Prey-dependent effects of fluprazine hydrochloride on predatory aggression in northern grasshopper mice (Onychomys leucogaster) and rats (Rattus norvegicus)

Treatment with the phenylpiperazine DU 27716 (fluprazine hydrochloride) inhibited the predatory killing of albino mice by northern grasshopper mice (Onychomys leucogaster) and of frogs by rats. This treatment had no effect on cricket predation by grasshopper mice or worm predation by rats. The prey-specific effect of fluprazine did not seem to result from a decreased tendency to attack nor was its effect restricted to prey showing characteristic rodent defensive responses. Rather, the drug seemed to increase fearfulness when the prey exhibited vigorous defensive behavior. It is possible that increased fearfulness induced by treatment with this drug may also contribute to its antioffensive effect during conspecific encounters.     

Effects of Fluprazine Hydrochloride on Three Aversively Motivated Tasks

The Psychological Record - Treatment with 8.0 mg/kg fluprazine hydrochloride had no effect on the acquisition of a step-down avoidance response but retarded its extinction. The drug also impaired...     

The offensive nature of maternal aggression in mice: Effects of fluprazine hydrochloride

The phenylpiperazine fluprazine hydrochloride was used to test the hypothesis that maternal aggression in laboratory mice reflects offensive motivation. Lactating females (n = 8 per condition) tested for aggression following drug treatment (1.0 mg/kg and 5.0 mg/kg of fluprasine) were significantly less aggressive than saline controls according to all measures used. The findings support the hypothesis that maternal aggression is offensive in nature, and provide no evidence that maternal attack is a mixture of offensive and defensive tendencies.     

Novel odors evoke risk assessment and suppress appetitive behaviors in mice

The effects of four novel odors on risk assessment by mice (i. e., flat back approach, stretched attention, immobility) and the suppression of appetitive behaviors were examined in two experiments. When novel odors were presented in a straight runway, subjects spent significantly less time in the odor compartment, relative to controls, when it contained sheep wool, chocolate, or citronella (but not cat fur) odors. Risk assessment behaviors occurred at similar levels among all groups and appetitive behaviors were not suppressed by the novel odors. When odorants were scattered over one half of the subjects' home cage floor in Experiment 2, all novel odors increased the duration of at least on e risk assessment measure and/or suppressed appetitive behaviors (i. e., eating, grooming, rearing). The results clearly reveal that a reasonably wide range of novel odors evoke at least some level of risk assessment which presumably reflects increased fearfulness. The odors of sheep wool and cat fur induced a wider range of such responses than did chocolate or cinnamon suggesting that mammalian odors may be particularly effective stimuli. If so, however, it is clear that predator odors are not uniquely effective in this regard. Experiment 1 also underscores the importance of the testing environment in assessing the behavioral effects of novel odors in mice. © 1993 Wiley-Liss, Inc.     

Altered grooming responses to stress in rats exposed prenatally to ethanol

The effects of prenatal alcohol exposure on grooming, locomotion, and rearing in response to stress were examined in adult rats whose mothers consumed a liquid diet containing 35% ethanol-derived calories (EDC). Offspring of both pair-fed 0% EDC mothers and ad libitum chow-fed mothers were included as controls. In Experiment 1, females groomed more than males following placement into a novel test chamber, but no differences due to prenatal treatment were observed. Ethanol-exposed animals groomed more than controls following the stress of a forced 1-min swim (Experiment 2), but when rats tested in Experiment 1 were observed again after forced swim stress (Experiment 3), no differences due to prenatal treatment or sex were observed. Experiment 4 examined the effects of pretreatment with 1 mg/kg naloxone on novelty-induced grooming and as in Experiment 1 prenatal treatment did not affect grooming responses. Females again groomed significantly more than males and naloxone reduced grooming equally for all groups. The results suggest that novelty-induced grooming is a sex-influenced behavior, with females grooming more than males, and that animals exposed prenatally to alcohol and tested as adults may have altered responses to certain stressors (i.e., forced swim) under specific conditions. The altered grooming response of alcohol-exposed rats to swim stress can be eliminated by preexposing them to novelty stress.     

Effects of morphine hydrochloride on social encounters between male mice

The effects of a single injection of morphine hydrochloride (0.3, 0.6, or 1.25 mg/kg) or physiological saline (0.9% NaCI) on the agonistic behaviour elicited by isolation in male mice were examined. Individually housed mice were exposed to anosmic “standard opponents” 30 minutes after drug administration, and the encounters were videotaped and evaluated using an ethologically based analysis. Morphine (at 0.6 and 1.25 mg/kg) significantly and dose-dependently decreased time spent in offensive (“threat” and “attack”) and “digging” behaviours but markedly increased “non-social exploration” without a significant increase of “immobility.” The lowest dose was completely ineffective in producing changes in any of the behaviours studied. It is concluded that these results present a specific ethopharmacological profile characterized by suppression of aggressive behaviour, increase in non-social explotation, and no evident impairment of motor activity. © 1993 Wiley-Liss, Inc.     

