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At least 217 records · Page 12Linked to original sources

PubMed1988

The sensory-efferent function of capsaicin-sensitive sensory neurons.

Capsaicin-sensitive sensory neurons convey to the central nervous system signals (chemical and physical) arising from viscera and the skin which activate a variety of visceromotor and neuroendocrine reflexes integrated at various levels (intramurally in peripheral organs, at level of prevertebral ganglia, spinal and supraspinal level). Much evidence is now available that peripheral terminals of certain sensory neurons, widely distributed in skin and viscera have the ability to release, upon adequate stimulation, their transmitter content. In addition to the well-known "axon reflex" arrangement, the capsaicin-sensitive sensory neurons have the ability to release the stored transmitter also from the same terminal which is excited by the environmental stimulus. The efferent function of these sensory neurons is realized through the direct and indirect (i.e. mediated by activation of other cells) effects of released mediators. The action of released transmitters on postjunctional elements covers a wide range of effects which may have a physiological or pathological relevance. Development of drugs capable of controlling the sensory-efferent functions of the capsaicin-sensitive sensory neurons represent a new and very promising area of research for pharmacological treatment of various human diseases.

Animals↗

PubMed1987

The contribution of capsaicin-sensitive innervation to activation of the spinal vesico-vesical reflex in rats: relationship between substance P levels in the urinary bladder and the sensory-efferent function of capsaicin-sensitive sensory neurons.

In acute spinal rats (C2-C3) the transvesical infusion of saline activates a vesico-vesical excitatory reflex (Brain Res., 380 (1986) 83-93). In bladders containing a subthreshold amount of fluid the topical application of capsaicin on the outer surface of the bladder dome activated this spinal reflex and also produced a transient rise in blood pressure and heart rate. The effects of systemic capsaicin desensitization (50 mg/kg s.c. 5 min, 60 days before) on the sensory (activation of the spinal vesico-vesical reflex) and 'efferent' (tetrodotoxin-insensitive capsaicin-induced contraction) functions mediated by the capsaicin-sensitive sensory fibers were correlated to changes in substance P-like immunoreactivity (SP-LI) content of the urinary bladder in adult rats. Blockade of both sensory and efferent functions was observed at a time (60 min from capsaicin administration) when the SP-LI content of the urinary bladder was unaffected. Four days after capsaicin desensitization the SP-LI levels of the bladder are almost depleted indicating that the neuropeptide(s) are entirely stored in sensory structures. At this time the sensory-efferent functions mediated by these fibers are still blocked. At 15-60 days from systemic capsaicin desensitization there was a progressive, time-related recovery of SP-LI levels in the bladder as well as of the sensory-efferent functions. These findings indicate a role of the capsaicin-sensitive innervation of the urinary bladder in activating the spinal vesico-vesical reflex. The present findings suggest that measurement of SP-LI levels in the rat bladder may be a useful biochemical index for monitoring the function(s) of the capsaicin-sensitive, peptidergic sensory neurons.

Animals↗

PubMed1979

Sensory neglect after lesions of substantia nigra or lateral hypothalamus: differential severity and recovery of function.

Sensory neglect was studied in cats after unilateral lesions of: lateral hypothalamus (LH); internal capsule (IC) adjacent to the LH; substantia nigra (SN) or the ventromedial hypothalamus (VMH). Special behavioral tests were employed to yield quantifiable data and also to exclude any confounding due to simple movement deficits. Lesions of SN or IC produced severe and enduring contralateral visual and somesthetic deficits and a facilitation of ipsilateral visual responsiveness. In contrast, LH lesions sparing the adjacent IC produced only weak and transient deficits and VMH lesions had no effects on sensory function. This suggests that lesions of the SN or its forebrain connections are important for producing sensory neglect and that sensory deficits after LH lesions are due to infringement on fibers of passage to or from the SN. Lesions which produced neglect often suppressed the amplitude of flash evoked responses in the ipsilateral caudate nucleus and visual and association cortex. However, these evoked potential effects were transient. There was no effect on the spontaneous EEG and this fails to support the hypothesis of a lack of hemispheric arousal in sensory neglect. The results are discussed in relation to nigrotectal projections and the process of attention. This lesion-behavior model is suggested for studies of recovery of function.

