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RESEARCH PRODUCT

DOES FETAL AND NEONATAL EXPOSURE TO ODOUR VARIETY AFFECT LATER RESPONSE TO NOVELTY IN MICE?

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description

Vertebrate embryos and neonates are competent to encode odor information, and to later use it in guiding neonatal, juvenile, and, sometimes, adult behaviour. These data generally derive from experiments in which single odorants were administered. Here, we consider whether the perinatal exposure to multiple odorants administered sequentially will affect later behaviour. Mouse perinates were exposed to contrasted chemosensory regimen through the mother's ingestion of odorized water from days E15 through P21. The effects of 3 treatments were considered: 1/ olfactory monotony (MON; females accessing a benzaldehyde solution 5 days/week; n=46); 2/ olfactory variety (VAR; females accessing each other day solutions of benzaldehyde, vaniline, lyral, limonene, cineol; n=45); 3/ Control (CON; females receiving non-odorized water; n=46). At weaning (P21), all groups received a standard regimen. Treatment influence was assessed in measuring exploration behaviour in contexts involving chemosensory or visual novelty. On P23, all mice underwent an open field test, and then an episode of confrontation with a novel object. On P27, half of each group underwent a 24-hr 2-bottle choice test pairing water and an unfamiliar odorant (anethole), the other half undergoing a paired-odour choice opposing familiar and novel odorants (benzaldehyde vs. anethole). Perinatal odour exposure influenced the behaviour of the pups. In the open field test, CON mice spent less time than MON and VAR young mice (which were not differentiable) in the central area before to introduce the object and more time in the coins areas in the object presence. In the 2-bottle choice test, MON and VAR mice indistinctly drank more of the novel odorant than CON mice. Finally, in the paired-odour choice test, VAR pups stayed longer in the odorized areas than MON pups, and spent more time closer to the unfamiliar odour. In sum, this study confirmed that the perinatal manipulation of the odour environment positively influences pup responses to odours. It further reveals that perinatal exposure to odour variability has contrasted effects on pup responsiveness in contexts bearing chemosensory and visual novelty.