Distribution And Accumulation Of Rare Earth Element Cerium And Neodymium In The Body And Their Effect On Gonadial Hormone Secretion In Mice

Distribution and accumulation of rare earth element (RE) cerium and neodymium in the mice body has been studied using the radioisotope tracer after intraperitoneal administration and feeding of RE. Effect of RE on the secretion of testosterone and progesterone has also been assay with RIA in this experiment. 1. Distribution and accumulation of RE (Ce or ?Nd) in mice body. Using radioisotope tracer, we find that the residue of Ce and Nd unevenly distribute in mice tissues, moreover, this distribution is dosage and time dependent. Of all the tissue assaied, eyes have the highest accumulation after feeding of Ce. The relative ratio of the lowosage group is 12. 70?. 14%, compared with that of the high? dosage group, which up to 24.05?.04%. The accumulation in bone, testes and brain are mediate, blood, kindneys and muscles have the lowest relative ratio. Because of the excretion and the redistribution, the accumulation of these elements in other tissues of the body is decrease with time, but while the accumulation in bone increase with time after once intraperitoneal administration. 2. Effect of cerium (Ce) on the testosterone secretion, weight of testis and misshape rate of spermatozoa. Feeding with Ce, the testosterone secretion of both group (high? dosage treated group and lowosage treated group) increases slightly compared with the control at the early days. But still not significant difference was found (P>0.05). At day 30 and 45, the concentration of testosterone in the plasma decrease, but no significantly, compared with the control. The testosterone concentration in serum significant decreased at the 5th day after intrapcritoneal injection of Ce (200 mg/kg) compared with that of the control, with a concentration of 5. 6 ng/mL and 18. 6 ng /mL respectively. At the 10th day after treatment, the testosterone concentration in serum is far below than the control, which are 9. 9 ng/mL and 27. 0 ng/mL. (P(0. 001) Feeding male mice with cerium, the weight of testes in both group (highosage treated group and lowosage treated group) decreases slightly but with no significant difference (P>0.05). The relative ratio between the testis weight and the body梬eight in high梔osage treated group is remarkable lower than that of control in early days (P<0.01), but with no significant difference (P>0.05) in the later period. In the Ceeeding group, the misshape rate of spermatozoa is always higher than that of control during the whole experimenbal period, and the significant difference was found on 30th day (P<0. 05) and on 45Lh day (P