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PubMed2002

Impaired dodging in food-conflict following fimbria-fornix transection in rats: a novel hippocampal formation deficit.

It is well known that damage to the hippocampal formation (Ammon's horn, dentate gyrus, fimbria-fornix, and other pathways) produces impairments in spatial navigation and in certain forms of learning. Lesions within these structures have also been reported to produce some motor impairments, but the nature of these impairments is less understood. The present study examined the effects of fimbria-fornix lesions on food wrenching and dodging, social interactions that occur when one rat attempts to steal food from a conspecific, who in turn attempts to protect the food by an evasive movement. Lesion effectiveness was confirmed histologically and electrophysiologically, by the loss of hippocampal rhythmical slow-wave activity (RSA or theta), and by changes in open field behavior (increased open field behavior, less thigmotaxis and more defecation). Analysis of the social interaction indicated when an eating control rat was approached by a conspecific that was attempting to steal its food, it prevented the theft by dodging, a rapid lateral maneuver involving forequarter turning and stepping with the rear limbs. Rats with fimbria-fornix lesions were significantly impaired in dodging and so were more likely to lose their food to the robber. This novel deficit in motor behavior is discussed in relation to contemporary theories of hippocampal function and it is suggested that the deficit may be caused by an inability of the fimbria-fornix damaged animals to disengage attention from eating in order to initiate an evasive movement to protect food. The finding of this novel deficit underscores the importance of considering both loss as well as release phenomena in the analysis of hippocampal formation function.

Agonistic Behavior↗
PubMed2004

(-)-Adamantyl-delta8-tetrahydrocannabinol (AM-411), a selective cannabinoid CB1 receptor agonist: effects on open-field behaviors and antagonism by SR-141716 in rats.

(-)-Adamantyl-Delta8-tetrahydrocannabinol (AM-411) is a 'classical' tricyclic cannabinoid CB1 receptor agonist in which the C-3 alkyl side-chain has been replaced with an adamantyl group. The compound is cannabinoid CB1 receptor subtype selective (CB1 Ki=6.86 nmol/l, CB2 Ki=52.0 nmol/l). We examined the effects of AM-411 alone and in combination with the cannabinoid CB1 receptor antagonist/inverse agonist, SR-141716, on open-field behaviors of rats. The lowest effective dose of AM-411, 3 mg/kg, suppressed ambulation (horizontal activity) and rearing (vertical activity) and increased circling frequency compared to vehicle control levels. Co-administration of SR-141716 normalized these changes. SR-141716 (3 and 5.6 mg/kg) also produced significant increases in scratching and grooming (both frequency and duration), effects that were not eliminated in the presence of AM-411. Coupled with previous drug discrimination data, the open-field profile of AM-411 suggests that this high-affinity CB1 cannabinoid receptor agonist induces behavioral effects similar to the natural cannabinoid Delta9-tetrahydrocannabinol and different from (R)-methanandamide, a chiral analog of the endogenous ligand anandamide.

Adamantane↗
PubMed1989

Antagonism of ethanol-reinforced behavior by the benzodiazepine inverse agonists Ro15-4513 and FG 7142: relation to sucrose reinforcement.

The partial inverse benzodiazepine agonist Ro15-4513 has been shown to antagonize many of ethanol's actions, including the reduction of behavior reinforced with ethanol presentation. The studies reported here compared the effects of the Ro compound on sucrose reinforcement alone and concurrently available with ethanol reinforcement. Also, a second inverse agonist, FG 7142, was tested. The result indicated that ethanol reinforcement was more sensitive to the inverse agonists compared to sucrose reinforcement. This was seen as a graded effect upon ethanol responding at doses which failed to have any effect upon sucrose-reinforced behavior. The Ro compound was approximately three times more potent than the FG compound in suppressing ethanol-reinforced responding. Possible explanations for the greater sensitivity of ethanol reinforcement compared to sucrose reinforcement was discussed in terms of ethanol's potential actions at the benzodiazepine-GABA receptor complex.

Animals↗
PubMed2001

Psychotogenic properties of benzodiazepine receptor inverse agonists.

