Prenatal exposure to methylazoxymethanol (MAM) acetate: effects on ultrasonic vocalization and locomotor activity in rat offspring.

Abstract

Methylazoxymethanol (MAM), a potent alkylating agent, produces marked microencephaly as well as long-term learning impairments in the progeny of rats injected at the beginning of the 3rd week of pregnancy (Spatz and Laqueur 1968; Vorhees et al. 1984). Interestingly, neurochemical studies have shown that prenatal exposure to MAM can lead to notable alterations of the central dopaminergic system in offspring of exposed dams (Balduini et al. 1984). The experiments reported here were performed in order to investigate, in infant rats, the effects of prenatal administration of MAM on behavioural models which are partly linked to dopaminergic mechanisms. In particular, the effects of prenatal MAM exposure on ultrasonic vocalization elicited by the removal of rat pups from their nest were evaluated. In this regard, we recently demonstrated that ultrasonic calling in rat pups may be considered as an early sensitive indicator of subtle changes produced by the developmental administration of drugs influencing the dopaminergic system (Cagiano et al. 1986).