An empirically derived scoring system for intermale aggression in mice

Scoring systems used to assess intermale aggression have been characterized by arbitrary scales and wide variability in the behaviors selected for measurement. The use of such different systems severely limits the ability of investigators to make meaningful comparisons among studies and indicates that there is a need for a common, statistically derived evaluative system for intermale aggression. We measured the frequency and duration of five major components of agonistic behavior exhibited by intact males toward olfactory bulbectomized stimulus males and then analyzed the data using a number of univariate and multivariate procedures. The results were used to generate two statistically based scoring systems, one a short-form index and the other a composite index for more detailed studies of aggression. It is hoped that these statistically derived systems will be adopted by other investigators to increase methodological congruence in the field.     

Quantitative chromatographic profiling of odours associated with dominance in male laboratory mice

Triads of male NMRI mice were housed together and dominance hierarchies allowed to form. At age 19 weeks the mice were ranked on the basis of wins in spontaneous aggressive encounters, and whole-body volatiles were sampled by the dynamic solvent effect and quantitatively analysed by capillary gas chromatography. At age 26 weeks the mice were again ranked on the basis of wins in aggressive encounters, number of aggressive encounters initiated, and scent marking patterns, and whole-body volatiles were sampled and analysed. Chromatographic odour profile ranks agreed perfectly with aggressive initiator ranks and poorly with encounter winner ranks. Eight components of the whole-body odour were identified by gas chromatography-mass spectrometry; two of these are known semiochemicals. The results demonstrate that murine semiochemicals are accessible to quantitative analysis at the level of the individual.     

恐惧记忆习得与消退的性别差异及其神经机制

大多数人在其一生中都会经历创伤事件,但只有少数人会发展成为创伤后应激障碍（PTSD）。焦虑障碍的易感性和保护因素成为一个重要议题。基于恐惧记忆习得与消退模型的研究发现女性个体表现出“易习得、难消退”的特点。在恐惧相关脑区的脑生理结构、功能/结构连接性、以及大脑可塑性的性别差异可能是该特征的根本原因。性激素作为一种焦虑障碍的保护因素,可以调节这种性别差异,这种调节效应可能是通过影响大脑结构形态（如神经细胞的形态和数量）、调控与记忆相关基因的表达（如HDAC4）而实现的。雌性激素水平的不稳定性可能是女性易感焦虑障碍的重要原因。未来对性别差异的深入研究将有助于推进个性化医疗。     

The effects of gormone manipulations on aggressive target-biting in mice

Aggressive biting of an inanimate target by mice was studied. Males attacked the bite-target more frequently than females, but this difference disappeared after castration when the response rate of the males approached that of the females. Ovariectomizing the females had little effect on their bite-attack frequencies. Subsequent androgen injections restored the biting-attack frequency of the castrated males to preoperative levels but had little effect on the intact males. Estrogen had little effect on the response frequency of the females, whereas androgen produced a slight increase in their bite-attack frequency. Results indicate that androgen is critical for the maintenance of this aggressive response and that the single subject paradigm utilized in this study was a sensitive measure of aggressive tendencies in mice.     

Fighting in female mice in lines selected for laterality

Male and female mice from the Collins HI and LO laterality strains were isolated for 3–5 days. Thereafter on Day 1 each was given the Intruder Test followed by a Training Test; the latter was repeated 1 week later. All males of 36 days or older fought vigorously, but without line differences. Females of the HI strain showed higher numbers of fighters and greater intensity of fighting than those of the LO strain, and by the second Training Test these differences were significant at p < 0.01. The HI and LO laterality strains thus provide useful tools for investigating the functions of female agonistic behavior and the possible relationship between laterality and the expression of aggression.     