The neurochemical, behavioral, and cognitive effects of the benzodiazepine receptor partial inverse agonist beta-carboline FG 7142 (FG), a drug traditionally described as exhibiting 'anxiogenic' effects, are proposed to model core components of present theories of the neuronal mechanisms of schizophrenia. FG activates the mesolimbic dopaminergic system and, via increases in dopaminergic activity in the nucleus accumbens, disinhibits corticopetal cholinergic projections. The latter effect of FG is hypothesized to mediate the hyperattentional impairments that contribute to the development of psychotic cognition. Furthermore, the FG-induced abnormal overprocessing of conditioned stimuli and contexts provides an explanation of the 'anxiogenic' effects of FG. The FG-induced increases in the activity of cortical cholinergic inputs and the FG-induced cognitive impairments in rats and monkeys were demonstrated to be attenuated by the administration of typical and atypical antipsychotic drugs. Compared to the classic psychotogenic drugs amphetamine and phencyclidine, the effects of FG serve as an alternative psychotogenic manipulation in research focusing on the cortical and cognitive aspects of current theories of schizophrenia.

Acetylcholine↗
PubMed1992

[Study of induced effects by selective CCKB agonists cholecystokinin in the nociception and behavior in rodents].

Potent and selective CCK-B agonists with good bioavailability have been designed by modifying the natural CCK-8 peptide. Thus, BC 264 [Boc-Tyr(SO3H)-gNle-mGly-Trp-Me(Nle)-Asp-PheNH2] is a highly potent (0.15 nM) and selective agonist for CCK-B receptors which cross the blood brain barrier. Following i.v. injection of [3H]pBC 264 in mouse, the ligand was found in its intact form in brain tissue. Analgesic studies and in vivo binding experiments have shown that the CCKergic system could modify the release of endogenous enkephalins, whereas mu and delta opioid receptor activation modulates the release of endogenous CCK. Behavioural studies performed after local injection of CCK-8 or BC 264 into the postero-median part of the nucleus accumbens have shown the involvement of CCK-A receptors in motivation and/or emotional states of rats. In the anterior part, CCK-B receptor stimulation could be involved in attention and memory processes. BC 264 systemically administered in mice increased fear and/or "anxiety" in the black and white box test. In the elevated plus maze, BC 264 increased the emotional responses of the "anxious" rat and decreased these responses in "non anxious" animals. These results suggest that endogenous CCK could play a critical role in mood modulation through CCK-A/CCK-B receptor stimulation. Dysfunctioning of the CCK-A/CCK-B pathways could be implicated in anxiety and panic attacks.

Animals↗
PubMed2003

Fos-like immunoreactivity in catecholaminergic brain nuclei after territorial behavior in free-living song sparrows.

The catecholaminergic cell groups of the brainstem play an important role in the regulation of motivated behavior, including reproductive behavior. In songbirds, these cell groups project to telencephalic nuclei involved in singing and contain steroid hormone receptors, implicating them in the seasonal regulation of song. Whether these nuclei are involved in the activation of song on a short-term, moment-to-moment basis is unknown. In this study, free-living male song sparrows (Melospiza melodia) were subjected to simulated territorial intrusion (STI), which stimulates territorial singing. The resulting fos-like immunoreactivity (FLI) was quantified in two HVc- and RA-projecting catecholaminergic regions of the brainstem: the area ventralis of Tsai (AVT) and the midbrain central gray (GCt). Males subjected to STI showed more FLI in both of these regions than control males. In addition, FLI in both nuclei was correlated positively with the number of songs sung in response to STI. The number of flights directed at the intruder was correlated with FLI in AVT but not GCt. These results suggest a role for AVT and GCt, and thus possibly catecholamines, in the regulation of territorial behavior in songbirds.

Agonistic Behavior↗
PubMed1980

Afferent projections to quiet attack sites in cat hypothalamus.

Quiet biting attack by a cat on a rat was elicited by electrical stimulation of sites in the cat's lateral hypothalamus. Horseradish peroxidase was deposited at the attack sites. Cells containing reaction products were found in gyrus proreus, anterior and central medial amygdaloid nuclei, lateral and medial preoptic areas, substantia innominata, the bed nuclei of stria terminalis, and anterior commissure. The dorsomedial area of the hypothalamus, paraventricular nucleus, supramammillary region, and posterior hypothalamic area also contained reactive cells. In the midbrain the ventral tegmental area of Tsai, the dorsal and superior central nuclei of the raphe, central gray matter and interpeduncular nucleus were regions with reactive cells. In the pontine region, the locus coeruleus, parabrachial nuclei, nucleus of the lateral lemniscus, and the dorsal tegmental nucleus of Gudden all had reactive cells. There are many structures which send afferent projections to quiet attack sites located in the hypothalamus and the pontine tegmentum. The commonality of afferents to attack sites lends credence to the notion that a complex, distributed, interactive network underlies the neural basis of attack behavior.

