Lipopolysaccharide (LPS) attenuates the primary conditioning of lithium chloride (LiCl)-induced context aversion but not the secondary conditioning of context aversion or taste avoidance.

A first-order association can be formed between toxin-induced nausea and a context, as well as nausea and a taste cue. However, comparatively little is understood about second-order associations. The present study examined if the bacterial endotoxin, LPS, could impair the first- and second-order conditioning of context aversion (anticipatory nausea paradigm) and subsequent conditioned taste avoidance (two-bottle task).

Disgusted snails, oxytocin, and the avoidance of infection threat.

Disgust is considered to be a fundamental affective state associated with triggering the behavioral avoidance of infection and parasite/pathogen threat. In humans, and other vertebrates, disgust affects how individuals interact with, and respond to, parasites, pathogens and potentially infected conspecifics and their sensory cues. Here we show that the land snail, Cepaea nemoralis, displays a similar "disgust-like" state eliciting behavioral avoidance responses to the mucus associated cues of infected and potentially infected snails.

Immune activation attenuates memory acquisition and consolidation of conditioned disgust (anticipatory nausea) in rats.

Anticipatory nausea is a classically conditioned response to cues (e.g. contexts) that have been previously paired with a nauseating stimulus, such as chemotherapy in humans.

Infection, learning, and memory: Focus on immune activation and aversive conditioning.

Here we review the effects of immune activation primarily via lipopolysaccharide (LPS), a cell wall component of Gram-negative bacteria, on hippocampal and non-hippocampal-dependent learning and memory. Rodent studies have found that LPS alters both the acquisition and consolidation of aversive learning and memory, such as those evoking evolutionarily adaptive responses like fear and disgust. The inhibitory effects of LPS on the acquisition and consolidation of contextual fear memory are discussed.

Social factors and the neurobiology of pathogen avoidance.

Although the evolutionary causes and consequences of pathogen avoidance have been gaining increasing interest, there has been less attention paid to the proximate neurobiological mechanisms. Animals gauge the infection status of conspecifics and the threat they represent on the basis of various sensory and social cues. Here, we consider the neurobiology of pathogen detection and avoidance from a cognitive, motivational and affective state (disgust) perspective, focusing on the mechanisms associated with activating and directing parasite/pathogen avoidance.

Odor-based mate choice copying in deer mice is not affected by familiarity or kinship.

Individuals pay attention to the social and mate decisions of others and use these to determine their own choices, displaying mate choice copying. The present study with deer mice, Peromyscus maniculatus, showed that females copied the odor preferences and appetitive components of the mate choice of other females. It was found that an association between male and female odors, which is indicative of the apparent interest expressed by a female in a male, enhanced the preference of another female for the odors of that male.

Differential effects of progesterone on social recognition and the avoidance of pathogen threat by female mice.

Although pathogen threat affects social and sexual responses across species, relatively little is known about the underlying neuroendocrine mechanisms. Progesterone has been speculated to be involved in the mediation of pathogen disgust in women, though with mixed experimental support. Here we considered the effects of acute progesterone on the disgust-like avoidance responses of female mice to pathogen threat.

Sex and age differences in locomotor and anxiety-like behaviors in rats: From adolescence to adulthood.

Risk-taking behaviors are a primary contributor to elevated adolescent injury and mortality. Locomotor and anxiety-like behaviors in rodents have been used to examine risk-taking. Here, we examined risk-taking behavior (i.

Conspecific infection threat rapidly biases the social responses of female mice: Involvement of oxytocin.

Pathogen threat affects social preferences and responses across species. Here we examined the effects of social context and the infection status of conspecific females and males on the social and mate responses of female mice. The responses of female mice to males were rapidly affected by the presence of infected female conspecifics and infected males.

Lipopolysaccharide (LPS) induced sickness in early adolescence alters the behavioral effects of the short-chain fatty acid, propionic acid, in late adolescence and adulthood: Examining anxiety and startle reactivity.

Early life immune challenges are risk factors for neurodevelopmental disorders. In adolescence, they elicit behavioral symptoms that resemble clinical disorders. Stressors during this time may alter signaling from the gut microbiome, which increases the risk for psychiatric disorders.

Predator odor exposure in early adolescence influences the effects of the bacterial product, propionic acid, on anxiety, sensorimotor gating, and acoustic startle response in male rats in later adolescence and adulthood.

It is becoming evident than the adolescent period is a sensitive period in stress response programming. Stressors during this time may alter signaling from the gut microbiome, which has been shown to increase the risk for psychiatric disorders. It was hypothesized that adolescent stressors may potentiate the symptoms of anxiety and sensory abnormalities induced by a gut bacterial product, the short-chain fatty acid, propionic acid (PPA).

Systemic Treatment with the Enteric Bacterial Fermentation Product, Propionic Acid, Reduces Acoustic Startle Response Magnitude in Rats in a Dose-Dependent Fashion: Contribution to a Rodent Model of ASD.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, characterized by cognitive and sensorimotor deficits, among others. Hypo-sensitivity and hyper-sensitivity to different stimuli within the same sensory modality, a prominent symptom of ASD, can be assessed by acoustic startle response (ASR) and prepulse inhibition (PPI). Propionic acid (PPA) is a short-chain fatty acid and a by-product of the human gut microbiome.