Expression of exploratory activity of rat offspring depends on the expression of exploratory activity of their parents at the moment of mating

The aim of this work was to study the, so far, unexplored possibility that non-genetic inheritance of animal behavioral characteristics could depend on the state of the parents at the time of conception. In this study, we measured the levels of motor and exploratory activity in rats at the ages of 2 and 5 months. Male and female rats were mated at the age of 5 months. The following groups were used: male and female rats with high motor activity at ages of 2 and 5 months (ACT+); male and female rats with high activity at the age of 2 months, but low activity at the age of 5 months (ACT–); male and female rats with low activity at the ages of 2 and 5 months (PAS–); male and female rats with low activity at the age of 2 months, but high activity at the age of 5 months (PAS+). It was found that both males and females ACT+ had significantly higher motor activity, which was observed in the first 10 minutes, in the next 20–60 minutes, in the center of the cage and more rearings as compared with PAS– rats. Significant differences in the severity of exploratory activity were found between the male offspring of ACT+ and ACT– rats. Differences between the offspring of PAS+ and PAS– rats were observed in both the male and female rats. The motor activity of animals in the period from 20 minutes after the start of registration did not differ between groups. Thus, it can be considered that individual characteristics of general motor activity are due to genetically inherited factors, while differences in the level of exploratory activity, apparently, are formed due to non-genetic influences from parents during mating.