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At least 199 records · Page 11Linked to original sources
PubMed1995

Episodic hypertension due to autonomic dysreflexia in acute and chronic spinal cord-injured rats.

Spinal cord injury results in abnormal sympathetic control of the cardiovascular system, consisting of exaggerated reflexes with resulting hypertension and bradycardia that has been termed autonomic dysreflexia. We studied changes in arterial pressure and heart rate caused by colon or urinary bladder distension in unanesthetized acute (7 day) and chronic (30 day) spinal cord-injured rats to evaluate the time course of these responses in an animal model of spinal cord injury. In conscious control rats colon and bladder distension caused brief (2-10 s) pressor responses of 10 mmHg associated with tachycardia and escape reactions. Colon distension in spinal cord-injured rats increased arterial pressure by 41 +/- 2, 22 +/- 3; and 49 +/- 5 mmHg at 24 h and 7 and 30 days after cord transection, respectively. These responses lasted 30 s-5 min and were accompanied by bradycardia. Distension of the urinary bladder caused similar responses in spinal rats after 24 h and 30 days of cord transection. We propose that the initial responses may be related to loss of descending inhibition of spinal reflexes but that plastic changes in the spinal cord is one of the mechanisms for the autonomic dysreflexia occurring 1 mo after injury.

Acute Disease↗
PubMed1995

Induction of fos-like immunoreactivity by electrocutaneous stimulation of the rat hindpaw.

Stimulation of peripheral nerves activates the proto-oncogene c-fos, which in turn generates its gene product, Fos. Fos and Fos-like proteins are produced in the central nervous system in response to chemical, mechanical, thermal, and electrical manipulation. The present study demonstrated a relationship between the number of Fos-like-immunoreactive nuclei in the spinal dorsal horn and graded intensities of electrical stimulation applied to the hindpaws of anesthetized and unanesthetized rats. Stimulation levels within the range of 0.1 to 1.0 mA were chosen on the basis of parmeters previously determined in behavioral investigations of escape reactions. Focal stimulation at these intensities activates peripheral axons directly, but does not injure or traumatize peripheral tissues. There was no evidence of inflammation or edema as a result of the focal electrical stimulation. As the stimulation intensity increased, the number and distribution of Fos-like-labeled nuclei increased with respect to rostral-caudal and laminar orientation. The threshold for expression of Fos-like immunoreactivity was different for anesthetized and unanesthetized animals. For anesthetized animals, the number of labeled nuclei increased significantly from the control level only when 1.0 mA was applied. However, in unanesthetized animals, the pattern of labeling was statistically significant at 0.2 mA. The present study demonstrates that electrical stimulation can evoke the expression of Fos-like immunoreactivity by activating nociceptors in the absence of tissue injury, and that the use of anesthetics can modulate this expression.

Afferent Pathways↗
PubMed1999

[The study of the anesthetic action of halothane on the rat spinal cord by fos immunoreactivity].

This study was performed to examine the anesthetic action of halothane on the spinal cord of rats by using fos immunoreactivity, a marker for neuronal activity following noxious stimulation. Sprague-Dawley rats were injected with 150 microliters of 5% formalin subcutaneously into the left hindpaw. Control group (n = 5) received 100% oxygen for 3 hours after injection. 1 MAC group (n = 5) and 1.5 MAC group (n = 5) of rats were anesthetized with 1 MAC or 1.5 MAC halothane, respectively, for 3 hours after injection. The number of fos immunoreactive cells was counted in the lumbar spinal cord of each rat. All rats showed escape reactions against noxious stimulation in the control group. In the 1 MAC and 1.5 MAC groups, two of five rats showed response to noxious stimulation and the another three showed no response, respectively. There was profound relation between the responding rats and the expression of fos immunoreactivity in the spinal dorsal horn. The number of fos immunoreactive cells decreased in the cord of rats that showed no response to noxious stimulation by halothane 1 or 1.5 MAC. These findings suggest that halothane has analgesic action on spinal nociceptive neurons in the rats on the condition that its reactions to noxious stimulation are suppressed by halothane of any concentration.

Anesthesia, Inhalation↗
PubMedDate not supplied

[The expression of the c-fos gene in the brain of mice in the dynamic acquisition of defensive behavioral habits].

