Fast Anxiolytic-Like Effect Observed in the Rat Conditioned Defensive Burying Test, after a Single Oral Dose of Natural Protein Extract Products

Anxiety appears among the most frequent psychiatric disorders. During recent years, a growing incidence of anxiety disorders can be attributed, at least in part, to the modification of our eating habits. To treat anxiety disorders, clinicians use benzodiazepines, which unfortunately display many side effects. Herein, the anxiolytic-like properties of two natural products (αS1–casein hydrolysate and Gabolysat®) were investigated in rats and compared to the efficacy of benzodiazepine (diazepam). Thus, the conditioned defensive burying test was performed after a unique oral dose of 15 mg/kg, at two time-points (60 min and then 30 min post oral gavage) to show potential fast-onset of anxiolytic effect. Both natural products proved to be as efficient as diazepam to reduce the time rats spent burying the probe (anxiety level). Additionally, when investigated as early as 30 min post oral gavage, Gabolysat® also revealed a fast-anxiolytic activity. To date, identification of bioactive peptide, as well as how they interact with the gut–brain axis to sustain such anxiolytic effect, still remains poorly understood. Regardless, this observational investigation argues for the consideration of natural compounds in care pathway.

Ethology, Neurophysiology, Neuropharmacology, Sex Differences, and Effects of Stress on the Defensive Burying Paradigm: A Review

The defensive burying paradigm can inform how stressor controllability affects stress adaptation, which has clinical implications with regards to adaptive coping responses following presentation with a stressful situation. Active coping (notably defensive burying) is associated with a controllable stressor, promoting stress adaptation, thus decreases stress hormone levels. In opposition, chronic stress and uncontrollable stressors lead to an increase in passive coping behaviours, with elevated stress hormone levels. Several brain regions have been implicated in active and passive coping, as well as neurotransmitter systems, which can be evaluated via pharmacological manipulation. No sex differences were found in defensive burying, although there were effects of sex hormones within sex.

Predator odor increases glutamatergic synaptic transmission in the prelimbic cortex via corticotropin-releasing factor receptor 1 signaling

ABSTRACTAcute exposure to a salient stressor, such as in post-traumatic stress disorder, can have lasting impacts upon an individual and society. To study stress in rodents, some naturalistic methods have included acute exposure to a predator odor, such as the synthetized fox odor 2,4,5, trimethyl-3-thiazoline (TMT). These experiments explore the stress-related behaviors and cortical activity induced by TMT exposure in adult male C57BL/6J mice and the influence of the stress neuropeptide, corticotropin-releasing factor (CRF) on these responses. Compared to H2O, mice exposed to TMT in the home cage showed increased avoidance and defensive burying indicative of evident stress responses. Consistent with stress-induced activation of the medial prefrontal cortex (mPFC), we found that the prelimbic (PL) and infralimbic (IL) subregions of the mPFC had elevated c-Fos immunolabeling after TMT compared to H2O. Slice physiology recordings were performed in layers 2/3 and 5 of the PL and IL, following TMT or H2O exposure. In TMT mice, PL layers 2/3 showed heightened spontaneous excitatory post-synaptic currents and synaptic drive, suggesting TMT enhanced excitatory transmission. Synaptic drive in PL was increased in both TMT and H2O mice following bath application of CRF, and systemic pretreatment with the CRF-R1 antagonist CP154526 reduced excitatory transmission in TMT mice, but not H2O mice. CP154526 also reduced stress-reactive behaviors induced by TMT.

26. Investigating the Role of Neuropeptide Y Infusions to the Ventral Hippocampus in Mediating Defensive Burying Behavior in Rats in the Shock-Probe Test

The current study will investigate the role of NPY in the ventral hippocampus in anxiety. NPY is a neuropeptide found in many structures in the brain, including the hippocampus, and is implicated in regulation of anxiety related behaviors. The hippocampus has also been found to play a role in anxiety and defensive behaviors – specifically, the ventral hippocampus regulates innate defensive behaviors. The effect of NPY in the ventral hippocampus will be investigated by infusing either NPY (n=12) or physiological saline (n=12) into the rat ventral hippocampus followed by behavioural testing in an animal model of anxiety; i.e., the shock-probe burying task. I expect to find a selective reduction in burying duration in NPY-infused rats.

A Fatty Acids Mixture Reduces Anxiety-Like Behaviors in Infant Rats Mediated by GABAA Receptors

Fatty acids (C6–C18) found in human amniotic fluid, colostrum, and maternal milk reduce behavioral indicators of experimental anxiety in adult Wistar rats. Unknown, however, is whether the anxiolytic-like effects of fatty acids provide a natural mechanism against anxiety in young offspring. The present study assessed the anxiolytic-like effect of a mixture of lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, and linoleic acid in Wistar rats on postnatal day 28. Infant rats were subjected to the elevated plus maze, defensive burying test, and locomotor activity test. Diazepam was used as a reference anxiolytic drug. A group that was pretreated with picrotoxin was used to explore the participation of γ-aminobutyric acid-A (GABAA) receptors in the anxiolytic-like effects. Similar to diazepam, the fatty acid mixture significantly increased the frequency of entries into and time spent on the open arms of the elevated plus maze and decreased burying behavior in the defensive burying test, without producing significant changes in spontaneous locomotor activity. These anxiolytic-like effects were blocked by picrotoxin. Results suggest that these fatty acids that are contained in maternal fluid may reduce anxiety-like behavior by modulating GABAergic neurotransmission in infant 28-day-old rats.