Agonistic Behavior In Male Mice Research Articles

GENETIC FEATURES of DEVELOPMENTAL PATTERNS OF AGONISTIC BEHAVIOR IN LABORATORY MALE MICE UNDER SOCIAL HIERARCHY CONDITIONS

Background. Agonistic behavior is necessary for formation of dominant-subordinate relationship and for maintenance of social hierarchy in animal communities. However? there are few reports about the genetic features of agonistic behavior development in animals living in stable social groups. The aim of the present study was to investigate the ontogeny of agonistic behavior in male mice of different genotype and social status under stable social hierarchy conditions. Materials and methods. We studied the age dynamics of offensive attacks, the vertical defensive postures and the “runaway” behavior in male mice of inbred strains PT and CBA/Lac housed in genetically heterogeneous pairs during puberty (from 38 to 70 days of life). Results. Dominant-subordinate relationships were stable in 80 % of pairs during the experiment. During the period of stable social hierarchy we observed a transient increase in the number of offensive attacks at the end of puberty in dominants of the strain CBA/Lac but not in PT. Conclusion. In conclusion, the study revealed a significant influence of social rank and genotype on the development of patterns of social behavior in laboratory male mice during puberty.

P.1.h.027 MBDB, a recreational drug similar to MDMA, alters sequential structure of agonistic behaviour in male mice

The synthetic drug 3,4-methylenedioxy-N-methylamphetamine (MDMA), also known as ecstasy, is one of the most abused dance drugs spread around the world. The number of seizures of ecstasy tablets increases every year. As MDMA is a chiral substance with one chiral center, it may occur as two enantiomers. These enantiomers have different physiological effects, therefore the reliable detection of individual enantiomers and a detailed structural description are highly desirable. In this work, the 3D structure of MDMA in solution was investigated by vibrational circular dichroism and electronic circular dichroism supplemented by conventional infrared and ultraviolet absorption spectroscopies. The obtained results were supported by density functional theory (DFT) calculations using different levels of theory. Initially, sixty-four starting geometries were optimized at the B3LYP/6-31G(d) level including the solvent effects. Four stable conformers were further reoptimized at higher levels of theory and the spectra were also simulated. The experimental and the calculated spectra were compared via the similarity index. The spectra comparison showed very good agreement, which enabled us to describe the molecular structure of MDMA in detail.

Environmental Enrichment Improves Novel Object Recognition and Enhances Agonistic Behavior in Male Mice

Environmental enrichment (EE) is an experimental paradigm in which rodents are housed in complex environments containing objects that provide stimulation, the effects of which are expected to improve the welfare of these subjects. EE has been shown to considerably improve learning and memory in rodents. However, knowledge about the effects of EE on social interaction is generally limited and rather controversial. Thus, our aim was to evaluate both novel object recognition and agonistic behavior in NMRI mice receiving EE, hypothesizing enhanced cognition and slightly enhanced agonistic interaction upon EE rearing. During a 4-week period half the mice (n = 16) were exposed to EE and the other half (n = 16) remained in a standard environment (SE). On PND 56-57, animals performed the object recognition test, in which recognition memory was measured using a discrimination index. The social interaction test consisted of an encounter between an experimental animal and a standard opponent. Results indicated that EE mice explored the new object for longer periods than SE animals (P < .05). During social encounters, EE mice devoted more time to sociability and agonistic behavior (P < .05) than their non-EE counterparts. In conclusion, EE has been shown to improve object recognition and increase agonistic behavior in adolescent/early adulthood mice. In the future we intend to extend this study on a longitudinal basis in order to assess in more depth the effect of EE and the consistency of the above-mentioned observations in NMRI mice.

Differential effects of modafinil, methamphetamine, and MDMA on agonistic behavior in male mice

The aim of the present study was to compare the behavioral effects of modafinil, an atypical psychostimulatory acting and cognitive-function improving drug, with the effects of the psychostimulants methamphetamine (MET) and MDMA (3,4-methylenedioxymethamphetamine, or “ecstasy”) in a model of mouse agonistic behavior. This model enables the observation of ethologically well-defined sociable, timid, aggressive, and locomotor behavioral acts and postures. Singly-housed male mice (isolates) were separated into 4 groups. The observations were performed in 4 sessions, 1week apart. In each interaction, singly-housed mice were paired with non-aggressive group-housed partners for 4min in a neutral environment. The isolates received, in a Latin square design, either a) a vehicle or modafinil at doses 2.0, 10.0, or 50.0mg/kg; or b) a vehicle or MET at doses 1.0, 5.0, or 10.0mg/kg; or c) a vehicle or MDMA at doses 2.5, 10.0, or 30.0mg/kg. The isolates were categorized as timid or aggressive according to their behavior in the control interaction (vehicle pre-treatment). Elements of locomotor, sociable, aggressive, and timid behavior were evaluated (one-way ANOVA).In the aggressive mice, no change in the sum of aggressive behavior was measured following modafinil administration, while both methamphetamine and MDMA produced dose-dependent inhibition of aggression (p<0.01). The substantial difference in the tested drug effects on agonistic behavior was an increased occurrence of sociable acts (p<0.01) accompanied by a simultaneous increase of timid acts (p<0.01) recorded after MDMA, but not after modafinil or methamphetamine administration. In the timid mice, at least some doses of modafinil decreased timidity (p<0.01) and increased aggression (p<0.01) with no effect on sociability. Administration of MDMA increased timid activities (p<0.01). Both MDMA and MET decreased sociability (p<0.01).

