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PubMed1981

Habituation of the head-poke response: effects of an amphetamine-barbiturate mixture, PLG and fenfluramine.

A test situation was developed in which the effects of drugs on habituation of exploratory behavior (head-poke responses) could be assessed independently of their effects on general activity (locomotion and rearing). Habituation, spontaneous recovery from habituation and stimulus specificity of habituation were studied. An amphetamine-barbiturate mixture attenuated habituation of the head-poke response without influencing general activity. Pro-Leu-Gly-NH2 (PLG), an oxytocin fragment, increased locomotor activity and did not alter the course of habituation of the head-poke response. Since exploratory behavior and general activity can be pharmacologically dissociated in the test situation used, it is concluded that the test situation is suitable for studying the effects of drugs on habituation of exploratory behavior. The amphetamine-barbiturate mixture did not influence the stimulus specificity of habituation of the head-poke response. Fenfluramine however increased the effects of stimulus change on the head-poke response while not influencing habituation of this response. These results show that habituation and stimulus specificity of habituation of exploratory behavior can be pharmacologically dissociated.

Amobarbital↗
PubMed2005

High and low rearing subgroups of rats selected in the open field differ in the activity of K+-stimulated p-nitrophenylphosphatase in the hippocampus.

Na(+)/K(+)-adenosinetriphosphatase (Na(+)/K(+)-ATPase) is of paramount importance for the proper functioning of the organism. The enzyme is involved in several aspects of brain function, such as the repolarization of the neuronal membranes and neurotransmitters uptake/release. Therefore, individual differences in the activity of brain Na(+)/K(+)-ATPase may result in differences in the functioning of the brain, which, in consequence, could lead to behavioral divergences. Individual differences in rearing, an exploratory behavior, have been shown to be genetically determined. In rats, the inhibition of the activity of Na(+)/K(+)-ATPase was reported to induce changes in the exploratory behavior. The aim of this work was to verify if subgroups of rats selected according to the number of rearings (high and low rearing subgroups) in the open field test differ in the activity of Na(+)/K(+)-ATPase in brain regions. Adult, male outbred Wistar rats were selected in the open field test according to the number of rearings in subgroups of high (HR) and low (LR) rearing responders. After a rest of about 20 days after the open field session, HR and LR rats were sacrificed. In the first experiment, frontal cortex, striatum, brainstem, hippocampus and the amygdala (including the overlying limbic cortex) were dissected. The reaction of dephosphorylation of Na(+)/K(+)-ATPase (K(+) stimulated p-nitrophenylphosphatase) was assayed in homogenates rich in synaptosomes. The results obtained showed a statistically significant higher activity of K(+)p-nitrophenylphosphatase only in the hippocampus of HR subgroup of rats. This result was replicated in two other subsequent experiments with different HR and LR subgroups of rats selected at different times of the year. Our data suggest that the difference in the activity of Na(+)/K(+)-ATPase in the hippocampus is innate and is involved in the expression of the rearing behavior.

4-Nitrophenylphosphatase↗
PubMed1994

Characterization of benzodiazepine-sensitive behaviors in the A/J and C57BL/6J inbred strains of mice.

Exploratory behaviors as well as pharmacological actions of gamma-aminobutyric acidA (GABAA)/benzodiazepine receptor agonists and inverse agonists were characterized in C57BL/6J and A/J strains of mice. C57BL/6J mice displayed higher levels of exploratory behavior than A/J mice in the light in equilibrium with dark exploration model of anxiety and in an open-field test, suggesting that C57BL/6J mice are less "emotional" and more active than A/J mice, respectively. However, C57BL/6J mice were more sensitive than A/J mice to the anxiolytic effects of diazepam in the light in equilibrium with dark exploration model. In contrast, A/J mice were more sensitive than C57BL/6J mice to the convulsant effects of methyl-beta-carboline-3-carboxylate. C57BL/6J mice showed no evidence of acquisition of a passive avoidance task, while A/J readily acquired this memory task at low levels of footshock. C57BL/6J and A/J mice should be useful parental strains in recombinant inbred lines for investigating the genetic determinants of benzodiazepine-sensitive behaviors and sensitivity to drugs acting on the GABAA/benzodiazepine receptor complex.

Animals↗
PubMedDate not supplied

Hyperactive behavior of rats after lesions of the globus pallidus.

