Postnatal exposure to synthetic predator odor (TMT) induces quantitative modification in fear-related behaviors during adulthood without change in corticosterone levels.

International audienceEnvironmental stimuli and adverse experiences in early life may result in behavioral and physiological changes in adulthood. In several animal species, the odors cues are crucial in the setting of adaptive behaviors, especially towards predators. However, little is known about the effects of postnatal exposure to predator odor on the later physiological and behavioral responses to this natural stressor. Thus, the aim of this study was to investigate the effects of a postnatal exposure to synthetic predator odor (TMT) in mice pups on later adult fear-related behaviors and corticosterone levels in response to this specific stimulus. Pups postnatally exposed to only water showed later in adult life behavioral responses when exposed to TMT that were statistically different from mice that were exposed as neonates to TMT. In addition, mice exposed as neonates to TMT showed a decrease of fear-related behaviors while no differences occurred in the corticosterone levels between both groups

Carbon dioxide effects on olfactory functioning: behavioral, histological and immunohistochemical measurements.

International audienceMost studies on toxic inhalation focus on solvent effects and few have dealt with gases on olfactory functioning. Among gases, the effects of carbon dioxide on general physiology have been well investigated contrary to the impact on olfactory neuroepithelium. Thus, this work was designed to evaluate in mice the possible effects of 3% CO(2) in two exposure periods: a 5h/day and a 12h/day conditions. Behavioral, histological and immunohistochemical observations were conducted every 2 weeks, i.e. before (W0), during (W2, W4) and after exposure (W6, W8). Firstly, behavioral evaluations of odor sensitivity showed differences in relation to the odor tested, i.e. no effect with congener urine odor and a reinforcement of 2,4,5-trimethythiazoline (TMT) (predator odor) repulsion. Secondly, histological evaluations showed a similar evolution of the epithelium thickness, i.e. a decrease along the exposure as well as during the post-exposure period and an increase of cell number (whatever the phenotype) although the kinetic appeared different in both experimental conditions. Thirdly, immunohistochemical quantification of olfactory marker protein (OMP)- and proliferating cell nuclear antigen (PCNA)-positive cells revealed that the number of mature olfactory neurons increased at the early beginning of exposure period in both conditions. While a decrease was observed in the following weeks (W4-W8) for the 12h/day condition, a stable amount of OMP-positive cells was maintained in the 5h/day condition. In contrast, the number of PCNA-positive cells followed a similar evolution, i.e. a constant decrease along the experiment. These findings indicate that the effects of CO(2) inhalation exposure are selectively dose-dependent

Postnatal predator exposure reduces fear and anxiety behaviors in adult mice

PosterPredator cues are very efficient to induce fear in rodents but most studies use adult subjects and not pups. Nevertheless, a perinatal stress can have a significant effect on behavior and on physiology at adulthood. An early stress (foot shock, restraint, mother separation) is able to modulate behaviors later and the aim of this study was to examine if the synthetic predator odor 2,3,5-trimethylthiazoline (TMT) presented to neonates modifies fear and anxiety-related behaviors in adult female mice

Postnatal predator exposure reduces fear and anxiety behaviors in adult mice

PosterPredator cues are very efficient to induce fear in rodents but most studies use adult subjects and not pups. Nevertheless, a perinatal stress can have a significant effect on behavior and on physiology at adulthood. An early stress (foot shock, restraint, mother separation) is able to modulate behaviors later and the aim of this study was to examine if the synthetic predator odor 2,3,5-trimethylthiazoline (TMT) presented to neonates modifies fear and anxiety-related behaviors in adult female mice

Olfactory Sensitivity for Six Predator Odorants in CD-1Mice, Human Subjects, and Spider Monkeys

Using a conditioning paradigm, we assessed the olfactory sensitivity of six CD-1 mice (Mus musculus) for six sulfurcontainingodorants known to be components of the odors of natural predators of the mouse. With all six odorants, themice discriminated concentrations ,0.1 ppm (parts per million) from the solvent, and with five of the six odorants the bestscoringanimals were even able to detect concentrations ,1 ppt (parts per trillion). Four female spider monkeys (Atelesgeoffroyi) and twelve human subjects (Homo sapiens) tested in parallel were found to detect the same six odorants atconcentrations ,0.01 ppm, and with four of the six odorants the best-scoring animals and subjects even detectedconcentrations ,10 ppt. With all three species, the threshold values obtained here are generally lower than (or in the lowerrange of) those reported for other chemical classes tested previously, suggesting that sulfur-containing odorants may play aspecial role in olfaction. Across-species comparisons showed that the mice were significantly more sensitive than the humansubjects and the spider monkeys with four of the six predator odorants. However, the human subjects were significantlymore sensitive than the mice with the remaining two odorants. Human subjects and spider monkeys significantly differed intheir sensitivity with only two of the six odorants. These comparisons lend further support to the notion that the number offunctional olfactory receptor genes or the relative or absolute size of the olfactory bulbs are poor predictors of a species’olfactory sensitivity. Analysis of odor structure–activity relationships showed that in both mice and human subjects the typeof alkyl rest attached to a thietane and the type of oxygen moiety attached to a thiol significantly affected olfactorysensitivity.Funding: The study was financially supported by a grant (J-51435-IV) from CONACYT Mexico (www.conacyt.mx) to LTHS. The funders had no role in study design,data collection and analysis, decision to publish, or preparation of the manuscript.</p