Short administration of ZnTe to male and female rats previous to mating and fertilization affects behavioural responses of litters during the prepuberal period

Abstract

Trace elements are an omnipresent group of chemical elements that are present practically in all types of environments sustaining life. Previous evidence from our laboratory has shown that chronic administration of ZnTe to pregnant rats affected several behavioural parameters related to motivated, lateralized exploration, and defensive behaviour in litter rats. In the present work, the possible effect of trace elements administration in a time period before fertilization to parent rats was investigated in its litter rats. Three experimental groups were formed: parent rats receiving water, as control; parent rats receiving ZnTe (0.3 g/L, “ZnTe Pre”) during a short period before mating, and parent rats receiving receiving ZnTe (0.3 g/L) after mating in the same schedule than previous research (“ZnTe Post”). Results showed that in group “ZnTe Pre,” trace elements treatment increased significantly some parameters of motor activity in litter rats, and a similar finding also was observed in motivated exploration. In lateralized exploration as measured in the Lateral Double Hole-board Labyrinth, both “ZnTe Pre” and “ZnTe Post” groups showed absence of the natural left-biased exploration of litter rats, decreasing the proportion of animals exploring the left side of the labyrinth. Defensive behaviour was affected in minor degree in the “ZnTe Pre” group and was significantly different both from Control and “ZnTe Post” group. Other behaviours, such as social interaction was not affected in the “ZnTe Pre” group, while as found previously social parameters were significantly altered in the “ZnTe Post” group. Present data are in agreement with previous results, and support the concept that trace elements can act on epigenetic mechanism regulation occurring prior to the ontogenetic development.