Afferent Pathways↗
PubMed1992

The performance of WKY rats on three tests of emotional behavior.

The behavior of Wistar, Fischer-344, and WKY male rats was observed on three tests of emotional behavior. These included the defensive-withdrawal test, the elevated plus maze, and the conditioned defensive-burying test. Rats were subsequently exposed to the water-restraint ulcerogenic procedure. Fischer-344 rats were more active in the defensive-withdrawal tests, but other behavioral measures in this test did not discriminate between the three strains. Scores reflecting anxiety in the elevated plus maze were lowest for Fischer-344 rats and highest for WKY rats, but the anxiety scores of WKY rats did not differ significantly from Wistar rats. The behavior of WKY rats was significantly different from the other two strains in the conditioned defensive burying test. While the degree of anxiety is measured by burying behavior, elicited by the novelty of prod shock, immobility was the prevalent response of WKY rats. WKY rats also revealed significantly higher ulcer severity scores when exposed to water-restraint stress after each behavioral test procedure. We propose that WKY rats are hyperresponsive to stress and that novelty stress elicits depression-like behavior, which is the prevalent behavioral stress response in WKY rats.

Agonistic Behavior↗
PubMed1992

Approach, avoidance, and contact behavior of individually recognized animals automatically quantified with an imaging technique.

A low-cost system was developed that allows the assessment of the location and the direction of movements of two individually recognized animals in a social interaction. The program was validated by (i) assessing deliberately induced approach and avoidance movements of artificial objects, (ii) the effects of known differences in social behavior between differently treated rats, and (iii) repeatedly testing social behavior under similar circumstances to assess enhanced social contact due to being familiar with the arena. Movements toward and away from each other of individually housed versus group-housed animals, and of young versus aged animals, were analyzed by the system. The results obtained, demonstrated that in the case of randomly moving artificial objects specific approachers or avoiders could not be identified, whereas isolated and young rats showed more approach behavior than their respective controls. In addition, the algorithm applied for calculating relative approach and avoidance movements elucidated differences between groups that were not noticed by human observers. Social contact behavior of rats was assessed automatically. Habituation to the testing situation in repeated testing increased social contact behavior.

Aging↗
PubMed1997

Some behavioral effects of AMPA/kainate receptor agonist and antagonists.

The effects of an agonist (S-AMPA, i.c.v.), as well as competitive (CNQX, NBQX, DNQX, i.p.), and noncompetitive antagonists (GYKI 52466, i.p.) at the AMPA/kainate receptors were examined in the open field and the Vogel tests of anxiety. It was found that both kinds of antagonists inhibited rat exploratory behavior in a dose-dependent manner, at the dose range exhibiting a clear-cut tendency to decrease rat locomotor activity. They appeared inactive in the Vogel test over an examined dose-range. S-AMPA, whereas not changing in a significant way rat behavior in the open field, significantly enhanced the suppressive influence of a shock on drinking in the Vogel test. The drug administered at the dose of 2 micrograms/5 microliters, i.c.v., revealed also a tendency to decrease the motor activity followed by prodromal symptoms of epileptic-like activity in some subjects. It is concluded that AMPA/kainate receptors probably are not directly involved in the control of rat emotional behavior. Thus, their primary role as putative neuroprotective and anticonvulsant agents is indirectly confirmed.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1985

Influence of imidazole on behavioral effects induced by dopaminergic agonists in rats.

Imidazole (IMI) (from 18.7 to 300 mg/Kg) i.p. injected in adult rats induced shaking, which was antagonized by both morphine (MOR) and haloperidol (HALO) but not by methysergide (MET). I.p. IMI pretreatment inhibited the penile erections (PE) and stretching and yawning (SY) typically elicited by N-n-propylnorapomorphine (NPA), a well-known CNS dopamine (DA) receptor stimulant, injected either i.p. or i.c.v., whereas it enhanced stereotyped behavior (SB). IMI had similar effects on the same parameters considered when injected before lisuride, an ergot derivative also active as a central DA receptor agonist. In this case not only SB but also and above all aggressiveness were markedly potentiated, both the signs appearing at doses of lisuride which were "per se" ineffective. Aggressiveness, like SB, was not sex linked and was antagonized by HALO and MOR, but not by MET. IMI alone potentiated the fighting induced by electrical shock, an effect which was abolished by HALO pretreatment. Considering the results obtained as a whole it is submitted that IMI antagonizes PE and SY through a selective blockade of a class of DA receptors, presumably DA presynaptic autoinhibitors, thus potentiating SB and aggressiveness, which involve stimulation of DA postsynaptic receptors.

