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Results for “Exploratory Behavior”

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At least 415 records · Page 23Linked to original sources

PubMed1987

Effect of voluntary exercise on open-field behavior and on aggression in the spontaneously hypertensive rat (SHR).

In the present study we investigated the influence of voluntary exercise on exploratory behavior and on aggression in the spontaneously hypertensive rat (SHR). Twenty-four SHR (8 weeks old) were randomly assigned to either an exercise group or a sedentary control group. The animals in the exercise group exhibited a spontaneous wheel running activity of 5-6 km/day during 6 weeks. The characteristic hyperexploratory behavior of SHR was lowered in the exercise group (p less than .001) as compared to the control group. The runners also showed a tendency for less aggression. In the postexercise period, when the runners' wheels were locked, the exercise group had a significant rise in aggression (p less than .01) vs the controls. The exploratory behavior returned immediately to the level of the controls, but we found no further increase in any of the parameters measured. However, the runners showed a type of displaced aggression exhibited as digging and biting in the test cage. This evidence suggests that voluntary exercise lowers the hyperexploratory behavior and aggression in the SHR and that an abrupt stop in exercise gives an "abstinence" reaction.

Aggression↗

PubMed2002

Reversal of biochemical and behavioral parameters of brain aging by melatonin and acetyl L-carnitine.

The potential utility of dietary supplementation in order to prevent some of the oxidative and inflammatory changes occurring in the brain with age, has been studied. The cerebral cortex of 27-month-old male B6C3F1 mice had elevated levels of nitric oxide synthase 1 (EC 1.14.13.39) (nNOS) and peptide nitrotyrosine relative to cortices of younger (4-month-old) animals. After 25-month-old mice received basal diet together with 300 mg/l acetyl L-carnitine in the drinking water for 8 weeks, these levels were fully restored to those found in younger animals. A partial restoration was found when old animals received basal diet supplemented with 200 ppm melatonin in the diet. Levels of mRNA (messenger RNA) for nNOS were unchanged following these treatments implying translational regulation of nNOS activity. Behavioral indices indicative of exploratory behavior were also depressed in aged animals. Dietary supplementation with melatonin or acetyl L-carnitine partially reversed these changes. These findings suggest that dietary supplementation cannot merely arrest but indeed reverse some age-related increases in markers of oxidative and inflammatory events occurring with the cortex.

Acetylcarnitine↗

PubMed1984

Behavioral effects of arginine in male rats.

The effects of aminoacid arginine on conditioned and unconditioned behavior were studied in male rats. Arginine was administered orally at different dose levels. Both acute and subchronic (7 days) treatment schedule was performed. Exploratory behavior of the rats was studied in an open field. Acquisition of active avoidance behavior was studied in the shuttle-box test situation, and retention of passive avoidance reaction was studied in a step-through type of passive avoidance behavior. Acute administration of arginine failed to affect the acquisition and the retention of avoidance responses, and exploratory behavior of the rats. A 7-day treatment with the aminoacid caused an increase in ambulation of rats of Wistar strain, and a facilitation of acquisition and retention of avoidance responses in rats of CDR strain with poor learning capacity. It is possible that behavioral effects or arginine depend on its involvement in nucleic acid synthesis.

Animals↗

PubMed2005

Behavioral characteristics of rats predisposed to learned helplessness: reduced reward sensitivity, increased novelty seeking, and persistent fear memories.

The congenitally helpless rat strain, which was selectively bred for increased susceptibility to learned helplessness, may model the predisposition to affective disorders, including depression and post-traumatic stress disorder. Other than the selected trait, the behavior of this strain is not well characterized. In this study, we assessed congenitally helpless rats on several behavioral tests. First, we assessed reward sensitivity by measuring their consumption of a 5% sucrose solution. Next, we assessed exploratory behavior and fearfulness in both a novel and familiar open field, and in a light-dark test. Finally, we assessed fear conditioning by exposing the animals to 4 tone-shock pairs on 1 day (acquisition) and then presenting 60 tones over the next 2 days (extinction). Compared to normal Sprague-Dawley controls, congenitally helpless rats showed less consumption of the sucrose solution and more exploratory behavior in the novel, but not the familiar, open fields. They also showed less fearfulness in the light-dark test, but more conditioned freezing to the tone predicting shock. Moreover, this freezing was resistant to extinction; congenitally helpless rats not only failed to show a fear decrement during extinction, but actually showed increased fear, a phenomenon termed "paradoxical enhancement." Thus, congenitally helpless rats appear to have a behavioral phenotype characterized by reduced sensitivity to reward, increased drive to explore novel environments, and increased propensity to form and maintain fear-associated memories. This behavioral phenotype is discussed as resembling the personality of humans vulnerable to post-traumatic stress disorder.