Animals↗

PubMed1997

Preliminary evaluation of a sensory and psychomotor functional test battery for carpal tunnel syndrome: Part 2--Industrial subjects.

This study evaluated the Wisconsin functional sensory and psychomotor test battery for carpal tunnel syndrome (CTS). Subjects were 27 employees recruited from a food processing plant. Both hands of all subjects were examined and categorized by presence or absence of symptoms and nerve conduction study (NCS) findings (Symptom-/NCS-, Symptom+/NCS-, Symptom-/NCS+, and Symptom+/NCS+). Symptom-/NCS- category hands had significantly better performance (15-60%) for most of the functional test battery variables than Symptom+/NCS+ category hands. A significant gap detection threshold difference (32%) was observed between NCS+ and NCS- hands regardless of symptoms, with NCS- having impaired performance. No significant effect of CTS symptoms on performance was observed. Stepwise discriminant analysis was used to select the best variables to differentiate between groups. The ratio of the change in pinch rate with respect to required pinch force differentiated NCS+ from NCS- hands, with a sensitivity of 0.71 and a specificity of 0.68. The same variable had a sensitivity of 0.74 and specificity of 0.83 for distinguishing Symptom-/NCS- hands from all other categories. Pinch rate had a sensitivity of 0.82 and a specificity of 0.81 for separating Symptom+/NCS+ hands from all other categories. Use of both gap detection threshold and the ratio of the change in pinch rate with respect to required pinch force could best differentiate Symptom+/NCS+ from Symptom-/NCS- cases for a sensitivity of 0.91 and specificity of 0.87. Outcomes could not be generalized to a specific work population but demonstrate that the non-invasive test battery may be useful for providing objective measures of deficits associated with CTS symptoms and electrophysiological parameters.

Adult↗

PubMed2001

Functional regeneration of chronically injured sensory afferents into adult spinal cord after neurotrophin gene therapy.

Lesioned axons within the dorsal roots fail to regenerate through the peripheral nerve transition zone and into the spinal cord. This regenerative failure leads to a persistent loss of sensory function. To induce axonal growth across this barrier, we used recombinant adenovirus to express fibroblast growth factor-2 (FGF2), nerve growth factor (NGF), L1 cell adhesion molecule (L1), or beta-galactosidase (LacZ) within the endogenous glia of the dorsal spinal cord 16 d after injury. Expression of either FGF2 or NGF, but not L1 or LacZ, induced robust axonal regeneration into normal as well as ectopic locations within the dorsal spinal cord. This regeneration led to near-normal recovery of thermal sensory function. Functional recovery and the majority of regenerating axons within the dorsal horn disappeared with recutting of the sensory roots. Injections of adenovirus encoding NGF, but not FGF2, also resulted in extensive sprouting of noninjured sensory axons, which we previously demonstrated could cause hyperalgesia and chronic pain. Thus, neurotrophic factor gene therapy administered as late as 16 d after injury may serve as a useful treatment to elicit recovery after dorsal root avulsion; however, the choice of neurotrophin is important to induce selective regeneration of damaged axons.

Adenoviridae↗

PubMedDate not supplied

Construct overlap in resource theories of memory aging. Commentary.

This article evaluates the conceptual status of working memory, processing speed, executive function and sensory function as mediational constructs to explain memory aging. The main difficulty for these mediational constructs is that they may not be independent. Mediational constructs may overlap with each other or with the dependent variable due to theoretical, substantive or methodological reasons. It is argued that sensory function has an advantage over processing speed, working memory and executive function as a mediational construct because it is non-cognitive. The problem of construct overlap is relevant to both cross-sectional and longitudinal studies. Further research is required to evaluate the relative importance of mediational constructs in theories of memory aging, general intellectual aging and dementia.

Aging↗

PubMedDate not supplied

Mitochondrial DNA deletions parallel age-linked decline in rat sensory nerve function.

