SEARCH · Search PubMed

Results for “Escape Reaction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources

PubMedDate not supplied

Complex effects of NMDA receptor antagonist APV in the basolateral amygdala on acquisition of two-way avoidance reaction and long-term fear memory.

Although much has been learned about the role of the amygdala in Pavlovian fear conditioning, relatively little is known about an involvement of this structure in more complex aversive learning, such as acquisition of an active avoidance reaction. In the present study, rats with a pretraining injection of the N-methyl-D-aspartate (NMDA) receptor antagonist, 2-amino-5-phosphonopentanoic acid (APV), into the basolateral amygdala (BLA) were found to be impaired in two-way active avoidance learning. During multitrial training in a shuttle box, the APV-injected rats were not different from the controls in sensitivity to shock or in acquisition of freezing to contextual cues. However, APV injection led to impaired retention of contextual fear when tested 48 h later, along with an attenuation of c-Fos expression in the amygdala. These results are consistent with the role of NMDA receptors of the BLA in long-term memory of fear, previously documented in Pavlovian conditioning paradigms. The APV-induced impairment in the active avoidance learning coincided with deficits in directionality of the escape reaction and in attention to conditioned stimuli. These data indicate that normal functioning of NMDA receptors in the basolateral amygdala is required during acquisition of adaptive instrumental responses in a shuttle box but is not necessary for acquisition of short-term contextual fear in this situation.

2-Amino-5-phosphonovalerate↗

PubMed1988

Inhibition of long-term memory formation by anti-ependymin antisera after active shock-avoidance learning in goldfish.

Ependymins are acidic glycoprotein constituents of goldfish brain cytoplasm and extracellular fluid which are known to participate in biochemical reactions of long-term memory formation. In earlier experiments, anti-ependymin antisera were found to cause amnesia when injected into goldfish brain ventricles after the acquisition of a vestibulomotoric training task. To investigate whether they also inhibit memory consolidation after other learning events the anti-ependymin antisera were injected after an active shock-avoidance learning paradigm, as follows: goldfish were trained in a shuttle-box to cross a barrier in order to avoid electric shocks (unconditioned stimulus) applied shortly after a light signal (conditioned stimulus). Anti-ependymin antisera blocked retention of the learned avoidance when injected 0.5, 4.5 or 24 h after acquisition of the new behavior. They had no effect, however, when injected 72 h after learning. Apparently, long-term memory was already consolidated at this point. Antisera injected 0.5 or 72 h prior to training, also did not influence learning or memory. Thirteen percent of the goldfish fled the light stimulus spontaneously. These fish therefore did not experience the unconditioned stimulus and thus were unable to learn the task. When they were treated with the anti-ependymin antisera and tested 3 days later, the spontaneous escape reaction was not affected (active control group). The ability of anti-ependymin antisera to inhibit memory consolidation and their efficacy after administration at specific time intervals are very similar for the active shock-avoidance learning and for the vestibulomotoric training. We conclude that ependymins are not task-specific, but serve a general function in biochemical reactions essential for long-term memory formation.

Animals↗

PubMed1998

Plunging ranula: clinical observations.

BACKGROUND: The plunging ranula is a relatively uncommon phenomenon which represents a mucus escape reaction occurring from disruption of the sublingual salivary gland. We present a series of 20 patients managed at Green Lane Hospital (Auckland, New Zealand) over a 9-year period. METHODS: A retrospective review of 13 patients with this condition was undertaken, and a prospective study was conducted on 7 patients. Information was collected on age, sex, ethnic origin, history of onset, predisposing factors, treatment, and outcome of treatment. RESULTS: The patients were all young adults with a median age of 31 years. The sex distribution was relatively equal, with 11 men and 9 women. All patients were Maori or Pacific Island Polynesians. Six patients gave a clear history of preceding trauma to the neck or oral cavity. Two recurrences were seen, both in patients who had had the sublingual gland excised via a cervical approach. Five patients sustained lingual nerve damage during surgery. Full function recovered in four patients, but the complication was still present in the fifth patient at 2 years, after which he was lost to follow-up. CONCLUSIONS: Plunging ranulas appear to occur with greater incidence in the Maori and Pacific Island Polynesian populations. The precise etiology of their predisposition is unknown, although local trauma or inherent mylohyoid dehiscences may play important roles. Removal of the sublingual gland via either a cervical or intraoral approach is important in the management of this condition. Excision of the pseudocyst is probably unnecessary and places surrounding structures at risk of damage, but a biopsy of the pseudocyst wall is important to confirm the diagnosis.

