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PubMed1990

[The effect of diazepam on exploratory behavior and its strain differences in inbred rats].

The effect of diazepam on exploratory behavior was investigated in two inbred strains of rats, Fischer 344 (F344) and Lewis (LEW). The total numbers of head-dips and head-dipping duration in the rat hole-board test, and the total number of rearing and locomotor activity in the open-field test were measured after diazepam administration. The numbers of head-dips and rearings, and head-dipping duration and locomotor activity in naive F344 were significantly greater than those in naive LEW (P less than 0.001), suggesting that LEW is more emotional than F344. Diazepam, 0.31 and 0.63 mg/kg for F344 and 0.31-1.25 mg/kg for LEW, increased head-dips, head-dipping duration and rearings. However, there were no strain differences in enhancing effect of diazepam on locomotor activity. On the contrary, higher doses of diazepam, 0.94-2.50 mg/kg for F344 and 2.50 mg/kg for LEW, decreased head-dips, head-dipping duration, and rearings. However, the effect of diazepam on rotarod performance in LEW was similar to that in F344. These results suggest that F344 is more sensitive to sedative effect of diazepam than LEW, and that the sensitivity to diazepam may be strongly influenced by genetic factors.

Animals↗
PubMed1990

Computer analysis of the exploratory behavior of insects and mites in an olfactometer.

A method of quantification of the exploratory behavior of small animals stimulated by an odorant in a four-choice olfactometer, taking into account the interindividual variability of responses, was developed: individual tracks were time sampled according to the animal's walking speed and its positions were recorded according to the X-Y coordinates of the grid set underneath the device, the mesh of the grid suiting the animal's body size. A software, written in BASIC APPLESOFT on an APPLE IIe computer, allowed us to analyze the coordinates either of a single individual or of an experimental sample, leading to: a) the quantification of the insect distribution all over the experimental chamber, expressed in a table numbered according to the grid, where the percentage of position per square either for a given time fraction or the total observation period were reported, b) a graphic representation of the data according to several levels of greys, expressing the frequentation for each square for a given duration of observation. An analysis per time fraction allowed the chronological setup of events to appreciate. c) The collection of the positions among each flow field of the olfactometer for each individual of the experimental sample, for a given duration, was translated as the percentage of time spent in each flow field. Data files gathered these percentages for further statistical treatments. This computer method, which requires little equipment and appears to be easily adaptable to the study of biological models of various size and speed such as honeybees, trichogrammas and varroas mites, is a powerful tool for behavioral studies of small organisms tested in restricted areas.

Animals↗
PubMed1988

Exploratory behavior and reaction to novelty in rats with hippocampal perforant path systems disrupted.

In this article, exploratory behavior and reaction to novelty were investigated in rats with either disruption of the total hippocampal perforant path projection (TPP), the medial perforant path (MPP), or lateral perforant path (LPP). All three experimental groups displayed increased locomotor activity, and the LPP group was even more active than the TPP and MPP groups. The TPP and LPP animals made more rearings than the control rats. The MPP and LPP groups exhibited less exploration of familiar objects than the TPP and control groups. TPP animals appeared unable to recognize novelty, LPP rats showed decreased preference for novelty, and MPP rats had only a slight deficit in recognition of novelty. It is suggested that perforant path disruptions reduce the hippocampal formation's access to sensory information of neocortical origin.

Animals↗
PubMed1985

Exploratory behavior of two species of murid rodents, Acomys cahirinus and Mus musculus: a comparative study.

The exploratory behavior of two species of murid rodents, Acomys cahirinus and Mus musculus, was compared in four experiments: In the first, the responses of the two species to a novel arena were studied. Mus was found to take longer to enter the arena, and to spend more time in the relatively familiar or safer start box, than was Acomys. The results suggest that Acomys may persevere longer in exploring particular areas, whereas Mus appear to explore in the open arena by using frequent shifts of attention. The second experiment investigated species differences in response to the addition of a small novel object. Although the species did respond differently, the major species differences seemed to be related more to the open arena than to the object. The third experiment tested the hypothesis that both species would explore more if there was somewhere to hide (e.g., an artificial burrow) than if there was not. It was found that Acomys treated the available artificial burrow as another novel object, while Mus, as predicted, spent more time hiding inside it than did Acomys. The fourth experiment investigated burrow use when a model "predator" was introduced: Both species increased their use of the burrow but some species differences were found. Mus responded to the model more by freezing, or running immediately into the burrow; Acomys responded more by fleeing.