Following bilateral lesions of the globus pallidus, rats living in a residential maze were hyperactive during the 12 hr dark cycle but not during the 12 hr light cycle. Lesioned rats were less exploratory during the light cycle than control rats but not during the dark cycle. Exploratory behavior of rats was photographed for 15 min during the light cycle. The duration of 6 behavior acts was significantly shorter than controls (scratching, grooming, sitting, sniffing, standing and rearing). The number of initiations of grooming, scratching, sniffing and smelling decreased while looking and walking increased in frequency. The linkage of behavior acts into sequences was diminished compared with controls. Similar, but not identical, changes were found when the structure of exploratory behavior of naive rats was compared with the exploratory behavior of experienced rats. It is concluded that naive control rats are hyperactive relative to experienced rats in this exploratory situation and that rats with pallidal lesions display changes in their behavior which are characteristic of hyperactive animals even when other tests under similar conditions, such as exploration during the light cycle in a maze, show the pallidal rats as hypoactive relative to control rats.

Animals↗
PubMed1987

Behavior of young children with Down syndrome before the mirror: exploration.

Exploratory behaviors of Down Syndrome (DS) and Nondelayed (ND) young children between the mental ages of 16 and 32 months were examined in 4 situations involving finding things seen in a large standing mirror: free play, marked face, finding the reflected mother, and finding a reflected toy. Behaviors coded from videotape included observing the self making faces, kissing the mirror, patting the mirror, comparing a person or object with the mirror image, looking behind the mirror, touching own body, and staring at another's image. Both ND and DS children used these behaviors and were able to adapt their choice of behaviors to demands of particular tasks. However, DS and ND children differed in number, type, and frequency of exploratory behaviors. DS children used a greater variety of behaviors and used them more frequently than ND children. DS children used a less focused selection of behaviors, and behaviors involving switching attention were performed only by ND children. For most behavior examined, mental and chronological age were not related to amount of exploration. Results are interpreted in terms of the role of different behaviors in exploration of the mirror.

Body Image↗
PubMed2000

A comparative study of the behavioral patterns of RLA/Verh and RHA/Verh rats in the exploration box.

Roman high- and low-avoidance (RHA/Verh and RLA/Verh) rats differ in their emotionality profiles. As emotional processes are considered to play an important role in exploratory behavior, differences between the Roman sublines in responding to a novel environment can be anticipated. The present study provides a quantitative (based on the frequency of particular responses) and qualitative (based on the frequency of behavioral sequences) comparison of exploratory behavior of RHA/Verh and RLA/Verh rats. Rats of both sexes were tested individually for 30 min in an exploration box containing a few objects. Observation periods were divided, based on earlier studies, into three consecutive blocks of 5, 10, and 15 min, respectively. Analysis of quantitative data showed differences in sniffing (RHA/Verh scoring higher) and in immobility (RLA/Verh scoring higher), both persisting throughout all measurement periods. Males of both sublines were generally more active and exploratory than their respective females. The analysis of sequential data revealed that during the first 5 min RHA/Verh rats showed a less diverse but more exploratory repertoire and that during the first 15 min males of both sublines showed more behavioral sequences than females. This study indicates that the Roman rat sublines should provide a useful model to study the mechanisms of exploratory behavior.

Animals↗
PubMed1999

Locomotor response to MDMA is attenuated in knockout mice lacking the 5-HT1B receptor.

3,4-Methylenedioxymethamphetamine (MDMA) is a psychoactive drug of abuse which is increasingly popular in human recreational drug use. In rats, the drug has been shown to stimulate locomotion while decreasing exploratory behavior. MDMA acts as an indirect agonist of serotonin (5-HT) receptors by inducing 5-HT release by a 5-HT reuptake transporter-dependent mechanism, although it is not known which 5-HT receptors are important for the behavioral effects of the drug. In order to examine the role of specific 5-HT receptors, we assessed the behavioral effects of MDMA on knockout mice lacking the 5-HT1B receptor. Knockout animals show a reduced locomotor response to MDMA, although delayed locomotor stimulation is present in these animals. This finding indicates that the locomotor effects of MDMA are dependent upon the 5-HT1B receptor, at least in part. In contrast, MDMA eliminates exploratory behavior in both normal and knockout mice, suggesting that the exploratory suppression induced by MDMA occurs through mechanisms other than activation of the 5-HT1B receptor. To confirm these findings, we tested the effects of MDMA on the locomotor and exploratory behavior of wild-type mice pretreated with GR 127935, a 5-HT1B/1D receptor antagonist. These mice had an attenuated locomotor response to MDMA, but still exhibited the drug-induced suppression of exploration.