Adolescent↗

PubMed1980

Opposing influences on behavior mediated by muscarinic and nicotinic receptors in the rat posterior hypothalamic nucleus.

Microinjection of carbachol into the posterior hypothalamic nucleus (PHN) of freely moving rats evoked marked behavioral changes characterized by an escape reaction. This response was quantitated by measuring locomotor activity. In contrast, cholinergic stimulation of the PHN with neostigmine produced sedation and inactivity. Local pretreatment with the nicotinic receptor blocking agent mecamylamine blocked the excitatory effects of carbachol while the muscarinic antagonist atropine abolished the inhibitory effect of neostigmine on motor activity. It is concluded that behavioral changes evoked through cholinergic stimulation of the PHN may be mediated by a muscarinic system which controls sedation and a nicotinic pathway which mediates arousal.

Acetylcholine↗

PubMed2004

Antagonizing potencies of saturated and unsaturated long-chain free fatty acids to isoflurane in goldfish.

PURPOSE: We have previously reported that myristate, a saturated free fatty acid (FFA) with 14 carbons (C14), antagonizes volatile anesthetics in goldfish. The hydrophobicity and molecular configuration of FFAs may play an important role in the antagonizing effect. To examine their contribution, we investigated the antagonizing potencies of saturated and unsaturated long-chain FFAs in goldfish. METHODS: Saturated and monounsaturated FFAs of C14-18 were tested. We determined the anesthetic concentration producing a 50% effect (EC50) of isoflurane in the absence or presence of FFA by observing the escape reaction of goldfish against an electrical stimulus. RESULTS: All FFAs increased the EC50 of isoflurane dose-dependently compared with reactions in the absence of FFA ( P < 0.05). For saturated FFAs, the relationship between chain lengths and antagonizing potencies was not linear. C18 was the most effective and C16 was the least effective antagonist ( P < 0.05). Among unsaturated FFAs, C14 was the most effective antagonist ( P < 0.05). In a comparison of saturated and unsaturated FFAs, saturated C14 and C18 were more effective antagonists than unsaturated FFAs of the same carbon numbers ( P <<0.05). CONCLUSION: The hydrophobicity of FFAs increases as the chain length increases. Therefore, our findings suggest that the antagonizing effect of long-chain FFAs in goldfish, in terms of their capacity to perturb the lipid membrane structure, may be determined not solely by their hydrophobicity but also by their molecular configuration.

Anesthetics, Inhalation↗

PubMed2005

Comparison of antagonizing potencies of dodecane analogues to isoflurane in goldfish.