Body size as a determinant of aggression during heterosexual encounters in hormone-treated gonadectomized pigs

Aggressive and sexual behavior was studied in 5-minute paired encounters between testosterone-treated castrated boars and estrogen-treated ovariectomized gilts. The boars were either 15 kg heavier (N = 6), or lighter (N = 6), than the gilts (N = 8). Tests were carried out over a 4-week period, during which time each boar was paired once with each gilt; the procedure was replicated over a further 4 weeks. Gilts usually initiated the aggression, especially in the first 4-week period; however, the degree of aggression was positively correlated with body size, irrespective of sex. Aggression was reduced in the second 4-week period in both sexes in tests with large, but not with small, boars. Large boars were more sexually active than small boars, and their sexual performance improved markedly with time, unlike that of the small boars. Champing was positively correlated with aggression duration in pigs of both sexes, and salivation was seen more often in boars than gilts.     

Relative contributions of aggression and reproduction to behavioral endocrinology

Reproductive activity has been the behavior of choice for research in behavioral endocrinology. Why this is so and the consequences to the study of aggression and to behavioral endocrinology in general are explored.     

Differential acquisition of lever pressing in inbred and outbred mice: comparison of one-lever and two-lever procedures and correlation with differences in locomotor activity

Recent progress in mouse genetics has led to an increased interest in developing procedures for assessing mouse behavior, but relatively few of the behavioral procedures developed involve positively reinforced operant behavior. When operant methods are used, nose poking, not lever pressing, is the target response. In the current study differential acquisition of milk-reinforced lever pressing was observed in five inbred strains (C57BL/6J, DBA/2J, 129X1/SvJ, C3H/HeJ, and BALB/cJ) and one outbred stock (CD-1) of mice. Regardless of whether one or two levers (an "operative" and "inoperative" lever) were in the operant chamber, a concomitant variable-time fixed-ratio schedule of milk reinforcement established lever pressing in the majority of mice within two 120-min sessions. Substantial differences in lever pressing were observed across mice and between procedures. Adding an inoperative lever retarded acquisition in C57BL/6J, DBA/2J, 129X1/SvJ, and C3H/HeJ mice, but not in CD-1 and BALB/cJ mice. Locomotor activity was positively correlated with number of lever presses in both procedures. Analyses of durations of the subcomponents (e.g., time to move from hopper to lever) of operant behavior revealed further differences among the six types of mice. Together, the data suggest that appetitively reinforced lever pressing can be acquired rapidly in mice and that a combination of procedural, behavioral, and genetic variables contributes to this acquisition.     

Hormones and Cognition: Current Concepts and Issues in Neuropsychology

This article provides an extensive and comprehensive review of the effects of hormones on cognition. Studies detailing specific neurocognitive functions affected by variation in hormone levels across the life span are presented. Dysregulation of hormone levels is considered from models of both normal and diseased functioning. Patterns of cognitive dysfunction are described for a range of syndromes involving the neuroendocrine system, and evidence of specific neurophysiological mechanisms that can account for these findings is outlined. This review includes discussion of treatment outcomes and the permanency of endocrine-related cognitive dysfunction. The authors present a set of guidelines for clinical neuropsychologists to use for assessment of patients with neuroendocrine system dysfunction. Clinical and methodological issues in research and treatment settings are discussed.     

Effects of the Novel Acetylcholinesterase InhibitorN-Octyl-1,2,3,4-tetrahydro-9-aminoacridine on Locomotor Activity and Avoidance Learning in Mice

The acetylcholinesterase reversible inhibitorN-octyl-1,2,3,4-tetrahydro-9-aminoacridine (THA-C8) is a new synthesized derivative of tacrine (THA) characterized by an alkyl chain in the molecular structure which ameliorates the penetrability of the compound into the central nervous system. THA-C8 (0.1–5 mg/kg) significantly reduced spontaneous locomotor activity in CD1 mice at a dose of 3 mg/kg. Moreover, THA-C8 (0.2–2 mg/kg) significantly improved shuttle-box avoidance acquisition at doses (0.25, 0.3, 1 mg/kg) not affecting locomotion and that are much lower than the doses reported to be effective for THA in animal models. From the data reported it seems that the new compound could be interesting for therapeutic purposes.