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PubMed1993

Olfactory bulbectomy in rats modulates feeding pattern but not total food intake.

The role of olfactory input in the regulation of food intake and feeding patterns in rats was investigated by performing bilateral olfactory bulbectomy. Compared to control rats, bulbectomized rats ate the same amounts of food, but did so via a decrease in meal size, and a doubling in meal number. Although no increase in meal duration occurred, the exploratory behavior of sniffing during meals and between meals also increased significantly. While it is not yet clear how the olfactory bulbs participate in regulating food intake configuration resulting in changed feeding patterns, their clinical role can be appreciated by observing the acute changes in feeding pattern that occur when their input to the lateral hypothalamic area is damaged experimentally.

Animals↗

PubMed1993

Nuzzling in the gray short-tailed opossum. II: Familiarity and individual recognition.

Nuzzling is a chemosensory exploratory behavior that enables South American gray short-tailed opossums to dissolved dry conspecific odor deposits in naso-oral secretions and incorporate them into their vomeronasal organs. This report documents that male opossums nuzzle novel (unfamiliar conspecific) male odors significantly longer than familiar (own of familiar conspecific) male odors or clean substrates. Such findings suggest that an important ethological function of nuzzling behavior involves individual recognition of conspecifics. The first experiment demonstrates that a very short (3-min) exposure to a conspecific odor is sufficient to establish familiarity. The second experiment reveals that a brief exposure results in prolonged (at least 2 h) odor retention. Both experiments establish that nuzzling by males is normally followed by scent marking; thus, novel male odors also elicit increased scent marking. We have identified four novel forms of scent marking by male Monodelphis domestica (ventral, chin, anal/cloacal, and neck) and our data suggest that marking style may be at least partially dependent on the physical properties of the substrata.

Animal Communication↗

PubMed1994

Comparison of different behavioral test situations used in psychopharmacology for measurement of anxiety.

In order to estimate the consistency of variables measured in different test situations classically used in psychopharmacology, a set of hybrid mice was confronted with five testing situations: responses to a novel object introduced in a familiar environment, responses to novel places, behavior in a light/dark choice situation, on the holeboard, and in an elevated plus maze. A principal component analysis was performed using two variables per device as active variables and 26 others as supplementary variables. The first factor was clearly due to opposition between high and low levels of neophobia. Only variables from the first two tests were strongly correlated to this factor. Variables from the holeboard and from the plus maze were highly correlated one another and with the second factor, which grouped locomotion and exploration criteria. The light/dark choice test was intermediate and seemed to be moderately related to both locomotion and neophobia. These results point out the difficulty in comparing different test devices from a psychological point of view.

Animals↗

PubMed1977

Technique for assessing visual discrimination learning in mice.

An automated technique for the study of visual discrimination learning in mice has been developed. The technique utilizes a nose-poke as the operant response. The nose-poke response requires no shaping, has a relatively high operant level and can be used to measure preacquisition exploratory behavior. CD-1 mice acquired a simultaneous brightness discrimination readily but a successive brightness discrimination proved more difficult. A 20 sec intertrial interval was optimal for acquisition of the simultaneous discrimination. Reversal learning was slow. This procedure should prove useful in the study of the effects of pharmacologic and toxic agents on learning and performance in both weanlings and adult mice.

Animals↗

PubMed1984

Novelty-oriented behavior in the rat after selective damage of locus coeruleus projections by DSP-4, a new noradrenergic neurotoxin.

Open-field behavior and reactions to a novel object (white-colored cube) or a familiar object (drinking bottle) were investigated in rats treated with DSP-4 N-(2-chloroethyl) -N-ethyl-2-bromobenzylamine, a new noradrenergic neurotoxin which selectively damages locus coeruleus projections. Altered behavior in the open-field and in the presence of the novel object (white cube) was observed in DSP-4 rats. This was reflected in decreased exploration-oriented locomotor responses and in longer latencies to approach the novel cube. Also, there was a trend towards fewer center entries and a shorter duration of object exploration. Although these behavioral responses of DSP-4 rats were indicative of enhanced neophobia, other measures of emotionality, such as grooming and defecation, were either unchanged or slightly decreased. Moreover, when the familiar drinking bottle was present in the open-field, water-deprived DSP-4 rats showed no change in any measure of fear including the latency to the first approach and lick, and the duration of the licking episodes. The results of this study suggest that noradrenergic neurons of the locus coeruleus are involved in the regulation of certain, but not all, novelty-oriented responses in the rat. Explorative behavior in the novel environment seems to be particularly dependent on central noradrenaline.

Amines↗

PubMed1992

Interaction of GABA and serotonin in the anxiolytic action of diazepam and serotonergic anxiolytics.