PURPOSE: We reported previously that long-chain fatty acids (carbon atoms > or =12) antagonize volatile anesthetics in goldfish. To examine the contribution of the carboxyl group to the antagonizing potency of fatty acids in vivo, we compared antagonizing potencies to isoflurane in goldfish among terminally substituted dodecane analogues. METHODS: Dodecane (carbon atoms = 12) analogues [fatty acid (DoAC), alcohol (DoAL), alkane (DoAK), sulfate (DoSF), trimethylammonium (DoTA)] were examined. We determined the EC50 (the anesthetic concentration producing a 50% effect) values of isoflurane in the absence or presence of these chemical compounds in goldfish by observing the escape reaction of goldfish from an electrical stimulus. RESULTS: DoAC at higher than 10 microM and DoAL at higher than 20 microM increased the EC50 values of isoflurane in a concentration-dependent manner compared with the control (P < 0.05). DoAC at 50 microM and DoAL at 100 microM increased the EC50 1.7- and 1.6 fold, respectively. DoAK, DoSF, and DoTA showed no significant differences from the control. In the comparison of DoAC and DoAL at the same concentration, DoAC was more effective than DoAL (P < 0.001). CONCLUSION: DoAC and DoAL showed antagonizing potencies to isoflurane, whereas DoAK, DoSF, and DoTA had no effect. DoAC was more effective than DoAL. The findings suggest that polarity of the chemical compounds may be necessary to exert antagonizing potency to isoflurane. Furthermore, a highly negative charge density of the carboxyl group may be responsible for the effective antagonization of DoAC to isoflurane.

Algorithms↗

PubMed1976

Effect of serotoninergic drugs on positive and negative reinforcing systems in cats.

Administration of tryptophan and 5-hydroxytryptophan produced inhibition of self-stimulation through hypothalamic electrodes which was accompanied by drowsiness and decrease of motor activity. In cats pretreated with Ro 4-4602, an inhibitor of peripheral decarboxylase, both drugs did not produce drowsiness and markedly activated self-stimulation. Both drugs prolonged the latency of the escape reaction and inhibited the punishment reaction. The data suggest an activating effect of serotonin on the system of reward and an inhibitory effect on the system of punishment.

5-Hydroxytryptophan↗

PubMed1987

Blockade by neuroleptics of water intake and operant responding for water in the rat: anhedonia, motor deficit, or both?

Four different neuroleptic drugs, haloperidol, metoclopramide, sulpiride and cis-flupenthixol, were tested for their ability to attenuate an operant lever-pressing response with water as reward and the corresponding consummatory act, i.e., the non-conditioned water intake. All four neuroleptic drugs tested more potently attenuated the operant lever-pressing response than the consummatory water intake, just as the conditioned avoidance response previously has been found to be more potently attenuated than the non-conditioned escape reaction. The results suggest that a certain class of learned behaviors, labelled operant or instrumental behaviors, are more susceptible to the attenuating effects of neuroleptic drugs than the class of behaviors labelled non-conditioned consummatory acts. It was further concluded that the attenuation of the lever-pressing response could be explained by a decreased ability of the animals to initiate or perform the required operant response (i.e., a motor deficit) while the attenuated water intake caused by higher doses of the neuroleptics could be interpreted as a motivational effect (e.g., "anhedonia"). When studying the effects of the neuroleptic drugs it is therefore of great importance to know whether the behavior measured in the particular experimental design used is operant or consummatory. The implications of the findings are discussed.

Animals↗

PubMed1996

Influence of long-term altered gravity on the swimming performance of developing cichlid fish: including results from the 2nd German Spacelab Mission D-2.

This study presents qualitative and quantitative data concerning gravity-dependent changes in the swimming behaviour of developing cichlid fish larvae (Oreochromis mossambicus) after a 9 resp. 10 days exposure to increased acceleration (centrifuge experiments), to reduced gravity (fast-rotating clinostat), changed accelerations (parabolic aircraft flights) and to near weightlessness (2nd German Spacelab Mission D-2). Changes of gravity initially cause disturbances of the swimming performance of the fish larvae. With prolonged stay in orbit a step by step normalisation of the swimming behaviour took place in the fish. After return to 1g earth conditions no somersaulting or looping could be detected concerning the fish, but still slow and disorientated movements as compared to controls occurred. The fish larvae adapted to earth gravity within 3-5 days. Fish seem to be in a distinct early developmental stages extreme sensitive and adaptable to altered gravity; However, elder fish either do not react or show compensatory behaviour e.g. escape reactions.

