The document discusses nicotinic acetylcholine receptors (nAChRs), which are critical in transmitting signals throughout the body and are targeted by various competitive modulators and agonists, particularly in insecticides. Neonicotinoids and sulfoximines are highlighted for their ability to mimic acetylcholine, leading to paralysis and death in insects by blocking receptor sites. The text also references several studies and sources related to the chemistry and efficacy of these insecticides.

1. Nicotinic Acetylcholine Receptor (nAChR)
Competitive Modulators/Agonists
Department of Agriculture Entomology Bahauddin Zakariya University, Multan
By: Muhammad Zeeshan Nazar
Email ID: mzeeshan_93@yahoo.com

2. • Neurotransmitters are Chemical Messengers that communicate
information throughout the body by neural system.
• They are found at the terminal region of axon in the synaptic vesicles.
• Acetylcholine neurotransmitters are involved in
 Contraction of skeletal muscles.
 Activate glandular functions in the endocrine system.
 Sensation of pain.
Acetylcholine Neurotransmitter

3. • Receptor proteins respond to the neurotransmitter, acetylcholine.
• Nicotinic Acetylcholine Receptors also respond to drugs, including the
Nicotinic Receptor Agonist.
• They are found in the CNS and PNS, muscle and
many other tissues of many organisms.
• In insects, limited to the central nervous system.
• Transmit outgoing signals from the presynaptic to
the postsynaptic cells.
Nicotinic Acetylcholine Receptors (nAChRs)
Agonist
nAChR

5. Receptor sites
Synaptic Vesicles

6. • Neuro-active, systemic insecticides.
• Mimics the action of acetylcholine at nAChRs.
• Chemically bind to acetylcholine receptors site.
 Block acetylcholine access to receptor sites.
• Continuous sending unwarranted neural transmissions.
• Receptors and cells involved in neural transmission become exhausted
and fail to function.
• Results in paralysis and death of insects.
Nicotinic Acetylcholine Receptors Competitive Modulators/Agonist
Mode of Action

7. Vesicles of acetylcholine
Insecticide
Nicotine receptors
blocked
Constant neuromuscular
stimulation

8. 1. Neonicotinoids
• Acetamiprid
• Imidacloprid
• Nitenpyram
• Thiacloprid
• Thiamethoxam
• Clothianidin
2. Sulfoximines
• Sulfoxaflor
Examples

9. References
Thomas, C. S., et al. 2013. Sulfoxaflor and the sulfoximine insecticides: Chemistry, mode of action
and basis for efficacy on resistant insects. Pesticide Biochemistry and Physiology
Lopez, O. and Fernandez, J.G. Green Trends in Insect Control. Royal Society of Chemistry. Cambridge, UK. pp. 132–162.
Tomizawa, M., Casida, J.E. 2011. Unique neonicotinoid binding conformations conferring selective receptor interactions.
Agric. Food. Chem. 59: 2825–2828.
Simon, D.N. 2015. Systemic insecticides (neonicotinoids and fipronil): trends, uses, mode of action and metabolites.
Environ Sci Pollut Res. Vol. 22:5–34
Wagner, S. 2016. Environmental Fate of Imidacloprid. Environmental Monitoring Branch Department of Pesticide
Regulation
Fishel, F.M. 2005. Evaluation of pesticides for carcinogenic potential. PI-37. Gainesville: University of Florida Institute of
Food and Agricultural Sciences.