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PubMed2006

Effects of novelty on behavior in the adolescent and adult rat.

Adolescence is a time of high-risk behavior and increased exploration. This developmental period is marked by a greater probability of initiating drug use and is associated with an increased risk to develop addiction and dependency in adulthood. Human adolescents are predisposed towards an increased likelihood of risk taking behaviors (Zuckerman, 1986), including drug use or initiation. The purpose of the study was to examine differences in developmental risk taking behaviors. Adolescent and adult animals were exposed to a novel stimulus in a familiar environment to assess impulsive behaviors, novelty preference, and exploratory behaviors. Adolescent animals had greater novelty-induced locomotor activity, greater novelty preference, and showed higher approach and exploratory behaviors compared to adult animals. These data support the notion that adolescents may be predisposed toward sensation seeking and consequently, are more likely to engage in risk-taking behaviors, such as drug use initiation.

Age Factors↗

PubMed1997

Handling and isolation in three strains of rats affect open field, exploration, hoarding and predation.

Male albino (Al), brown hooded (Br) and black hooded (Bl) rats were raised in social isolation or in pairs, with or without systematic handling. At 90 and 180 days of age, the animals were individually tested for activity in an open field (Of), exploratory behavior in a complex environment, food hoarding (Hd) and insect predation (Pd). Multivariate analysis of the results showed significant influences of all three factors (strain, handling and social isolation) and interactions among them. Strain affected Of, Hd and Pd, with contrastingly high performances of Br in Of, Al in Hd and Bl in Pd. Handling increased Of and exploration scores in both test series. Isolation induced higher performances in all the four behaviors in the second test series. Accentuated and stable individual differences occurred in the performances off all the behaviors. The results emphasize the subtleness and complexity of the interplay of genetic and environmental influences and stress the independence of the regulatory processes of different behaviors.

Animals↗

PubMed1978

Effects of amphetamine and haloperidol on avoidance behavior and exploratory activity.

The effect of graded doses of D-amphetamine and haloperidol were tested on retention of a one trial learning passive avoidance response, on extinction of pole-jumping active avoidance behavior and on open-field activity. Low doses of amphetamine (10 microgram/animal) increased passive avoidance latency when given s.c. 1 h prior to the retention test. Higher doses (20 and 1000 microgram/animal) caused a bimodal distribution of avoidance latencies. Haloperidol (0.03 or 1.0 microgram/animal) significantly attenuated passive avoidance behavior. Amphetamine caused a delay of extinction of pole-jumping avoidance behavior in a dose-dependent manner (10, 30 or 90 microgram per rat). Conversely, haloperidol induced a dose-dependent facilitation of extinction (0.03 or 0.1 microgram per rat). Open-field activity was not significantly affected by 30 microgram amphetamine or 0.03 microgram haloperidol; 90 microgram amphetamine significantly increased rearing activity and 0.1 microgram haloperidol decreased ambulation. The data show that passive and active avoidance behavior are sensitive measures to test the activity of psychomotor stimulant and neuroleptic drugs. Exploratory behavior allows more specific behavioral effects to be dissociated from locomotor influences.

Animals↗

PubMed2000

Phencyclidine-induced abnormal behaviors in rats as measured by the hole board apparatus.

RATIONALE: Phencyclidine (PCP) and methamphetamine (MAP) are known as psychotomimetic agents. Both agents produce behavioral alterations in animals. OBJECTIVE: The present study investigated the difference in behavioral alterations in rats induced by these two psychotomimetic agents using the hole board apparatus (HBA). In addition, mechanisms underlying PCP-induced behavioral changes were also investigated. METHODS: After the administration of PCP (1-4 mg/kg SC) or MAP (1-4 mg/kg SC), locomotor activity and dipping behavior were assessed using HBA. Effect of selective NMDA antagonists, (+)MK801 and 3-((+/-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP), on rat behaviors were also assessed. The effects of D-alanine (D-Ala), a coagonist of NMDA receptors, or neuroleptics, haloperidol, clozapine and risperidone, on PCP-induced behavioral changes were investigated. RESULTS: PCP increased locomotor activity and decreased exploratory behaviors of rats in HBA. On the other hand, MAP increased locomotor activity but did not decrease exploratory behaviors. (+)MK-801 produced hyperactivity as well as decreased exploratory behaviors, eliciting behavioral changes very similar to those of PCP. CPP decreased the exploratory behavior but failed to produce hyperactivity. D-Ala attenuated both behavioral changes induced by PCP. Three neuroleptics tested here inhibited hyperactivity but did not attenuate decreases in exploratory behavior. CONCLUSION: These results suggest that PCP-induced decrease in exploratory behavior are attributable to antagonism of NMDA receptors and may not involve dopaminergic transmission via D2 receptors.

