectively, were significant after ANS blockade; even so the decrease and increase, respectively, levelled off at BP_S around 160 mmHg before ANS blockade. For BP_S below 160 mmHg, correlations between δCBF and BP_S were significant before inhibition and after inhibition of ANS. For BP_S above 160 mmHg, BP_S and δCBF were not correlated before inhibition of ANS, and were significantly correlated after inhibition of ANS. For BP_S below 160 mmHg, CBF response to the BP_S increase was the same before and after ANS blockade, i.e. ANS control did not predominate; even so, for BP_S above 160 mmHg, the CBF response to BP_S increase was different before and after ANS blockade: CBF varied significantly after ANS blockade as it varied for BP_S below 160 mmHg, while it remained constant before ANS blockade that elicited ANS control of CBF. In conclusion, sympathetic nerve regulation via its vasomotor tone at the level of cochlear microcirculation occurred markedly when the blood pressure was above 160 mmHg; the autonomic nervous system would appear to control the cochlear blood flow against large variations in blood flow in response to hypertensive phenomena. Accepted: 7 October 1996     

The influence of tactile stimulation of nipples on the milk ejection reflex in the rat

Summary Changes of positive pressure exerted by pups on nipples during sucking were investigated using anesthetized, lactating dams. It was found that, every 50–60 s, individual pups performed bouts of pressure oscillations (3/s) of high amplitude which lasted about 10–12 s and coincided with periods of increased motor activity. During the intervals, when pups were quiet, series of low-amplitude oscillations (3/s) were also observed. Using a strain measuring method to record the activity of sucking pups, synchronization of activity of two or more pups was found to occur periodically every 25–30 s and, most frequently, 10–30 s before the reflex increase of milk pressure. In further experiments, artificial tactile stimulation was applied to the dam's nipples using the joint action of suction and positive pressure. Following a short-term (10–20 s) increase in frequency and amplitude of artificial nipple stimulation, 60%–80% of all reflexive peaks of milk pressure were elicited with a latency of 19 ± 5 s. This suggests that there are specific conditions under which the stimulation of nipples by pups may trigger the formation of the milk ejection reflex in the rat.Abbreviation MER milk ejection reflex     

Changes in blood level of catecholamines during arterial blood pressure rise induced with sciatic nerve stimulation

In experiments on rabbits and dogs it was demonstrated that electrical stimulation of the centripetal fibres of the cut sciatic nerve causing a rise of the arterial blood pressure produced a significant increase in the plasma levels of adrenaline and noradrenaline. This effect was not observed in animals with sympathetic system blockade caused by administration of reserpine. These observations indicate that pressure increase after sciatic nerve stimulation is due to stimulation of the adrenergic system.     

The effect of electrical stimulation of vestibular-complex formations on systemic arterial pressure and regional blood flow

Electrical stimulation of the descending and medial vestibular nuclei produced increased arterial blood pressure and also changes in regional blood flow. On stimulation of the descending vestibular nucleus there was a decrease in blood flow in the hind-limb muscles, which might be a response to stimulation of the ventrolateral parts of the nucleus; when the central parts of the nucleus were stimulated the blood flow decreased both in the hind-limb muscles and in some of the viscera. Stimulation of the medial vestibular nucleus, particularly its ventral parts, caused a decrease in blood flow in the skin of the hind limbs, often accompanied by a decrease in visceral blood flow. On the basis of analysis of the afferent and efferent connections of the descending and medial vestibular nuclei, it is suggested that the cerebellum takes part in the transmission of vasomotor influences.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 2, No. 1, pp. 35–42, January–February, 1970.     

