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Imidacloprid, a neonicotinoid insecticide, facilitates tyrosine hydroxylase transcription and phenylethanolamine N-methyltransferase mRNA expression to enhance catecholamine synthesis and its nicotine-evoked elevation in PC12D cells
- Source :
- Toxicology. 394
- Publication Year :
- 2017
-
Abstract
- Imidacloprid is a neonicotinoid insecticide acting as an agonist of nicotinic acetylcholine receptors (nAChRs) in the target insects. However, questions about the safety to mammals, including human have emerged. Overactivation of mammalian peripheral catecholaminergic systems leads to onset of tachycardia, hypertension, vomiting, etc., which have been observed in acutely imidacloprid-poisoned patients as well. Physiological activation of the nAChRs is known to drive catecholamine biosynthesis and secretion in mammalian adrenal chromaffin cells. Yet, the impacts of imidacloprid on the catecholaminergic function of the chromaffin cells remain to be evaluated. In this study using PC12D cells, a catecholaminergic cell line derived from the medulla chromaffin-cell tumors of rat adrenal gland, we examined whether imidacloprid itself could impact the catecholamine-synthesizing ability. Imidacloprid alone did facilitate tyrosine hydroxylase (TH) transcription via activation of α3β4 nAChR and the α7 subunit-comprising receptor. The insecticide showed the TH transcription-facilitating ability at the concentrations of 3 and 30 μM, at which acetylcholine is known to produce physiological responses, including catecholamine secretion through the nAChRs in adrenal chromaffin cells. The insecticide-facilitated TH transcription was also dependent on PKA- and RhoA-mediated signaling pathways. The insecticide coincidentally raised levels of TH and phenylethanolamine N-methyltransferase (PNMT) mRNA, and as a consequence, increased catecholamine production, although the efficacy of the neonicotinoid was lesser than that of nicotine, indicating its partial agonist-like action. Intriguingly, in cultured rat adrenal chromaffin cells, imidacloprid did increase levels of TH and PNMT protein. When the chromaffin cells were treated with nicotine in the presence of the insecticide, nicotine-elevated adrenaline production was enhanced due to facilitation of nicotine-increased TH and PNMT protein expression, and simultaneous enhancement of nicotine-elevated adrenaline secretion also took place. These findings thus suggest that imidacloprid may facilitate the physiological functions of adrenal glands in mammals.
- Subjects :
- 0301 basic medicine
rho GTP-Binding Proteins
endocrine system
medicine.medical_specialty
Insecticides
Nicotine
Epinephrine
Transcription, Genetic
Tyrosine 3-Monooxygenase
Chromaffin Cells
Toxicology
PC12 Cells
03 medical and health sciences
chemistry.chemical_compound
Neonicotinoids
0302 clinical medicine
Catecholamines
Imidacloprid
Internal medicine
parasitic diseases
Adrenal Glands
medicine
Animals
RNA, Messenger
Cells, Cultured
Catecholaminergic
Tyrosine hydroxylase
Chemistry
Phenylethanolamine N-Methyltransferase
Neonicotinoid
Drug Synergism
Nitro Compounds
Cyclic AMP-Dependent Protein Kinases
Phenylethanolamine N-methyltransferase
Rats
Phenylethanolamine
030104 developmental biology
Endocrinology
Nicotinic agonist
Gene Expression Regulation
Catecholamine
Female
030217 neurology & neurosurgery
medicine.drug
Subjects
Details
- ISSN :
- 18793185
- Volume :
- 394
- Database :
- OpenAIRE
- Journal :
- Toxicology
- Accession number :
- edsair.doi.dedup.....1f97032a22f13ba410b23019cc9cce36