Paternal preconceptional health factors, such as exposures to stress, diet and exercise, have been found to significantly influence offspring phenotypes in a range of animal models. Preclinical studies have provided evidence that paternal stress is associated with increased stress responsivity and anxiety-related traits, particularly in male offspring. It was previously reported that a paternal history of maternal separation (MS) led to male offspring (PatMS) displaying reduced cautious behavior during exploration of a novel environment. The neural basis for that absence of behavioral moderation is unclear. Here, we investigated the adaptive behavioral responses of control and PatMS male offspring in the predator odour risk-assessment task (PORT). PatMS mice failed to moderate their behaviors in the presence of a predator odour trimethylthiazoline (TMT). c-Fos mapping revealed reduced cellular activation in fear-regulating brain regions of PatMS mice, such as in the cingulate cortex, dentate gyrus of the hippocampus, and the basolateral amygdala. Expression of the paternally imprinted gene Grb10 (previously identified as a key molecular regulator of risk-taking behavior) was unaltered in PatMS mice. However, other paternal imprinted genes such as Igf2 and PEG3 were differentially expressed in PatMS mice. Overall, our study provides the first evidence of an intergenerational influence of preconceptional paternal stress exposure on offspring brain function relevant to risk-taking behavior, which is also independent of Grb10 gene expression.

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