Acoustic and postural displays in a miniature and transparent teleost fish, Danionella dracula

Individuals can reveal their relative competitive ability or mate quality through acoustic communication, varying signals in form and frequency to mediate adaptive interactions including competitive aggression. We report robust acoustic displays during aggressive interactions for a laboratory colony of Danionella dracula, a recently discovered miniature and transparent species of teleost fish closely related to zebrafish (Danio rerio). Males produce bursts of pulsatile, click-like sounds and a distinct postural display, extension of a hypertrophied lower jaw, during resident-intruder dyad interactions. Females lack a hypertrophied lower jaw and show no evidence of sound production or jaw extension under such conditions. Novel pairs of size-matched or mismatched males were combined in resident-intruder assays where sound production and jaw extension could be linked to individuals. Resident males produce significantly more sound pulses than intruders in both dyad contexts; larger males are consistently more sonic in size-mismatched pairs. For both conditions, males show a similar pattern of increased jaw extension that frequently coincided with acoustic displays during periods of heightened sonic activity. These studies firmly establish D. dracula as a sound-producing species that modulates both acoustic and postural displays during social interactions based on either residency or body size, thus providing a foundation for investigating the role of these displays in a new model clade for neurogenomic studies of aggression, courtship and other social interactions.

Structural Degradation in Midcingulate Cortex Is Associated with Pathological Aggression in Mice

Pathological aggression is a debilitating feature of many neuropsychiatric disorders, and cingulate cortex is one of the brain areas centrally implicated in its control. Here we explore the specific role of midcingulate cortex (MCC) in the development of pathological aggression. To this end, we investigated the structural and functional degeneration of MCC in the BALB/cJ strain, a mouse model for pathological aggression. Compared to control animals from the BALB/cByJ strain, BALB/cJ mice expressed consistently heightened levels of aggression, as assessed by the resident-intruder test. At the same time, immunohistochemistry demonstrated stark structural degradation in the MCC of aggressive BALB/cJ mice: Decreased neuron density and widespread neuron death were accompanied by increased microglia and astroglia concentrations and reactive astrogliosis. cFos staining indicated that this degradation had functional consequences: MCC activity did not differ between BALB/cJ and BALB/cByJ mice at baseline, but unlike BALB/cByJ mice, BALB/cJ mice failed to activate MCC during resident-intruder encounters. This suggests that structural and functional impairments of MCC, triggered by neuronal degeneration, may be one of the drivers of pathological aggression in mice, highlighting MCC as a potential key area for pathologies of aggression in humans.

Intranasal oxytocin reduces pre-courtship aggression and increases paternal response in California mice (Peromyscus californicus)

Oxytocin (OXT) is a neuropeptide that can facilitate prosocial behavior and decrease social stress and anxiety. We investigated whether acute pulses of intranasal (IN) OXT influenced social behavior during social challenges that are likely to occur throughout the lifespan of a wild mouse. To test this, we examined the acute effects of IN OXT in the male California mouse (Peromyscus californicus), a monogamous, biparental, and territorial rodent, using a within-subjects longitudinal design. Social challenges included a pre-courtship male-female encounter conducted during the initial aggressive and not the following affiliative phase of courtship, same-sex resident intruder test, and parental care test, with each test and dose separated by at least two weeks. Males were treated with intranasal infusions of 0.8 IU/kg OXT or saline controls 5-min before each behavioral test, receiving a total of three treatments of either IN OXT or saline control. We predicted that IN OXT would 1) decrease aggression and increase affiliation during the pre-courtship aggression phase, 2) increase aggression during resident intruder paradigms and 3) increase paternal care and vocalizations during a paternal care test. As predicted, during pre-courtship aggression with a novel female, IN OXT males displayed less contact aggression than control males, although with no change in affiliative behavior. However, post-pairing, during the resident intruder test, IN OXT males did not differ from control males in contact aggression. During the paternal care test, IN OXT males were quicker to approach their pups than control males but did not differ in vocalizations produced, unlike our previous research demonstrating an effect on vocalizations in females. In summary, during pre-courtship aggression and the paternal care test, IN OXT promoted prosocial approach; however, during the resident intruder test IN OXT did not alter social approach. These data suggest that IN OXT promotes prosocial approach specifically in social contexts that can lead to affiliation.

