Central nervous system involvement in experimental Trypanosomiasis cruzi.

A review of the available literature on central nervous system involvement in experimental trypanosomiasis cruzi is undertaken. From a critical analysis of 26 works on experimental infections with Trypanosoma cruzi (23 on the acute phase, 2 on the chronic phase, and one describing sequentially both phases), all supported by neuropathologic studies, it can be concluded that: 1) central nervous system involvement during the acute phase, in the form of encephalitis in multiple foci, with variable intensity of the parasitism and inflammatory changes, is frequent and well documented; 2) in animals with more severe central nervous system involvement death occurs as a result of the brain lesions or acute chagasic myocarditis, the latter being always present; 3) in animals with more discrete brain involvement death during the acute phase is due to complications not related to the nervous system, among which congestive heart failure secondary to acute chagasic myocarditis, a condition that is always present, regardless of whether or not the central nervous system is infected; 4) it is possible that in surviving animals that had mild encephalitis the inflammatory changes from the acute phase usually regress as the infection progress to the chronic phase.     

Cerebellar degenerative changes in patients with acute leukaemias and non-Hodgkin's lymphomas.

In patients with neoplasms located outside the central nervous system can appear degenerative changes within nervous tissue. Neuropathological investigations have been done on 101 cases with acute Non-Lymphoblastic Leukaemias (ANLL) and Non-Hodgkin's Lymphomas (NHL). Cerebellar degenerative changes especially granular layer rarefaction or atrophy appear more frequently in ANLL than in NHL.     

Studies on the mechanism of postetorphine catalepsy. Effects of clotiapine, haloperidol and rompun on postetorphine changes in concentrations of dopamine and noradrenaline in central nervous system of rats

Changes in dopamine (DA) and noradrenaline (NA) concentrations in various central nervous system structures were compared in rats after administration of haloperidol, clotiapine and rompun with changes in these concentrations during etorphine-induced catalepsy. Besides that, these changes were compared with changes in DA and NA concentrations after etorphine administration during full action of haloperidol, clotiapine and rompun. Haloperidol, clotiapine and rompun prolonged the duration of etorphine-induced catalepsy in rats and modified significantly postetorphine changes in DA and NA concentrations in the investigated central nervous system structures. The action of haloperidol, clotiapine and rompun increasing the intensity of postetorphine catalepsy and the previously demonstrated anticataleptic and antietorphine action of agents stimulating the postsynaptic adrenergic structures in the central nervous system in rats may suggest that DA release from presynaptic structures is inhibited after etorphine.     

Changes in the intramural neural apparatus of the stomach and gallbladder in the late periods after vagotomy

By means of morphological methods changes in the wall of the stomach central part and in that of the bile bladder have been studied in 15 patients after a remote vagotomy (in 7-17 years). Material of biopsies and resections has been investigated. In the wall of the organs in question focal and diffuse mono- and plasmocytic infiltrates, leucocytic invasion of the mucous membrane epithelium, microerosions, microfocal hemorrhages in the external layers of the muscular sheath have been revealed. Inflammatory-degenerative and dystrophic changes are observed in the intramural ganglia, in large and small fasciculi of the muscular-intestinal nervous plexuses. In the tissues of the organs studied there are no myelin fibers, that are ++pre-ganglial and receptor conductors. The degeneration of these fibers after vagotomy and loss of connections in the organs investigated with the CNS are supposed to result in essential changes not only of the nervous trophic of tissues in all membranes and sheaths, but bring about changes in the intramural nervous apparatus itself. These changes, in their turn, cause imbalance + in the neurogumoral regulation and can be considered as the base of a number of postvagotomic structural-functional disturbances.     

Quantitative and qualitative changes in protein biosynthesis induced by hypoxia and transplantation of embryonic nerve tissue into the brain of adult mammals

The changes in biochemical processes in brain cortex in rats with experimental hypoxia and hypoxia with consequent transplantation of embryonic nervous tissue into brain of adults have been studied. A small increase (2-3 times) in incorporation of biosynthesis precursors was observed as a result of transplantation both in normal and in hypoxic rats. These changes could be observed 100 days after the transplantation. These changes in biosynthesis led to selective increase in the amounts of 40-45 and 35-39 kDa proteins, which are characteristic both for local trauma caused by transplantation and for general one caused by hypoxia. The effect observed may be explained as a reaction of nervous cells on damage, and not on the presence of an embryonic brain transplant.     