Pituitary-adrenal activity in acute and chronically stressed male and female mice lacking the 5-HT-3A receptor

The serotonin (5-HT)-3A receptor has been localized in limbic and brainstem structures that regulate hypothalamic--pituitary--adrenal (HPA) activity. We previously showed that 5-HT-3A receptor knock-out (KO) male mice displayed lower ACTH responses to acute restraint or lipopolysaccharide administration compared to age-matched wild-type (WT) males. In the present study, we found that pituitary-adrenal responses to acute stress were not different in female WT and KO mice. Furthermore, we examined the role of the 5-HT-3A receptor in regulation of chronic stress-induced HPA activity in both male and female WT and KO mice. The results show that ACTH, but not corticosterone, responses to novel restraint are lower in chronically cold stressed females compared to non-stressed control females but no effect of 5-HT-3A receptor deletion was observed. In contrast, male mice showed facilitated responses to novel restraint after chronic cold stress and this facilitation produced sex differences in ACTH responses to novel restraint between male and female chronically stressed KO mice. Together, these results indicate that there are sex differences in HPA responses to novel restraint in chronically stressed mice and these differences are partly related to 5-HT-3A receptor function.     

Increased novelty-induced grooming in aged rats: a preliminary observation

Age-related changes in grooming activity in female Fischer-344 rats were observed in a home cage and in a novel testing chamber for 50 min. Compared to the home cage condition with brief handling treatment, excessive grooming was found in the novel situation. The amount of novelty-induced grooming of aged rats (26-28 months) was about two times that of young animals (6-8 months). This increase in novelty-induced grooming of aged animals was attributable to an increase in the number of grooming bouts, prolongation of each grooming bout, and a slight increase in the duration of licking elements. However, there were no age differences in the percentage of face washing and the duration of face-washing elements. These results are discussed in terms of behavioral aging and age-related changes in peptidergic pathways in the brain.     

Effects of Eltoprazine Hydrochloride on Predatory Behavior in Rats

Treatment of rats with the potent antiaggressive compound eltoprazine hydrochloride (1.0 & 2.0 mg/kg) slowed both predatory attack and killing of frogs. These results demonstrate a specific predation-inhibiting action of the drug which is not obscured by the elements of conspecific aggression seen during muricide. Unlike the closely related compound fluprazine, eltoprazine increased both attack and kill latencies implying that the effects of the two drugs on predation are mediated by at least somewhat distinct drug actions. It is further suggested that eltoprazine may be more specifically antiaggressive in its actions than related phenylpiperazine compounds.

     

Brain weights correlate with behavioral parameters in individual inbred mice housed in a common and enriched environment

Fifty 8-week-old Balb/c mice were individually identified and housed together in a large and enriched environment for 5 months. Maze and open field exploration, response to an aversive noise, swimming, and induced grooming tests were applied to each mouse in an initial search for possible relationships between brain morphology and spontaneous behavior in isogenic individuals living in a complex social and physical environment. The tasks generated 39 quantitative behavioral indices which include locomotion, rearing, still, and grooming bout frequencies, latencies, total, and mean bout durations. At the end of the tests, the 7-month-old mice were sacrificed and the fresh weights of their whole brain, cerebellum, brain stem, diencephalon, telencephalon, and prosencephalon were rapidly obtained. Behavioral data have wide variations and do not adjust to normal population distributions. Means of the same parameter differ between tests. A Spearman correlation matrix of all data yielded many significant correlations between indices of the same task which can be interpreted in terms of time budget and sequence probability. Significant correlations between indices of different tests suggest diverse emotionalities, exploratory strategies, and motor skills. The correlations between body and brain weights and among separate brain regions were not significant. There were several low but significant correlations between brain weights and behavioral indices. Such correlations, the resulting factors, and significant behavioral differences between mice with large and small brains suggest that mice displaying low motor activity in novel environments have larger brains and forebrain/hindbrain ratios than mice with high activity, and that animals with high scores of some specific behaviors have larger brain areas physiologically related to such behaviors.(ABSTRACT TRUNCATED AT 250 WORDS)     

Behavior of the rat after removal of the neocortex and hippocampal formation

After surgical removal of the neocortex and hippocampal formation, rats retained most of the movement patterns of locomotion, climbing, grooming, feeding, and fighting. However, forepaw immobility during swimming was abolished. Feeding behavior was suppressed temporarily but recovered partially. The distinctive postures of sleep and walking and a circadian rhythm of motor activity were retained. However, behaviors were often not performed at the appropriate time and place. The normal sequence of grooming behavior was disrupted; food hoarding and social behavior were essentially abolished. Removal of the neocortex alone had much the same effect as removal of neocortex and hippocampus together. Removal of hippocampus alone produced only a mild disruption of behavior. It is suggested that ascending nonspecific projections to the cerebral cortex play an important role in the moment-to-moment control of behavior but are not essential for the sleep-waking cycle.     

