Function Of Sensory Receptors Research Articles

Evolution of sensory systems.

Sensory systems evolve and enable organisms to perceive their sensory Umwelt, the unique set of cues relevant for their survival. The multiple components that comprise sensory systems - the receptors, cells, organs, and dedicated high-order circuits - can vary greatly across species. Sensory receptor gene families can expand and contract across lineages, resulting in enormous sensory diversity. Comparative studies of sensory receptor function have uncovered the molecular basis of receptor propertiesand identified novel sensory receptor classes and noncanonical sensory strategies. Phylogenetically informed comparisons of sensory systems across multiple species can pinpoint when sensory changes evolve and highlight the role of contingency in sensory system evolution.

Developmental studies on the acquisition of perception conducting pathways via TRP channels in rat molar odontoblasts using immunohistochemistry and RT-qPCR

Odontoblasts act as dentin formation and sensory receptors. Recently, it was reported that transient receptor potential ankyrin (TRPA) 1, TRP vanilloid (TRPV) 4 and pannexin 1 (PANX-1) play important roles in odontoblast sensory reception. However, it is not known when odontoblasts begin to possess a sense reception function. The aim of this study was to clarify the development of odontoblasts as sense receptors. Sections of mandibular first molars from postnatal day (PN) 0 to PN12 Wistar rats were prepared for hematoxylin–eosin staining. Immunohistochemically, we used anti-dentin sialoprotein (DSP), anti-TRPA1, anti-TRPV4, anti-PANX-1, and anti-neurofilament (NF) antibodies. In addition, we investigated TRPA1 and TRPV4 expression by reverse transcriptional quantitative polymerase chain reaction (RT-qPCR). At PN0, undifferentiated odontoblasts showed no immunoreaction to anti-DSP, anti-TRPA1, anti-TRPV4, or anti-PANX-1 antibodies. However, immunopositive reactions of these antibodies increased during odontoblast differentiation at PN3 and PN6. An immunopositive reaction of the anti-NF antibody appeared in the odontoblast neighborhood at PN12, when the odontoblasts began to form root dentin, and this appeared later than that of the other antibodies. By RT-qPCR, expression of TRPA1 at PN6 was significantly lower than that at PN0 (p < 0.05) and PN3 (p < 0.01). Expression of TRPV4 at PN6 was significantly lower than that at PN0 (p < 0.01) and PN3 (p < 0.01). The results of this study suggest that odontoblasts may acquire sensory receptor function after beginning to form root dentin, when TRPA1, TRPV4, PANX-1 channels, and nerve fibers are completely formed.

Sensory receptors—design principles revisited

Sensory receptors—design principles revisited

Taste and Appetite Loss in the Aged

Abstract “My father is 93 years old and has stopped eating (except soup) because of lack of taste. He is in CA and is not strong enough to make a cross country trip. His health is deteriorating bec...

Interactions between the sympathetic nervous system and the kidneys in arterial hypertension.

Elevated sympathetic activity changes renal function and accelerates the development of hypertension. Principles of sympatho-renal interactions in chronic hypertension are reviewed. Alterations in the ontogeny of the sympathetic nervous system and the kidney, inherited abnormalities in sensory receptor function and exaggerated responsiveness to mental stress contribute to inappropriately high sympathetic activity in primary or essential hypertension. Careful characterization of clinical study populations shows that elevated sympathetic activity and "essential" hypertension are not unequivocally associated. Prospective clinical studies which investigate a broader array of physiological functions and experiments in recombinant inbred rodents with less traumatic nerve recording techniques than currently available will help to define under which conditions elevated sympathetic activity is indeed a cause of primary hypertension. Signals arising from the kidney which activate the renin-angiotensin system and afferent renal nerves increase sympathetic activity. These mechanisms importantly contribute to the pathogenesis of hypertension secondary to renal artery stenosis and end-stage renal disease.

Foot and ankle sensory neuropathy, proprioception, and postural stability.

