Prenatal Exposure to Methylazoxymethanol (MAM) Alters Patterns of Interlimb Movement Synchrony in Fetal Rats

Abstract

It has long been suspected that early exposure to toxins may contribute to the development of some neurological disorders (e.g. ALS, cerebral palsy, and Parkinson\u27s Disease). Although methods associating early exposure and neurological outcome are widely available, methods for determining the immediate developmental effects of exposure have, until recently, been unavailable. Previous work with fetal behavior in this lab has shown that quantification of spontaneous movement reveals clear patterns across development. One such measure, interlimb synchrony, quantifies the temporal relationship of movements between pairwise combinations of limbs. The aim of this study was to assess whether arrested neural development, induced by exposure to the neurotoxin methylazoxymethanol (MAM, Midwest Research Institute), would be evident in the organization of spontaneous motor activity in fetal rats. Fetuses were exposed by administering MAM to pregnant rats on E17 of gestation via IP injection and were then prepared for in vivo behavioral observation on E20. Motor activity was quantified during playback of videotape records. Overall results showed no differences in litter size or fetal weight between the treatment groups and saline controls. However, alterations in patterns of synchrony involving the hindlimbs were seen in treated subjects. These findings of behavioral deficits in fetal subjects exposed to MAM, which appear otherwise normal, suggest that direct measures of fetal behavior, such as interlimb synchrony, may be useful in the early diagnosis of developmental disorders of the nervous system