Grooming and yawning trace adjustment to unfamiliar environments in laboratory Sprague-Dawley rats (Rattus norvegicus)

The authors studied grooming and yawning caused by mild stress in laboratory Sprague-Dawley rats (Rattus norvegicus). Two groups received 3 and 6 sequences of 5 foot shocks at random intervals (RI) and fixed intervals (FI), respectively. A 3rd group was not shocked (NS). The groups were exposed for 60 min twice. Grooming did not differ among groups, but yawning diminished with RI. Yawning increased and grooming decreased with the 2nd exposure, except in RI in which grooming increased. In NS and FI, grooming prevailed during the first 20 and 30 min, respectively, whereas yawning dominated the remainder of the time. In RI, grooming occurred more than yawning. An upward shift on this scale causes grooming to substitute yawning, whereas a downward shift causes the reverse effect.     

Automated assessment of conditioning parameters for context and cued fear in mice

A behavioral technique often used to evaluate the cognitive performance of rats and mice is the fear conditioning paradigm. During conditioned fear experiments, freezing responses shown by rodents after exposure to environmental stimuli previously paired to an aversive experience provide a behavioral index of the animal's associative abilities. The present study examined the ability of a computer-controlled automated Freeze Monitor system for recording immobility behavior in mice. The sensitivity of the automated procedure to detect group differences caused by the application of various training protocols was also evaluated. Statistical analyses revealed significant positive correlations between immobility scores obtained with the automated apparatus and hand-scored data collected by a continuous or a time-sampling method. Behavioral patterns recorded by the computerized system were very similar to those obtained by the hand-scoring methods adopted. In particular, during context testing, exposure to environmental stimuli previously paired with a mild foot shock (unconditioned stimulus [US]) evoked increased immobility behavior in mice conditioned with the US compared with levels of immobility displayed by mice previously confined to the same contextual stimuli without receiving the US. Moreover, although during conditioned stimulus (CS) testing, mice previously exposed to the US displayed high levels of immobility when confined to environmental cues much different from those paired with the US (contextual fear generalization), both hand-scored and automated results revealed the effect of CS–US pairing (increased immobility) only in mice trained to associate the two stimuli (paired group) but not in mice exposed to both CS and US separated by a 40-sec time interval (unpaired group) or in mice receiving only the US (US group) during conditioning sessions. Overall, the results show associative conditioning measured in an automated apparatus and highlight the utility of obtaining both latency as well as beam interruption parameters.     

Immobility and supination in garter snakes (Thamnophis elegans) following handling by human predators

A common response of animals to physical restraint is tonic immobility. The authors observed the behavior of garter snakes, Thamnophis elegans, in the field to determine the frequency of immobility as a response to handling. Most snakes fled after release, but the remainder remained immobile, sometimes on their backs (supination), for up to 10 min. Immobility was seen most often in pregnant snakes, which also were more likely than other snakes not to have moved before capture. Failure to move, either before or after capture, might be a consequence of the limited locomotory ability of gravid snakes. However, the lack of observations of interactions between snakes and their natural predators impedes researchers' understanding of the antipredator value, if any, of tonic immobility.     

Effects of acute administration of nicotine and lobeline on agonistic encounters in male mice

The effects of acute administration of two nicotinic ligands, (‐)‐nicotine and (‐)‐lobeline were examined on isolation‐induced aggression in mice. Individually housed male mice confronted anosmic “standard opponents” in a neutral arena 10 min after drug administration. Encounters were videotaped and evaluated using an ethologically based analysis facilitating estimation of time allocated to 11 broad behavioral categories. Nicotine did not have significant effects on threat or attack but significantly diminished time allocated to digging. The lowest dose of lobeline significantly diminished attack and induced a slight increase of immobility without significantly diminishing other behaviors with motor components. The intermediate and highest dose of lobeline reduced time allocated to all behaviors with motor components. It is concluded that these two nicotinic agonists produce different behavioral profiles during agonistic encounters in mice but that this test may not facilitate assessing the impact of such drugs on irritability. Aggr. Behav. 26:376–385, 2000. © 2000 Wiley‐Liss, Inc.     