Animals↗
PubMed1990

Delayed effects of amphetamine or phencyclidine: interaction of food deprivation, stress and dose.

Tritium-labelled phencyclidine (PCP) hydrochloride (12 mg/kg) was injected SC for six consecutive days into two groups of eight male rats maintained at 85% of their initial free-feeding weights. Eight days after the last injection, electric footshock raised fat levels of PCP 28% over nonshocked controls, and lowered blood levels 18%, but did not alter brain levels of the drug significantly. Thus, application of an acute stressor does result in redistribution of tissue stores of phencyclidine as predicted in the literature; however, the direction of the redistributions was to fat, rather than to brain. To explore the relation of a long-term stressor (one that eliminates adipose tissue as a sink for mobilized PCP), exploratory behavior was evaluated in male rats during six days of food deprivation commencing after six daily injections of PCP HCl (2 or 4 mg/kg, SC). Exploratory behavior of the 4 mg/kg dose group was abruptly altered, compared to saline controls, at six days of food deprivation, when the rats' body weights were about 70% of initial weights and when body fat would be severely reduced or depleted. To assess replicability and generalizability of this phenomenon, PCP HCl (4 or 8 mg/kg, SC) or dextroamphetamine sulfate (3.2 or 6.4 mg/kg, SC) was injected into male rats for six days and food deprivation followed afterward for nine consecutive days, or until similar body weight reductions as in the first experiment were achieved. Again, exploratory behavior was altered in comparison to saline controls in phencyclidine-treated rats (at the 4 mg/kg dose level) when rats reached about 70% of initial weights.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1982

Baseline exploratory activity predicts anxiolytic responsiveness to diazepam in five mouse strains.

Inbred mouse strains showing variability in spontaneous exploratory behaviors displayed differential responsiveness to diazepam in an anxiety-related exploration model. C57B1/6J, BALB/cJ, Swiss Webster/NIH, Swiss Webster/Harlan Sprague-Dawley, and CF-1 mice demonstrated a significant correlation between baseline exploratory activity and maximal percentage increase in exploratory behavior induced by diazepam. No correlation was seen between those behavioral responses and the characteristics of brain benzodiazepine binding sites in the different strains. Anti-anxiety responsiveness appears to be a function of some genetically-determined substrate for spontaneous exploratory behaviors which may have multiple neurochemical substrates.

Animals↗
PubMed1990

Food deprivation alters behavioral and plasma corticosterone responses to phencyclidine in rats.

Phencyclidine (PCP) sensitivity of rats, whose body weights were maintained at 70% of free-feeding controls, was compared to drug sensitivity of the controls in terms of unconditioned (exploratory) behavior and plasma corticosterone levels. Low doses of PCP HCl [0 (saline vehicle), 0.3 or 0.9 mg/kg, SC] were given to food-deprived rats and to free-feeding controls 15 minutes before measuring unconditioned behavior for 90 minutes; then PCP in brain and corticosterone in plasma were assayed. An additional group (0.43 mg/kg) was established from the reduced-weight rats in order to compare with free-feeding rats given 0.3 mg/kg, the same absolute dose-a circumstance reflecting "street" usage in which doses are not adjusted for body weight differences among users. These low doses of PCP altered exploratory behaviors, but there did not appear to be an interaction between food-deprivational status and drug, with the possible exception of an altered effect of PCP upon habituation in the lighter animals. PCP elevated plasma corticosterone levels over saline controls only in the reduced-weight rats. The drug, possibly reflecting a tranquilizing action of the lowest dose, reduced corticosterone levels in free-feeding controls. Brain levels of drug were directly related to dose, and were elevated in the food-deprived animals 26-30% over those at the same per-weight dose levels in the free-feeding rats, in spite of being given lower absolute amounts of drug. In the 0.43 mg/kg reduced-weight dose group, given the same absolute dose as the 0.3 mg/kg free-feeding group, brain levels were doubled over the latter group, and exploratory behavior was correspondingly different from the free-feeding group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Nucleus tractus solitarius lesions block the behavioral actions of cholecystokinin.