In vivo antidepressant efficacy of 3-substituted thietane-1, 1-dioxide derivative - a preliminary study for novel anti-depression therapy in neurological disorders

Background: Psychosocial stress-induced depressive behavior is linked to etiology of several neurological diseases viz., PTSD, and neurodegenerative disease like Alzheimer’s disease (AD). The repeated bouts of social stress defeat can be induced using Resident-Intruder-Paradigm (RIP) and chronic mild social stress (CMSS) animal models to assess the stress-induced depressive behavioral patterns. Objectives: The aim of this study to examine the anti-depressive efficacy of 3-methoxythietane-1,1-dioxide (N-14) in RIP models of behavioral alterations. Methods: In this study, we have used Sprague-Dawley rats in Resident-Intruder-Paradigm (RIP), where intruders interacted with residents Day 0 to Day +5 for 10 minutes to invoke CMSS in intruders and became defeated/submissive rats due to the depressive-like behavioral alterations in social activity, explorations, grooming, defense, aggressive behavior, and social interaction, freeze, and rearing etc., with residents. Group I is control intact animals, group II received N-14 alone; group III received CMSS, and group IV received cotreatment of N14 with CMSS. N-14 (2 mg/kg) was administered intraperitoneally from Day 0 to Day +5 to intact animals and intruder animals under conditions of CMSS. Results: Several behavioral tests viz., forced swim test, open field test, and elevated-plus maze test were used to examine the above behavioral dynamic parameters. The dynamic interaction between Residents and Intruders during the study showed substantial alterations in exploratory activity, aggressiveness, and defensive behavior, body weight, and thymus mass in stressed animals. N-14 cotreatment has mitigated sociability, exploratory activity, and aggressiveness and increased social adaptability and defensive behavior. Extensive rise in active forms of defense and submission latency indicate that N-14 has induced antidepressant activity with a psycho-sedative component of action. Conclusion: Serendipitously, we observed the ameliorative capability of N-14 cotreatment to mitigate depressive-behavioral symptoms in intruders.

Pharmacological analysis of the effects of the neuropeptide Y antagonist BMS 193885 on the emotional, intraspecies behavior and reinforcing properties of ethanol in rats

Purpose. Our previously data on orexigenic peptides (orexin, ghrelin) showed antagonists of peptides receptors as correctors of the emotional-motivational and cognitive spheres. Currently, a close relationship between ghrelin and orexin with neuropetide Y has been shown in feeding and emotional behavior. The aim of this work was to analyze the effect of the NPY antagonist Y1R BMS 193885 on emotional and intraspecies behavior, as well as on the reinforcing properties of ethanol in rats. Methods. We used the open field test, elevated plus-maze, Porsolts forced swimming test, resident intruder test, conditional place preference (CPP). BMS 193885 1 mg/ml, 20 l intranasally did not cause an anxiogenic effect in the elevated plus-maze. Results. In the Porsolts test, there was also no increase in the level of depression. Moreover, there was a significant decrease in the number and time of dives, as an indirect indicator of a decrease in the level of depression. At the same time, in the resident intruder test were decreased protective behavior, as an indicator of a decrease in the stress of intraspecific interaction in the absence of aggression. Moreover, local movements were increased in the open field test as an indicator of the animals activity impaired by fear. BMS 193885 had no effect on the expression of the CPP of ethanol. Conclusion. Thus, it was previously shown that the BMS 193885 is a powerful, selective, brain-penetrating Y1 receptor antagonist, it reduces food intake and body weight in animal models of obesity both after acute and chronic administration. Our data indicate that the decrease in food intake is not associated with the level of anxiety, depression, or with a change in intraspecific interaction. It has been previously shown that NPY reduces alcohol consumption. Our data indicate that the Y1R antagonist of the neuropeptide Y BMS 193885 does not cause a change in the CPP of alcohol.