Foot and ankle sensory neuropathy may result from a variety of pathologic conditions, especially diabetes mellitus. Decreased sensation, particularly on the plantar surface of the feet, leads to obvious risks of cutaneous injury. Less obvious are the risks of fall-related injury associated with changes in other sensory systems of the foot and ankle, such as the receptors involved in joint movement and position perception. The results of a number of studies demonstrate that the neuropathic process affects these receptors in individuals with diabetes mellitus. Associated with the decreased sensory function of the foot and ankle is decreased performance on tests of static and dynamic postural stability. Subjective feelings of instability and an increased incidence of fall-related injuries have also been reported. The reduced postural stability in persons with diabetic neuropathy cannot be attributed exclusively to loss of plantar cutaneous sensation; it appears to be the result of a general loss of peripheral sensory receptor function in the lower legs, including that of the muscle spindles. During the evaluation of an individual with foot and ankle sensory neuropathy, the possibility of balance deficits should be given proper attention. Assessment of balance deficits could be particularly important when planning the course of rehabilitation for individuals with foot and ankle neuropathy who use modified footwear or have an amputation of a section of the foot or lower extremity.

An immunocytochemical study of the carbonic anhydrase I isoenzyme in human oral Merkel cells

Merkel cells in human buccal mucosa and hard possess the carbonic anhydrase I isoenzyme (CAI). CAI colocalized immunocytochemically with a range of Merkel cell cytokeratins, namely CK 7, 8, 18, 19 and 20. No other cells in the oral epithelium were immunoreactive for the CAI antibody. The presence of the enzyme may be related to the function of sensory receptors that produce a sustained response to a maintained mechanical stimulus.

Sensory ecology of salps (Tunicata, thaliacea): More questions than answers

There is still relatively little known about the natural history of gelatinous animals in the plankton, and their sensory ecology remains largely a matter of surmise, based on limited morphological, physiological and behavioral data. Pelagic tunicates are among the most widely distributed and abundant of the gelatinous zooplank‐ton, and display a range of behavior that is apparently cued by aspects of their environment. Different kinds of information may be important for different scales of behavior. Feeding and predator avoidance are likely to be affected by near‐field stimuli from visual, chemical or mechanical sources, while far‐field information such as gravity, light, temperature, or pressure are likely to cue behavior spanning larger time and space scales, such as vertical or ontogenetic migration, aggregation and reproductive cycles. A variety of sensory structures have been described in pelagic tunicates, including photoreceptors of varying complexity, and several structures that have been suggested to be mechano‐ or chemoreceptors. Focussing on salps, this paper describes behavior that depends on sensory information, reviews the known structure and function of sensory receptors, and suggests some hypotheses on mechanisms defining the sensory ecology of these planktonic organisms.

The effects of capsaicin, bradykinin, PGE2 and cicaprost on the discharge of articular sensory receptors in vitro

The responses of articular sensory receptors to capsaicin, bradykinin, PGE2, and the selective IP-receptor agonist cicaprost were studied in a rat isolated hindlimb in vitro preparation. Long-term maintenance of normal sensory receptor function was achieved in vitro under conditions of combined superfusion and slow perfusion. Response characteristics to mechanical or chemical stimuli on articular sensory receptors identified in this study did not differ to those reported in vivo. This preparation lacks complex effects mediated via spinal or central reflex mechanisms and allows greater control over the physiological environment of the receptors being studied. These results support the conclusion that the effects of capsaicin, bradykinin and the prostanoids are mediated by distinct pharmacological receptors associated with articular sensory nerve endings. The potent potentiating effects of cicaprost on bradykinin-induced excitation suggests that these actiosn are mediated via IP-receptors.

Discrimination strategies in animal psychophysics and their role in understanding sensory receptor function.

