Prenatal carbon monoxide exposure alters behavioral development

The potential for mild prenatal carbon monoxide (CO) exposure by means of maternal cigarette smoking or industrial and ambient air sources is extremely high, but the biological consequences and, in particular, the neurobehavioral effects are undetermined. We have exposed pregnant rats to 150 ppm in air and examined the behavioral development of the infant rats using tests of righting reflexes, negative geotaxis and homing. The offspring of CO exposed rats weigh less at birth and show reduced growth rates prior to weaning. Cross fostering does not ameliorate the retarded growth curves of experimental subjects. Behavioral testing revealed poorer than normal performance on the negative geotaxis and homing tests among the CO exposed rats. No difference in steady state brain catecholamine levels was seen between groups. The results complement an earlier report showing reductions in locomotor activity following mild prenatal CO exposure and indicate that such exposure has significant functional consequences for the developing rat.