Age-related changes in the innervation of the prostate gland

The adult prostate gland grows and develops under hormonal control while its physiological functions are controlled by the autonomic nervous system. The prostate gland receives sympathetic input via the hypogastric nerve and parasympathetic input via the pelvic nerve. In addition, the hypogastric and pelvic nerves also provide sensory inputs to the gland. This review provides a summary of the innervation of the adult prostate gland and describes the changes which occur with age and disease. Growth and development of the prostate gland is age dependent as is the occurrence of both benign prostate disease and prostate cancer. In parallel, the activity and influence of both the sympathetic and parasympathetic nervous system changes with age. The influence of the sympathetic nervous system on benign prostatic hyperplasia is well documented and this review considers the possibility of a link between changes in autonomic innervation and prostate cancer progression.     

Hypoxia-induced changes in neuronal network properties

Because of their high energetic demand, neurons within the mammalian central nervous system are extremely sensitive to changes in partial pressure of oxygen. Faced with acute hypoxic conditions, an organism must follow a complex and highly dynamic emergency plan to secure survival. Behavioral functions that are not immediately essential for survival are turned off, and critical behaviors (such as breathing) undergo a biphasic response. An augmentation of breathing is initially adaptive, whereas prolonged hypoxic conditions are better served by an energy-saving mode. However, the hypoxic response of an organism depends on many additional factors. Environmental conditions, the animal's age and health, and the pattern (continuous vs intermittent) and duration (chronic vs acute) of hypoxia greatly determine the specific course of a hypoxic response. Different forms of hypoxia can cause pathology or be used as therapy. Therefore, it is not surprising that the hypoxic response of an organism results from widespread and highly diverse reconfigurations of neuronal network functions in different brain areas that are accomplished by diverse hypoxic changes at all levels of the nervous system (i.e., molecular, cellular, synaptic, neuronal, network). Hypoxia-induced changes in synaptic transmission are generally depressive and result primarily from presynaptic mechanisms, whereas changes in intrinsic properties involve excitatory and inhibitory alterations involving the majority of K+, Na+, and Ca2+ channels. This article reviews the response of the nervous system to hypoxia, accounting for all levels of integration from the cellular to the network level, and postulates that a better understanding of the diversity of cellular events is only possible if cellular and network events are considered in a functional and organismal context.     

Regional differences in brain gangliosides of a teleost fish following thermal acclimations

The ability of ectothermic vertebrates to adapt to thermal fluctuations in their environment is mainly based upon adaptive changes within the CNS. These changes are thought to be correlated with functional, metabolism changes in the central nervous system, especially in neuronal membranes. Gangliosides, being highly enriched in synaptic membranes (1)show characteristic perculiarities concerning concentration and molecular composition with regard to their sialylation status (2,3,4). In order to get further information concerning the biological function of gangliosides with respect to thermal adaptation, it was of interest to investigate possible correlation between the nervous ganglioside metabolism of different brain regions after various temperature adaptations.     

Effect of quinolinic acid on neurons in dissociated cultures of cells of different structures of the brain

Using neurohistological and cytochemical methods in the living cells, the peculiarities of the action of endogenous neurotoxin, quinolinic acid (QUIN), on the neurons developing in the cell cultures of the hippocamp, neocortex and septum have been investigated in 17-19-day-old mouse embryos. The addition of 500 microM of QUIN on the 21st--22nd day into the nutrition medium in vitro resulted in the rapid destruction of neurons localized in glioneuronal aggregates, while the isolated nervous cells as well as septal cholinergic neurons remained intact. At earlier stages of cultivation (up to 2 weeks) QUIN did not provoke degenerative changes in the cultivated neurons. The comparison of our results with the literary data suggests that in nervous cell cultures QUIN, having mature synaptic connections with afferent nervous fibers, causes destruction of neurons.     