Alanine↗

PubMedDate not supplied

Neurobehavioral effects of the pyridinium aldoxime cholinesterase reactivator HI-6.

A series of neurobehavioral testing procedures was used to evaluate the behavioral effects of the pyridinium aldoxime cholinesterase reactivator HI-6 in male Sprague-Dawley rats. These procedures were fixed-ratio (FR) responding, shuttle-box conditioned avoidance response (CAR), conditioned taste aversion (CTA), drinking behavior, open-field exploratory behavior, negative geotaxis, and wire suspension time. Dose-response studies of HI-6 at dose-levels of 25, 50 and 100 mg/kg, or saline (IP) were evaluated. HI-6 disrupted FR responding in a dose-dependent fashion, with significant effects occurring at doses of 50 and 100 mg/kg. The pattern of disruption was characterized by extended periods of nonresponding having an abrupt onset and offset. HI-6 produced CTA in a dose-related manner, with significant effects at doses equal to those that disrupted FR performance. HI-6 did not alter CAR, drinking motivation, exploratory behavior, negative geotaxis, or wire suspension time. These data suggest that there may be a commonality in the underlying mechanism(s) for the disruption in FR performance and the induction of the CTA. This mechanism may relate to the presumed drug-induced adverse internal state inducing the CTA.

Analysis of Variance↗

PubMed1991

Individual differences in behavioral measures: correlations with nucleus accumbens dopamine measured by microdialysis.

Rats were placed in one of two novel test environments for behavioral observation. In one, exploratory behavior (assessed by hole pokes) and locomotion were assessed during a 10-min test session. In the other, the chewing of varied objects on the cage floor was rated over a 20-min session. Within 2-18 days, animals were anesthetized and microdialysis probes were implanted into the nucleus accumbens for measurement of basal and d-amphetamine-stimulated levels of dopamine (DA). These measures were then correlated with the individual behavioral rating collected earlier from the drug-free animals. We found a significant correlation between duration of exploratory behavior and amphetamine-induced DA release. Locomotor activity did not correlated with either basal or amphetamine-stimulated DA release. Duration of chewing episodes correlated with basal levels of DA, as well as with amphetamine-induced DA release. Our studies indicate that differences in the dopaminergic responsivity of the nucleus accumbens (or other circuitry influencing nucleus accumbens DA function) may contribute to individual differences in certain behaviors displayed by the animals when placed in a novel environment.

Amphetamine↗

PubMedDate not supplied

Longterm effects of early cadmium exposure on locomotor activity in the rat.

The present study investigated the hypothesis that changes in the frequency of specific behaviors, not assessed by the traditionally employed global measures of locomotor activity, may occur following exposure to cadmium. Two groups of newborn male rat pups were treated orally with either 1.0 mg/kg CdCl2 for 14 days or 10.0 mg/kg CdCl2 for one day followed by 13 days of the treatment vehicle only. A control group received only the vehicle. At 50 days of age, animals were observed in their home cage for 12 hours and the amount of time spent engaged in each of eight separate categories of behavior was recorded. Subsequently, exploratory behavior in an open field was assessed. The single large dose of cadmium resulted in weight loss and a significantly slower growth rate significantly increased rearing in the home cage and significantly decreased inner square exploratory behavior in the open field. Implications of emotional hyporeactivity and physiological explanations which may account for the differences observed between the two treatment regimens are discussed.