Cholecystokinin (CCK) has been implicated as a signal for the syndrome of satiety in a variety of species. Several lines of evidence point to a peripheral site of action for the behavioral effects of CCK. Peripheral CCK receptors appear to activate a gut-brain pathway involving the sensory fibers of the vagus nerve. To investigate the central anatomical substrate of this visceral-behavioral control system, the terminal regions of the sensory tract of the vagus were lesioned. Radiofrequency lesions of the nucleus tractus solitarius abolished the effects of acute doses of CCK on exploratory behaviors. Sham lesions had no effect on baseline exploratory behaviors and did not influence the ability of CCK to decrease spontaneous exploratory behaviors. These findings delineate the first central site along the ascending sensory pathway which appears to mediate the satiety-related behavioral effects of CCK.

Animals↗
PubMed1983

Some behavioral effects of microinjections of noradrenaline and serotonin into the hippocampus of the rat.

The effects of intra-hippocampal (dentate gyrus) microinjections of noradrenaline (NA) and serotonin (5HT) on various forms of rats' behavior were studied. NA injections produced an increase in the rats' exploratory behavior in the open field test, potentiated the animals' reaction to pain and significantly increased the aversive properties of an electric shock in the conflict test. 5HT injections inhibited the rats exploratory behavior in the open field test, attenuated the retention of a passive avoidance reaction and increased suppressant effects of shock in the conflict test. The findings indicate an antagonistic role of both monoamines in the regulation of various aspects of animal behavior and point to the hippocampus as a one of possible anatomic substrates for such an interaction.

Animals↗
PubMed2002

Motor effects of acute and chronic inhibition of nitric oxide synthesis in mice.

RATIONALE: Systemic injections of nitric oxide synthase (NOS) inhibitors have been shown to decrease exploratory behavior in rats. This effect may be related to motor impairments since these drugs can induce catalepsy in rodents. OBJECTIVE: To compare the effects of two NOS inhibitors in tests aimed to investigate exploratory behavior and to assess motor control. METHODS: The acute effects of the NOS inhibitors NG-nitro- L-arginine ( L-NOARG, 10-80 mg/kg IP) and 7-nitroindazole (7-NIO, 3-30 mg/kg IP) on exploratory activity were analyzed in an open field arena. Drug effects on catalepsy were examined in the hanging-bar and wire-ring test. Footprint pattern after treatment with the two NOS inhibitors was evaluated and the results compared with those obtained with the dopamine D2 receptor antagonist haloperidol (1-2 mg/kg IP). Sub-chronic (twice a day for 4 days) effects of L-NOARG (40 mg/kg) or 7-NIO (30 mg/kg) were also tested in the open field arena and catalepsy test. RESULTS: L-NOARG and 7-NIO decreased locomotion and rearing in the open field arena. Both drugs induced catalepsy in the hanging-bar test but did not change footprint pattern. The cataleptic effect of L-NOARG in the hanging bar and wire-ring tests were highly correlated ( r=0.927). The exploratory and cataleptic effects of L-NOARG and 7-NIO provided evidence for tolerance after sub-chronic treatment. CONCLUSION: These results confirm that inhibition of neuronal NO formation induces impairment of exploratory behavior. This effect does not seem to involve aspects evaluated by footprint analysis, such as weight support, trunk stability and foot placement. They could, however, be related to drug-induced catalepsy.

Animals↗
PubMed1997

Involvement of septal muscarinic receptors in cholinergically mediated changes in rat rearing activity.

We tested the hypothesis that septal muscarinic receptors of the rat are involved in exploratory behavior control, at least as reflected in the measure of rearing activity. At a dose capable of inducing hippocampal theta rhythm, carbachol injection into the septum significantly increased the number of rearings from the 2nd to the 5th min postinjection. The increase was maximal in the 3rd min and gradually declined until the 9th min postinjection, when it was near the control level. This behavioral effect was blocked by prior injection of atropine. These data, when considered with other findings showing a similar motor response caused by the hippocampal injection of the cholinergic agonist, strongly suggest that the cholinoceptive cholinergic components of the septohippocampal system play a role in the release of exploratory behavior. This role might be mediated via muscarinic receptors at the septal level. Moreover, the time course of behavioral action of carbachol injected into the septum is of particular importance for studies on the effect of the drug on performance of the rat in learning and memory tests requiring contribution of exploratory behavior.

Animals↗
PubMedDate not supplied

Paraventricular nucleus lesions abolish the inhibition of feeding induced by systemic cholecystokinin.

