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At least 415 records · Page 23Linked to original sources
PubMedDate not supplied

Effects of alcohol consumption on the prevention and alleviation of stress-reactions.

Alcohol's Stress-Response-Dampening (SRD) effect has been the subject of much research, but little has been done to examine the effects of drinking alcohol after experiencing a stressor (Stress-Response-Recovery; SRR). In this study, 65 male and 65 female moderate or heavy drinking undergraduates were randomly assigned (with equal numbers of each sex per group) to 1 of 13 groups. Six experimental conditions were used to compare alcohol's SRD and SRR effects with two doses (moderate: .75 ml/kg; low: .33 ml/kg) and a placebo, and seven control conditions were used to measure the effects of the stressor (uncontrollable aversive noise) and the alcohol doses alone on the dependent measures. The major dependent variable was escape learning in a human shuttle box. In the SRD conditions, subjects who drank a moderate dose of alcohol learned to escape faster than those drinking the low dose or placebo. However, in the SRR conditions, subjects in the placebo group did not show escape learning deficits, in contrast to the impaired performance of subjects in the two alcohol groups. These results suggest a complex alcohol-stress relationship in which timing, dose, and expectations about alcohol lead to differential SRD and SRR effects.

Adult↗
PubMed1996

[Spontaneous and visually-induced oculomotor reactions in microgravity (Results of Austrian-Russian Experiment "Optovert" performed within the frame of program "Austromir", part II)].

Results of investigation of spontaneous and induced by vertical linear and sinusoid optokinetic stimulation oculomotor reactions in short- and long-term space missions are reported. Adaptation to microgravity was shown to be associated with rearrangement in sensory interactions even on a background of good subjective well-being and absence of abnormal autonomous nervous reactions. In the early period of adaptation to microgravity records were made of modified spontaneous oculomotor activity (spontaneous vertical nystagmus) and vertical optokinetic nystagmus (VOKN) including alterations in amplitude and VOKN amplification coefficient.

Adaptation, Ocular↗
PubMedDate not supplied

[Effect of diazepam on interference processes].

It has been found in experimental behavioral interference during training in two conditioned reflexes, rapidly following each other, that intraperitoneal injection of diazepam (2 mg/kg) 30 min before training potentiates the inhibitory effect of the defensive reaction to the drinking one. Electrophysiological analysis of the modulating effect of amygdaloid stimulation on the peripheral signal transmission via the central gray matter has demonstrated that in the majority of the neurons, diazepam produced a longer and pronounced inhibition of the excitatory reactions in response to electrocutaneous stimulation after conditioning stimulation of the amygdaloid. The data obtained allow an assumption that inhibitory processes determined by the activity of the GABAergic amygdalofugal system underlie the interference interrelations.

Amygdala↗
PubMedDate not supplied

[Vasoactive peptides in the structure of defensive motivational excitation].

In experiments on rabbits, the action was studied of vasoactive peptides angiotensin-II, bradykinin and lysyl-vasopressin, injected into the brain ventricles, on a passive defensive reaction to electrical stimulation of the ventromedial hypothalamus. It was found that angiotensin-II and lysyl-vasopressin had a pronounced inhibitory influence, while bradykinin had a facilitatory effect on this reaction. Electrical stimulation of the ventromedial hypothalamus predominantly facilitated reactions of individual neurones of the sensorimotor cortex to angiotensin-II and bradykinin. Intraperitoneal injection of P-substance to rats in conditions of an acute conflict situation producing an emotional stress, brought about a significant diminution of sudden death incidence from cardiovascular insufficiency.

Angiotensin II↗
PubMed1971

Analgesia from electrical stimulation in the brainstem of the rat.

Stimulation at several mesencephalic and diencephalic sites abolished responsiveness to intense pain in rats while leaving responsiveness to other sensory modes relatively unaffected. The peripheral field of analgesia was usually restricted to one-half or to one quadrant of the body, and painful stimuli applied outside this field elicited a normal reaction. Analgesia outlasted stimulation by up to 5 minutes. Most electrode placements that produced analgesia also supported self-stimulation. One placement supported self-stimulation only in the presence of pain.