Animals↗

PubMed2003

Lack of midazolam-induced anxiolysis in the plus-maze Trial 2 is dependent on the length of Trial 1.

The influence of the first exposure length upon the effect of midazolam (MDZ) administration prior to the second exposure in the elevated plus-maze (EPM) was investigated. Drug-free rats were assigned to freely explore the EPM for 1, 2 or 5 min (Trial 1). Twenty-four hours later, each group was subdivided in two further groups, which were retested in the EPM for 5 min, 30 min after either saline or MDZ (1.5 mg kg(-1)) administration (Trial 2). The data showed that during Trial 2, the percentage of entries (%Open arm entries) and time spent in the open arms (%Open arm time) were decreased if rats were pre-exposed to the EPM for 2- or 5-min Trial 1, while the group submitted to 1-min Trial 1 length displayed decreased %Open arm time only. The anxiolytic effect of MDZ prior to Trial 2 was present in the group submitted to 1-min, impaired in the group submitted to 2-min and absent in the group submitted to 5-min Trial 1 length. Data are analyzed taking into account the emotional learning which underlies the exploratory behavior during the EPM Trial 2.

Animals↗

PubMed1997

Effect of prenatal stress on opioid component of exploration in different experimental situations.

Prenatal stress interferes with the expression of opioid systems in rats. The present study determined the effect of prenatal stress on the opioid-influenced component of exploratory behavior, defined as the difference between the behavior of vehicle-treated and naloxone-treated rats, in three novel situations previously shown to cause different degrees of arousal. Pregnant rats were stressed three times weekly on a random basis by noise and flashing lights. Experiments were performed on 60-70-day-old offspring (male and female) of control and stressed dams. Fifteen minutes after injection of vehicle or naloxone (1 mg/kg), the proportion of time spent in eight different behavioral parameters, including locomotion, rearing, sniffing, hole poking, pivoting, and grooming, was assessed during 4 min of exposure to an open field, either with or without prior exposure to a hole box. The magnitude of the depressant effect of naloxone on exploration depended on the nature of the environment, previous experience of the animal in another situation, and the parameter of exploration assessed. The opioid-influenced component of locomotion and rearing was significantly reduced by prenatal stress, particularly in female rats. Further studies using a cross-fostering design are needed to assess the relative contributions of pre- and postnatal factors to the reduction of opioid activity in prenatally stressed rats. More specific opioid antagonists could be used to determine the nature of the opioid receptors involved.

Animals↗

PubMed1970

Drinking and eating elicited by cortical spreading depression.

Single waves of unilateral and bilateral cortical spreading depression were administered to rats by electrophoretic injection of potassium ions into the occipital cortices. Aggressive and stereotyped eating, drinking, and exploratory behavior were elicited by unilateral and bilateral spreading depression. Onset of the elicited behaviors varied among rats from 4 to 8 minutes after injection of the ions. Direct activation of, or rebound from, inhibition of subcortical motivational mechanisms may be responsible for the effects.

Aggression↗

PubMed1984

Analysis of the behavioral activity of C- and N-terminal fragments of cholecystokinin octapeptide.