The general purpose of the present study was to analyze the possible interactions between the GABA-benzodiazepine and the serotonergic (5-HT) systems in the anxiolytic action of diazepam and the 5-HT1A agonists, ipsapirone, indorenate, and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). The effect of the benzodiazepine receptor antagonist, flumazenil (10.0 mg/kg), on the anxiolytic action of ipsapirone (5.0 mg/kg), indorenate (5.0 mg/kg), and 8-OH-DPAT (0.125 mg/kg) was examined on the avoidance exploratory behavior paradigm in mice. The effect of the 5-HT1 blockers, methiotepin (0.31 mg/kg), pindolol (3.1 mg/kg), and alprenolol (5.0 mg/kg), on the anxiolytic action of diazepam (0.5 mg/kg) was also studied. In the last part of this work, the putative potentiation between diazepam (0.25 mg/kg) and each of the serotonergic anxiolytics was investigated. The antianxiety effect of diazepam, ipsapirone, indorenate, and 8-OH-DPAT was prevented by flumazenil. The serotonergic/beta-blocker, alprenolol, partially antagonized the diazepam effect. Finally, a potentiation of suboptimal doses of diazepam and ipsapirone, but not with indorenate or 8-OH-DPAT, was observed. The findings suggest an interaction between both systems on the anxiolytic action of diazepam and the 5-HT1A agonists.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1996

Daily rhythms in spontaneous and diazepam-induced anxiolysis in Syrian hamsters.

The diurnal variations in spontaneous and diazepam-induced anxiolysis and exploratory behavior were examined in Syrian hamsters in a plus-maze paradigm. The administration of diazepam or flunitrazepam augmented the percentage of time spent in the open arms, the percentage of entries to the open arms, and the number of crosses to both arms, whereas ethyl-beta-carboline injection decreased them. These three behavioral parameters showed significant daily variations, with the maxima being found at night (2400-0400 h). Flumazenil (5 mg/kg) injected at 0400 h decreased significantly the percentage of time spent in open arms and of entries to the open arms, without affecting significantly the total number of entries to both arms. Day-night differences in anxiety-related behavior persisted in hamsters kept under constant darkness for 3 days. Diazepam (0.5 mg/kg) increased the time spent in the open arms at 1600 and 2000 h only, and augmented the percent of entries to the open arms at 2000 h only. The total number of entries to both arms was augmented significantly by diazepam at all time intervals tested, except for 0400 h. The results indicate that Syrian hamsters exhibited significant diurnal changes in anxiolysis-related behavior in the plus-maze paradigm.

Animals↗

PubMed1996

Effects of chlordiazepoxide on maternal aggression in mice depend on experience of resident and sex of intruder.

Lactating mice respond differentially to intruders of differing sex, displaying defensive attack against the male and offensive attack against the female. Such a phenotypic dichotomy appears to have adaptive value in that unfamiliar males pose a much greater threat to the offspring than do females. The present study examined the effects of the benzodiazepine anxiolytic chlordiazepoxide (CDP) (2.5-10.0 mg/kg) on this differential response pattern in aggression-naive (nonscreened) (NS) and aggression-experienced (screened) (S) lactating female mice (Mus musculus domesticus) confronting intruders of either sex in a 10-min test. This procedure was used to evaluate the influence of both the type of opponent and previous aggressive experience on basal behavioural profiles and drug action. Results showed that both intruder sex and prior screening for attack modulated the behaviour of lactating females toward intruders. In turn, both variables strongly influenced CDP effects on maternal aggression. In particular, in S dams, CDP dose-dependently increased maternal attack against males but decreased attack against female intruders. Conversely, in NS dams, CDP decreased attack (and fear) against males but did not affect it against females. In both S and NS conditions, CDP modified the attack strategy of lactating females against the male, switching it from a defensive to an offensive pattern. Exploration, social investigation, eating, and immobility were differentially affected by the drug treatment, depending on screening and/or intruder sex condition. These differential effects of CDP between S and NS conditions, toward either male or female intruders, cannot be fully explained by differences in the baseline levels of these behaviours. Alternative hypotheses are discussed. These findings demonstrate that the effects of CDP on maternal attack behaviour depend on not only the drug but also the object of attack, and hence the function of attack and the prior experience of the attacker.

Aggression↗

PubMed1985

Benzodiazepines and behavior.

This article sets the background for the following series of articles on the behavioral actions of drugs acting at the GABA-benzodiazepine receptor complex. The articles provide detailed analyses of particular behaviors and emphasise the danger of interpreting all behavioral effects in terms of anxiety. What also emerges clearly from several of the articles is that any agonist/inverse agonist classification is test-dependent and that global categorisation is not possible for many of the novel compounds.

Animals↗

PubMed1987

Persistence of habituation deficits after neurological recovery from severe thiamine deprivation.