Adaptation, Physiological↗

PubMed2004

Neuronal nitric oxide synthase knock-out mice show impaired cognitive performance.

Nitric oxide (NO) plays a role in a series of neurobiological functions, underlying behavior and memory. The functional role of nNOS derived NO in cognitive functions, however, is elusive. We decided to study cognitive functions in the Morris water maze (MWM) and the multiple T-maze (MTM) in 3-month-old male nNOS-knock-out mice (nNOS KO). To study the influence of neurology and behavior, we performed tests in an observational battery, the rota-rod, the elevated plus maze (EPM), the open field (OF), and a social interaction test. In the memory and relearning task of the MWM, most nNOS KO failed whereas performing better in the MTM. nNOS KO displayed significantly increased frequency of grooming, center crossings, and entries into the center in the OF. The observational battery revealed significantly increased scores for touch-escape reaction, body position, locomotion, and pelvic- and tail-elevation together with reduced vocalization. In the EPM, the time spent in the closed arm and the grooming frequency were significantly increased whereas urination was absent. We conclude that nNOS KO show impaired spatial performance in the MWM and herewith confirm the role of nNOS in cognitive functions such as processing, maintenance, and recall of memory. It must be taken into account that the major behavioral findings of increased grooming and anxiety-related behaviors may have led to impaired function in the MWM. The fact that nNOS KO performed well in the MTM, reflecting a low stress situation points to the interpretation that nNOS inhibition affects cognitive functions under stressful conditions (MWM) only.

Animals↗

PubMed2001

The 14th Datta Lecture. TFIIH: from transcription to clinic.

Once a large proportion of the genes responsible for genetic disorders are identified in the post-genome era, the fundamental challenge is to establish a genotype/phenotype relationship. Our aim is to explain how mutations in a given gene affect its enzymatic function and, in consequence, disturb the life of the cell. Genome integrity is continuously threatened by the occurrence of DNA damage arising from cellular exposure to irradiation and genotoxic chemicals. This mutagenic or potentially lethal DNA damage induces various cellular responses including cell cycle arrest, transcription alteration and processing by DNA repair mechanisms, such as the nucleotide excision repair (NER) pathway. Disruption of NER in response to genotoxic injuries results in autosomal recessive hereditary diseases such as Xeroderma pigmentosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD). One of the most immediate consequences of the induction of strand-distorting lesions is the arrest of transcription in which TFIIH plays a role in addition to its role in DNA repair. The observations made by clinicians close to XP, TTD and CS patients, suggested that transcription defects responsible for brittle hair and nails for TTD, or developmental abnormalities for CS, resulted from TFIIH mutations. Here a story will be related which could be called 'a multi-faceted factor named TFIIH'. As biochemists, we have characterized each component of TFIIH, three of which are XPB and XPD helicases and cdk7, a cyclin-dependent kinase. With the help of structural biologists, we have characterized most of the specific three-dimensional structures of TFIIH subunits and obtained its electron microscopy image. Together these approaches help us to propose a number of structure-function relationships for TFIIH. Through transfection and microinjection assays, cell biology allows us to determine the role of TFIIH in transcription and NER. We are thus in a position to explain, at least in part, transcription initiation mechanisms and their coupling to DNA repair. We now know how the XPB helicase opens the promoter region for RNA synthesis and that one of the roles of XPD helicase is to anchor the cdk7 kinase to the core-TFIIH. In XP and CS associated patients, we have demonstrated that some XPD mutations prevent an optimal phosphorylation of nuclear receptors by cdk7 with, as a consequence, a drop in the expression of genes sensitive to hormone action. We have thus shown that hormonal responses operate through TFIIH. Careful analysis of each TFIIH subunit also shows how the p44 Ring finger participates in certain promoter escape reactions. We are also able to localize the action of TFIIH in the sequence of events that lead to the elimination of DNA lesions. Thanks to the combination of these different approaches we are obtaining a much clearer picture of the TFIIH complex and its integration into the life of the cell.