Aggression↗
PubMedDate not supplied

[Midantan activation of memory trace retrieval in rats].

The authors studied the action of amantadine in recovery processes of the memory in some types of retrieval impairment: normal forgetting, "psychogenous" amnesia and latent inhibition. Antraperitoneal injection of amantadine (25 mg/kg) to rats I h before testing the preservation of the conditioned passive avoidance reaction was discovered to restore the conditioned reaction which went out as a result of long-term preservation. To restore the memory in amnesia and latent inhibition, 50 mg/kg amantadine was required. Thus, it has been shown that amantadine has reactivating properties in memory processes.

Amantadine↗
PubMedDate not supplied

[The role of the emotiogenically negative brain structures in realizing an acid-defensive instrumental motor reaction].

In experiments in dogs it has been found that testing electrical stimulation of the lateral hypothalamus (duration of this stimulation--5-7 s), of the ventromedial hypothalamus and of the substantia grisea centralis of mesencephalon reproduced earlier elaborated acid-defensive instrumental conditioned reflex. This fact takes place due to the activation of the brain structures of negative emotion.

Animals↗
PubMedDate not supplied

[Poststressor change in attractiveness of mice odourgens].

It was shown, that under physiological conditions, intact noninbred mice or high-inbred mice-testers in reaction of preference-avoidance prefer volatile components secreted by mice of a genetically identical group. After exposure to stress factors, mice release with urine the volatile components, which are more preferable by testers than the volatile secretion of intact mice indepedently of the genotype of mice.

Animals↗
PubMed1994

Fear of humans in Japanese quail selected for low or high adrenocortical response.

Behavioral reactions to a nearby human were recorded in male Japanese quail of two lines selected for reduced (LS; low stress) or exaggerated (HS; high stress) plasma corticosterone (B) response to brief mechanical immobilization. Their adrenocortical responses to one of three treatments were then examined. These were: no human disturbance (undisturbed controls, CON), capture and return to the home cage before recapture and bleeding after 5 min (CR), or capture and manual restraint for 5 min before blood sampling (CREST). Quail of the HS line showed more fear-related behavior (crouching, escape) and avoidance of the experimenter than did their LS counterparts. Plasma B concentrations were markedly elevated following each capture treatment (CREST > CR) and the response appeared to be more pronounced in quail of the HS than the LS line. These findings indicate that HS quail perceived human contact to be more aversive than did those of the LS line. Avoidance scores and the adrenocortical responses to capture were positively correlated within individual birds. Therefore, simple behavioral tests of fear may have predictive value concerning physiological responsiveness to stressful stimulation.

Animals↗
PubMed1987

Differential ontogenetic peaks and drops in various conditioned reactions.

A survey of results obtained by the authors was compared with the body of recent data of the literature on the development of learning and memory. The following conclusions were pointed out: The development of learning and memory is not a monotonous process; one or more peaks followed by temporary drops or lasting decay are characteristic for it. There is no coincidence in time between learning and memory peaks, both are greatly dependent on the experimental design and conditions. Learning of more complex reactions and prolonged retention intervals shift the peaks toward later age periods. Early learning and memory that occurs at earlier age periods than thought before may be proved in the very first postnatal days in altricial mammals for inhibitory conditioning as well, if neurobiological and developmental specificities of this age are respected.

Animals↗
PubMed1993

Yohimbine potentiates active defensive responses to threatening stimuli in Swiss-Webster mice.

Yohimbine HCl, an antagonist at alpha 2-noradrenaline receptors with putative panicogenic effects in human subjects, was administered to Swiss-Webster mice at doses of 0.5, 1.0, and 2.0 mg/kg. Animals were then tested in two defense test batteries. Yohimbine produced increases in flight from an approaching/contacting human and potentiated animals' reactions to dorsal contact. During a 5-min exposure to a cat (separated from the mouse by a wire-mesh screen) and the 15-min period thereafter, yohimbine produced a dose-dependent pattern of changes in defensive behaviors that included increases in locomotion, transits from one segment of the test chamber to another, fore- and hindpaw wall climbing, screen climbing and hanging, and roof pushing. Crouching (relative immobility while in a hunched-back posture) was notably decreased at all doses. During the postcat period, two different response patterns, "high-escape" and "low-escape," characterized in part by high and low frequencies of wall climbing, were observed in cat-exposed groups. In yohimbine-injected mice, the low-escape behavior pattern also included a tendency to avoid the segment of the test chamber closest to the cat compartment. Both patterns differed from the crouching and immobility generally exhibited by vehicle-injected, cat-exposed controls. It was suggested that yohimbine effected these behavioral changes by either potentiating neural mechanisms mediating flight or inhibiting mechanisms mediating freezing. This model may have some utility for the investigation of panicogenic and antipanic compounds and may contribute insights into the etiology of panic disorder.

