Fachbereich Veterinärmedizin



    Reproduktionstoxikologische und toxikokinetische Untersuchungen an männlichen Ratten, die gegenüber y-Hexachlorcyclohexan (Lindan) während der Laktationsperiode exponiert waren (1996)

    Dalsenter, Paulo Roberto
    Berlin, 1996 — 112 Seiten
    Institut für Tierschutz und Tierverhalten

    Königsweg 67
    Gebäude 21, 1. OG
    14163 Berlin
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    Abstract / Zusammenfassung

    Concern about the susceptibility of the male reproductive system to drugs or environmental agents has recently assumed a great increasing interest. It is well known that the male reproduction is sensitive to toxic substances. Disturbances of hormonal regulation during pre orearly postnatal development may induce effect on male fertility. Changes associated with prenatalor early postnatal exposure are generally irreversible.Lindane (r-hexachlorocyclohexane) is an organochlorine pesticide and was shown by differentauthors to possess an endocrine effect. It was used for a long time as a broad spectruminsecticide to control agriculture pests and is still used as a pesticide for some agriculturalpurposes. Lindane is also employed in both human and veterinary medicine against ectoparasites.Several studies from different countries show that lindane is detected in food and human milk. Dataon effects of lindane on the reproduction of male offspring are scanty.The objective of the present study was to ascertain reproductive effects of lindane on maleoffspring rats exposed during different period of lactation. The lactating dams were treated orallywith low doses of lindane, namely single dose of 6 mg/kg or 1 mg/kg for six days. Followingendpoints were then investigated: sexual development, sperm and spermatid number, spermmorphology, testosterone level, sexual behaviour and fertilityThe results obtained are summarised below:ù No general toxicity was observed either in the dams or in male offspring ats.ù Age at testis descent as well as age at prenuptial separation was delayed.ù Testis weight of the exposed groups was approximately 10 % reduced compared to the controlgroup. However, the weight of epididymis, seminal vesicle and prostate was not at all affected.ù In the treated groups, the number of spermatids and number of sperm was approximately 10 %reduced.ù The serum concentration of testosterone revealed a great variation between the various groupsand individual animals, however, the concentration in the treated groups was generally lower thanthe control group.ù The results of the sexual behaviour investigation showed a reduced sexual stimulation in alltreated groups.ù The fertility of the exposed male offspnng rats was comparable to the control group.A considerable amount of lindane was detected in the testis and in brain of the male offspring. Theamount of a substance found in the target organ represents an important source of information forthe risk assessment. The effects observed in the present study may be attributed either to theconcentration of lindane determined in the testis or to the indirect interference of the pesticide onhormonal regulation.The results obtained in the present study indicate that substances with endocrine effect (such aslindane) exposed to rats during lactation could induce reproductive effects on male offspring.Reproductive toxicity studies that include only an evaluation of he effects of a chemical onbreeding studies may provide inadequate data for determining a chemical"s potential reproductivehazards, because natural mating of laboratory animals is an insensitive parameter for assessingthe effects of chemicals on fertility.