In rats, the function of sensory nerves in the hind limb declines significantly with age. Normally aging rats and rats treated neonatally with capsaicin were studied here. Quantification of vascular response and substance P in young (3 months) and old (24 months) rats showed additive effects of age and capsaicin treatment. The levels in dorsal root ganglion of a particular deletion in mitochondrial DNA (mtDNA(4834)) were about 300-fold higher in old compared to young rats. Capsaicin treatment had no significant effect on mtDNA(4834) abundance. Dorsal root ganglia of old (but not young) rats were found to contain a spectrum of multiple deletions. The abundance of mtDNA(4834) in dorsal root ganglia from individual rats correlated strongly with their decline in vascular function, even where vascular responses were systematically depressed due to prior capsaicin treatment. One possibility is that mitochondrial DNA mutations directly lead to functional decline at mitochondrial and tissue levels. Alternatively, loss of mitochondrial DNA integrity and physiological decline may be consequences of the same factor, such as oxidative stress.

Aging↗

PubMed1995

Recovery of function, peripheral sensitization and sensory neurone activation by novel pathways following axonal injury in Aplysia californica.

Recovery of behavioural and sensory function was examined following unilateral pedal nerve crush in Aplysia californica. Nerve crush that transected all axons connecting the tail to the central nervous system (CNS) eliminated the ipsilateral tail-evoked siphon reflex, whose sensory input travels in the crushed tail nerve (p9). The first reliable signs of recovery of this reflex were observed within 1 week, and most animals displayed tail-evoked siphon responses within 2 weeks. Wide-dynamic-range mechanosensory neurons with somata in the ventrocaudal (VC) cluster of the ipsilateral pleural ganglion exhibited a few receptive fields (RFs) on the tail 3 weeks after unilateral pedal nerve crush, indicating that the RFs had either regenerated or been reconnected to the central somata. These RFs were smaller and sensitized compared with corresponding RFs on the contralateral, uncrushed side. Centrally conducted axon responses of VC sensory neurones to electrical stimulation distal to the nerve crush site did not reappear until at least 10 days after the crush. Because the crush site was much closer to the CNS than to the tail, the failure of axon responses to be restored earlier than the behavioural responses indicates that early stages of reflex recovery are not due to regeneration of VC sensory neurone axons into the tail. Following nerve crush, VC sensory neurones often could be activated by stimulating central connectives or peripheral nerves that do not normally contain the sensory neurone's axons. These results suggest that recovery of behavioral function after nerve injury involves complex mechanisms, including regenerative growth of axotomized VC sensory neurones, sensitization of regenerating RFs and sprouting of VC sensory neurone fibres within the CNS. Furthermore, the rapidity of behavioural recovery indicates that its initial phases are mediated by additional mechanisms, perhaps centripetal regeneration of unidentified sensory neurones having peripheral somata, or transient reconnection of proximal and distal stumps of axotomized VC cells.

Animals↗

PubMed1988

Effects of chronic dietary restriction on sensory-motor function and susceptibility to stressor stimuli in the laboratory rat.

Two sets of experiments describing the effects of chronic undernutrition on sensory-motor function and susceptibility to environmental stressors are described. In the first, Fischer 344 rats between 10 and 12 months of age were placed on an every-other-day feeding regimen. Behavioral tests designed to assess sensory function (auditory and visual thresholds), somato-motor competence (hang time from a horizontal wire, balance on a narrow beam, descent of a wire mesh pole), and sensory-motor integrity (auditory startle) were then conducted every 3 to 6 months. Chronic undernutrition significantly increased life span and increased somato-motor competence but did not affect sensory function or sensory-motor integrity. In the second set of experiments both acute and chronic dietary restriction impaired the ability of young adult Sprague-Dawley rats to effectively thermoregulate in response to a cold environment. Body temperature dropped more rapidly and recovered at a slower rate in the dietarily restricted animals. Fischer 344 rats maintained on a restricted diet for 16 months were similarly impaired. The latter findings suggest that techniques for extending life span based on laboratory animal models may have little relevance to either animals or humans living in their natural habitats where a wide variety of environmental stressors are encountered.

Animals↗

PubMed1984

Behavioral evidence in rats for a peptidergic-noradrenergic interaction in cutaneous sensory and vascular function.

Cutaneous sensory and vascular function was examined following application of capsaicin to the sciatic nerve and systemic injection of guanethidine. Together the two drugs produced a reduction in sensitivity to heat-pain, inflammatory pain (formalin test), tactile stimulation and skin temperature of the foot that exceeded the effects of either drug alone. The inflammation produced by an injection of formalin to the plantar surface of the hind paw was reduced equally by capsaicin or capsaicin + guanethidine. Cold sensitivity and inflammation produced by yeast injection were unaffected by all treatments. The data imply a peripheral interaction between peptidergic and noradrenergic systems with significant functional implications that may be important in the pathology of familial dysautonomia.

