EFFECT OF DIAZINON ON BEHAVIOR OF JAPANESE MEDAKA (ORYZIAS LATIPES) AND GENE EXPRESSION OF TYROSINE HYDROXYLASE AS A BIOMARKER

Abstract

This paper reports on the development of a biomarker used to monitor abnormal behaviors caused by diazinon in Japanese medaka (Oryzias latipes) as a model organism. Tyrosine hydroxylase (TH) activity in tissues was measured and the TH enzyme production in specific organs using a in situ cytochemical technique was monitored. These data were comparatively analyzed with those from semi-quantitative RT-PCR utilizing medaka TH gene that could be a potential biomarker for neuronal modulations and behaviors. For monitoring experiments at behavioral and molecular biological levels, the fish were treated under different sublethal conditions of diazinon (O, O-diethyl O-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] phosphorothioate) and their behavioral responses were observed. There were no significant differences in activity of TH head and body portions when the fish were exposed to lower concentrations (0.5-10 ppb) of diazinon including control treatment (0 ppb) for 24 hr. In temporal change of TH activity at 100 ppb diazinon treatment, however, the activity of body portion appeared to be inhibited during the first 30 min exposure but later seemed to recover slightly after 1 hr. TH appeared to be expressed mainly in the olfactory bulb, midbrain and brain stem regions as assessed by in situ immunohistochemistry. The treatment (1000 ppb) significantly suppressed TH protein production in the olfactory bulb, midbrain and brain stem regions. In kidney from the body portion the higher concentration treatment (1000 ppb) caused little suppression compared with the control. The RT-PCR showed that a production of TH mRNA transcript was significantly inhibited at 5 ppm diazinon treatment in the body portion. It was concluded that a suppression of TH activity would be one of the causes for the abnormal behaviors of the medaka that could be quantitatively monitored using an image processing system. This study provides molecular and neurobehavioral bases of a biomonitoring system for toxic chemicals using a model organism such as fish.

Histopathological evaluation of the interrenal gland (adrenal homolog) of Japanese medaka (Oryzias latipes) exposed to graphene oxide

“…40,50 To verify our hypothesis, we have used both adults and larvae of Japanese medaka fish exposed to GO either by IMR (adults and lar- Previously, these cells were identified by cellular morphology 27,39 or immunostaining with cell-specific enzymes such as 3β-hydroxysteroid dehydrogenase (3β-HSD) for steroidogenic cells 51 and TH for chromaffin cells. 28 In this study, we have attempted to identify the adrenal medullary cells (chromaffin cells) which express TH enzyme, the ratelimiting enzyme of catecoholamine biosynthesis. 26 However, to make or cords containing 2-3 cells thick which is similar to the distribution pattern of steroidogenic (IR cells) and chromaffin cells in medaka 27 as well as in other teleost species.…”

“…In teleost, the adrenal homolog (IR axis) consists of at least two types of cells having endocrine functions (steroidogenic cells and chromaffin cells). Previously, these cells were identified by cellular morphology 27,39 or immunostaining with cell‐specific enzymes such as 3 β ‐hydroxysteroid dehydrogenase (3 β ‐HSD) for steroidogenic cells 51 and TH for chromaffin cells 28 . In this study, we have attempted to identify the adrenal medullary cells (chromaffin cells) which express TH enzyme, the rate‐limiting enzyme of catecoholamine biosynthesis 26 .…”

“…For specific location of the IRG in the head kidney of medaka, we have used immunohistochemical technique for the detection of TH, the rate‐limiting enzyme in catecholamine biosynthesis that expressed in the chromaffin cells of IRG using the method described by Shin et al, 28 with some modifications. Briefly, tissue sections (5 μm thickness) on glass slides containing kidney with IRG were deparaffinized and brought to tap water.…”

Comparative Developmental Neurotoxicity of Organophosphate Insecticides: Effects on Brain Development Are Separable from Systemic Toxicity

“…With in vitro models or lower organisms, diazinon, like chlorpyrifos, has been shown to interfere with neural cell replication and differentiation ( Axelrad et al 2003 ; Morale et al 1998 ; Qiao et al 2001 ; Shin et al 2001 ). Here, in neonatal rats, diazinon exhibited less systemic toxicity than chlorpyrifos, with no growth impairment or significant loss of viability up to a dose of 5 mg/kg.…”

Do human activities influence survival and orientation abilities of larval fishes in the ocean?

“…Manmade chemical pollutants, such as pesticides and industrial‐use heavy metals, are almost ubiquitous in aquatic environments close to human settlements. Exposure to these chemicals has been documented to result in hyposmia, or the diminished sensitivity of the olfactory systems in fish (Moore & Waring ; Shin et al ; Baldwin et al ). Indeed, common components of urban runoff such as copper, cadmium and aluminum can damage the olfactory epithelium, while chemicals from pesticides can be linked to increased mucus coverage of the olfactory organs (Klaprat et al ; Sloman ; Baldwin et al ).…”