Effect Of Formaldehyde On Reproduction And Development In Rats

Objective The effect of formaldehyde on reproduction and development in rats is studied. Methods Wistar rats were randomly divided into 4 groups. One is control group(C), with natural air, and three exposed groups, exposed to dosages of formaldehyde were 119.6±15.4mg/m~3(H), 25.2±4.6mg/m~3(M), 4.8±1.3mg/m~3(L); Formaldehyde was inhaled for 1h per day. The parental rats were exposed to formaldehyde for 8 weeks, and continuously exposed during mating, pregnancy and breast-feeding. After the breast-feeding was stopped for their offspring, formaldehyde was exposed until the experiment was finished. The indexes were observed during the experiment or were determined after the experiment. Results (1) With the raise of exposed dose of formaldehyde, body weighs increased in the high dose group were significantly lower than that in the controlled group. The coefficients of heart, liver, lungs, kidney, testicle and brain were all significantly increased, especially in the high dose group (P<0.05). (2) The rates of the pregnancy, normal parturition, survival and feeding survival in the high dose group were lower than control group. The rates of fetus death increased gradually (P<0.05). (3) From birth to stopping breast-feeding, the weighs of rats' offspring in the high dose group were lighter distinctly than that in the control (P<0.05). The positive rates of the pinna detachment, incisor budding, eye opening in high dose group were lower than that in other dose groups and the control. (4) The number of luteal, the gross weigh of placenta and the gross weigh of litter were reduced slowly with the raise of exposing dose of formaldehyde. But the difference was not significant (P>0.05). The rates of embryonic death were increased remarkably in the high dose group (P<0.05). The appearance and bones of embryo appeared malformed. (5) The difference of the positive rates of nerve reflex were significant between in high dose group and in the controlled group (P<0.05). In every exposed dose, thetraining times and time of reaching the goal were increased and prolonged by exposed doses of formaldehyde (P<0.05). The times of the tests of swimming stamina and enduring anoxia were descended in accordance with the increase of exposing dose of formaldehyde. Especially in the high dose group, it was more obvious (P<0.05). The change of hippocampal formation was significant in 14lh, 21st, 281'1 day in the high dose group. The number of C-fos positive cells were increased with the raise of exposing dose of formaldehyde (P<0.05) , and reached highest peak in 21st day; While with the increase of exposing dose of formaldehyde ,the number of GAP-43 positive cells were reduced (P>0.05) , and its highest peak was the 28lh day. The number of C-fos positive cells in the high dose groups were increased significantly in 21st, 28th and 45th day (PO.05) Conclusion Under this condition, formaldehyde distinctly had adverse effects on the reproductive system by affecting the normal structure of sperm; formaldehyde had inhibition on the growth and development of rats, slowing some development of physiological function, especially for neurobehavioral function; Teratogetic toxicity was not significant for formaldehyde while embryotoxicity was strong; The experimental study demonstrated that the harmful effects were cause by formaldehyde on the abilities of learning and memory of the offspring. The synthetic stamina of rats was reduced. It showed that formaldehyde displayed the distinct adverse effects on the nerve system of rats.