Animals↗

PubMed1991

New autonomic and sensory neuropathy with loss of adrenergic sympathetic function and sensory neuropeptides.

A 30-year-old woman with longstanding dizziness was found to have a severe postural fall in blood pressure and a reduced skin axon-reflex flare response. Autonomic tests indicated selective impairment of adrenergic sympathetic function. Plasma noradrenaline, adrenaline, dopamine, and dopamine beta hydroxylase were undetectable. Skin biopsy specimens showed loss of tyrosine hydroxylase and neuropeptide Y (markers of adrenergic sympathetic fibres) and of substance P and calcitonin gene-related peptide (sensory neuropeptides). A sural nerve biopsy specimen showed severe depletion of unmyelinated fibres. The constellation of losses were compatible with nerve growth factor (NGF) deprivation, which was confirmed on assay. This new syndrome may be explained by loss of trophic action of NGF.

Adrenergic Fibers↗

PubMed1991

Autonomic and sensory nerve function in diabetic foot ulceration.

Peripheral sensory and autonomic nerve dysfunction are thought to be crucial factors in the pathogenesis of diabetic foot ulceration. However, their relative importance is not known. In this study we have compared peripheral sensory nerve function and cardiac autonomic reflexes in 51 diabetics with a history of foot ulceration and 480 diabetic control subjects. In the diabetics with ulceration ankle reflexes were absent or impaired and vibration perception threshold reduced in 96.1% and 82.4%, respectively, compared with 40.8% and 25.8%, respectively, in control subjects (P less than 0.001). Cardiac autonomic tests were abnormal more frequently in the diabetics with ulceration and an autonomic score derived from four tests was abnormal in 62.8% of those with ulceration compared with 13.5% of those without ulceration (P less than 0.001). Discriminant analysis of the two groups of diabetes showed that an abnormal autonomic score was the best predictor of foot ulceration in diabetic patients.

Diabetic Neuropathies↗

PubMed1981

Function of sensory input in insect motor systems.

The organization and function of sensory input has been examined in three insect motor systems: locust jumping, cockroach walking, and locust flight. In these three systems sensory input is primarily involved in the production of the normal patterns of motor activity rather than in the compensation for sudden changes in the external environment. At least two general functions for sensory input in the normal patterning of motor activity can be identified: (1) compensation for changes in the peripheral elements of the motor system which occur as a result of use and maturation and (2) regulation of switching from one phase of a movement to another following the attainment of a specific state by peripheral structures. Reflex pathways may exist for compensating for sudden environmental disturbances but these have not yet been clearly demonstrated.

Animals↗

PubMed1997

Anatomy and histology of joint innervation.

Joint diseases are mostly accompanied with hyperalgesia and/or pain in the joint region. As about 60% of the knee joint innervation may be classified as nociceptive, the structure of joint afferents became a matter of interest. The function of a sensory nerve fibre may be defined by its location, its morphology and its biochemical composition. This review is therefore focused on the composition of articular nerves, the morphology of sensory endings, their content of mitochondria and neuropeptides, and the plasticity of neuropeptide synthesis during joint inflammation. As the knee joint of the cat belongs to the best examined articular tissue concerning the sensory function of its afferent innervation, most of the morphological data have also been determined in this model. The histological studies revealed a dense afferent innervation of all parts of joints. Most of the afferents terminate in non-corpuscular endings. Although the ultrastructure of these endings has been examined in great detail, up to now no morphological and biochemical details can be used to discriminate between mechanosensitive and nociceptive afferents. Only the differences in the content of mitochondria in single nerve fibres may be related to different sensory functions. The content of different neuropeptides in joint afferents highlights an additional efferent function of a proportion of joint afferents. The dense innervation with peptidergic joint afferents indicates an important, but up to now mainly unknown role of neuropeptides in a normal joint. Pathological conditions like joint inflammations lead to an enhanced release of neuropeptides into the joint tissue and a specific upregulation of neuropeptide biosynthesis in articular afferents.

Cartilage, Articular↗

PubMed1990

[Sensory sphere function in children with enuresis].

