| With the extensive application of rare earth, close attention was gradually payed to the accumulation of rare earth in vivo. Previous studies on the effect of lanthanum on animals mainly focused on the toxicity to livers, stomachs and spleens. But few studies on the reproductive effect of lanthanum were carried.out. Forty-eight male mice weighed about twenty-five grams were divided into four groups at random in this experiment, and were given intragastric administration with lanthanum at varied doses of 0μg/g, 25μg/g, 50μg/g and 100μg/g of body weight, respectively. After seven and fifteen days treatment, the changes of the weight and the qualities of the sperms were analyzed. The organ index, the pathological changes and enzyme activities of testis were assayed after fifteen days treatment. The aim of the research was to provide scientific evidences for safety evaluation of lanthanum usage in agriculture, by means of investigating the reproductive toxicity in male mice.The main results are showed as follows:(1) The changes of the weight of male mice in every dose groups showed similar regularity, in other words, after intragastric administration, the growth speed of male mice in every dose groups were more than control groups, but after intragastric administration was stopped, the growth speed of male mice recovered gradually. This phenomenon indicated that Lanthanum could facilitate the growth of animals to certain extent. Compared to controls, the colour of organ of male mice in every dose groups did not change significantly, the effects on organ weight and organ index of male mice in every dose groups were significant (P < 0.05). After seven days treated, no obvious effect on the quality of sperms in male mice was observed(P > 0.05), except for the rate of live sperms at dose of 100μg/g(P< 0.05). However, the effects on the deformity of sperms at doses of 25,50,100μg/g were distinct (P<0.05) and significant (P< 0.01) after fifteen days treated, and the effects on the rate of live sperms and the rate of perforatorium integrity at doses of 50,100μg/g were distinct (P<0.05) and significant (P < 0.01).(2) The main pathological changes in testicular tissue were that: Testicular spermatogenic cells of control groups were clearly demarcated; The spermatids in every developmental stages were complete; The lumens were filled with a great quantity of sperms; In low-dose groups, there were 4 to 6 layers of spermatids in seminiferous tubule of male mice, the quantity of leydig cells around the seminiferous tubule was decreased; In middle-dose groups, the quantities of leydig cells and sperms in the seminiferous tubule were much less than that of in control groups,where there were 2 to 4 layers of spermatids, and many spermatids in seminiferous tubule ablated; In high-dose groups, Almost no Leydig cells and sperms was in seminiferous tubule. (3) The activities of lactate dehydrogenase decreased significantly in the treated mice, and the activities of nitric oxide synthase and alkaline phosphatase increased significantly(P< 0.05, compared to controls), but the activities of acid phosphatase did not changed significantly(P > 0.05,compared to controls).Above results manifested that: During the intragastric administration, lanthanum at varied doses could promote growth, and with the concentration of lanthanum increased, the promotion increased. After stopping intragastric administration, the growth was revived to certain extent. In other words, according to the doses designed in the research, lanthanum at varied doses did not cause non-anastatic effect on the growth and the development of male mice. Lanthanum could damage parenchyma of the testis, cause spermatogenic cells degeneration and necrosis, damage the structures of testis, and affect the acticities of enzymes in testis in varying degrees. Although the degrees of effect on quality of sperms in every dose groups were not significant, but the more content of lanthanum in animal bodies, the more toxicity to genital system as a whole. |
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