Neuronal mechanisms of learning in an in vitro Aplysia preparation: sites other than the sensory-motor neuron synapse are involved

Classical conditioning of the gill withdrawal reflex can be demonstrated in two different in vitro Aplysia preparations. The data obtained show that as conditioning of the gill withdrawal reflex proceeds there are changes in synaptic efficacy at the central sensory-motor neurone synapse. These changes in synaptic efficacy, however, are not necessary nor are they sufficient for the observed changes in gill reflex behaviour. Changes must be occurring at other loci within the nervous system to mediate the associative learning. We hypothesized, based on data obtained from one type of in vitro preparation, that changes occur in the ability of the motor neurone to elicit a gill withdrawal response as a result of classical conditioning training. In order to test this hypothesis we depolarized an identified gill motor neurone before and after classical conditioning and found that the motor neurone's ability to elicit a gill movement was facilitated following classical conditioning training. In control preparations that received an explicitly unpaired stimulus paradigm (which does not lead to classical conditioning of the reflex) there was a decrease in the efficacy of a gill motor neurone to elicit a gill withdrawal response. There are a number of possible sites within the integrated central (CNS) and peripheral (PNS) nervous systems where changes could occur to bring about the alterations in motor neurone efficacy. Our results suggest that changes in neuronal activity which underlie learning occur at multiple sites within the nervous system and that a complete understanding of the mechanisms of associative learning can only be obtained when all of these sites are taken into account.     

Effects of death of a single neuron on the functional organization of the neuronal ensemble in the leech

The reaction of leech nervous system after elimination of individual mechanosensory neuron by intracellular Pronase injection were studied. In the motor neurons connected with killed cells at 14-90th days after the operation there were the changes of the resting membrane potential and amplitude of postsynaptic potentials developed by the stimulation of mechanosensory neuron. It is suggested that the leech nervous system serves as the dynamic formation depending on changes of neuronal ensemble structure.     

What has transcranial magnetic stimulation taught us about neural adaptations to strength training? A brief review

The evidence for neural mechanisms underpinning rapid strength increases has been investigated and discussed for over 30 years using indirect methods, such as surface electromyography, with inferences made toward the nervous system. Alternatively, electrical stimulation techniques such as the Hoffman reflex, volitional wave, and maximal wave have provided evidence of central nervous system changes at the spinal level. For 25 years, the technique of transcranial magnetic stimulation (TMS) has allowed for noninvasive supraspinal measurement of the human nervous system in a number of areas such as fatigue, skill acquisition, clinical neurophysiology, and neurology. However, it has only been within the last decade that this technique has been used to assess neural changes after strength training. The aim of this brief review is to provide an overview of TMS, discuss specific strength training studies that have investigated changes, after short-term strength training in healthy populations in upper and lower limbs, and conclude with further research suggestions and the application of this knowledge for the strength and conditioning coach.     

The role of the parasympathetic nervous system in the regulation of microsomal monooxygenase activity in the liver of rats

The effect of vegetative nervous system activation or depression (subdiaphragmatic vagotomy, atropine, proserine and acetylcholine treatments) on the hepatic microsomal enzymes activities has been studied on Wistar male rats. It is found, that hepatic denervation and atropine treatment decreased cytochrome P450 content and aniline hydroxylase activity. Proserine and acetylcholine induced an opposite effect. It is considered that these different changes in the microsomal enzyme activities with variations in the vegetative nervous system state have proved the nervous control of these processes.     

Effect of aging on baroreflex function in humans

Arterial blood pressure (BP) is regulated via the interaction of various local, humoral, and neural factors. In humans, the major neural pathway for acute BP regulation involves the baroreflexes. In response to baroreceptor activation/deactivation, as occurs during transient changes in BP, key determinants of BP, such as cardiac period/heart rate (via the sympathetic and parasympathetic nervous system) and vascular resistance (via the sympathetic nervous system), are modified to maintain BP homeostasis. In this review, the effects of aging on both the parasympathetic and sympathetic arms of the baroreflex are discussed. Aging is associated with decreased cardiovagal baroreflex sensitivity (i.e., blunted reflex changes in R-R interval in response to a change in BP). Mechanisms underlying this decrease may involve factors such as increased levels of oxidative stress, vascular stiffening, and decreased cardiac cholinergic responsiveness with age. Consequences of cardiovagal baroreflex impairment may include increased levels of BP variability, an impaired ability to respond to acute challenges to the maintenance of BP, and increased risk of sudden cardiac death. In contrast, baroreflex control of sympathetic outflow is not impaired with age. Collectively, changes in baroreflex function with age are associated with an impaired ability of the organism to buffer changes in BP. This is evidenced by the reduced potentiation of the pressor response to bolus infusion of a pressor drug after compared to before systemic ganglionic blockade in older compared with young adults.     

