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Prepubertal exposure to Di(2-ethylhexyl) Phthalate

kinetics and effects on the reproductive system of the boar

Ljungvall, Karl (2006). Prepubertal exposure to Di(2-ethylhexyl) Phthalate. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2006:15
ISBN 91-576-7064-1
[Doctoral thesis]

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Abstract

The aims of this thesis were to increase the knowledge about endocrine disruption and the relations between prepubertal exposure and delayed, long-lasting effects on the reproductive system. Furthermore, the generality of knowledge in reproductive toxicology, generated in rodents was challenged by using a non-rodent species, the pig. In two different experimental sets the immediate and late effects of prepubertal exposure to low repeated doses of the abundant plasticizer di(2-ethylhexyl) phthalate (DEHP) on several reproductive traits were investigated in boars. In an additional experiment, the kinetics of DEHP and mono(2-ethylhexyl) phthalate (MEHP the primary, bio-active metabolite of DEHP) in the boar were investigated. After parenteral exposure to DEHP for five weeks, from the sixth week of age, the plasma concentrations of testosterone were higher and the area of the Leydig cells larger at 7.5 months, compared with the control group. Because the plasma concentrations of LH were unaffected, these data suggest that DEHP early in life causes long-lasting derangements in the fine tuning of the feedback loop in the hypothalamic-pituitary-gonadal axis (HPG-axis). After oral exposure to DEHP for four weeks, from the fourth week of age, LH profiles of the exposed and non-exposed boars differed slightly, both during the exposure period, and after stimulation with a GnRH analogue at nine months of age. These results corroborate the hypothesis that DEHP is an endocrine disruptor following prepubertal exposure. In the same pigs orally exposed to DEHP, the gross morphology as well as the microscopic morphology of the testes was unaffected at seven weeks of age. However, at nine months of age, the bulbourethral glands were larger in the boars exposed to although the microscopic morphology of the testes was unaffected. In addition, the mating behaviour of the boars was examined between six and nine months of age. The libido as well as the mating success was tested to determine whether DEHP affected the central nervous system. However, the mating behaviour and mating ability of DEHP-exposed boars was found to be unaffected. In young boars the concentrations of MEHP in plasma after oral exposure to DEHP were analyzed. It seemed that the systemic exposure to MEHP was lower in pigs compared to rats at the same oral dosage of DEHP. This may also explain some of the differences in the effects of this compound in different species. While corroborating the hypothesis that prepubertal exposure to the industrial chemical DEHP affects the reproductive endocrinology in mammals, the contents of this work do not suggest any behavioural effects of DEHP in mammals. It is noteworthy that the effects seen on testosterone concentrations and bulbourethral gland size are seen in the boars after the onset of puberty and not at the time of exposure. In view of the above, the use of pigs as a non-rodent complement in the field of reproductive toxicology is relevant.

Authors/Creators:Ljungvall, Karl
Title:Prepubertal exposure to Di(2-ethylhexyl) Phthalate
Subtitle:kinetics and effects on the reproductive system of the boar
Year of publishing :March 2006
Volume:2006:15
Number of Pages:34
Papers/manuscripts:
NumberReferences
ALLI. Ljungvall K, Tienpont B, David F, Magnusson U, Torneke K. 2004. Kinetics of orally administered di(2-ethylhexyl) phthalate and its metabolite, mono(2-ethylhexyl) phthalate, in male pigs. Archives of Toxicology 78, 384-9. With kind permission from Springer Science and Business Media. II. Ljungvall K, Karlsson P, Hulten F, Madej A, Norrgren L, Einarsson S, Rodriguez-Martinez H, Magnusson U. 2005. Delayed effects on plasma concentration of testosterone and testicular morphology by intramuscular low-dose di(2-ethylhexyl)phthalate or oestradiol benzoate in the prepubertal boar. Theriogenology. 64, 1170-84.With kind permission from Elsevier. III. Ljungvall K, Spjuth L, Hulten F, Einarsson S, Rodriguez-Martinez H, Andersson K, Magnusson U. 2006. Early post-natal exposure to low dose oral di(2ethylhexyl) phthalate affects the peripheral LH-concentration in plasma, but does not affect mating behavior in the post-pubertal boar. Reproductive Toxicology 21, 160-6. With kind permission from Elsevier. IV. Ljungvall K, Hultén F, Magnusson U. 2006. Morphology and morphometry of the reproductive organs in both prepubertal and postpubertal male pigs exposed to Di(2ethylhexyl) Phthalate before puberty. Manuscript.
Place of Publication:Uppsala
ISBN for printed version:91-576-7064-1
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:boars, behaviour, endocrinology, hormones, testes
Keywords:behaviour, boar, endocrine disruption, endocrinology, DEHP, testis
URN:NBN:urn:nbn:se:slu:epsilon-997
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-997
ID Code:1073
Department:(VH) > Dept. of Clinical Sciences
Deposited By: Karl Ljungvall
Deposited On:28 Mar 2006 00:00
Metadata Last Modified:02 Dec 2014 10:09

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