The Effect Of N-hexane On The Female Gonads Toxicity And Reproductive Endocrine Secretion Interference

【Objective】This study examined the effects of N-hexane on the female gonadal toxicity and the female reproductive endocrine disruption, in order to provide further research on the prevention and control of N-hexane on the effects of gonadal reproductive toxicity.【Methods】(1) Adult female rats were randomly assigned to four groups based on weight. N-hexane was given asp 4h/d, seven days/week for five weeks at doses of 0,3.0,15.1,75.8ml/m3. Following euthanasia, estrus stages,organ weights,organ coefficients of ovaries and uterus were observed. The constituent ratio of the distinct follicle number on ovaries was observed with the HE staining and the ultramicrostructure were observed with the transmission electron microscope. Serum follicle stimulating hormone(FSH),luteinizing hormone (LH),estradiol (E2) and progesterone (P4) were detected with the radio immunoassays. Estradiol and progesterone receptor in the ovary and uterus were examined with the immunohistochemical assay.The number and death rate of superovulation were observed with stereomicroscope.The apoptotic rate of the granulose cell on the ovaries was detected with the DeadEndTM Fluorometric TUNEL system.(2) Adult female rats were randomly assigned to four groups based on weight. N-hexane was given asp 8h/d, days/week for one weeks at doses of 0,5.7,22.7,90.9 ml/m3. Following euthanasia, the levels of progesterone (P4) and estadiol (E2) in the culture medium were then measured by radioimmunoassay. The constituent ratio of the distinct follicle number on ovaries was observed with the HE staining. The number and death rate of superovulation were observed with stereomicroscope. The apoptotic rate of the granulose cell on the ovaries was detected with the DeadEndTM Fluorometric TUNEL system. (3) In vitro studies were done using the ovaries of adult rats in different stages of estrous (proestrus,estrus,metestrus and diestrus). Individual ovaries were collected, placed into culture medium and exposed to 0,20,40,60 mmol/L of 2,5-HD, the levels of P4 and E2 in the ovary culture serum were determined by radioimmunoassay.【Results】(1) In the subchronic test, the period of estrous stages in rats decreased than that of the control, the period of postestrus decreased significantly in the 75.8ml/m~3 group, compared to the control. In the short period exposure test, the consitituent rate of the atresic follicle number increased significantly in the 75.8ml/m~3 group, compared to the control. In the subchronic test, there were significantly differences in the consitituent rate of primordial follicle,atresic follicle,mature follicle and corpus Luteum/albicans number in the 75.8ml/m~3 group, compared to the control. The level of serum P4 decreased significantly in the 75.8ml/m~3 group, compared to the control.(2) In vivo, the levels of E2 and P4 in the culture serum in the ovaries decreased significantly in the 90.9 ml/m~3 group, compared to the control. In vitro, there were significant differences in the level of E2 and P4 in the ovaries between the 20,40,60mmol/L groups amd estrus cycles.(3) In the short period exposure superovulation test, the number of superovulation decreased significantly in the 75.8ml/m~3 group, compared to the control. In the subacute superovulation test, the number of superovulation decreased significantly in the 3.0,15.1,75.8ml/m~3 groups, compared to the control, the death rate of superovulation decreased significantly in the 15.1 and 75.8ml/m~3 groups, compared to the control.(4) In the subchronic test, there were no significantly differences in the estradiol and progesterone receptor in the ovary and uterus between the 5.7,22.7,90.9 ml/m~3 groups, compared to the control.(5) In the short period exposure test, there were no significantly differences in the apoptotic rate of the granulose cell between the 5.7,22.7,90.9 ml/m~3 groups, compared to the control. In the subchronic test, the apoptotic rate of the mature follicle and corpus Luteum/albicans increased significantly in the 22.7 and 90.9 ml/m~3 groups, compared to the control.【Conclusions】(1) N-hexane has obvious female gonads toxicity, N-hexane can decrease the organ weights and organ coefficients of ovaries, the period of estrous stages in rats decreased significantly, the consitituent rate of primordial follicle,atresic follicle,mature follicle and corpus Luteum/albicans number were in disorder.(2) N-hexane can decrease the level of serum P4, N-hexane can inhibit P4 and E2 release in the ovaries, having the direct adverse effects, which might be the important mechanism in endocrine disruption.(3) Under our experiment, N-hexane did not have direct disrupting effect on the estradiol and progesterone receptor in the ovary and uterus, which might be not the mechanism of the endocrine disruption.(4) N-hexane can decrease the reaction of super gonadotrophic hormones, but it not sure of the reaction of normal gonadotrophic hormones.(5) N-hexane can induce the cell apoptosis on the ovaries, which might be the important mechanism of ovaries damage.