Effects of Naproxen, in Gammarus pulex / Seker ____________________________________________________________________________________
2 of 8
INTRODUCTION
The Gammarus family, Gammaridae: Amphipoda, drew the attention
of experts in taxonomy and ecology but in recent years, professionals
in molecular biology, genetics, agriculture, and notably, toxicology
also have been interested. Gammarus species have rapidly gained
use in ecotoxicology due to their high abundance [1], distinct sexual
dimorphism, ease of collection, and tolerance to a wide range of toxic
substances [2, 3]. While the primary focus of research within the
domain of aquatic toxicology currently centers on identifying sensitive
long–term markers for a variety of test species including gammarids,
the role in oxidative stress of acute toxicity exposure continues its
popularity in elucidating the effects of toxins [1, 4, 5]. The assessment
of chemical screening and the compliance of wastewater with
discharge regulations is primarily based on physiological toxicity
data. This approach plays a critical role in determining the potential
effects of wastewater on human health and the environment.
The common use of non–steroidal anti–inflammatory drugs,
including naproxen and other chemicals has been documented in
various regions all around the world [6]. Naproxen, the propionic
acid derivative, is a non–steroidal anti–inammatory drug (NSAID),
widely used for the treatment of primary dysmenorrhoea, rheumatoid
arthritis, osteoarthritis, ankylosing, tendinitis, bursitis, acute gout
and juvenile arthritis in human [7, 8]. These applications have
disrupted the balance within aquatic ecosystems, containing rivers,
streams, lakes, estuaries, and coastal and deep oceans. Although
it is known the pollution of NSAIDs, their potential toxic impacts
on aquatic organisms have become the subject of research and
experiment recently. Whereas the mechanisms of action of these
substances are well–established in humans and other vertebrates
[9], they remain largely unknown in aquatic invertebrates, that are
continuously exposed to these compounds. As a result, there is
considerable uncertainty regarding the environmental risks related
to their presence [10]. The primary way NSAIDs work is by inhibiting
the enzyme cyclooxygenase (COX). This enzyme is essential for
converting arachidonic acid into thromboxanes, prostaglandins,
and prostacyclins. The therapeutic benets of NSAIDs result from
the reduced production of these eicosanoids [9]. Studies on the
effects of naproxen on aquatic organisms have primarily concentrated
on planktonic species such as water fleas (Daphnia magna and
Moina macrocopa) and sh (Oryzias latipes and Danio rerio) [11, 12,
13]. Exposure to naproxen has been shown to affect the genetic
material, inammatory processes, and metabolic processes of aquatic
organisms [13]. Additionally, it has been reported that naproxen poses
an ecological risk to Daphnia manga [14].
Nonsteroidal anti–inammatory drugs (NSAIDs) which encompass
analgesic compounds constitute a highly notable category of
pharmaceuticals globally with an approximate annual production
of multiple kilotons [15]. Until now, the studies have indicated
the presence of NSAIDs in the aquatic ecosystem, specically in
wastewater and surface water [16]. Naproxen is a kind of NSAID
drugs. Ever since its introduction to the market in 1976, naproxen
has consistently remained highly popular [17]. Induction of oxidative
stress and the impact of detoxification mechanisms by various
NSAIDs in aquatic organisms have also been evaluated through the
measurement of activities of enzymes taking part in a variety of
biochemical pathways [18, 19, 20, 21, 22, 23].
Oxidative stress happens as a consequence of an imbalance
between the generation of reactive oxygen species (ROS) and the
detoxication of these reactive compounds within an organism. ROS
are naturally produced as byproducts of various essential biochemical
reactions that play crucial roles in energy transfer, cellular defense,
and cell signaling [24]. ROS have the potential to harm vital biological
macromolecules and induce peroxidation of membrane lipids in
biological systems, leading to the disruption of membrane structure
and function. The exposure to environmental stressors can trigger
a disproportionate increase in ROS levels, resulting in cellular and
tissue damage [25]. Maintaining a balance between oxidants and
antioxidants is a crucial for cellular homeostasis.
Gammarus pulex is a tiny amphipod crustacean that inhabits
freshwater environments throughout Europe. This species is well–
suited for biomonitoring studies due to its notable role in freshwater
ecosystems. G. pulex serves as a vital food source for various
invertebrates, sh, and birds, making it an important link in the food
chain [26]. This organism has also been widely utilized in monitoring
contaminants, including toxicity tests for a range of pollutants like
metals, PAHs/PCBs, and pharmaceutical substances. This highlights
its crucial role in assessing environmental risks [ 27, 28, 29, 30].
The current investigation aims to contribute to the assessment
of aquatic toxicity tests employed for evaluating the potential
toxicological inuence of naproxen on aquatic organisms. Regarding
that all effects are not necessarily detrimental, the primary objective
of these tests is to identify chemicals that may have adverse impacts.
The bioassay tests will yield a database that can be utilized to evaluate
the risks associated with a given scenario.
MATERIALS AND METHODS
Living material
A model invertebrate species, G. pulex (L., 1758), was used for the
exposure experiment. G. pulex samples were collected from the
Munzur River (39.156820 N, 39.499640 E) in Tunceli province, from
the slower owing and relatively deeper parts of the source, using
hand nets from under leaves and stones. G. pulex samples, which
were quickly brought alive to the laboratory in air–reinforced plastic
bottles, were placed in two 80×40×25 cm aerated stock aquariums
prepared similar to their natural environment. Rested water taken
from the natural environments where the samples were obtained was
placed in the aquariums, and 50% of the water in the aquariums was
replaced with rested water once a week.
Experimental setup and naproxen exposure
Before being used in experiments, G. pulex samples were fed with
rotten willow tree leaves collected from their natural habitat in a
room kept at a constant temperature of 18°C, in a 12:12 h light:dark
cycle, for 15 days [28]. During adaptation, the feeding and mobility
of the creatures were observed.
In the study, after 15 days of adaptation, G. pulex samples selected
from stock aquariums; Care was taken to ensure that they were male
individuals who had reached sexual maturity, completed their molting,
were in good health, and had an average weight of approximately
0.350–0.400 g.
Gammarus pulex samples were divided into four groups after
a two–week adaptation period to laboratory conditions. The
experimental setup included a control and three experimental
groups, each consisting of three replicates. 2 liter glass jars were