Peripherally administered cholecystokinin (CCK) initiates a behavioral syndrome which includes reduced food consumption and reduced exploratory behaviors. Previous studies suggest that CCK stimulates receptors in the gut, activating the vagus nerve, which relays sensory information to the nucleus tractus solitarius (NTS) and its ascending pathways. Terminal regions of ascending NTS projections include the paraventricular nucleus of the hypothalamus (PVN), the central nucleus of the amygdala (CNA), and the bed nucleus of the stria terminalis (BNST). Lesions of these three target sites were performed in rats to test the hypothesis that structures postsynaptic to the NTS mediate the behavioral syndrome induced by CCK. Knife cut lesions of the PVN abolished the reductions in feeding induced by CCK (5 and 10 micrograms/kg IP), as compared to sham lesioned control rats. PVN lesions only partially attenuated the reductions in exploration induced by CCK (2.5, 5, and 10 micrograms/kg IP), as compared to sham lesioned control rats. Electrolytic lesions of the CNA partially attenuated the reductions in exploratory behavior induced by CCK (2.5, 5, and 10 micrograms/kg IP), and had no effect on the reductions in feeding induced by CCK (5 and 10 micrograms/kg IP). Electrolytic lesions of the BNST had no effect on either the reductions in feeding or the reductions in exploration induced by CCK. The PVN appears to be one critical forebrain target site for mediating the actions of CCK on feeding. The CNA appears to facilitate the actions of CCK on exploration. Individual components of the behavioral syndrome induced by CCK may be mediated by anatomically distinct forebrain loci.

Amygdala↗
PubMed1996

Effects of preweaning environmental stimulation on neuronal and behavioral impairment produced by undernutrition.

The present study investigates the effects of sensorimotor stimulation on the basal dendrogenesis of superficial cerebrocortical neurons and the accomplishment in the associated exploratory behavior in rats simultaneously exposed to nutritional deprivation. Sprague-Dawley albino rats were submitted to nutritional-environmental influences from birth to the 21st postnatal day. Exploratory behavior was assessed by the evaluation of locomotor activity in the open-field apparatus. In order to evaluate changes in neuronal morphology induced by nutritional-environmental variables, brains were stained according to the Golgi-Cox-Sholl procedure. Dendritic development was assessed under camera lucida by measuring basal dendritic branching of layer II and III pyramidal neurons, located in the dorsomedial region of the visual cortex of the rat. Morphometrical analysis revealed that both basal dendritic length and branching were significantly reduced by undernutrition. In contrast, environmental stimulation during the suckling period compensated for the neuronal impairment produced by protein-calorie deprivation. An improvement was also observed in exploratory behavior although to a lesser degree, as shown by the open field test data. In conclusion, the present results indicate that sensorimotor stimulation applied during the period of fastest rate of cortical cytodifferentiation compensates for neuronal and behavioral impairment produced by undernutrition.

Animals↗
PubMed2004

Chemical signaling in a wolf spider: a test of ethospecies discrimination.

Chemical signals from female wolf spiders that elicit exploratory behavior and courtship in males are often assumed to be species-specific, but males of some species court in response to silk cues deposited by closely related heterospecific females. Such is the case with the wolf spiders Schizocosa ocreata and S. rovneri, ethospecies reproductively isolated on the basis of differences in behavioral mechanisms during courtship. We explored whether male S. ocreata and S. rovneri reciprocally discriminate species-specific chemical or mechanical cues associated with female silk by using male behavioral response as an assay. Males were exposed to stimulus treatment categories including silk, washed silk, silk extract, and appropriate controls within conspecific or heterospecific female stimulus categories. Male S. ocreata and S. rovneri did not discriminate between conspecific or heterospecific female stimuli, and courtship intensity was greatest on untreated silk. There were no differences in latency to begin courtship or in rates of courtship behaviors attributed to species origin of silk. However, silk treatment (washed silk, extract) had a significant effect on display and exploratory behaviors (e.g., chemoexplore) in both species. Methanol extraction of female silk successfully removed or inactivated a component necessary to elicit active courtship, but extraction did not significantly reduce exploratory behavior, suggesting that a separate compound may be responsible for releasing this behavior. Together, these experiments support the characterization of S. ocreata and S. rovneri as ethospecies reproductively isolated only by female discrimination of species-specific male courtship, and indicate that chemical, but not mechanical cues associated with silk are critical for eliciting male courtship in both species.

Animal Communication↗