Rats were fed a thiamine-deficient diet for 4 weeks and injected daily with pyrithiamine during the last two weeks of the diet. This regime induced severe neurological anomalies such as ataxia, loss of righting reflex and visual place reflex, and finally full tonic-clonic seizures. These symptoms are reminiscent of the clinical Wernicke-Korsakoff syndrome. Injection of thiamine dramatically reversed these symptoms within one or two hours as seen in Wernicke patients. Six weeks later these rats showed a marked deficit in habituation of exploratory behavior and of the auditory orienting response. To what extent this chronic deficit in habituation contributes to the cognitive dysfunctions seen in Wernicke-Korsakoff patients is discussed. Histological examination of the brains of 6 of the rats revealed a heterogeneous pattern of damage to the brainstem, including mamillary bodies and several thalamic nuclei, reminiscent of that seen in Korsakoff patients. In addition there were many dark abnormal cells in limited fields of hippocampus neocortex and thalamus in almost all animals.

Animals↗

PubMed1990

The reaching reaction in the rat: a part of the digging pattern?

The relationship between acquired lateralized reaching and analogous innate movement patterns was examined in adult rats. In Expt. I, 8 naive rats were trained to reach into a narrow trough-shaped feeder. Analysis of the videorecorded movement showed that the forelimb extension starts 120 ms before the forepaw enters the feeder, lasts 190 ms and can be repeated at 280-ms intervals. Before reaching, the rat assumes a stereotyped posture and inserts its nose into the feeder entrance. Twelve rats used in Expt. II were raised from weaning with limited opportunity to practice manipulative skills. Six of these animals were then trained as in Expt. I. In spite of the lack of experience, they learned the reaching task as efficiently as normal rats. The remaining 6 rats were offered food placed into a wide tunnel-shaped feeder. The animals did not take advantage of the possibility of using both forelimbs, but developed typical lateralized reaching. In Expt. III, 4 rats were trained to retrieve food pellets buried under a layer of sand. The videorecorded digging movement essentially resembled reaching but the two forepaws alternated, the extension amplitude was shorter and the movement was never terminated by grasping. It is concluded that the lateralized reaching develops from modified digging and that the kinship of the two movements accounts for the stereotypy and limited modifiability of the acquired reaction.

Animals↗

PubMed1995

Subcortical modulation of synaptic plasticity in the hippocampus.

A two-stage model of memory trace formation in the hippocampus considers exploratory behavior associated with theta activity and consumatory behaviors or immobility associated with the occurrence of synchronous pyramidal cell discharges. Threshold, frequency and extent of CA3 bursts differ between differently performing strains of mice and are subject to subcortical modulation. Mechanisms for such actions are described: interference with potassium and other cation channels through second messengers and a direct action of histamine on the NMDA receptor channel. Furthermore long-lasting potentiations of synaptic transmission and excitability following brief exposures of hippocampal slices to histamine, noradrenaline, and serotonin are mediated by cyclic AMP and presumably protein kinase A.

Animals↗

PubMed1993

Neurotoxicity screening methods are sensitive to experimental history.

Toxicity studies commonly include unavoidable environmental differences (experimental history) among test groups, such as chemical taste, odor and irritation. The influence of environmental variables on USEPA guideline neurotoxicity tests was evaluated using an environmental enrichment model. 6-week-old male Fischer 344 rats were housed for 13 weeks in pairs with access to an exercise wheel, trained to run on a rotating rod and handled frequently. Control animals were housed singly, lacked the exercise wheel and rotating rod training, and had only routine interaction with caretakers. At the end of 13 weeks, flash evoked potentials (FEPs), somatosensory evoked potentials (SEPs), auditory brainstem responses (ABRs), grip performance, motor activity (MA), elements of the functional observational battery (activity and reactivity to handling/restraint) and brain histopathology with glial fibrillary acidic protein immunohistochemistry (GFAP IHC) were evaluated. Animals from the enriched group demonstrated changes (P < 0.05) in FEPs, SEPs and grip performance. Enriched animals were more active and reactive to their surroundings, and were highly reactive to physical restraint. Control (unenriched) animals showed little to no exploratory behavior and were more tolerant of restraint. Differences in experimental history can be detected using elements of standard guideline tests and may confound interpretation of such data if not taken into consideration.

Analysis of Variance↗

PubMed1985

Neurochemical investigation of the afferent pathway from the vagus nerve to the nucleus tractus solitarius in mediating the "satiety syndrome" induced by systemic cholecystokinin.