Levels of c-fos mRNA expression in mouse cerebral cortex and hippocampus at different stages of footshock escape and avoidance learning were studied by Northern hydridization. In the first series of experiments a mouse was presented with 30 electric footshock daily in a chamber where it could escape from the floor by jumping on the safe platform attached to the wall. A large increase in c-fos mRNA level in the cerebral cortex and hippocampus was observed during the first day of training. Mice that were trained for 9 consecutive days and acquired a footshock escape reaction showed no elevation of c-fos expression in the brain as compared to the quiet control group. In the second series of experiments the levels of c-fos expression were compared in individual mice trained to avoid the footshock by jumping on the platform in response to an auditory conditioned stimulus. Mice which acquired avoidance behavior more rapidly had lower c-fos mRNA levels than slow learners. There was no such to difference between the corresponding yoked control groups which consisted of animals matched the rapid and slow learners by the number of footshocks received. It is concluded that achievement of adaptive results in the course of learning leads to a suppression of further c-fos induction by motivational excitation.

Adaptation, Physiological↗
PubMedDate not supplied

[Plunging ranula].

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 retrospective study over a 10 years period on patients suffering of plunging ranula treated in Oral and Maxillo-Facial Clinic, resumed by a clinical example. These 7 patients with plunging ranula are related to all the patients operated for ranula in the same period of time in our clinic and were analyzed on age, sex, imaging exploration technique, treatment, and outcome. We found this kind of lesion both in children and young adults, between 10 to 40 years, more frequent on male (1.33/1). Two patients presented only the cervical form of ranula instead of the other five patients (both oral and cervical ranula). Only two of them received IRM examination. All of them received surgical treatment, the approach being cervical; it was removed both the cyst and the sublingual salivary gland. The surveying period, except the last case, was 1 year and includes no recurrences. We consider, besides esthetic loss that the cervical approach of plunging ranula seems to be the optimal access both on lesion and sublingual gland.

Adolescent↗
PubMed1987

Neural substrates of opioid tolerance and dependence.

Opiate dependence is not represented by a single neuronal substrate but probably reflects actions at multiple functional sites in the central nervous system. Classical measures of opiate dependence such as escape reactions and wet dog shakes may be elicited by neural substrates in the medial thalamus and periaqueductal gray. Our work and others suggests that the region in the nucleus accumbens and its afferent and efferent connections may be an important substrate to reinforcing properties of opiates. The nucleus accumbens is also an important substrate for the reinforcing properties of stimulant drugs. These data suggest that opiate dependence may represent functional changes not only in neural substrates responsible for physical dependence, but also in brain sites responsible for the reinforcing actions of opiates. It should be noted that there was inability in the early days when the endorphins first came to the forefront, to show correlations between changes in opiate binding and endorphin levels associated with dependence. This may be due to a failure to identify functionally significant substrates that may be implicated from what one would call the top-down approach. Perhaps the "neurohumor" that Dr. Cochin was thinking about is an opioid peptide located in brain regions high in opiate receptors and functionally sensitive to opiate antagonists. New work isolating particular loci for opiate actions may point to potential sites and neurochemical substrates for opiate dependence.

Animals↗
PubMed1987

[Changes in the learning ability of epiphysectomized rats].

The experiments on rats have shown changes in the learning ability of animals. The learning of locomotor reactions of escape and avoidance conditioned reflex was accelerated in animals after pinealectomy. Training of rats in U-shaped and 16-door mazes was significantly affected after pinealectomy. The index of reflex retention (1 and 7 days later) was not changed in the operated animals. Epithalamin (0.5 mg/kg for 5 days) selectively facilitated learning of visual and space discrimination.

Adaptation, Physiological↗
PubMed1984

Genotype-dependent behavioral sensitivity to mu vs. kappa opiate agonists. II. Antinociceptive tolerance and physical dependence.

Antinociceptive tolerance, cross-tolerance and an expression of physical dependence to morphine (MRP) and (+/-)-ethylketazocine (EKC) were quantitatively compared using two inbred strains of mice. The measure of analgesia was the area of a time-response curve (escape reaction, 52 degrees C heated plate). (-)-EKC was 1.5 to 1.8 times more potent than MRP in both C57B1/6J (C57) and DBA/2J (DBA) mice. The latter strain was significantly more sensitive to both analgesics. Paradoxically, after an identical dose, the MRP content in DBA plasma, brain and spinal cord was only 56 to 73% of that in C57 tissues. Mice rendered tolerant to MRP (32 mg/kg s.c./b.i.d./1 week) exhibited equivalent cross-tolerance to EKC. In contrast, mice made tolerant to EKC (32 mg/kg s.c./b.i.d./1 week) retained substantial sensitivity to MRP. Comparisons between drugs and strains indicate that analgesic tolerance and physical dependence did not develop in parallel.

Analgesics↗
PubMed1980

[Contribution of biological tests in the evaluation of professional asthma (author's transl)].