Cell Cycle↗

PubMed1999

Paradoxical inhibition of nociceptive neurons in the dorsal horn of the rat spinal cord during a nociceptive hindlimb reflex.

Nociceptive-specific and multireceptive neurons in the lumbar dorsal horn are excited by noxious stimuli applied to the hindpaw and inhibited by noxious stimuli applied to distant body regions. Given that at least a subset of these neurons are part of the circuit for nociceptive reflexes, inhibition of nociceptive-specific and multireceptive neurons should inhibit nociceptive reflexes. Unfortunately, previous attempts to test this hypothesis have been inconclusive because of methodological differences between electrophysiological and behavioral experiments. The present study overcame this problem by recording neural and reflex activity simultaneously. Rats were anesthetized with halothane and surgically prepared for single-unit recording from the lumbar dorsal horn. Hindpaw heat caused a burst of activity that reliably preceded hindpaw withdrawal in 10 nociceptive-specific and 17 multireceptive neurons. A distant noxious stimulus (tail in 50 degrees C water or ear pinch) inhibited the evoked activity of both nociceptive-specific and multireceptive neurons and simultaneously changed the topography of the hindpaw reflex from flexion to extension without altering reflex latency. The present data are consistent with previous reports of inhibition of nociceptive-specific and multireceptive neurons during application of a distant noxious stimulus. However, inhibition of nociceptive-specific and multireceptive neurons concomitant with a shift in the hindlimb reflex from flexion to extension suggests that these neurons are part of the circuit for flexor reflexes specifically. Presumably, lateral inhibition from the flexor to extensor circuit allows for the release of hindlimb extension when neurons in the flexion circuit are inhibited by a distant noxious stimulus. Such a system reduces the chance of injury by allowing for withdrawal reflexes to a single noxious stimulus and escape reactions, such as running and jumping, to multiple noxious stimuli.

Action Potentials↗

PubMed2005

Transcranial magnetic stimulation highlights the sensorimotor side of empathy for pain.

Pain is intimately linked with action systems that are involved in observational learning and imitation. Motor responses to one's own pain allow freezing or escape reactions and ultimately survival. Here we show that similar motor responses occur as a result of observation of painful events in others. We used transcranial magnetic stimulation to record changes in corticospinal motor representations of hand muscles of individuals observing needles penetrating hands or feet of a human model or noncorporeal objects. We found a reduction in amplitude of motor-evoked potentials that was specific to the muscle that subjects observed being pricked. This inhibition correlated with the observer's subjective rating of the sensory qualities of the pain attributed to the model and with sensory, but not emotional, state or trait empathy measures. The empathic inference about the sensory qualities of others' pain and their automatic embodiment in the observer's motor system may be crucial for the social learning of reactions to pain.

Adult↗

PubMed2002

Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.

The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.

Amino Acid Sequence↗

PubMed1999

Light perception and the role of the xanthophyll cycle in blue-light-dependent chloroplast movements in lemna trisulca L

In most higher plants, chloroplasts move towards the periclinal cell walls in weak blue light (WBL) to increase light harvesting for photosynthesis, and towards the anticlinal walls as an escape reaction, thus avoiding photo-damage in strong blue light (SBL). The photo- receptor(s) triggering these responses have not yet been identified. In this study, the role of zeaxanthin as a blue-light photoreceptor in chloroplast movements was investigated. Time-lapse 3D confocal imaging in Lemna trisulca showed that individual chloroplasts responded to local illumination when one half of the cell was treated with light of different intensity or spectral quality to that received by the other half, or was maintained in darkness. Thus the complete signal perception, transduction and effector system has a high degree of spatial resolution and is consistent with localization of part of the transduction chain in the chloroplasts. Turnover of xanthophylls was determined using HPLC, and a parallel increase was observed between zeaxanthin and chloroplast movements in SBL. Ascorbate stimulated both a transient increase in zeaxanthin levels and chloroplast movement to profile in physiological darkness. Conversely, dithiothreitol blocked zeaxanthin production and responses to SBL and, to a lesser extent, WBL. Norflurazon preferentially inhibited SBL-dependent chloroplast movements. Increases in zeaxanthin were also observed in strong red light (SRL) when no directional chloroplast movements occurred. Thus it appears that a combination of zeaxanthin and blue light is required to trigger responses. Blue light can cause cis-trans isomerization of xanthophylls, thus photo-isomerization may be a critical link in the signal transduction pathway.