Aggression↗
PubMed2006

Effects of intra-PAG infusion of ovine CRF on defensive behaviors in Swiss-Webster mice.

The midbrain dorsal periaqueductal gray (DPAG) is part of the brain defensive system involved in active defense reactions to threatening stimuli. Corticotrophin releasing factor (CRF) is a peptidergic neurotransmitter that has been strongly implicated in the control of both behavioral and endocrine responses to threat and stress. We investigated the effect of the nonspecific CRF receptor agonist, ovine CRF (oCRF), injected into the DPAG of mice, in two predator-stress situations, the mouse defense test battery (MDTB), and the rat exposure test (RET). In the MDTB, oCRF weakly modified defensive behaviors in mice confronted by the predator (rat); e.g. it increased avoidance distance when the rat was approached and escape attempts (jump escapes) in forced contact. In the RET, drug infusion enhanced duration in the chamber while reduced tunnel and surface time, and reduced contact with the screen which divides the subject and the predator. oCRF also reduced both frequency and duration of risk assessment (stretch attend posture: SAP) in the tunnel and tended to increase freezing. These findings suggest that patterns of defensiveness in response to low intensity threat (RET) are more sensitive to intra-DPAG oCRF than those triggered by high intensity threats (MDTB). Our data indicate that CRF systems may be functionally involved in unconditioned defenses to a predator, consonant with a role for DPAG CRF systems in the regulation of emotionality.

Aggression↗
PubMed2002

[The dynamics of neuronal, autonomic and movement parameters in animals during the reproduction of a learned habit].

Data by the authors, as well as from other laboratories, show that the intertrial responses correlated with accuracy of avoidance or feeding behaviour. Moreover our previously data demonstrated the definite changes of neuronal activity, heart rate and respiration during intertrial responses. In this study we investigated the time-course of intertrial response appearance, the pattern of neurophysiological parameters during intertrial periods, and the types of intertrial responses. Experiment 1 showed that different environmental stimuli influenced the level of intertrial responses and successfulness of the avoidance learning. In experiment 2, in which learning and extinction procedures were presented in rabbit passive-avoidance conditioning, two types of intertrial responses were observed; the first type repeated the pain reinforcement, the second one imitated the conditioned reaction of neuronal activity, heart rate, respiration, and moving. These investigations suggest that the processes of intertrial eliciting of avoidance effector programs may be one of the mechanisms of fixation in memory and play an important role in acquisition of more effective results.

Acoustic Stimulation↗
PubMed1989

[Are we overdiagnosing and overtreating mild arterial hypertension?].

Mild hypertension is the most difficult type of hypertension do diagnose in clinical practice due to the great variability of blood pressure and to the alert reaction. There is evidence that overdiagnosis and overtreatment of mild hypertension are a common finding. We suggest that more baseline readings should be obtained before establishing the diagnosis. Also an individualized approach should be used and in selected cases, the 24-hour blood pressure monitoring can be useful.

Blood Pressure↗
PubMed2000

The chemical defense ecology of marine unicellular plankton: constraints, mechanisms, and impacts.