Ultrastructure and distribution of somatostatin-like immunoreactive neurons and nerve fibres in the coeliac ganglion of cats

Summary Somatostatin-like immunoreactivity was localized in nerve cell bodies and nerve terminals in the cat coeliac ganglion. Two types of somatostatin-immunoreactive cell bodies were revealed, the first being large (diameter 35 m), numerous and weakly labelled, where—as the second was considerably smaller (diameter 10.4 m), sparsely distributed and heavily stained. The immunoreactive nerve terminals were in synaptic contact with many immunonegative large neurons and dendrites. However, in a few cases, somatostatin-immunoreactive nerve terminals could also be observed on the surface of lightly stained neurons. Transection of vagal or mesenteric nerve failed to affect the distribution or density of somatostatin-like immunoreactive nerve terminals. These results demonstrate the existence of a synaptic input to the principal neurons of the coeliac ganglion of the cat by somatostatin-containing nerve terminals and suggest that this peptide may act as a neuromodulator or neurotransmitter. It is proposed that somatostatin-positive neurons provide intrinsic projections to other somatostatin-positive and to somatostatin-negative neurons throughout the coeliac ganglion, thereby creating a complex interneuronal system.     

Presence and co-localization of vasoactive intestinal polypeptide with neuronal nitric oxide synthase in cells and nerve fibers within guinea pig intrinsic cardiac ganglia and cardiac tissue

The presence of vasoactive intestinal polypeptide (VIP) has been analyzed in fibers and neurons within the guinea pig intrinsic cardiac ganglia and in fibers innervating cardiac tissues. In whole-mount preparations, VIP-immunoreactive (IR) fibers were present in about 70% of the cardiac ganglia. VIP was co-localized with neuronal nitric oxide synthase (nNOS) in fibers innervating the intrinsic ganglia but was not present in fibers immunoreactive for pituitary adenylate cyclase-activating polypeptide, choline acetyltransferase (ChAT), tyrosine hydroxylase, or substance P. A small number of the intrinsic ChAT-IR cardiac ganglia neurons (approximately 3%) exhibited VIP immunoreactivity. These few VIP-IR cardiac neurons also exhibited nNOS immunoreactivity. After explant culture for 72 h, the intraganglionic VIP-IR fibers degenerated, indicating that they were axons of neurons located outside the heart. In cardiac tissue sections, VIP-IR fibers were present primarily in the atria and in perivascular connective tissue, with the overall abundance being low. VIP-IR fibers were notably sparse in the sinus node and conducting system and generally absent in the ventricular myocardium. Virtually all VIP-IR fibers in tissue sections exhibited immunoreactivity to nNOS. A few VIP-IR fibers, primarily those located within the atrial myocardium, were immunoreactive for both nNOS and ChAT indicating they were derived from intrinsic cardiac neurons. We suggest that, in the guinea pig, the majority of intraganglionic and cardiac tissue VIP-IR fibers originate outside of the heart. These extrinsic VIP-IR fibers are also immunoreactive for nNOS and therefore most likely are a component of the afferent fibers derived from the vagal sensory ganglia. This work was supported by NIH grant HL65481 (R.L.P.) and HL54633 (D.B.H.). Use of the DeltaVision Restoration microscope was provided through the Imaging/Physiology Core supported by NIH Grant P20 RR16435 from the COBRE program of the National Center for Research Resources     

氟骨症不同动物模型的建立与评价

目的 为选择合适的实验动物并建立氟骨症动物模型,研究不同动物对氟化物致骨骼损伤的敏感性.方法 分别选取离乳新西兰兔、Hartley豚鼠、Wistar大鼠、KM小鼠各16只,每种动物随机分为两组,每组8只,即对照组(C):饲喂标准饲料,饮用去离子水;模型组(M):饲喂标准饲料,饮用150 mg/L氟化钠(NaF)去离子水.在饲喂60 d后取股骨制作组织切片观察组织形态变化,并测定股骨骨氟、骨钙、骨磷的含量及血清碱性磷酸酶(ALP)活性.结果 与对照组相比,各种实验动物模型组生长发育受到显著的抑制,股骨形态破坏明显,骨矿化显著减少,骨氟含量显著升高,血清ALP活性显著增强,但股骨钙和磷含量差异无显著性(P＞0.05).结论 高氟可不同程度的损害豚鼠、家兔、小鼠、大鼠的生长发育及骨骼系统,导致产生氟骨症,但综合考察,以豚鼠、家兔较为敏感,其次为小鼠、大鼠.     