Changes in Catechol-O-Methyltransferase Gene Expression Associated with Agonistic Behavior in Male Mice

Catechol-O-methyltransferase (COMT) is anenzyme catalyzing the transfer of the methyl groupfrom S-adenosine-methionine to the hydroxyl group ofcatecholamines, which are thereby inactivated. COMTfunctions in the central nervous system (CNS) andperipheral tissues plays an important role in catabolismof brain dopamine and noradrenaline, which areinvolved in regulation of human and animal behavior,both normal and pathological. We suggested that thelevel of the COMT gene expression may play a certainrole in basic behavioral processes, such as agonistic(competitive) behavior characteristic of animals at var-ious levels of evolutionary hierarchy. This behavior isused to defend the dominated territory or to establishthe domination–submission relationships. In this study,we used the midbrain of male C57BL/6J mice witheither aggressive or submissive behavioral type to ana-lyze the possible changes in the COMT gene expres-sion (the level of mRNA) with the use of quantitativepolymerase chain reaction (PCR).To obtain alternative types of behavior in mice, weused the sensory contact model [1]. The individualsocial victory or defeat experienced in the first pairwisesocial confrontation was subsequently reinforced bydaily contacts with the animal exhibiting the oppositetype of behavior. After aggressive interactions during10 to 20 days (tests), we obtained groups of animalswith experience of several consecutive victories (win-ners, or aggressors) or defeats (losers, or victims). Thewinners always displayed pronounced aggression andattacked the opponents, whereas the losers submitted orran away, thus displaying submissive behavior. Intactmice served as a control group; they were kept individ-ually for five days to reduce the effect of the group rela-tionships.On day after the last agonistic interaction, bothexperimental and control animals were decapitated,their brain was withdrawn in the cold, and the midbrainand pons were isolated (these structures contain mostof the monaminergic, i.e., noradrenergic, dopaminer-gic, and serotonergic neurons). Tissues were pooled(two midbrains per sample) and stored at t = –70 ° Cuntil biochemical analysis. Three measurements weremade with simultaneous analysis of brain tissue sam-ples from all animal groups.Total RNA was isolated [2], dissolved in water, andtreated with DNAse. The qualitative pattern of the prep-aration was obtained by electrophoresis in 1.5% agar-ose gel. The amount of RNA was measured spectropho-tometrically in each sample. RNA samples were storedat – 70i C before use. cDNA was obtained by means ofreverse transcription of 300 ng of the total RNA for 1 hat 37 i C using 5 µ M d (ð T )

Abstracts: Serotonergic modulation of social and agonistic behaviour in male mice by Helen Hobson, B.A., The Queen’s University of Belfast, 1993.

Abstracts: <b>Serotonergic modulation of social and agonistic behaviour in male mice</b> by <b>Helen Hobson</b>, B.A., The Queen’s University of Belfast, 1993.

Psychotropic effects of adrenergic beta-blockers on agonistic behavior between resident and intruder mice.

The present study was conducted to investigate the effect of adrenergic beta-blockers on agonistic behavior in male mice, using quantitative ethological methods. Agonistic behavior was evoked using a resident-intruder paradigm. The following drugs were administered orally at four dose levels (vehicle, 5, 10 and 20 mg/kg) to either resident or intruder mice: dl-propranolol, practolol, d-propranolol, and l-propranolol. When the resident was treated with either dl-propranolol or l-propranolol, aggressive episodes (offensive sideways posture, attack bite, tail rattle) were suppressed significantly in a dose-dependent manner, whereas practolol and d-propranolol were ineffective. All treatments except the high dose of l-propranolol failed to affect the resident's solitary behavior (locomotion). When the intruder was treated with beta-blockers, agonistic behavior was not altered. Since practolol does not cross the blood-brain barrier, the differential suppression of agonistic behavior is due to the central action of beta-blockers. d-Propranolol does cross the blood-brain barrier but is devoid of beta-receptor blocking property; hence l-propranolol suppression of agonistic behavior implies inactivation of brain adrenergic beta-receptors. The findings seem to indicate that beta-blockers such as dl-propranolol and l-propranolol have a psychotropic action.

The inheritance of agonistic behavior in male mice: A diallel analysis

The diallel cross genetic design was employed to determine the pattern of inheritance of male-male agonistic behavior in laboratory mice. The results indicated strong strain differences in agonistic behaviors and strain ranks that replicated previous findings. The genetic analysis showed the presence of additive and nondirectional dominance effects on the behaviors measured. This pattern has been characterized as indicating the action of stabilizing selection and indicates that the trait has not been under directional selection.

Threat postures signal impending attack in mice

Attacks exhibited by male mice toward olfactory bulbectomized stimulus males are classified as either ritualized or nonritualized according to whether they are or are not immediately (within 2 sec) preceded by a species-typical threat display. Comparisons between these two classes of attack behavior show that ritualized attacks are significantly shorter in duration than nonritualized attacks. These data indicate that a particular component of agonistic behavior in male mice, the threat posture, functions as a signal that limits the intensity of intermale aggression.

Manipulation of aggressive behavior in adult DBA/2/Bg and C57BL/10/Bg male mice implanted with testosterone in silastic tubing

Adult DBA/2/Bg and C57BL/10/Bg male mice were orchidectomized and implanted subcutaneously with one of two doses of testosterone (T) in Silastic tubing. Steroid doses which resulted in significant atrophy and hypertrophy of accessory sex tissues were determined for each strain. Relative to sham-castrated vehicle-implanted controls, both hypophysiological and hyperphysiological implants caused augmentation of aggression in C57BL/10/Bg males. In DBA/2/Bg mice, the hypophysiological dose reduced and the hyperphysiological implant increased aggression scores. The results demonstrate that agonistic behavior in male mice is influenced by the titer of circulating T and emphasize the importance of genetic variance in the study of hormones and behavior.