Animals↗
PubMed1988

Intra-amygdala injections of corticotropin releasing factor facilitate inhibitory avoidance learning and reduce exploratory behavior in rats.

The effects of intra-amygdala injections of corticotropin-releasing factor (CRF) on memory and exploratory behavior in rats were examined in the present study. Rats with chronically implanted cannulae received intra-amygdala injections of vehicle or CRF at a dose of 0.01, 0.1 or 1.0 micrograms, either immediately after the inhibitory avoidance training or prior to the open field activity test. Results indicated that while CRF at low (0.01 microgram) and high (1.0 micrograms) doses produced no significant effect on retention or exploration, immediate post-training intra-amygdala injections of CRF at the medium dose (0.1 microgram) significantly improved retention of the inhibitory avoidance response. The same dose of CRF, given shortly prior to the open field activity test, decreased locomotor activity, rearing and hole-poke responses in rats. These results suggest that the amygdala is one of the anatomical loci involved in CRF modulation of memory processing and exploration in rats. The implication of CRF in mediating the influences of stress on behavior is discussed.

Amygdala↗
PubMed1985

Effects of nicotine on exploratory behavior in rats: correlation with regional brain monoamine levels.

The results of a dose-response study of the effects of nicotine on exploratory behavior in male rats is reported. Nicotine at 0.5 mg/kg elevated locomotor activity without significantly changing other parameters of exploration. Low-dose nicotine (0.2 mg/kg) did not produce any effect on exploration measures, while high-dose nicotine (0.8 mg/kg) produced a state of ataxia in animals and decreased most exploration measures in general. Additional, nicotine at high doses seems to reduce the animal's state of fear/anxiety, while at low dose the drug seems to increase the animal's level of curiosity in a novel environment. Biochemically, nicotine has been found to accelerate dopamine synthesis and norepinephrine turnover, and to decrease serotonin turnover. More importantly, the amino acid precursors tyrosine and tryptophan were found to be the neurochemical measures most related to the behavioral changes produced by nicotine.

Animals↗
PubMed1979

Effects of maternal interference on the attachment and exploratory behavior of one-year-olds.

Effects of maternal interference on social behavior toward mother and exploratory play were examined in a laboratory experimental paradigm. Subjects were 40 1-year-olds and their mothers. Mothers of the 20 interference-group infants were instructed periodically to physically interfere with their child's independent object play during the first half of the observation session. A postinterference free-play period immediately followed. The 20 control-group infants were permitted by mother to play freely throughout the session. Groups were matched for exposure to play materials. Despite its aversiveness, interference had no subsequent effect on infant social initiatives to mother, responsiveness to mother's social bids, or exploratory play.

Exploratory Behavior↗
PubMed1987

Exploratory behavior and the dual activity of some psychoactive drugs: Part II.

Exploration is an essential, life-preserving component of animal higher nervous functions. The experiments presented here show that exploratory behavior may differ according to the experimental subject's emotional baseline, and that exploratory performance is accordingly affected differently by some nutrients and central stimulants.

Animals↗
PubMed1989

Genetic control of hippocampal cholinergic and dynorphinergic mechanisms regulating novelty-induced exploratory behavior in house mice.

