Trubiroha, Achim; Kroupova, Hanna; Frank, Sabrina N.; Sures, Bernd; Kloas, Werner:

Inhibition of gametogenesis by the cestode Ligula intestinalis in roach (Rutilus rutilus) is attenuated under laboratory conditions.

In: Parasitology, Jg. 138 (2011) ; Nr. 5, S. 648-659
ISSN: 0031-1820
Zeitschriftenaufsatz / Fach: Biologie
Reproductive parameters of Ligula intestinalis-infected roach (Rutilus rutilus) which were held under long-tem laboratory
conditions with unlimited food supply were investigated. Although uninfected and infected roach showed no difference in
condition factor and both groups deposited perivisceral fat, the gonadosomatic-index was significantly lower in infected
female and male roach. Quantitative histological analysis revealed that gonad development was retarded upon parasitization
in both genders. In contrast to the phenotype described in the field, infected females were able to recruit follicles into
secondary growth, but a high percentage of secondary growth follicles underwent atresia. In both genders, the histological
data corresponded well with reduced expression of pituitary gonadotropins and lowered plasma concentrations of sex
steroids, as revealed by real-time RT-PCR and ELISA, respectively. Furthermore, a reduction of vitellogenin mRNA and
modulated expression of sex steroid receptors in the liver was demonstrated. Like in the field, there was a significant adverse
impact of L. intestinalis on host reproductive physiology which could not be related to parasite burden. Our results show, for
the first time, that maintenance under laboratory conditions can not abolish the deleterious effect of L. intestinalis on
gametogenesis in roach, and indicate a specific inhibition of host reproduction by endocrine disruption.

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