Patterns of co-existence of peptides and differences of nerve fibre types associated with noradrenergic and non-noradrenergic (putative cholinergic) neurons in the major pelvic ganglion of the male rat

Summary The pelvic ganglia supply cholinergic and noradrenergic nerve pathways to many organs. Other possible transmitters are also present in these nerves, including peptides. Multiple labelling immunofluorescence techniques were used in this study of the male rat major pelvic ganglion (MPG) to examine: (1) the peptides present in noradrenergic (tyrosine hydroxylase (TH)-positive) and non-noradrenergic (putative cholinergic) neurons, and (2) the types of peptide-containing nerve fibres closely associated with these two groups of neurons. The distribution of the peptide galanin (GAL) within the MPG was also investigated. All of the TH-neurons contained neuropeptide Y (NPY), but none of the other tested peptides. However, many NPY neurons did not contain TH and may have been cholinergic. TH-negative neurons also displayed vasoactive intestinal peptide (VIP), enkephalin (ENK) or GAL. VIP and NPY formed the most common types of putative cholinergic pelvic neurons, but few cells contained both peptides. Many ENK neurons exhibited VIP, NPY or GAL. Varicose nerve terminals surrounding ganglion cells contained ENK, GAL, somatostatin (SOM) and cholecystokinin (CCK). These peptide-immunoreactive fibres were more often associated with the non-noradrenergic (putative cholinergic) than the noradrenergic neurons; two types (SOM and CCK) were preferentially associated with the non-noradrenergic NPY neurons. GAL was distributed throughout the MPG, in small neurons, scattered small, intensely fluorescent (SIF) cells, and both varicose and non-varicose nerve fibres. The nerve fibres were concentrated near the pelvic and penile nerves; most of the varicose fibres formed baskets surrounding individual GAL-negative somata.     

Effect of phentolamine on the reflex increase in arterial pressure

Experiments were carried out in anaesthetized and curarized cats to study the effects of the alpha-blocker phentolamine on arterial pressor response to stimulation of group I afferent fibers from gastrocnemius-soleus muscles. It has been found that increasing doses of phentolamine given i.v. cause a decreasing pressor response until complete disappearance occurs at 2.5 mg/Kg. It is concluded that pressor response is present only when the adrenergic control system is effective and, therefore, it is due mainly to an increase in peripheral vascular resistances.     

Co-existence and origin of peptidergic and adrenergic nerves in the guinea pig uterus

Summary The occurrence and distribution of peptidergic nerves in the guinea pig uterus was studied by means of immunocytochemistry using numerous neuropeptide antisera. Neuropeptide Y (NPY)-immunoreactive (IR) nerves were the most abundant, whereas substance P (SP)-, calcitonine gene-related peptide (CGRP)-, and neurokinin A (NKA)-IR nerves were less frequent, and peptide histidine isoleucine (PHI)-IR nerves were the most sparse. Chemical sympathectomy by means of 6-hydroxydopamine, and capsaicin treatment revealed the division of the peptidergic nerves into three separate populations: (1) NPY-IR nerves, which co-existed with adrenergic nerves, (2) SP-, CGRP-and NKA-IR nerves, which mutually co-existed, and (3) PHI-IR nerves. Parallel-running adrenergic/NPY-IR and SP-IR nerves could be found with very similar although not completely identical morphological appearance. Paracervical ganglia contained neurotensin-and dynorphin A-IR cell bodies in addition to cell bodies with immunoreactivities similar to those in prevertebral ganglia. Combined retrograde tracing with True blue and immunocytochemistry showed that the adrenergic and NPY-IR uterine nerves originate in paracervical and prevertebral ganglia. In the prevertebral ganglia the cellular origin was the same for adrenergic and NPY-IR nerves. In contrast, SP-, CGRP-,and NKA-IR nerves originated in dorsal root ganglia. At full-term pregnancy all the neuropeptide immunoreactivities had vanished, probably reflecting a fetus-induced general nerve degeneration.