Prenatal Exposure to Methylazoxymethanol (MAM) Alters Coordination in Facial Wiping and Oral Grasping Responses of Fetal Rats

One of the sequelae of neurodevelopmental disorders such as cerebral palsy is impaired movement coordination. There is considerable clinical interest in identifying diagnostic methods to detect such disorders early in development, when therapies may be more effective. However, few assessment tools are available for detecting CNS deficits in the fetus. In the present study, methylazoxymethanol (MAM, Midwest Research Institute) was used to induce deficits in CNS development in fetal rats to assess effects on coordinated fetal behavior. Fetuses were exposed by administering MAM to pregnant rats on E17 of gestation via IP injection and were then prepared for behavioral testing 3 days later on E20. After externalization from the uterus into a warm saline bath, fetal subjects were secured in a supine posture for observation. The first subject received an intraoral infusion of lemon extract to evoke a facial wiping response, which involves coordination of both forepaws in contact with the face. The second subject was presented with an artificial nipple to evoke oral grasping responses. Both MAM-treated fetuses and saline controls were responsive to both stimuli. However, interlimb coordination and paw-face contact during facial wiping were disrupted in MAM-exposed fetuses. Similarly, MAM exposure diminished the ability of fetuses to grasp or maintain oral contact with the artificial nipple. These findings suggest that behavioral assessments of motor coordination during stimulus-evoked action patterns may be useful in identifying neural insult during prenatal development.