The eventual difficulties of diagnosing professional asthma sometimes need the help of methods of complementary diagnosis. The histamine-release test and that of basophils granules liberation are studied in this work, concerning 12 substances with a suspected allergenic action (saw-dust, textile fibres, chemicals, products of plant origin). The histamine-release and granules liberation tests were performed according to the techniques described respectively by Lichtenstein and Benveniste. Both examinations were positive in a concording manner in 8 cases out of 12, but this positivity was difficult to interprete for etiopathogenic reasons. The study of the curve of histamine-release in relation with the dose of allergen used in the test nevertheless enables to differentiate two types of answers, one related to an allergic mechanism, the other to an irritative one. These observations led to the deduction that a positive granules liberation test could be due to a non allergic mechanism. Negativity in both tests does not allow the rejection of the part played by these substances into the genesis of respiratory signs. Indeed these tests only investigate one part of the mechanisms which can be involved: direct stimulation of vagal irritant receptors and the plain pharmacological reactions escape from this type of biological investigations. The biological tests studied in this work can be used in a complementary fashion in the etiological survey of professional asthma but they cannot replace the realistic tests, more reliable because they react whatever the etiopathogenic mechanism involved.

Adult↗
PubMed1982

[Polymodal sensory input in command neurons of snails].

Putative command neurones of snail's escape behaviour reacted with excitatory postsynaptic potentials and spikes to tactile, vestibular, light-off and thermal stimuli evoking behavioural escape reactions. Presented data confirm the command function of identified neurones. No monosynaptic connections have been revealed between intracellularly recorded primary cells of the statocyst and command neurones, but it has been shown that command neurones reacted to strong stimulation of the acoustic nerve. Presence of second-order sensory neurones in the vestibular pathway was assumed.

Acoustic Stimulation↗
PubMed1978

[Participation of thalamic nuclei in the elaboration of conditioned avoidance reflexes of rats. IV. Lesions of the nucleus reuniens].

The elaboration of conditioned avoidance reflexes in a Y-maze and in the jumping test was scarcely influenced by lesion of the n. reuniens of the thalamus in hooded rats. The increase of intertrialreactions in the jumping test after such lesions in contrast to the control group indicates changes in the regulation of motivational processes. After additional lesion of the n. rhomboideus neither the conditioned avoidance nor the unconditioned escape reaction were elaborated in the jumping test.

Animals↗
PubMedDate not supplied

[Changes in the higher nervous activity of the progeny of alcoholized male white rats].

Some forms of behaviour of the offsprings of male rats, which within a period more than 1 month gave preference to 20% ethanol solution over water (I group), were compared with behaviour of the offsprings of males, in which alcoholic motivation had been interrupted after a period of preferential consumption of ethanol during 1 month (II group), and behaviour of the offsprings of intact males (III group). Exploratory and locomotor activity in the animals of the I group was lower, and the level of anxiety was higher, than in the animals of the II group; there were no distinctions between the animals of the II and the III groups (by testing in elevated plus-maze). Memory traces in a test of avoidance by swimming retained worse in the females of the I group, than in the females of the II group; there were no distinctions between males. Capability for bilateral active avoidance conditioning was higher in the animals of the I group, but at the same time the number of animals, which demonstrated non-escape reaction, increase. Forced alcoholization of males of the I and the II groups was carried out beginning from the age of 7 months. Within 2.5 months after the beginning of alcoholization 2/3 of the rats of the I group demonstrated ethanol preference during a testing period of 1 month. Such preference retained only in 14.3% of the animals of the II group. It is supposed that the main factor, which determines predisposition of the offsprings to alcohol consumption, is alcohol consumption by parents rather than their own predisposition.

Alcohol Drinking↗
PubMed1995

Simple sublingual ranulas: pathogenesis and management.

Simple ranulas in the floor of the mouth usually reflect a mucus escape reaction that develops after disruption of sublingual gland elements. As such, they comprise an accumulation of mucus within connective tissue and lack an epithelial lining. Simple ranulas should be distinguished from cervical, or plunging, ranulas. Recommended treatments for simple ranulas usually involve excision of the ipsilateral sublingual gland, "marsupialization," or simple excision of the cyst. Alternatively, the ranula can be treated with the placement of a silk suture or seton into the dome of the cyst. Four cases using this technique are reported.

Adult↗
PubMed1998

Physiological properties of the Mauthner system in the adult zebrafish.

