Effects of caffeine and nicotine administration on growth and ossification of the ICR mouse fetus.
The objective of this study was to determine how fetal effects are altered when nicotine (N) and caffeine (CA) are administered concurrently at dosages that individually produce minimal effects to the fetus. Female ICR mice were bred overnight and were assigned to four groups: CA (125 mg/kg), N (12mg/kg), CA plus N (125 mg/kg plus 12 mg/kg, respectively) treated, and control (distilled water) groups. Dams were intubated with these dosages three times daily during gestational days (GD) 6-18 and were euthanized on GD 18. Live fetuses were sexed, weighed, and examined for external malformations. One-half of the fetuses were fixed in 10% formalin and examined for internal malformations using Wilson's method. The remaining half was fixed in 95% ethanol (ETOH), stained, and cleared (Inouye's method) for skeletal examinations. Ossification was assessed by staging and measuring craniofacial bones, and counting ossification centra in sternbrae and in cervical and sacrococcygeal vertebrae. Data were analyzed by analysis of variance (ANOVA) followed by Student-Newman-Keuls post-hoc tests set at p < .05 significance level. The litter was used as the unit of measure and the ANOVA main effects were CA, N, and an interaction term (CA+N). In comparison to controls, CA treatment resulted in reduced bone measurements or reduced ossification scores in 5 of the 19 parameters examined, whereas for N only five parameters were significant. The main effects for interaction of CA+N were significant for seven parameters measured. Although it is difficult to assign the specific type of drug interaction that occurred because results were not completely consistent for all parameters measured, it may be concluded that in most parameters measured both CA and CA+N were different from controls, but CA was not different from CA+N. Under the experimental conditions of this study, we found that of the two drugs, caffeine had a significantly greater effect on fetal growth and ossification than nicotine.