Animals↗

PubMed1997

Role of medical conditions in the exacerbation of self-injurious behavior: an exploratory study.

Self-injurious behavior (SIB) is common among people with severe mental retardation who may also have multiple complex medical problems coupled with communication difficulties. This combination of factors sometimes makes it difficult to obtain accurate and detailed medical histories. In this exploratory descriptive study of 25 patients with SIB, 28% had previously undiagnosed medical conditions that could be expected to cause pain or discomfort. Six of the 7 patients experienced decreased SIB with treatment of their medical conditions. In patients with SIB, impaired communication skills, and complex medical histories, medical conditions that may be associated with pain or discomfort must be a consideration in determining the etiology of the SIB.

Adolescent↗

PubMed2006

Effect of intrauterine position on sex differences in the gabaergic system and behavior of rats.

In multiparous species such as the rat (in this case the albino Wistar strain), steroid influence during fetal growth is affected by the relative intrauterine position of male and female fetuses and is stronger when the potential effects of contiguity and caudal position are combined. The effect of intrauterine position on gonadal steroid levels in neonatal and adult animals was examined using radioimmunoassay techniques. Since the organizing effect of prenatal steroids may influence the postnatal GABA content, HPLC was used to determine the gabaergic content in several hypothalamic and limbic areas in the adult rat. The effects of intrauterine position on adaptive behavior were examined by recording exploratory behavior (using the corridor and hole board tests) and intraspecific aggression (induced by isolation). Female pups influenced by males during development produced more testosterone. In adult males, those that developed closer to the cervix (and with no influence from other fetuses) produced more testosterone and less estradiol. The same animals also produced more hypothalamic GABA and showed greater exploratory capacity. No significant differences were seen between any experimental groups with respect to aggression. These results show increased variability between males with respect to adult exploratory behavior, and in the neurochemical and endocrine systems involved, due to intrauterine position during development. The effect of this physiological phenomenon on the structure of rodent populations is discussed.

Aggression↗

PubMed2006

Intrathecal administration of a cylcooxygenase-1, but not a cyclooxygenase-2 inhibitor, reverses the effects of laparotomy on exploratory activity in rats.

Studies of hypersensitivity to mechanical stimuli after incisional surgery suggest that cyclooxygenase (COX)-1, but not COX-2, in the spinal cord participates in postoperative pain. In the current study, we sought to determine the role of COX isoenzymes after laparotomy, examining spontaneous exploratory behavior rather than withdrawal reflexes. Adult male Sprague-Dawley rats underwent subcostal laparotomy surgery under isoflurane anesthesia or received anesthesia without surgery. Exploratory locomotor activity was measured on the first postoperative day after intrathecal injection of dimethyl sulfoxide (vehicle) or COX-1 (SC-560) or COX-2 (NS-398) inhibitors. Laparotomy reduced ambulation, rearing, and rapid small movements (stereotypy) similarly in animals without intrathecal catheters and those receiving intrathecal vehicle control. SC-560 produced a dose-related return to normal exploratory behavior with complete return at doses of 20 mug and larger. In contrast, NS-398 in doses up to 50 mug failed to increase exploratory behavior. These data with exploratory behavior and laparotomy agree with studies with reflexive withdrawal responses after incisional surgery and indicate that COX-1 inhibition reduces pain responses after surgery. Spinal COX-1 inhibition completely restores exploratory activity, including rearing behavior that stretches the abdominal muscles. These data suggest that targeting COX-1 in the spinal cord may produce postoperative analgesia.

Animals↗

PubMed1998

Effects of hallucinogens on locomotor and investigatory activity and patterns: influence of 5-HT2A and 5-HT2C receptors.