Adrenergic Agonists↗
PubMed2001

A preliminary behavioral comparison of two captive all-male gorilla groups.

Gorillas live in polygamous harem groups, generally composed of one male, several adult females, and their offspring. With an equal numbers of male and female gorillas born in captivity, however, housing gorillas in social breeding units inevitably means that some males will not have access to female social partners. Thus, the future of the captive gorilla population depends on the collective ability of zoos to house equal numbers of males and females. This study examined the behavioral profiles of two all-male groups of captive lowland gorillas (Gorilla gorilla gorilla) to provide information on this type of housing situation. One group consisted of three subadult individuals, while the other consisted of two subadults and a silverback. Data were collected during two 6-month intervals, for a total of 284 hr. The behavioral profiles of the animals were stable over the course of the study but proximity patterns changed. Differences in feeding, solitary play, and object-directed behavior were found between groups, while no significant differences were observed in affiliative or agonistic social behavior. At both institutions, group cohesion appeared to be high, particularly between subadults; these individuals spent approximately 10% of their time engaging in social behavior and 25-50% of their time in close proximity (within 5 m). However, the Zoo Atlanta males spent significantly more time within 1 m and 5 m of each other than the Santa Barbara males, which may reflect a higher level of cohesiveness among members of the Zoo Atlanta group. The behavioral profiles of the animals in this study were similar to those found in bachelor groups of wild mountain gorillas. One notable exception was the absence of homosexual behavior between the silverback and subadults in Santa Barbara and the low frequency of this behavior between subadults in both groups. Although more longitudinal data are needed, these data suggest that all-male groups can be a feasible housing strategy for males at certain periods of their life span. Zoo Biol 20:27-40, 2001. Copyright 2001 Wiley-Liss, Inc.

Journal Article↗
PubMed1993

Immune responses in male mice with aggressive and submissive behavior patterns: strain differences.

Immune responses in two strains of male mice with aggressive and submissive behavior patterns was studied. In aggressive CBA males immunized on the 10th day of agonistic confrontations with submissive partners, greater numbers of plaque-forming cells (PFC) and rosette-forming cells (RFC) were noted compared to control mice. Unlike the CBA strain, both PFC and RFC levels in aggressive C57BL males did not increase, but both PFC and RFC numbers decreased in submissive animals.

Agonistic Behavior↗
PubMedDate not supplied

[Discrete and continuous mathematical models of intraspecific behavior in the pharmacoethology of the mouse].

An algorithm and software library were compiled in order to interpret the intraspecies agonistic animal behaviour in terms of discrete or continuous mathematical model. Applied aspects of the use of mathematical models in pharmacoethology were shown on concrete examples. The ways of construction of standard prototypes, and the integrative criteria of psychotropic drugs action were developed. The possibility was shown of identification of unknown substances by comparing with standard drugs by calculating the norm of standardized matrices.

Aggression↗
PubMed2025

Social status in zebrafish modulates the behavioral response to 5-HT2C receptor agonists and antagonists.

The effects of previous social experiences on social behavior have been demonstrated across species both in cooperative and competitive contexts. In dominance-subordinate hierarchies, differences across social ranks have been observed in many different mechanisms. Dominance hierarchies interfere in defensive behavior, where subordinate animals present a greater defensive behavior, regarding potential threats ("anxiety-like behavior"), than dominant animals. The serotonergic system plays a key role in regulating and mediating threat responses, including 5-HT2 receptors in the types of proximal threat responses modulated by the stress of social defeat. We separated 148 adult zebrafish in pairs and allowed them to interact for five days; after that, the dominant-subordinate rank was determined, and animals were treated with a 5-HT2C receptor agonist (MK-212) or antagonist (RS-102221) before being observed in the novel tank test. While MK-212 increased bottom-dwelling, erratic swimming, and freezing across all statuses, RS-102221 decreased these variables in dominants but increased them in subordinates. Moreover, the effects of MK-212 were larger in subordinates than in controls or dominants, suggesting a sensitization of the 5-HT2C receptor.

Animals↗