Excessive grooming induced by the administration of codeine and morphine

Previous studies have shown that peripheral injections of the codeinone RX 336-M can induce excessive grooming in rats in an age-dependent fashion. The present experiment demonstrates that codeine, itself, also induces excessive grooming but with apparent equal effectiveness at all ages tested. Because of the structural similarity between codeine and morphine, the effects of intraperitoneally administered morphine were examined as well. Morphine was found to produce a temporal course of excessive grooming quite different from that produced by codeine. Morphine did not affect grooming in the first half (30 min) of the observation period, but accentuated it, briefly, for the next 30-45 min. Intraventricular administration of codeine at doses of 0.3 or 1.0 microgram/3 microliter had no effect on grooming in animals previously shown to demonstrate excessive grooming in response to either dose.     

Seasonal changes in open-field behavior in wild male meadow voles (Microtus pennsylvanicus)

Open-field behavior of free-living meadow voles was measured in males held overnight in the laboratory. Movement variables were positively correlated, and had negative associations with grooming and freezing. Parameters including activity, freezing, urinating, and grooming showed annual fluctuations related to the reproductive season. Together with the results of a previous study showing castration of wild voles results in altered open-field behavior, these results emphasize the role of testicular hormones in influencing this behavior. Factor analysis identified an activity component accounting for 39% of the variation, but other parameters were little simplified by this procedure. Most factors cycled annually, and significant variation was found in all eight factors during the 4-year sample. Open-field behavior varied between different reproductive and age segments of the population, and may be related to population processes such as dispersal.     

Receptivity of the female rat (Rattus norvegicus) after male devocalization: a ventral perspective

Male rats (Rattus norvegicus) emit at least two patterns of vocalization during copulation, the mating call and the pre-ejaculatory call. Both calls promote immobility of the female during lordosis, but the pre-ejaculatory calls are more effective. We undertook, through ventral observations of the mating pair, to determine if the female failed to assume or maintain the lordosis posture when mounted by a devocalized male and also to determine if the devocalized male was providing adequate stimulation to induce receptive behavior. Females were more likely to move away from the devocalized males before assuming the full lordosis posture. Furthermore, they were more likely to move away before the males had a chance to engage in intromissive behavior. However, when the females remained immobile long enough for the males to achieve a mount or intromission, there was little difference in the behavior of either animal that resulted from the devocalization of the male.     

Behavioral profile of L‐655,708, a selective ligand for the benzodiazepine site of GABA‐A receptors which contain the α5 subunit,in social encounters between male mice

GABA‐A receptor is a transmembrane hetero‐oligomeric protein which consists of five subunits, the combination of which confers unique pharmacological properties to the receptor. It is well‐known that the GABAergic system is involved in the modulation of aggression. However, the role of α5/GABA‐A receptors has not been explored. In this study, we examined the effect of L‐655,708 (0.625‐5 mg/kg), a selective ligand for the benzodiazepine site of GABA‐A receptors which contain the α5 subunit, on agonistic behavior elicited by isolation in male mice. Individually housed mice were exposed to an anosmic “standard opponent” 30 min after drug administration, and the encounters were videotaped and evaluated using an ethologically based analysis. L‐655,708 (5 mg/kg) exhibited an ethopharmacological profile characterized by a marked reduction of the time spent in offensive behavior (threat and attack) without affecting immobility, accompanied by a significant increase of avoidance/flee and nonsocial exploration behaviors, suggesting that the antiaggressive effect of the drug is unselective. Overall, this behavioral profile might indicate the existence of an anxiogenic‐like activity of L‐655,708 in mice. Aggr. Behav. 30:319–325, 2004. © 2004 Wiley‐Liss, Inc.     

Play fighting and the development of agonistic behavior in male and female rats

Two longitudinal studies were conducted to quantify the social behaviors exhibited by both male and female Long-Evans rats from the immediate postweaning period until young adulthood. In Experiment 1, male sibling pairs engaged in a high level of play fighting during the early juvenile period but such activity declined to a level significantly lower than that of female and mixed-sex pairs after 54 days of age. In Experiment 2, social exchanges during maturation were examined during the presence and absence of the piloerection response in an effort to distinguish play fighting from agonistic interactions. In male pairs, piloerection was rarely seen before 55–75 days of age but thereafter occurred with increasing frequency especially among dominant males. Furthermore, subordinate males retreated from their dominant partners and remained in an escape chamber for a significant amount of time only during encounters involving the exhibition of piloerection. This finding suggests that piloerection can be useful in identifying play and aggressive interactions. In female and heterosexual pairs, piloerection was observed infrequently during social encounters occurring throughout maturation. In addition, when given the opportunity to escape, females were less likely to retreat from play activity if their partner was another female than a male.