The kinesthetic and acoustic analyzers were investigated in 62 enuretic and 50 healthy children. In patients, the sensitivity thresholds of the analyzers were substantially increased. The fall in function of the sensory sphere is a major pathogenetic factor of the disease.

Adolescent↗

PubMedDate not supplied

Factors in prostate cancer metastasis.

Death related to prostate cancer is invariably due to the tumor metastasis (to lungs, skeleton and lymph nodes). Tumor cell metastatic behaviour is still poorly understood. The R3327 prostate tumor model in the male Copenhagen rat offers an opportunity to investigate the different aspects of metastatic processes in vivo and to evaluate effects of current and new treatment approaches. Lymphatic spread of cancer cells can be measured by determining volume of local load in successive draining lymph node stations. Surgical removal of primary tumor and inguinal lymph node shows that lymphatic metastasis in the R3327-MATLyLu tumor variant is a continuous progressive phenomenon, which starts already in early stages of tumor growth after subcutaneous transplantation. Spread to the lungs can be quantified by enumeration of macroscopically visible pleural lung colonies. Metastatic spread to the lungs can be mimicked by intravenous injection of monodispersed tumor cell suspension. Within 10 days pleural tumor colonies become visible. Effects of different agents and treatments like chemotherapeutic drugs, heparin, surgery and high energy shock wave (HESW) treatment have been described using these methods. Recently, metastasis to the vertebral column was induced by temporal occlusion of venous blood flow through the caval veins while injecting tumor cells in the lateral tail vein. The resulting osteoblastic metastatic lesions in the lumbar vertebrae and the concomitant spinal cord compression led in time to the loss of motoric and sensory function of the hind legs. These observations permit investigation of the mechanisms of bone metastasis based on biological functions, i.e. sensory and motoric function of the hind legs. Finally, it can be said that the various variants of the R3327 rat prostate tumor offer an appropriate model to study various aspects of prostate cancer and metastasis.

Animals↗

PubMed1998

Associations of sensory-motor functions with poor mobility in 75- and 80-year-old people.

This study investigated the associations of sensory-motor functions with mobility in elderly people. All 75- and 80-year-old residents of the city of Jyväskylä, Finland, were invited to take part in the study. A total of 617 (93%) persons were interviewed, and 500 (75%) took part in laboratory examinations. Self-reported mobility was recorded during the interview. Basic mobility functions (maximal walking speed and stair-mounting ability) and sensory-motor functions (maximal isometric muscle strength, standing balance, reaction time and visual acuity) were measured in the laboratory. Multivariate analyses showed that poor sensory-motor functions were significantly associated with poor performance in basic mobility functions and that poor performance in basic mobility functions was associated with self-reported disability in mobility. The associations discovered were consistent with models of the disablement process. Muscle strength, balance, reaction time and vision all have individual significance for mobility, underlining the need for multifactorial approaches in prevention and rehabilitation.

Activities of Daily Living↗

PubMed2003

Behavioral phenotyping of mice in pharmacological and toxicological research.

The evaluation of behavioral effects is an important component for the in vivo screening of drugs or potentially toxic compounds in mice. Ideally, such screening should be composed of monitoring general health, sensory functions, and motor abilities, right before specific behavioral domains are tested. A rational strategy in the design and procedure of testing as well as an effective composition of different well-established and reproducible behavioral tests can minimize the risk of false positive and false negative results in drug screening. In the present review we describe such basic considerations in planning experiments, selecting strains of mice, and propose groups of behavioral tasks suitable for a reliable detection of differences in specific behavioral domains in mice. Screening of general health and neurophysiologic functions (reflexes, sensory abilities) and motor function (pole test, wire hang test, beam walking, rotarod, accelerod, and footprint) as well as specific hypothesis-guided testing in the behavioral domains of learning and memory (water maze, radial maze, conditioned fear, and avoidance tasks), emotionality (open field, hole board, elevated plus maze, and object exploration), nociception (tail flick, hot plate), psychiatric-like conditions (porsolt swim test, acoustic startle response, and prepulse inhibition), and aggression (isolation-induced aggression, spontaneous aggression, and territorial aggression) are described in further detail. This review is designed to describe a general approach, which increases reliability of behavioral screening. Furthermore, it provides an overview on a selection of specific procedures suitable for but not limited to behavioral screening in pharmacology and toxicology.

Animals↗