We investigated the morphological and electrophysiological properties of the Mauthner (M-) cell and its networks in the adult zebrafish (Danio rerio) in comparison with those in the goldfish (Carassius auratus). The zebrafish M-cell has an axon cap, a high resistivity structure which surrounds the initial segment of the M-axon, and accounts for an unusual amplification of the fields generated within and around it. Second, extra- and intracellular recordings were performed with microelectrodes. The resting potential was approximately -80 mV with an input resistance of approximately 0.42 M omega. The M-cell extracellular field was large (10-20 mV), close to the axon hillock, and the latency of antidromic spikes short (approximately 0.4 milliseconds), confirming a high conduction velocity in the M-axon. The extrinsic hyperpolarizing potential (EHP), which signals firing of presynaptic cells and collateral inhibition, was markedly lower at frequencies of spinal stimulation > approximately 5/second, suggesting an organization of the recurrent collateral network similar to that in the goldfish. Inhibitory postsynaptic potentials (IPSPs) were highly voltage-dependent; their decay time constant was increased by depolarizations. The presynaptic neurons which are numerous could be identified by their passive hyperpolarizing potential (PHP) produced by the M-spike current. Auditory responses, mediated via mixed synapses (electrical and chemical), had short delays and hence are well suited to trigger the escape reaction. The similarities of their properties indicate that the wealth of information generated over decades in the goldfish can be extrapolated to the zebrafish.

Animals↗
PubMed1987

Effects of repeated as compared to single aggressive confrontation on nociception and defense behavior in C57BL/6 and DBA/2 mice.

Behavioral reactions (submissive postures, escape, immobility, activity, locomotion) in C57BL/6 and DBA/2 test mice were recorded during single (50 bites) or three repeated (3 X 50 bites, separated by 24 hr) aggressive confrontations, as well as during a nonaggressive confrontation 24 hr after the last aggressive confrontation with opponents of the opposite strain. Nociception (hot plate response latency) was measured 1 min after aggressive or nonaggressive confrontations. During repeated aggressive confrontation, DBA mice reacted with a stable pattern of escape and analgesia, whereas C57 mice failed to develop an analgesic response and changed their behavioral defense strategy during repeated aggressive confrontations (decrease of escape, increase of defensive upright). The conditioned display of submission and of escape behavior during nonaggressive confrontation did not change as a function of earlier repeated aggressive confrontations in DBA mice, while C57 mice showed a significant increase of defensive upright postures and immobility. Conditioned analgesia was not observed after nonaggressive confrontations. The results point toward a dissociation between attack-elicited behavior and antinociception and suggest that encounter-induced analgesia may influence the processing of aversive experience.

Aggression↗
PubMed1992

A comparative physiological and behavioral study of freeze and hot-iron branding using dairy cows.

A public debate has recently arisen, largely surrounding the issue of pain, over whether freeze or hot-iron branding should be the preferred method of permanently identifying cattle. This study addressed that question by quantifying the following accepted measures of distress and pain over a 25-min sampling period: elevated heart rate, concentrations of cortisol, epinephrine, and norepinephrine, and escape-avoidance reactions and vocalizations. Twenty-four dairy cows (15 Holsteins and 9 Jerseys) were assigned to one of three treatments: freeze-branded (F), hot-iron-branded (H), or sham-branded (S), in which a room-temperature brander was applied. Plasma epinephrine and norepinephrine concentrations showed no discernible trends. Plasma cortisol concentrations were elevated in the F and H cows from 5.5 min to 25.5 min postbranding (P = .04). Heart rate, analyzed as a proportion of the prebranding mean, showed that H cows had a greater, more acute, response than did F cows (P = .04), which exhibited a more prolonged response (P = .07). No cows vocalized during branding; however, H cows had a greater escape-avoidance reaction toward branding than did the F and S cows. Both methods of branding produced elevated heart rates and cortisol concentrations indicative of pain sensations. Because the cows exhibited a greater escape-avoidance reaction and heart rate proportions to hot-iron branding, freeze banding would be preferable to hot-iron branding when feasible.

Animal Identification Systems↗
PubMed1996

Serotonin-induced short- and long-term sensitization in the crab Chasmagnathus.

On sudden presentation of a passing shadow (a visual danger stimulus), the crab Chasmagnathus granulatus responds with a running reaction that we term an escape response (ER). A single administration of 5-HT in a dose range between 0.005 and 0.1 microgram/g enhances the ER at 30 min, and a dose of 10-15 micrograms/g has a similar effect for at least 24 h. The classical 5-HT antagonist cyproheptadine (CYP) given within a dose range 0.01-2.0 micrograms/g has no effect on ER at 30 min, but 0.5 microgram/g blocks the 5-HT-induced short-term sensitization. An enhancing effect of CYP on the ER is shown at 24 h with 1.0-2.0 micrograms/g doses. An explanation of this results in terms of a model similar to that proposed for Aplysia, that is two sensitizing processes linked in parallel and mediated by two different types of 5-HT receptors is discussed. Results indicate that the sensitizing effect of 5-HT is confined to high responders, thus suggesting that crabs of a same population have different degrees of sensitivity to the drug according to their different degrees of reactivity to the visual danger stimulus.

Animals↗