Lateral Threat Research Articles

Maternal aggression in Wistar rats: effect of 5-HT2A/2C receptor agonist and antagonist microinjected into the dorsal periaqueductal gray matter and medial septum

The objective of the present study was to assess the role of the 5-HT2A/2C receptor at two specific brain sites, i.e., the dorsal periaqueductal gray matter (DPAG) and the medial septal (MS) area, in maternal aggressive behavior after the microinjection of either a 5-HT2A/2C receptor agonist or antagonist. Female Wistar rats were microinjected on the 7th postpartum day with the selective agonist alpha-methyl-5-hydroxytryptamine maleate (5-HT2A/2C) or the antagonist 5-HT2A/2C, ketanserin. The agonist was injected into the DPAG at 0.2 (N = 9), 0.5 (N = 10), and 1.0 microg/0.2 microl (N = 9), and the antagonist was injected at 1.0 microg/0.2 microl (N = 9). The agonist was injected into the medial septal area (MS) at 0.2 (N = 9), 0.5 (N = 7), and 1.0 microg/0.2 microl (N = 6) and the antagonist was injected at 1.0 microg/0.2 microl (N = 5). For the control, saline was injected into the DPAG (N = 7) and the MS (N = 12). Both areas are related to aggressive behavior and contain a high density of 5-HT receptors. Non-aggressive behaviors such as horizontal locomotion (walking) and social investigation and aggressive behaviors such as lateral threat (aggressive posture), attacks (frontal and lateral), and biting the intruder were analyzed when a male intruder was placed into the female resident's cage. For each brain area studied, the frequency of the behaviors was compared among the various treatments by analysis of variance. The results showed a decrease in maternal aggressive behavior (number of bites directed at the intruder) after microinjection of the agonist at 0.2 and 1.0 microg/0.2 microl (1.6 +/- 0.7 and 0.9 +/- 0.3) into the DPAG compared to the saline group (5.5 +/- 1.1). There was no dose-response relationship with the agonist. The present findings suggest that the 5-HT2A/2C receptor agonist has an inhibitory effect on maternal aggressive behavior when microinjected into the DPAG and no effect when microinjected into the MS. Ketanserin (1.0 microg/0.2 microl) decreased locomotion when microinjected into the DPAG and MS, but did not affect aggressive behavior. We interpret these findings as evidence for a specific role of 5-HT2A/2C receptors in the DPAG in the inhibition of female aggressive behavior, dissociated from those on motor activity.

Orbital prefrontal cortex, dopamine, and social-agonistic behavior of male long evans rats

The prefrontal cortex of the rat consists of two subareas, a medial and an orbitofrontal. The anatomical dissociation is accompanied by a functional dissociation. In this study the behavioral effects of two manipulations of the orbitofrontal cortex were investigated. Social-agonistic behavior of male rats of the Long Evans strain was observed in dyadic interactions. Bilateral thermal lesions of the orbitofrontal cortex resulted in an enhancement of aggression (experiment 1), evident from higher scores for lateral threat and keeping down. The prefrontal cortex is one of the very few cortical areas to receive a dopaminergic innervation. When dopamine was depleted by means of local infusion of 6-hydroxydopamine (6-OHDA) in the orbitofrontal cortex, similar behavioral changes were recorded (experiment 2). These findings are indicative of the important role of the mesocortical dopaminergic pathway in the regulation of social-agonistic behavior.

Sound Communication During the Reproductive Behavior of Notropis analostanus (Pisces: Cyprinidae)

Field and laboratory observations were made on the reproductive behavior, ecology and sounds produced by males of Notropis analostanus during reproductive behavior. Based on these observations, experiments were performed on sound communication during the repro- ductive behavior of this species. Reproductive activities began in middle to late May when the males set up territories around a suitable egg site. The males defended these territories by chasing and fighting behavior which included the lateral threat display. During this aggressive behavior, single knocks and rapid series of knocks were produced. Courtship behavior began when a female approached the territory and the male swam out to her. If the female did not swim away, the male swam in circles around her and then swam to the egg site where it would perform solo-spawning motions. Spawning was accomplished when the female followed the male to the egg site and assumed a spawning position with the male in a dorsolateral position to her. During the courtship behavior the male produced single knocks and purrs. The functions of sounds produced by male Notropis analostanus during reproductive behavior were studied by playing back these sounds under experimental conditions designed to clarify their functions as com- municative signals. The following conclusions were reached: 1. The single knocks were not effective in influencing aggressive behavior of males nor did they promote courtship. 2. The rapid series of knocks stimulated aggressive behavior by a dominant male and inhibited the entry of a submissive male into the territory. 3. The rapid series of knocks inhibited the courtship behavior of the male and reduced cooperation by the female during courtship. 4. The purrs increased the courtship behavior of the male and pro- moted the cooperation of the female during courtship.

The ontogeny of agonistic behavior and the onset of sexual maturation in the paradise fish, Macropodus opercularis (linnaeus)

Fish 20–100 days of age were observed in brief conflicts with a stimulus fish of similar size and age. Four stages of behavior development were identified, based on quantitative changes in behavior which occurred with increasing age. Relatively little aggressive behavior occurs in the larval stage which includes fish up to about 40 days of age. Juveniles, age 40–70 days, approach, chase, and attack each other much more than do the larva. In the adolescent stage, 70–100 days of age, the incidence of species typical displays increases paralleling the onset of puberal changes in the testis and ovary. No sex differences in behavior were seen in fish up to 100 days of age. Among adult fish of unknown age males performed lateral threat displays more frequently than females as has been previously reported.

The Behavior of the Pumpkinseed Sunfish, Lepomis Gibbosus (Linneaus), With Notes On the Behavior of Other Species of Lepomis and the Pigmy Sunfish, Elassoma Evergladei

The Behavior of the Pumpkinseed Sunfish, Lepomis Gibbosus (Linneaus), With Notes On the Behavior of Other Species of Lepomis and the Pigmy Sunfish, Elassoma Evergladei