Cholecystokinin (CCK) is a gut peptide which induces a syndrome of satiety, including reduced food intake and reduced exploratory behaviors. To investigate the minimal active sequence within the octapeptide molecule for reducing exploratory behavior, all C- and N-terminal fragments of CCK 26-33 (CCK8) were synthesized. Only CCK26-33 [H-Asp-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2] and CCK 27-33 [H-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-Phe-NH2] induced the behavioral effects within a physiological dose range. Smaller fragments as well as unsulfated CCK26-33 and CCK27-33 were inactive in doses as high as 10(-3) mol/kg. The requirement of the entire C-terminal heptapeptide for the behavioral effects of CCK is contrasted against the activity of smaller fragments at pancreatic, gastrointestinal and brain CCK receptors.

Amino Acid Sequence↗

PubMed2003

Correlation between age-related changes in open field behavior and plaque forming cell response in DA female rats.

We investigated the relationship between immunological and behavioral changes during ageing in Dark Agouti female rats. Results showed that ageing was associated with decreased exploratory behavior and increased emotionality (open field test) and decreased pain perception (writhing assay), but not with altered depression-like behavior (forced swim test). The observed behavioral changes were paralleled with decreased innate immunity in middle-aged and old rats, as revealed by reduced peroxide production of peritoneal macrophages; and decreased specific immunity, measured by the plaque-forming cell response, in old rats in comparison with young rats. Correlation analyses between behavioral and immune parameters demonstrated a significant correlation between the lines crossed in the open field test and the plaque-forming cell response. Taken together, the demonstrated age-dependent association between exploratory behavior and specific immune response suggests a senescent decline of a common neuroimmune regulatory mechanism.

Aging↗

PubMed1987

Permissive role of D-1 receptor stimulation for the expression of D-2 mediated behavioral responses: a quantitative phenomenological study in rats.

The syndrome of behavioral stimulation induced in male Sprague-Dawley rats by two dopaminergic agents was studied by distinguishing specific behavioral items and quantifying them in terms of their incidence. The specific D-2 agonist LY 171555 elicited yawning, genital grooming, exploratory behavior, downward sniffing and licking but failed to induce gnawing even at high doses. On the other hand, the D-1/D-2 agonist apomorphine elicited the full stereotyped syndrome including gnawing. Depletion of endogenous dopamine (DA) by alpha-methyltyrosine (alpha-MT) prevented the ability of LY 171555 to elicit all the items of behavioral stimulation including the stereotyped ones (sniffing and licking). In contrast, the ability of apomorphine to induce stereotypies was not reduced by depletion of endogenous DA by alpha-MT pretreatment. Blockade of D-1 receptors with SCH 23390 abolished the capacity of both LY 171555 and apomorphine to elicit all the items of behavioral stimulation. In alpha-MT pretreated rats, administration of low doses of the D-1 agonist SKF 38393 (2.5 mg/kg s.c.) reinstated the ability of LY 171555 to elicit behavioral stimulation and eventually conferred the ability of inducing gnawing. The results support the hypothesis that stimulation of D-1 receptors exerts a permissive role for the expression of behavioral stimulation following D-2 receptor stimulation. Endogenous DA appears to provide sufficient D-1 input to permit full expression of yawning, genital grooming, exploratory behavior, downward sniffing and licking following D-2 stimulation; pharmacological stimulation of D-1 in addition to D-2 receptors seems however necessary for full expression of the highest rank stereotypy item, gnawing.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1989

Differential effects of pimozide and SCH 23390 on acquisition of learning in mice.

Our main purpose was to clarify the differences between the effects of dopamine D-1 (SCH 23390) and D-2 (pimozide) antagonists on memory acquisition in a water-finding and a one-trial passive avoidance task with ddY mice. In the water-finding task, pimozide (0.1 and 0.2 mg/kg i.p.) enhanced the acquisition of latent learning of mice although it suppressed exploratory behavior. In contrast, SCH 23390 (0.1 mg/kg i.p.) attenuated the acquisition of latent learning and suppressed exploratory behavior. In the passive avoidance task, pimozide (0.1 and 0.2 mg/kg i.p.) enhanced the acquisition of the passive avoidance response of mice. SCH 23390 (0.05 and 0.1 mg/kg i.p.) failed to enhance the acquisition of the passive avoidance response. These results could suggest that a moderate block of D-2 receptors enhances memory acquisition but blocking D-1 receptors affects it in an opposite way.

