Change search
ReferencesLink to record
Permanent link

Direct link
Schistocephalus solidus infections increase gonadotropins and gonadotropin releasing hormone (GnRH3) mRNA levels in the three-spined stickleback, Gasterosteus aculeatus
Stockholm University, Faculty of Science, Department of Zoology.
Show others and affiliations
2012 (English)In: Parasitology international, ISSN 1383-5769, Vol. 61, no 3, 470-474 p.Article in journal (Refereed) Published
Abstract [en]

Parasites often impair the reproduction of their hosts, one well known case being the cestode Schistocephalus solidus which is a common parasite in three-spined sticklebacks. Gasterosteus aculeatus. One of the possible ways that this could be exerted is by suppression on the brain-pituitary-gonadal (BPG) axis. In this study, mRNA levels of FSH-beta and LH-beta and of GnRH2 (cGnRH II) and GnRH3 (sGnRH) were measured via Q-PCR in infected and uninfected fish sampled from the field a few weeks before the onset of breeding. The pituitary mRNA levels of both FSH-beta and LH-beta were higher in infected males than in uninfected males. Also in females, FSH-beta mRNA levels were higher in infected individuals than in others, whereas there was no significant difference found in LH-beta expression. Brain mRNA levels of GnRH3 were higher in infected fish than in uninfected fish in both sexes, but no difference was found in GnRH2 mRNA levels. Thus, infection by S. solidus was able to alter the expressions not only of gonadotropins (GtHs), but also of GnRH which has not been observed previously. However, the effects are opposite to what should be expected if the parasite suppressed reproduction via actions on the brain-pituitary level. The gonads are perhaps more likely to be impaired by the parasites in other ways, and changed feedbacks on the BPG axis could then lead to the increases in GtHs and GnRH.

Place, publisher, year, edition, pages
2012. Vol. 61, no 3, 470-474 p.
Keyword [en]
Schistocephalus solidus, GnRH2, GnRH3, LH-beta, FSN-beta, Stickleback, mRNA
National Category
Natural Sciences
URN: urn:nbn:se:su:diva-80632DOI: 10.1016/j.parint.2012.03.006ISI: 000305501900014OAI: diva2:556463


Available from: 2012-09-25 Created: 2012-09-25 Last updated: 2014-10-13Bibliographically approved
In thesis
1. The brain-pituitary-gonadal axis of the three-spined stickleback, Gasterosteus aculeatus
Open this publication in new window or tab >>The brain-pituitary-gonadal axis of the three-spined stickleback, Gasterosteus aculeatus
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The seasonal reproduction of the three-spined stickleback is stimulated by long day photoperiod. As in other vertebrates, the reproductive system of stickleback is regulated by the brain-pituitary-gonadal (BPG) axis which is largely controlled by feedback effects. Both negative and positive feedback effects on the BPG axis have been found in fish. So far, the roles feedback effects on the BPG axis play in the photoperiodic regulation of seasonal reproduction are still unclear. This thesis focused on the photoperiodic regulation and gonadal feedback effects on the gene expressions of gonadotropin (GtH) and gonadotropin-releasing hormones (GnRH) in the brain and pituitary, and how gonadal feedback regulated the steroid homeostasis in stickleback.Both GnRH2 and GnRH3 mRNA was found in the hypothalamus. Higher expression levels of both GnRH2 and 3 in breeding than in post-breeding males suggested that they are both involved in seasonal reproduction. There was no evidence for a role of GnRH3, which may be the dominating form, in the photoperiodic control of reproduction. However, the polarity of the feedback effect on gnrh3 gene expression may turn from positive to be negative when the males went into post-breeding state. Tapeworm, Schistocephalus solidus, infection inhibited the reproduction of sticklebacks. However, the infection caused higher expression levels of both GnRHs and GtHs genes, which may be due to feedback effect on the BPG axis.Under short day, both lh-β and fsh-β were suppressed by low androgen levels. This negative feedback may inhibit maturation completely, unless a rise of androgens triggers positive feedback under long day. The change in feedback polarity may result in all or nothing maturation. Furthermore, the androgen inhibitory effect on lh-β and fsh-β under short day could be abolished by aromatase inhibitor, which means the estrogen may cause negative feedback in males under short day.There was no compensation effect on plasma androgen level in fully mature hemi-castrated fish. However, both testosterone and 11-ketoandrostenedione treatments increased plasma levels much less in sham-operated fish than in castrated ones, indicating that homeostatic mechanisms are nevertheless present.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2012. 39 p.
BPG axis, GnRH, lh-β, fsh-β, three-spined stickleback, Gasterosteus aculeatus, homeostasis, feedback
National Category
Research subject
Functional Zoomorphology
urn:nbn:se:su:diva-80473 (URN)978-91-7447-568-5 (ISBN)
Public defence
2012-10-19, William-Olssonsalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:00 (English)

At the time of the doctoral defense, the following papers were unpublished and had a status as followsPaper 1: Submitted. Paper 3: Submitted. Paper 4: Submitted.

Available from: 2012-09-28 Created: 2012-09-20 Last updated: 2013-05-08Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Shao, Yi TaBorg, Bertil
By organisation
Department of Zoology
In the same journal
Parasitology international
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 103 hits
ReferencesLink to record
Permanent link

Direct link