The 5-HT2A and 5-HT2C antagonists MDL 100,907 and SER-082 were tested with the 5-HT2A/C agonist DOI and the 5-HT1A/2A/2C agonist LSD in the Behavioral Pattern Monitor, which provides multiple measures of locomotor and investigatory activity. Previous investigations have shown that these measures load onto three independent behavioral factors: amount of activity, exploratory behavior, and behavioral organization. Rats pretreated with saline, MDL 100,907 (0.25-2.0 mg/kg), or SER-082 (0.5-1.0 mg/kg) were treated with saline, 0.25 mg/kg DOI, or 60 micrograms/kg LSD. All effects of DOI were blocked by all doses of MDL 100,907, but only by the highest dose of SER-082. While the effects of LSD on activity and exploratory behavior were largely unaffected, either pretreatment antagonized the effects of LSD on behavioral organization. Thus, all of these effects of DOI were attributable to 5-HT2A receptors, whereas the effect of LSD on behavioral organization was influenced by both 5-HT2A and 5-HT2C receptors.

Amphetamines↗

PubMed1979

Opiate stimulation increases exploration in the mouse.

Adult male Swiss-Webster mice were injected with a low dose of morphine sulfate or vehicle and placed in an apparatus which allowed the assessment of exploratory behavior. Two measures of exploration (rearing, nose poking) were recorded during a single brief exposure. Both exploratory behaviors increased after drug treatment. This suggests opiate involvement in behavioral arousal, and more specifically, in exploratory behavior.

Animals↗

PubMed2006

Pharmacological and genetic influences on hole-board behaviors in mice.

Head dipping on a hole-board is frequently used as an indicator of exploratory tendencies in rodent studies. Drugs with diverse pharmacological properties alter head dipping suggesting that many neurotransmitter systems are involved in the expression of exploratory behavior. The aim of the current experiments was to determine the effects of several drugs from different classes on head dipping, and to compare the effects of some of these agents in lines of mice that have been selectively bred for divergent expression of head dipping on a hole-board. In the current experiments, the effects on head dipping of three doses each of fluoxetine, desipramine, GBR-12909, methamphetamine, pentylenetetrazol, and diazepam were evaluated in genetically heterogeneous mice. Most drugs altered the number of head dips in a predictable manner, but the effects on locomotion were generally as large as those seen for head dipping. Locomotion could completely account for the effects of fluoxetine and pentylenetetrazol, and to a lesser extent, diazepam. We have also developed replicate lines of mice selectively bred for high (High Exploratory Behavior: HEB) or low (Low Exploratory Behavior: LEB) head dipping on a hole-board and evaluated the effects of diazepam and methamphetamine on hole-board behaviors in these mice. Diazepam increased head dipping and locomotion equivalently in both lines of mice, but methamphetamine stimulated locomotion in HEB mice more than in LEB mice. These results broadly suggest that the effects of most drugs we tested are not specific for head dipping, since almost all drugs tested affected head dipping and locomotion equivalently. However, the results with the genetically heterogeneous mice and HEB and LEB mice suggest that some aspects of the dopaminergic system are involved in head dipping.

Animals↗

PubMed1979

Effects of a histamine synthesis inhibitor and antihistamines on the sexual behavior of female rats.

Intraventricular administration of alpha-hydrazinohistidine, a histamine synthesis inhibitor, at different doses and times before testing produced a significant decrease of lordotic responses and sexual receptivity in ovariectomized estrogen plus progesterone-primed female rats. The H1-antihistamines pyrilamine and chlorfeniramine and the H2-antihistamine metiamide, injected in the lateral ventricle, significantly decreased the lordosis quotient but did not modify receptivity; antihistamine-injected rats showed no soliciting behavior. Exploratory activity was decreased by both alpha-hydrazinohistidine and metiamide but not by the H1-antihistamines. It is concluded that treatments which either deplete histamine or block their receptors can alter female copulatory responsiveness. The mechanism of this antihistamine effect appears to be unrelated to that of other side effects, such as motor impairment, sedation, or local anesthesia.

Animals↗

PubMed2004

The topography of three-dimensional exploration: a new quantification of vertical and horizontal exploration, postural support, and exploratory bouts in the cylinder test.