Investigating the Autonomic Nervous System Response to Anxiety in Children with Autism Spectrum Disorders

Assessment of anxiety symptoms in autism spectrum disorders (ASD) is a challenging task due to the symptom overlap between the two conditions as well as the difficulties in communication and awareness of emotions in ASD. This motivates the development of a physiological marker of anxiety in ASD that is independent of language and does not require observation of overt behaviour. In this study, we investigated the feasibility of using indicators of autonomic nervous system (ANS) activity for this purpose. Specially, the objectives of the study were to 1) examine whether or not anxiety causes significant measurable changes in indicators of ANS in an ASD population, and 2) characterize the pattern of these changes in ASD. We measured three physiological indicators of the autonomic nervous system response (heart rate, electrodermal activity, and skin temperature) during a baseline (movie watching) and anxiety condition (Stroop task) in a sample of typically developing children (n = 17) and children with ASD (n = 12). The anxiety condition caused significant changes in heart rate and electrodermal activity in both groups, however, a differential pattern of response was found between the two groups. In particular, the ASD group showed elevated heart rate during both baseline and anxiety conditions. Elevated and blunted phasic electrodermal activity were found in the ASD group during baseline and anxiety conditions, respectively. Finally, the ASD group did not show the typical decrease in skin temperature in response to anxiety. These results suggest that 1) signals of the autonomic nervous system may be used as indicators of anxiety in children with ASD, and 2) ASD may be associated with an atypical autonomic response to anxiety that is most consistent with sympathetic over-arousal and parasympathetic under-arousal.     

Morphologic changes in the nervous apparatus of the pharynx, esophagus and stomach of cats following a single gravitational stress]

Under investigation were the pharynx, oesophagus and stomach of 23 cats subjected to a single maximum endurable gravitation stress. The material was treated after Bielschowski-Gross. It has been established that as early as within 48--72 hours after gravitation effects there appear changes of different elements of the nervous apparatus of the organ under study such as increased argirophilia of nervous structures and reactive changes of different sensory nerve terminations. Motor animal nerve terminations do not change. Most of myelinated afferent fibres and non myelinated vegetative fibres undergo reactive changes. Within 7 days there appear certain myelinated fibres which are in the stage of granular desintegration,     

Calcium ions and the nervous system plasticity

The nervous system is different from all other systems of the organism by extreme flexibility of the structural and functional properties of its elements. This unique feature of the nervous system can be best described as plasticity in a broad sense of the word. All forms of plastic changes in the nervous system functioning have common basic mechanisms, the changes at the free Ca2+ cytosol ions being the most important one. These "calcium signals" trigger an extremely complicated intracellular machinery capable of controlling the structural and functional properties of the nervous system during the whole life span. This review summarises data on the intracellular Ca2+ ions mechanisms controlling the developmental plasticity of neuronal elements, synaptic plasticity of the mature nervous system, and the decline of plastic capabilities with ageing.     

The role of synaptic ion channels in synaptic plasticity

The nervous system receives a large amount of information about the environment through elaborate sensory routes. Processing and integration of these wide-ranging inputs often results in long-term behavioural alterations as a result of past experiences. These relatively permanent changes in behaviour are manifestations of the capacity of the nervous system for learning and memory. At the cellular level, synaptic plasticity is one of the mechanisms underlying this process. Repeated neural activity generates physiological changes in the nervous system that ultimately modulate neuronal communication through synaptic transmission. Recent studies implicate both presynaptic and postsynaptic ion channels in the process of synapse strength modulation. Here, we review the role of synaptic ion channels in learning and memory, and discuss the implications and significance of these findings towards deciphering the molecular biology of learning and memory.     

Control of retinal growth and axon divergence at the chiasm: lessons from Xenopus

Metamorphosis in frogs is a critical developmental process through which a tadpole changes into an adult froglet. Metamorphic changes include external morphological transformations as well as important changes in the wiring of sensory organs and central nervous system. This review aims to provide an overview on the events that occur in the visual system of metamorphosing amphibians and to discuss recent studies that provide new insight into the molecular mechanisms that control changes in the retinal growth pattern as well as the formation of new axonal pathways in the central nervous system. BioEssays 23:319-326, 2001.