Discrimination is defined in a restricted sense here as a precise and specifiable relation between stimuli and responses. Experimenter control of stimulation is one significant feature of this relation. It is suggested that there may be some important differences between discrimination of drugs and exteroceptive stimulation. However, a discussion of current strategies in animal psychophysics might uncover similarities between these two discrimination formats useful in formulating questions and designing future research. Traditionally animal psychophysics has focused on basic questions of acuity and sensitivity (threshold). Beyond their obvious value in the study of comparative sensory function and evolutionary development, these experiments have provided particularly important new insights into the understanding of peripheral sensory transduction and processing and their relation to perception. Our experiments have been carried out in animals whose hearing has been impaired by drugs and cryolesions, and relations have been sought between the subsequent hearing loss and the histopathological changes occurring in the auditory receptor cells of the inner ear. But threshold sensitivity is only one of many perceptual dimensions and tells us nothing of the discriminations that are made among stimuli which are clearly above minimum detectable levels. For example, discriminations occur along stimulus dimensions such as wavelength of light, sound pressure, acoustic frequency, and so on. Sensory systems also permit the accurate location of the source of stimulation at a distance, the selection of certain frequencies or wavelengths and the rejection of others, and finally the discrimination among very complex but biologically useful signals such as speech. Prototypical experiments are described; the results suggest significant and orderly relations with peripheral sensory processing mechanisms. The power of operant behavior to examine perception from a variety of perspectives is discussed.

Electrophysiological changes in the primary sensory neuron following subchronic soman and sarin: Alterations in sensory receptor function

Cats were administered soman or sarin either in a single high dose (1 mg/kg) with pretreatment or in multiple sublethal doses to determine whether these potent organophosphorus agents could produce a delayed neurotoxicity and what, if any, pathophysiological changes occurred in peripheral sensory receptors. Neither soman nor sarin, when administered as a single high dose, produced a delayed neurotoxicity as observed behaviorally for up to 60 days. There were also no observable signs of delayed neurotoxicity when these agents were administered in multiple doses. Functional tests of proprioceptors and mechanoreceptors were performed on the cats which received multiple sublethal doses of either soman or sarin. It was found that the discharge rates of muscle spindle primary endings were depressed while the discharge rates of secondary endings were facilitated following the administration of either soman or sarin. The discharge rates of slowly adapting type 1 mechano-receptors were also depressed. The total number of identified mechanoreceptors was reduced in both the soman- and sarin-treated animals. Conduction velocities of several of the muscle spindle and mechanoreceptor afferents were significantly decreased. The alterations in muscle spindle function may be due to changes in the muscle resulting from acetylcholinesterase inhibition. Another explanation for the changes in both muscle spindle and mechanoreceptor function may be the direct effect of the organophosphorus agents on the afferents themselves, thus altering their excitability.

The neurohistology and neurophysiology of the itch sensation in man.

The skin is a vast sentient surface, attuned to numerous environmental changes. Although it was first viewed as representing only the fifth sense, i. e., touch, the last century of research has disclosed that the skin is a far more complex sensory receptor. This area of study has long been an actively disputative one, and indeed within the year critical essays have challenged all previously held concepts of both the form and the function of sensory receptors in the skin of man. It is our purpose to review the field of knowledge concerning the itch sensation in man, to report experimental observations of our own, and to attempt an interpretative analysis of the neurophysiological basis for itching. The modern era of conceptual thinking on the problem of sensory reception in the skin began in 1838, when Johannes Müller¹enunciated his doctrine of specific energy, i. e., he

Poll Evil

Sensory systems evolve and enable organisms to perceive their sensory Umwelt, the unique set of cues relevant for their survival. The multiple components that comprise sensory systems — the receptors, cells, organs, and dedicated high-order circuits — can vary greatly across species. Sensory receptor gene families can expand and contract across lineages, resulting in enormous sensory diversity. Comparative studies of sensory receptor function have uncovered the molecular basis of receptor properties and identified novel sensory receptor classes and noncanonical sensory strategies. Phylogenetically informed comparisons of sensory systems across multiple species can pinpoint when sensory changes evolve and highlight the role of contingency in sensory system evolution.