The study of exploratory behavior in confined spaces can provide insights into both the spatial and the motor behavior of animals. In the present study, the behavior of rats placed inside of a cylinder (the cylinder test) for 5 min was examined to uncover: (1) the overall organization of exploratory behavior, (2) pattern of movement on the horizontal surface, (3) pattern of movement on the vertical surface, and (4) supporting and stepping movements. The results show that exploratory behavior is organized into a number of bouts of lateral and vertical scans with each bout ending by movement arrest and face washing. Within bouts, activity consists of alternating horizontal and vertical progressions that vary systematically over the course of a bout. Horizontal progressions consist of head scans, turning, and stepping, and decrease in amplitude across a bout. Vertical progressions consist of rears, head scans, and descent with an amplitude expressed by an inverted-U across bouts. Each horizontal and vertical progression is directed toward a different portion of the cylinder and the direction of lateral movements alternate within progressions and between progressions. For each rat, bouts tended to end in the same location suggesting the establishment of a home base. Eshkol-Wachmann movement analysis indicates that during progressions, the forepaws are mainly used for postural support and follow forequarter movements, while upward, downward, and sideward shifts in body weight are generated from the hind limbs. These findings illustrate that in even brief exploratory tests the three-dimensional exploratory behavior of rats is organized. The results are discussed in relation to the use of the cylinder test for analyzing a number of behaviors including exploration, locomotion, and supporting reactions.

Animals↗

PubMed1987

Interaction between chronic stress and clomipramine treatment in rats. Effects on exploratory activity, behavioral despair, and pituitary-adrenal function.

The interaction between the effects of chronic electrical tail shock and clomipramine (CMI) on exploratory activity, behavioral despair and pituitary-adrenal function was studied in adult male rats. Both CMI and shock administered alone significantly reduced exploratory activity in a novel environment (holeboard). Neither interaction nor additive effects were observed when the two treatments were combined. In contrast, chronic shock increased the immobility in the forced swimming test (behavioral despair) and this effect was completely prevented by concomitant CMI administration. Pituitary-adrenal function was not significantly influenced by any of the treatments. The results indicate that: (a) chronic CMI treatment prevented some but not all behavioral changes caused by chronic shock, and (b) no interaction with basal and stress levels of pituitary-adrenal hormones was observed.

Adrenocorticotropic Hormone↗

PubMed1985

Behavioral perturbations in the vitamin K-deficient rat.

Anecdotal observations of the behavior of rats with a vitamin K-deficiency suggested that this deficiency was associated with hypoactivity, general malaise, and a lack of exploratory behavior. These observations were pursued by assessing locomotor activity in a circular photocell-monitored track, open-field activity, and radial-arm maze performance in rats rendered vitamin K-deficient by dietary depletion or by warfarin treatment. There was a significant reduction (approximately 25% at the median) in the locomotor activity of dietary vitamin K-deficient rats compared with rats fed a control diet. In the open-field, warfarin administration was associated with a significant shift from more exploratory behaviors to less exploratory behaviors. Consistent with these findings, radial-arm maze assessment showed a comparative reduction in locomotor activity in the dietary vitamin K-deficient rats with no alteration in performance, i.e., short-term memory. These animal behavioral studies suggest that sub-clinical and clinical vitamin K-deficiency may contribute to physical and psychiatric symptomatology.

Animals↗

PubMed2004

Reduced anxious behavior in mice lacking the CCK2 receptor gene.

Cholecystokinin 2 (CCK2) receptors have been implicated as mediators of anxiety in standard mouse models such as exploratory behavior both in black and white test boxes and in elevated plus-mazes. We investigated the role of the CCK2 receptor in anxiety by evaluating the behavior of mice lacking the gene for this receptor in these standard anxiety models (i.e., exploratory behavior in a black and white test box and exploratory behavior in an elevated plus-maze). In the black and white test box, mice lacking the CCK2 receptor gene showed significantly increased numbers of transitions between the boxes compared to control mice. In the elevated plus-maze, mice lacking the CCK2 receptor gene displayed significantly more head dips than control mice. These results suggest that mice lacking the CCK2 receptor gene are less anxious than normal mice.

Analysis of Variance↗