Animals↗

PubMed1981

Preschool children's field independence: prediction from antecedent and concurrent maternal and child behavior.

This study was designed to explore the stability of early precursors of field independence. Field independence at preschool age (3 1/2 yr.) was measured by the Preschool Embedded-figures Test and was regressed on measures of 24 children's social and exploratory behaviors at infancy (1 yr.) and at preschool and on measures of maternal interaction behaviors at infancy and at preschool. The children's exploratory behaviors and the mothers' behaviors at infancy and preschool were not predictive of cognitive style. The children's social behaviors at both ages were highly related to their cognitive styles. Examination of the regression equations suggested the field-dependent children seek more emotional reassurance from their mothers at both times of observation than field-independent children. The data did not provide support for the idea that mothers' proximal and distal behaviors towards their children influenced the early development of field independence.

Child Development↗

PubMed1995

Spatial exploration in transgenic mice expressing human beta-S100.

beta-S100 is a calcium-binding protein in the CNS which is involved in the development of the nervous system. In addition, it has been postulated to play a role in long-term potentiation (LTP) in the hippocampus. To test its role in behavior related to hippocampal function, the gene was overexpressed (80 copies) in CD-1 transgenic mice, and the exploration of a novel environment was examined in two experiments. In both experiments subjects' exploratory behavior was observed in an open-field arena containing four objects. No differences in emotional behavior were found between transgenic mice and their controls as measured by the subjects' motility, defecation, and urination. The results of Experiment 1 revealed that transgenic mice explored objects significantly less than the controls, and they did not respond overtly to the spatial change after object displacement. The control CD-1 subjects, on the other hand, showed increased selective reexploration of the displaced object. The results of Experiment 2 replicated the findings of Experiment 1 and revealed more subtle differences in object exploration between the groups. Transgenic mice climbed objects less often and they had longer latencies of object approach than normal CD-1 mice. The study suggests the possible involvement of beta-S100 protein in general exploratory behavior, which includes learning of spatial characteristics of the environment. Specifically, the overexpression of the beta-S100 gene seems to affect the subjects' reactivity to the arousal-inducing properties of novel stimuli.

Animals↗

PubMed1983

Location response to a startling noise depends on the preferred grooming site in mice.

The exploratory behavior of adult male Balb/c mice was observed in both a small black box and an open field. The normal exploratory pattern included a strong tendency to groom in a preferred place (G-site); thus, an average of 86% (black box) and 92% (open field) of the total grooming time was spent in a single location, specific for each animal and environment. The response of the animals to a 2-sec, 100 dB auditory stimulus varied according to their location. If the unexpected sound occurred when the mice were in their G-site, they remained there an average of 67% (black box) and 75% (open field) of the trials. If elsewhere, they escaped and ran to their G-site 89% (black box) and 73% (open field) of the times. Mice treated with diazepam (5 mg/kg) showed the normal tendency to groom in a preferred place, but never escaped after the stimulus, even if it occurred when they were outside their G-site, nor did they resume normal exploratory behavior. It seems that the preferred grooming location is the place that serves as a refuge from an aversive noise signal, but only the latter behavior is abolished by diazepam, presumably by reduction of stress.

Animals↗

PubMed2003

The effects of PACAP and PACAP antagonist on the neurobehavioral development of newborn rats.

Recent studies show that pituitary adenylate cyclase activating polypeptide (PACAP) plays an important role in the development of the nervous system. The aim of the present study was to investigate the effects of PACAP38 and the PACAP antagonist PACAP6-38 on the development of neonatal behavior in rats. Pups were treated subcutaneously until day 14, a period during which the blood-brain barrier is not yet complete. Rats were tested daily for the appearance of physical features, sensory and motor neurological signs, and for exploratory behavior on days 14 and 21. Facial development and most neurological signs were accelerated by PACAP treatment, while anti-PACAP retarded ear unfolding, eye opening, hindlimb placing and righting reflex. PACAP-treated animals also showed altered behavior in the open-field, in particular at 3 weeks of age. The number of areas entered and rearings were much higher than in the vehicle-treated group, and they spent less time along the walls and in corners. Anti-PACAP had little effect in the exploratory behavior of the pups. In summary, these data provide additional evidence for the neurotrophic effects of both endogenously present and exogenously administered PACAP-38.