Neurobehavioral genetics endeavors to trace the pathways from genetic and environmental determinants to neuroanatomical and neurophysiological systems and, thence, to behavior. Exploiting genetic variation as a tool, the behavioral sequelae of manipulating these neuronal systems by drugs and antisera are analyzed. Apart from research in rats, this paper deals mainly with the genetically-influenced regulation in mice of exploratory behaviors that are adaptive in novel surroundings and are hippocampally-mediated. Special attention is paid to neuropeptidergic, GABAergic, and cholinergic synaptic functions in the mouse hippocampus. The behaviorally different inbred mouse strains C57BL/6 and DBA/2 show opposite reactions (reductions and increases, respectively, in exploration rates) to peripheral and intrahippocampal injections with agents that interfere with peptidergic, cholinergic, and GABAergic neurotransmission. These findings can be explained by an interdependent over-release of opioids, arrested GABA release, and excess acetylcholine in the hippocampal neuronal network of DBA/2 mice, as compared to C57BL/6 mice where these systems are functionally well balanced. Very similar results have been obtained with the lines SRH and SRL, derived from C57BL/6 and DBA/2, and genetically selected for rearing behavior. Most probably, the opioids act to disinhibit exploratory responses. An additional genetic approach is mentioned, in which four inbred mouse strains and one derived heterogeneous stock are used for estimating genetic correlations between structural properties of the hippocampal mossy fibers and levels of hippocampal dynorphin B, on the one hand, and frequencies of exploratory responses to environmental novelty, on the other.

Animals↗
PubMed1991

Reduction of exploratory behavior by intraperitoneal injection of interleukin-1 involves brain corticotropin-releasing factor.

The behavior of mice was scored in a multicompartment chamber one hour following intraperitoneal injection of recombinant human interleukin-1 (IL-1). Both IL-1 alpha and IL-1 beta dose-dependently reduced the mean duration for which mice were in contact with novel stimuli without altering measures of locomotor activity, such as movements between the compartments or rears. These behavioral changes resemble those previously observed with prior restraint or intracerebroventricular (ICV) injection of corticotropin-releasing factor (CRF). Effective doses were in the range 0.1-10 ng for IL-1 alpha, and 1-10 ng for IL-1 beta. The reduction in stimulus-contact times induced by 1 ng of IL-1 beta was reversed by prior ICV injection of the CRF antagonist, alpha-helical CRF9-41, suggesting that IL-1 causes secretion of brain CRF which in turn elicits the behavioral changes. These results indicate that peripheral administration of IL-1 alpha or IL-1 beta in low doses can alter behavior. They provide additional evidence that IL-1 administration stimulates brain CRF secretion, and that brain CRF can modulate exploratory behavior, and thus reinforces the concept that IL-1 administration can induce stress.

Analysis of Variance↗
PubMed1986

A differential sex effect of amphetamine on exploratory behavior in maturing mice.

The effects of amphetamine (5-20 mg/kg) were studied 60 min after injection in mice aged 2, 3, 4 and 6 weeks postpartum. Exploratory behavior as indicated by the "head poke" test was depressed at all ages, but appeared to be relatively uncomplicated by other effects at the 5 mg/kg dose. At 4 and 6 weeks control females showed significantly greater activity than males, and amphetamine produced a greater reduction for control levels than in males.

Age Factors↗
PubMed1987

A corticotropin-releasing factor antagonist reverses the stress-induced changes of exploratory behavior in mice.

Corticotropin-releasing factor (CRF) administered intracerebroventricularly (ICV) to rats and mice has been shown to elicit a variety of behaviors resembling those that occur in stress. In a novel multicompartment chamber, ICV CRF altered the behaviors in a manner closely resembling that observed following a period of restraint. In particular, 75 ng CRF ICV or 30-40 min restraint markedly reduced the time mice spent in contact with novel stimuli. ICV injections of a peptide antagonist of CRF, alpha-helical CRF9-41 (ahCRF), reversed the effects of restraint on this measure. This effect of ahCRF was dose dependent, with a minimal effective dose of 10 micrograms. Other behavioral measures appeared normal, and ahCRF did not significantly alter the stimulus-contact time in unrestrained mice. These results provide strong evidence to support the hypothesis that endogenous CRF may be a factor affecting stress-induced changes in exploratory behavior in mice.

Animals↗