The satiety syndrome induced by intraperitoneally administered cholecystokinin (CCK) requires an intact visceral sensory feedback system involving the afferent vagus nerve and the nucleus tractus solitarius (NTS). Since both the vagus and the NTS contain CCK, the vagal-NTS synapse could conceivably employ CCK as a transmitter. To test this hypothesis, CCK was injected directly into the NTS region in awake rats. CCK at doses of 1 ng, 10 ng, and 100 ng had no effect on food consumption or exploratory behaviors associated with the satiety syndrome. The acetylcholine agonist carbachol, injected directly into the NTS region, effectively mimicked the actions of intraperitoneally administered CCK on feeding and exploration. These data suggest that CCK is not the transmitter at the vagal-NTS site in the visceral sensory pathway projecting to brain regions mediating the reduced feeding and exploration actions of systemic CCK.

Afferent Pathways↗

PubMed1990

Inconsistencies and misperceptions putting college students at risk of HIV infection.

College students are often viewed as being at high risk for human immunodeficiency virus (HIV) infection, due to their needs to engage in exploratory behavior and their needs for peers' social approval, and their sense of invulnerability. The proportion of adolescents who are sexually active is known to be relatively stable; however, the amount of unsafe sex taking place on the college campus is still in question, as well as the relationship between dating patterns and HIV-risk behavior. In this study college students' self-reports of sexual and dating practices were related to sexual frequency and condom use. The results highlight the amount of unprotected sexual behavior in the college group and the difficulty in assessing adolescents' risk of HIV transmission on the basis of self-reported sexual activity and dating behavior. Key issues to target in educating college students about HIV infection are the roles of planning and spontaneity in dating and the fact that inaccurate self-perceptions of monogamy and abstinence may lead them to assume falsely that they are safe from sexually transmitted diseases.

Acquired Immunodeficiency Syndrome↗

PubMed1990

Refinement of animal research technique and validity of research data.

Refinement of research techniques using animals will lead to less animal distress and, at the same time, will usually lead to higher quality and more robust data. For example, acclimation of laboratory animals to handling and experimental procedures will produce not only an animal that is easier to handle but also one that reacts to the experimental stimulus rather than to the handler. Even when the animal is acclimated to handling, handling or anesthesia can cause marked changes to commonly measured biological parameters such as serum hormone and tissue metabolite levels. Standard animal housing systems are also stressful to the animals. One research report, for example, found that mice in conventional facilities had plasma corticosterone values of 150-500 ng/ml compared to values below 35 ng/ml from mice kept in special "low-stress" housing. However, assessment of stress in animal research is not easy and few technicians or research scientists are good judges of moderate stress. Investigators in the United Kingdom have recently published a report on a new technique that might allow more objective assessment of discomfort in laboratory rats and mice. The amount of exploratory behavior in treated and control animals can be used for developing a Disturbance Index (DI). The DI is a measure of the extent to which a procedure or treatment causes a departure from normal behavior. The initial data using the DI indicate that it could be a promising approach for assessing animal well-being (or the lack of it).

Animal Husbandry↗

PubMed1980

Blockade of high frequency rhythmical slow activity by intrahippocampal injection of a glutamic acid antagonist.

Intrahippocampal injections of glutamic acid diethylester (GDEE) were performed in rats in order to study a possible implication of glutamate in the mediation of high frequency (8-12 Hz) rhythmical slow activity (RSA) elicited by 100 Hz electrical stimulation of the dorsomedial hypothalamus. This 8-12 Hz RSA was selectively and reversibly suppressed in hippocampal EEG 6 min and 15 min after 150 micrograms or 400 micrograms of GDEE, whereas no modifications were found in the low frequency RSA (6-8 Hz) evoked in hippocampus during exploratory behavior.

Animals↗

PubMed1989

A neuroanatomical and biochemical basis for attention deficit disorder with hyperactivity in children: a defect in tonic adrenaline mediated inhibition of locus coeruleus stimulation.

Attention deficit disorder with hyperactivity (ADDH) is characterized by a high level of inappropriate activity, distractability and impulsivity as well as learning deficits. In mammals, the protective mechanism for acquisition of sensory information, processed for its survival value, can be termed "vigilance". In ADDH, a low threshold for novel or sensory stimuli, results in a "hard wired" mammalian response, orienting, followed by exploratory behavior, the orienting reaction. This behavior is mediated in the brainstem through sensory neurons in the reticular formation regulating the discharge of locus coeruleus noradrenergic neurons. It is proposed that adrenaline acts as a tonic inhibitor of these neurons, modulating the level of sensory stimulation necessary to elicit locus coeruleus excitation. An imbalance in adrenaline formation or alpha-2 adrenergic receptor number (or affinity) leads to the inability to maintain the appropriate threshold for discharge of locus coeruleus neurons. The consequences are inability to maintain focused attention, difficulty in falling asleep or light levels of sleep, inattention to consumptive behavior, and probable inappropriate response for reward as all these behaviors require disruption of processing of sensory stimuli. Cognitive deficits may occur secondarily.

Animals↗