title: Neuropathological effect of carbamate molluscicides on the land snail, Eobania vermiculata.
abstract: The present study was designed to investigate the neuropathological effect of the two carbamate pesticides: methomyl and methiocarb on the neurons of the buccal ganglia in the land snail Eobania vermiculata using topical application and baiting technique. Their in vivo effects on acetylcholinesterase (AChE, EC 3.1.1.7) activity were also investigated. Sublethal dose and concentration (1/4 LD(50) and 1/4 LC(50)) of both pesticides were used, and the experiment lasted for 14 days. Histopathological and ultrastuctural alterations in the buccal ganglia were more obvious after the baiting technique treatment than after the topical application method, and methomyl was found to be more toxic than methiocarb. These alterations included shrinkage of the perikarya of neurons, increased cytoplasmic basophilia, and extreme indentation of the plasma membrane. In addition, the nuclei appeared karyolitic, eccentric, and highly shrunken with an irregular nuclear envelope. The most outstanding symptom observed after topical application of methiocarb was a highly vacuolated cytoplasm with a peripheral increase in electron density associated with dense accumulations of free ribosomes. On the other hand, an increased number of lysosomes and autophagosomes were observed after topical application of methomyl. Mitochondrial damage, increased number of lipid droplets, and myelin figures were frequently observed in ganglia treated with either methomyl or methiocarb. Moreover, it was noticed that both compounds induced reductions in AChE activity. However, methomyl exhibited more potency in reducing AChE activity than methiocarb.
authors.affiliation: Zoology Department, Faculty of Science, Alexandria University, Alexandria, Egypt. amina_essawy@yahoo.com
authors.forename: Amina E
authors.initials: AE
authors.lastname: Essawy
authors.forename: Nabila E
authors.initials: NE
authors.lastname: Abdelmeguied
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Radwan
authors.forename: Sherifa S
authors.initials: SS
authors.lastname: Hamed
authors.forename: Amira E
authors.initials: AE
authors.lastname: Hegazy
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects; D002490:Central Nervous System / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D022083:Cytoplasmic Structures / Q000187:drug effects / Q000473:pathology; D017952:Ganglia, Invertebrate / Q000187:drug effects* / Q000648:ultrastructure; D007306:Insecticides / Q000633:toxicity*; D008714:Methiocarb / Q000633:toxicity*; D008724:Methomyl / Q000633:toxicity*; D009474:Neurons / Q000187:drug effects* / Q000648:ultrastructure; D010525:Peripheral Nerves / Q000187:drug effects / Q000201:enzymology; D012908:Snails / Q000187:drug effects* / Q000502:physiology; D014617:Vacuoles / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D007306:Insecticides; D014874:Water Pollutants, Chemical; D008724:Methomyl; D000110:Acetylcholinesterase; D008714:Methiocarb