The activities of unicellular microbes dominate the ecology of the marine environment, but the chemical signals that determine behavioral interactions are poorly known. In particular, chemical signals between microbial predators and prey contribute to food selection or avoidance and to defense, factors that probably affect trophic structure and such large-scale features as algal blooms. Using defense as an example, I consider physical constraints on the transmission of chemical information, and strategies and mechanisms that microbes might use to send chemical signals. Chemical signals in a low Re, viscosity-dominated physical environment are transferred by molecular diffusion and laminar advection, and may be perceived at nanomolar levels or lower. Events that occur on small temporal and physical scales in the "near-field" of prey are likely to play a role in cell-cell interactions. On the basis of cost-benefit optimization and the need for rapid activation, I suggest that microbial defense system strategies might be highly dynamic. These strategies include compartmented and activated reactions, utilizing both pulsed release of dissolved signals and contact-activated signals at the cell surface. Bioluminescence and extrusome discharge are two visible manifestations of rapidly activated microbial defenses that may serve as models for other chemical reactions as yet undetected due to the technical problems of measuring transient chemical gradients around single cells. As an example, I detail an algal dimethylsulfoniopropionate (DMSP) cleavage reaction that appears to deter protozoan feeding and explore it as a possible model for a rapidly activated, short-range chemical defense system. Although the exploration of chemical interactions among planktonic microbes is in its infancy, ecological models from macroorganisms provide useful hints of the complexity likely to be found.

Animals↗
PubMed2000

Electrical stimulation of the midbrain tectum enhances dopamine release in the frontal cortex.

One widely used animal model of anxiety is the electrical stimulation of a given structure supposed to be involved in the neural circuitry underlying emotional behavior. Indeed, electrical stimulation of midbrain structures with substrates for the processing of fear-like responses, such as the dorsal periaqueductal gray matter (DPAG) or the inferior colliculus (IC), produces behavioral, sensorial and autonomic responses very similar to the defense reactions observed in environmental threatening situations. It has also been proposed that the required level of integration of all these components of the defense reaction needs an integrative process situated at higher brain level, as the prefrontal cortex. As a matter of fact, substantial cortical inputs to the midbrain tectum have already been found. In view of this evidence, it seems important to know whether animals stimulated in the midbrain tectum would present neurochemical changes in the prefrontal cortex. To this end, we examined the temporal course of the effects of the electrical stimulation of the DPAG and IC on the dopamine (DA) release in the prefrontal cortex. Electrical stimulation of these structures was performed at the alertness (control) and escape thresholds. Electrical stimulation of the inferior colliculus at the escape threshold produced a long-lasting increase in the levels of corticofrontal dopamine in relation to these measurements in the control group. No significant changes in extracellular DA release in this cortical area could be observed following DPAG electrical stimulation. These findings bring evidence for the involvement of dopamine of the frontal cortex in the setting up of adaptive responses to stressful situations generated at the inferior colliculus level.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1978

Aggression and flight behaviour of the marmoset monkey Callithrix jacchus: an ethogram for brain stimulation studies.

The aggressive and flight behaviour of the common marmoset monkey (Callithrix jacchus) is described and split into behavioural units, allowing analysis of agonistic behaviour evoked by electrical stimulation of the hypothalamus. The social context of the described units is also considered. C. jacchus shows clearly recognizable behavioural patterns. Free-born animals are very timid and show typical flight reactions. Within aggressive behaviour, two types of aggression can be distinguished: very violent attacks causing severe injuries, often accompanied by particular threat displays and observed during dominance and territorial encounters, and, on the other hand, relatively harmless short attacks, together with a noisy vocalization, for defensive purposes or keeping group members at a distance.

Aggression↗
PubMedDate not supplied

[The effect of analogs of the C-termination fragment of arginyl vasopressin on the dynamics of the acquisition of an active avoidance conditioned reaction in rats].

The effect of original analogues of the 6-9 C-terminal AVP fragment, D-MRP and D-MPRG, on the active avoidance behaviour of rats was studied using intranasal administration in a wide range of doses. The dose in 0.1 mcg/kg was the most efficient for D-MPR and 0.01 mcg/kg for D-MPRG, which for the tripeptide was ten times, and for the tetrapeptide hundred times lower than the corresponding dose of AVP used in the similar experiments. The tri- and tetrapeptide were shown to facilitate the active avoidance behaviour affecting both the formation of the reaction and consolidation of memory trace. The peptides mostly affect the perception processes, i.e., the detection of a specific stimulus from the environment, the estimation and memorizing of its biological significance.

Acoustic Stimulation↗