title: Modulation of dopaminergic neurotransmission induced by sublethal doses of the organophosphate trichlorfon in cockroaches.
abstract: Organophosphate (OP) insecticides have been used indiscriminately, based on their high dissipation rates and low residual levels in the environment. Despite the toxicity of OPs to beneficial insects is principally devoted to the acetylcholinesterase (AChE) inhibition, the physiological mechanisms underlying this activity remain poorly understood. Here we showed the pharmacological pathways that might be involved in severe alterations in the insect locomotion and grooming behaviors following sublethal administration of the OP Trichlorfon (Tn) (0.25, 0.5 and 1 µM) in Phoetalia pallida. Tn inhibited the acetylcholinesterase activity (46±6, 38±3 and 24±6 nmol NADPH/min/mg protein, n=3, p<0.05), respectively. Tn (1 µM) also increased the walking maintenance of animals (46±5 s; n=27; p<0.05). Tn caused a high increase in the time spent for this behavior (344±18 s/30 min, 388±18 s/30 min and 228±12 s/30 min, n=29-30, p<0.05, respectively). The previous treatment of the animals with different cholinergic modulators showed that pirenzepine>atropine>oxotremorine>d-tubocurarine>tropicamide>methoctramine induced a decrease on Tn (0.5 µM)-induced grooming increase, respectively in order of potency. Metoclopramide (0.4 µM), a DA-D2 selective inhibitor decreased the Tn-induced grooming activity (158±12 s/30 min; n=29; p<0.05). Nevertheless, the effect of the selective DA-D1 receptor blocker SCH 23390 (1.85 µM) on the Tn (0.5 µM)-induced grooming increase was significative and more intense than that of metoclopramide (54±6 s/30 min; n=30; p<0.05). Taken together the results suggest that a cross-talking between cholinergic M1/M3 and dopaminergic D1 receptors at the insect nervous system may play a role in the OP-mediated behavioral alterations.
authors.affiliation: CIPBiotec, Universidade Federal do Pampa, (UNIPAMPA), Campus São Gabriel, Av. Antônio Trilha, 1847, Centro, CEP 97300-000, São Gabriel, Rio Grande do Sul, Brasil.
authors.forename: Graziele Daiane
authors.initials: GD
authors.lastname: Stürmer
authors.affiliation: CIPBiotec, Universidade Federal do Pampa, (UNIPAMPA), Campus São Gabriel, Av. Antônio Trilha, 1847, Centro, CEP 97300-000, São Gabriel, Rio Grande do Sul, Brasil.
authors.forename: Thiago Carrazoni
authors.initials: TC
authors.lastname: de Freitas
authors.affiliation: CIPBiotec, Universidade Federal do Pampa, (UNIPAMPA), Campus São Gabriel, Av. Antônio Trilha, 1847, Centro, CEP 97300-000, São Gabriel, Rio Grande do Sul, Brasil.
authors.forename: Marines de Avila
authors.initials: Mde A
authors.lastname: Heberle
authors.affiliation: Instituto do Cérebro do Rio Grande do Sul, Pontifícia Universidade, Católica do Rio Grande do Sul, PUCRS, Porto Alegre, RS, Brasil.
authors.forename: Dênis Reis
authors.initials: DR
authors.lastname: de Assis
authors.affiliation: CIPBiotec, Universidade Federal do Pampa, (UNIPAMPA), Campus São Gabriel, Av. Antônio Trilha, 1847, Centro, CEP 97300-000, São Gabriel, Rio Grande do Sul, Brasil.
authors.forename: Lúcia
authors.initials: L
authors.lastname: Vinadé
authors.affiliation: CIPBiotec, Universidade Federal do Pampa, (UNIPAMPA), Campus São Gabriel, Av. Antônio Trilha, 1847, Centro, CEP 97300-000, São Gabriel, Rio Grande do Sul, Brasil.
authors.forename: Antônio Batista
authors.initials: AB
authors.lastname: Pereira
authors.affiliation: CIPBiotec, Universidade Federal do Pampa, (UNIPAMPA), Campus São Gabriel, Av. Antônio Trilha, 1847, Centro, CEP 97300-000, São Gabriel, Rio Grande do Sul, Brasil.
authors.forename: Jeferson Luis
authors.initials: JL
authors.lastname: Franco
authors.affiliation: CIPBiotec, Universidade Federal do Pampa, (UNIPAMPA), Campus São Gabriel, Av. Antônio Trilha, 1847, Centro, CEP 97300-000, São Gabriel, Rio Grande do Sul, Brasil. Electronic address: charistonbelo@unipampa.edu.br.
authors.forename: Cháriston André
authors.initials: CA
authors.lastname: Dal Belo
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology; D003058:Cockroaches / Q000187:drug effects* / Q000378:metabolism; D006120:Grooming / Q000187:drug effects; D007306:Insecticides / Q000633:toxicity*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects*; D014236:Trichlorfon / Q000633:toxicity*
chemical_list: D007306:Insecticides; D014236:Trichlorfon; D000110:Acetylcholinesterase
keywords: Acetylcholinesterase; Dopaminergic signaling; Neurotoxicity; Phoetalia pallida; Trichlorfon