Journal Article↗

PubMed2005

Sensory suppression during feeding.

Feeding is essential for survival, whereas withdrawal and escape reactions are fundamentally protective. These critical behaviors can compete for an animal's resources when an acutely painful stimulus affects the animal during feeding. One solution to the feeding-withdrawal conflict is to optimize feeding by suppressing pain. We examined whether rats continue to feed when challenged with a painful stimulus. During feeding, motor withdrawal responses to noxious paw heat either did not occur or were greatly delayed. To investigate the neural basis of sensory suppression accompanying feeding, we recorded from brainstem pain-modulatory neurons involved in the descending control of pain transmission. During feeding, pain-facilitatory ON cells were inhibited and pain-inhibitory OFF cells were excited. When a nonpainful somatosensory stimulus preactivated ON cells and preinhibited OFF cells, rats interrupted eating to react to painful stimuli. Inactivation of the brainstem region containing ON and OFF cells also blocked pain suppression during eating, demonstrating that brainstem pain-modulatory neurons suppress motor reactions to external stimulation during homeostatic behaviors.

Animals↗

PubMed1990

Grazing in a turbulent environment: behavioral response of a calanoid copepod, Centropages hamatus.

Models of marine ecosystem productivity rely on estimates of small-scale interactions, particularly those between copepods and their algal food sources. Rothschild and Osborn [Rothschild, B. J. & Osborn, T. R. (1988) J. Plankton Res. 10, 465-474], hypothesized that small-scale turbulence in aquatic systems increases the perceived abundance of prey to predators. We tested this hypothesis by exposing the planktonic copepod Centropages hamatus to turbulent and nonturbulent environments at different prey concentrations. Our results fell into two main categories. First, the response to turbulence was characterized by an initial period having a high number of escape reactions. This period was followed by one of increased foraging. C. hamatus responded to the higher encounter rates due to turbulence as if it were experiencing altered prey concentrations. Second, the termination of turbulence resulted in an increased foraging response, which was not directly related to the encounter rate. Functional response curves do not adequately explain this foraging response because the time course of the foraging response depends on prior encounter experience and foraging motivation.

Journal Article↗

PubMed1995

"Latent" inhibitory connections become functional during activity-dependent plasticity.

Simultaneous pre- and postsynaptic recordings from identified glycinergic inhibitory interneurons and the Mauthner cell showed that 25% of the afferents produced no or extremely small postsynaptic responses. Morphological determination of the number of contacts made by these cells on the Mauthner cell revealed a connectivity similar to that of functional neurons which always produce clear inhibitory postsynaptic potentials, suggesting that most of the endings, made by weak interneurons are silent. Intraaxonal injection of 4-aminopyridine or Ca2+ greatly enhanced transmission at functional connections but did not modify those which were ineffective. However, after eighth nerve tetanic stimuli, transmission at the weak connections was unmasked or enhanced for prolonged periods and was twice as likely to be potentiated, with a 6-fold greater mean enhancement than the potent ones. This result provides additional support for long-term potentiation of inhibitory synapses. Furthermore, weakly functional junctions represent a "reserve" pool which can be critical for the expression of plasticity within a network, and, consequently, for setting the threshold of reflex activities such as the escape reaction mediated by the Mauthner cell.

4-Aminopyridine↗