Animals↗

PubMed2001

Haptic discrimination of size and texture in squirrel monkeys (Saimiri sciureus).

The present study analyzed haptic abilities of four squirrel monkeys. Using a two-alternative forced-choice procedure, stimuli were presented in a visually opaque box, allowing unrestrained test subjects to grab through a small opening and touch the discriminanda. Difference thresholds were determined by a modified method of limits. In the first experiment we determined size difference thresholds for the discrimination of circular cylinders using standard stimuli differing in diameter from 10 mm to 35 mm. In the second experiment a texture difference threshold was obtained for the discrimination of grooved surfaces (groove width 2-7 mm). The squirrel monkeys achieved a mean size difference threshold of 8% stimulus difference. The linear increase of absolute thresholds as a function of the starting stimulus size showed that haptic size discriminations in squirrel monkeys correspond to Weber's law. Three of the animals achieved a texture difference of 10% stimulus difference, while one monkey showed a distinctively lower haptic acuity. An analysis of the exploratory behavior points to a subject-related difference in the significance of cutaneous and kinesthetic information during size discriminations. Whereas differences in the animals' exploratory behavior did not correlate with the size difference threshold a subject achieved, different thresholds for texture discrimination can be explained by the different exploratory procedures the monkeys used to touch grooved surfaces. The low difference thresholds determined for the squirrel monkeys in the present study point to the significance of unrestrained test conditions for the assessment of the haptic capacity of a species.

Animals↗

PubMed1998

Prenatal ethanol exposure differentially alters behavior in males and females on the elevated plus maze.

Rodents prenatally exposed to ethanol demonstrate hypothalamic-pituitary-adrenal and behavioral hyperactivity to a variety of stressful situations. The present study examined both behavioral and corticosterone (CORT) responses to the elevated plus maze (+-maze), an anxiety- or fear-provoking task. Sprague-Dawley male and female offspring from fetal ethanol-exposed (E), pair-fed (PF), and ad libitum-fed control (C) groups were tested at 60 to 90 days of age. In experiment 1, behavior was measured in animals exposed to the +-maze for 5 min on two consecutive days; 2 weeks later, both behavioral and CORT responses were measured in animals confined to the open and closed arms of the maze for 20 min. In experiment 2, animals were placed in an open field (OF) for 5 min before a single 5-min exposure to the +-maze. Factor analysis of the scored behaviors from the two experiments indicated two main factors, designated "exploration" and "fear." E males and females both exhibited higher levels of exploratory behaviors when placed directly on the +-maze from their homecages without prior exposure to the OF, compared with C males and females. In addition, when confined to the closed arms of the +-maze, E males and females demonstrated higher levels of activity, compared with C males and females. After OF exposure, however, both E males and females demonstrated lower levels of exploratory behaviors than C males and females, and E females also had increased CORT levels, compared with PF and C females. Interestingly, E females, but not E males, showed an increase in fear-related behaviors on the +-maze, compared with controls, regardless of prior OF exposure. These data demonstrate that prenatal ethanol exposure may differentially affect both behavioral and hormonal responses of males and females in an aversive behavioral task and suggest that there may be a sex difference in the sensitivity of the mechanism(s) underlying these responses.

Animals↗

PubMed2004

Alterations in opioid system of the rat brain after cat odor exposure.

The effect of cat odor exposure was studied on morphine-induced increase of exploratory behavior and on the expression of opioid genes in forebrain structures of male Wistar rats. Treatment with morphine (1 mg/kg) induced a significant increase in exploratory behavior in an unfamiliar environment in rats. Previous exposure of animals to cat odor completely abolished this stimulating action of mu-opioid receptor agonist on exploratory activity. Cat odor exposure induced a significant increase in the expression of pro-opio-melanocortin (POMC) and mu-opioid receptor (MOR) genes in the brain structures related to anxiety and motivation. This study clearly demonstrates that cat odor exposure increases the activity of opioid system in rat forebrain structures.

Analgesics, Opioid↗