| The human' s reproductive ability has shown a declining tendency with many cases of abnormal babies born by the reason from the spear side. Animal experiments have confirmed that many harmful environ-mental and occupational factors can affect reproductive ability, among which pesticides have caused broad attention of the public.Pyrethroids are a group of synthetic pesticides based on the struc-tures of natural pyrethrins. Due to their high effects, low residues and selective toxicities, pyrethroids have been broadly used world wide in-cluding China. Both home and abroad researchers have reported manystudies on their neurotoxicity and immunotoxicity. The reproductive toxicity of this kind of pesticides to human have drawn much attention due to their broad applications all over the world.β - cypermethrin ( β - CP) is a broadly used pesticides among pyrethroids and it is a pair of eriantioamers of cypermethrin ( CP) . It is a high effective, broad spectrum and quick action pesticide with the potency of 2 times higher than CP. β - CP is produced in large scale in China and applied to control agriculture pests, hygiene pests, hus-bandry pests and so on. However, reproductive toxicity to male rats has been reported from CP and deltmethrin but not from β - CP up to date.Testicle is the main reproductive organ of male animals. Chemi-cals directly exert harmful effect on testicle or indirectly by regulating sex hormone secretion through hypothalamus - pituitary system. The study tries to explore β - CP' s effect on reproductive function of male rats by sperm analysis, serum sex hormone level determination and testicle tissue pathological examination.Materials and Methods1. Animal grouping and administration40 adult male Wistar rats were randomly assigned into 4 groups with each 10 rats. And the 4 dosages were 0, 20, 40 and 80 mg/kg. B - CP was dosed orally for 8w daily with edible salad oil as control.2. Observation and determination2. 1 Body weight and testicular and epididymal index 2. 2 Sperm examination: sperm counts, sperm motility and mal-formation sperms were performed with routine procedures.2. 3 Serum sex hormone determination-, serum testosterone (T) , follicle stimulating hormone ( FSH ) and lutenizing hormone (LH) were determined with radioimmunity methods.2. 4 Tissue pathological examination: one testicle was processed with general methods for optical microscope examination. The other testicle was treated for electron microscope examination.3. Data statistical analysis; Chi - square test and q ?test were performed with SPSS packages.Results1. Body weight and testicular and epididymal index; no signifi-cant difference was found between the test groups and control group (p>0.05).2. Sperm examination; no significant difference was observed in total sperm counts and abnormal sperm counts between the control and test groups (p >0. 05) . The rate of viable sperms (60. 5% ) and the degree of sperm motility(56. 55% ) in high dosage group were signifi-cantly lower than those in control group (78. 75% ,72. 20% respec-tively) (p <0. 05) ,but no significant difference was found in the mid-dle and low dosage groups (p >0. 05) .3. Serum sex hormone determination; serum T ( 3. 56ng/ml) and FSH (3.56mIU/ml) levels increase, but serum LH (6. 98mIU/ml) level decrease in high dosage group. While these data from control group were 2. 20ng/ml, 2. 89mIU/ml and 8.46mIU/ml, respectively. There were significant differences between high dosage group and con-trol (p <0. 05). No significant difference was found in the middle and low dosage groups( p > 0. 05 ) .4. Pathological examination4. 1 Findings with optical microscope; enlarged lumen, loosen arrangement of spermatogenic epithelia cells and large quantities of de-ciduous spermatogenic cells were found in the seminiferous tubuls of the testes of the rats in the high dosage group. Also the sperms inlaid within the supporting cells were: significantly fewer than those in con-trol grou...
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