In Vivo Antidepressant Efficacy of 3-substituted Thietane-1, 1-dioxide Derivative - A Preliminary Study for Novel Anti-depression Therapy in Neurological Disorders

Background: Psychosocial stress-induced depressive behavior is linked to etiology of several neurological diseases viz., PTSD, and neurodegenerative disease like Alzheimer’s disease (AD). The repeated bouts of social stress defeat can be induced using Resident-Intruder-Paradigm (RIP) and chronic mild social stress (CMSS) animal models to assess the stress-induced depressive behavioral patterns. The aim of this study to examine the anti-depressive efficacy of 3-methoxythietane-1,1-dioxide (N-14) in RIP models of behavioral alterations.Methods: In this study, we have used Sprague-Dawley rats in Resident-Intruder-Paradigm (RIP), where intruders interacted with residents Day 0 to Day +5 for 10 minutes to invoke CMSS in intruders and became defeated/submissive rats due to the depressive-like behavioral alterations in social activity, explorations, grooming, defense, aggressive behavior, and social interaction, freeze, and rearing etc., with residents. Group I is control intact animals, group II received N-14 alone; group III received CMSS, and group IV received cotreatment of N14 with CMSS. N-14 (2 mg/kg) was administered intraperitoneally from Day 0 to Day +5 to intact animals and intruder animals under conditions of CMSS. Several behavioral tests viz., forced swim test, open field test, and elevated-plus maze test were used to examine the above behavioral dynamic parameters.Results: the dynamic interaction between Residents and Intruders during the study showed substantial alterations in exploratory activity, aggressiveness, and defensive behavior, body weight, and thymus mass in stressed animals. N-14 cotreatment has mitigated sociability, exploratory activity, and aggressiveness and increased social adaptability and defensive behavior. Extensive rise in active forms of defense and submission latency indicate that N-14 has induced antidepressant activity with a psycho-sedative component of action.Conclusion: Serendipitously, we observed the ameliorative capability of N-14 cotreatment to mitigate depressive-behavioral symptoms in intruders. Since it is a preliminary study, we have not examined any pathophysiological and molecular signaling to delineate the efficacy of N-14 in retarding depressive-behavioral symptoms. Our future studies will address these aspects to fully consider N-14 as a novel therapy against stress-induced depression in neuropsychiatric and neurodegenerative disorders (ex. AD) using in vivo and clinical models.

Long Term Benefits on Social Behaviour after Early Life Socialization of Piglets

Early life socialization of piglets has been shown to reduce piglet aggression at weaning, but information on sow health and long-term benefits is lacking. We aimed to assess how socialization impacts sow udder quality and long-term pig behaviour and growth. At two weeks of age, 65 litters either experienced socialization with one other litter (SOC) or did not (control; CON). Sows (housed in farrowing crates) were scored for teat damage and piglets were observed for aggressive behaviour (resident-intruder test) and growth and skin lesions up to 11 weeks under conventional farm conditions (including weaning and regrouping). At weaning, SOC sows had more teat damage than CON sows (p = 0.04). SOC piglets had double the number of lesions 24 h post-socialization compared to the control (19 versus 8; p < 0.001). In the resident-intruder test, more SOC pigs attacked the intruder (SOC 78%; CON 66%; p < 0.01), and attacked more quickly (p = 0.01). During regrouping (week 8), SOC pigs had 19% fewer lesions (SOC 68; CON 84; p < 0.05), but three weeks later, groups did not differ. Growth was unaffected by treatment. Overall, socialized piglets seem to be equipped with greater confidence or agonistic skills, leading to fewer injuries from fighting up to at least six weeks after socialization.