Aim of the study
The aim of the study is to examine if pesticides can
development (metamorphosis, sexual differentiation and growth) and
function in amphibians and if pesticides through these modes of action
contributing factors to amphibian decline. In order to study this, an
model, applying Rana temporaria as a model species, was
The project has been financed by the Norwegian
<>Professor Bjørn Munro Jenssen
Post doc Angels Leiva-Presa
Professor Rolf A. Andersen>
Associate professor Augustine Arukwe
Summary of the project
of environmental contamination on amphibians are of particular concern
there are reports of declining populations in most parts of the world.
the last decade there has been increased focus on the role of
organic pollutants as endocrine disrupters. To study the effects of
different pesticides (p,p’-DDE,
one of the most persistent metabolites
of the pesticide DDT, Fenitrothion
and Permethrin) on endocrine
systems of adult amphibians, we subcutaneously exposed adult European
frogs (Rana temporaria) to 0, 0.01, 0.1, 1 and 10 mg
mass and studied the effect of a 14 days-exposure. The study showed
that of the
three examined pesticides, p,p’-DDE was the only compound which had
effects on the examined endocrine variables in the adult European
Permethrin and Fenitrothion did not
have any major significant effects, and therefore seem to be more
environmentally safe with regards to endocrine disruptive effects in
common frogs. The project has documented that the hepatic Vitamin A
was affected by exposure to p,p’-DDE, possibly by decreasing
expression and thus levels of this enzyme which is involved in the
of retinoids. The project also documented that p,p-DDE
induced changes of TRα and TRβ mRNA expression in the brain, testes,
liver. Furthermore, the project indicates that antioxidant stress
related to SOD activity are affected by p,p’-DDE,
while CAT is not affected by by p,p’-DDE
exposure. In gonads a decrease in MT synthesis at low doses of p,p’-DDE exposure could indicate a
repression of the defence systems. The project also showed that the
density was negatively affected following exposure to p,p’-DDE.
In frogs exposed to PCB, a significantly higher variation
in the estradiol-testosterone ratio in the exposed groups than in the
group may indicate that the sex-hormone homeostasis of male R.
temporaria is affected by PCBs
shortly after arousal from hibernation, but that the effects are subtle
several different mechanisms are involved. The effects on the retinol
homeostasis of adult male European common frogs documented in the
project, warrants the need for further studies on other wildlife
respect to retinol related effects caused by persistent organic
There is also a need for linking the documented effects on retinoid
to ecological effects which occur in the natural environment.
Publications from the project
A, 2006. Organ-specific
Patterns of P450arom Gene Isoforms are modulated by p,p′-DDE in Adult
European Common Frog, Rana temporaria
Mar Environ Res 62: S215-S218 .
A, Jenssen BM, 2005.
Differential organ expression patterns of thyroid receptor isoform
p,p'-DDE-treated adult male common frogs, Rana temporaria. Environ
A, Mortensen AS,
Arukwe A, Jenssen BM, 2006. Altered hepatic retinol and cyp26 levels in
European frog (Rana temporaria)
exposed to p,p'-DDE. Mar Environ Res 62:
A, Jenssen BM, 2006a.
Effects of p,p’ DDE on retinoid homeostasis and sex hormones of adult
European common frogs (Rana temporaria). J Toxicol Environ Health in
Lundberg R, Leiva-Presa A, Jenssen
BM, Rönn M, Hernhag C, Wejheden C, Larsson S, Örberg J, Lind PM, 2006.
of short-time exposure to the DDT metabolite p,p’-DDE on bone tissue in
common frog (Rana Temporaria). J
Toxicol Environ Health in press.
Jenssen BM, 2006. Polychlorinated
biphenyls, sex steroid hormones and liver retinoids in adult male
common frogs (Rana temporaria).
Leiva-Presa A, Asensio Herrera V,
Hansen BH, Andersen RA, Jenssen BM, 2005a. Impact of the organic
p,p'-DDE on heavy metal detoxification systems of adult frogs Rana
In: International Conference on Heavy Metals in the Environment
(ICHMET). Rio de Janeiro;
Leiva-Presa A, Jenssen BM, 2006b.
Endocrine effects of pesticides in the European common frog, Rana
In: Society of Environmental Toxicology and Chemistry, SETAC Europe
16th Annual Meeting. den Hague, The Netherlands.
Leiva-Presa A, Mortensen AS,
Arukwe A, Jenssen BM, 2005c. Hepatic retinol and cyp26 levels in adult
European frog (Rana temporaria) after
subcutaneous exposure to the organochlorine metabolite p,p'-DDE. In:
PRIMO 13. Alessandria,