Cyclophosphamide effects on fetal mouse cephalic acetylcholinesterase.

Pregnant C3H mice were exposed to a teratogenic dose of cyclophosphamide (CP, 20 mg/kg body weight) on the 10th day after copulation. Embryos or fetuses were examined 2-9 days later for gross abnormalities, weighed, and assayed for cephalic acetylcholinesterase (EC 3.1.1.7, AChE) activity, and haemoglobin content. In embryos examined 2 days after CP administration, fetal weight and brain weight were less than controls, but cephalic AChE was higher (p less than 0.001). The higher cephalic AChE was associated with a higher absorbance for haemoglobin, although at 14 days there was no apparent difference in the cephalic AChE and absorbance for haemoglobin, compared with controls. At 19 days, fetal weight, brain weight and brain AChE activity were less than controls (p less than 0.001 in each case). The raised cephalic AChE activity in 12-day embryos is explained by the presence of blood, which appears to have resorbed by day 14, whereas the reduced brain AChE activity in 19-day fetuses is accounted for by the growth inhibitory effects of the drug.