Electrophysiological evidence for synergism between carbamate (bendiocarb) and an essential oil component (menthol)

• Autorzy: Jankowska M. , Stankiewicz M.
• Języki publikacji: EN

Abstrakty

EN

Bendiocarb is an acetylcholinesterase inhibitor belong‑ ing to the carbamate class of insecticides. It causes rapid knock-down of an insect. However, its effective concentra‑ tions are relatively high (10-4 M). In our previous toxicity tests performed on American cockroach (Periplaneta amer‑ icana), we have shown that the presence of menthol, a com‑ pound found in some essential oils, improved the effective‑ ness of bendiocarb. The aim of our study was to investigate the interaction between bendiocarb and menthol on the cockroach nervous system in order to clarify their com‑ bined mode of action. Experiments were performed using an extracellular electrodes technique on the P. americana connective nerve leaving the terminal abdominal ganglion. Two types of bioelectric signals were evaluated: the size of response to stimulation of cerci mechanoreceptors and the total activity of the nerve, including spontaneous activity and response to stimulation. Bendiocarb did not modify the size of response to stimulation but it increased the to‑ tal activity of the nerve. It caused bursts in spontaneous activity in a concentration-dependent manner, which re‑ sulted in an increase of total activity compared to control. 60 min after application of bendiocarb (10-6 M) activity was measured at 3.21 times higher than control. Coapplication of menthol potentiated this effect, as 60 min after appli‑ cation of the mixture of bendiocarb (10-6 M) and menthol (10-6 M) total activity was 6.71 times higher than control. Statistical analysis performed on data obtained with differ‑ ent bendiocarb concentrations (10-7 , 5x10-7 , 2x10-7 , 10-6 M) in the presence and absence of menthol revealed that the addition of menthol decreased the ED50 value by two fold and increased the maximum effect. The combinational in‑ dex calculated via Chou and Talalay was much lower than 1, which indicates strong synergism between compounds. We assumed that the strengthening effect of menthol takes place via octopaminergic receptors. Menthol decreased the total activity of the nerve; the same effect was observed for octopamine. Phentolamine, an octopamine receptor an‑ tagonist, abolished the effect of menthol and eliminated the effect of the menthol + bendiocarb mixture. Menthol increased the effectiveness of bendiocarb in electrophys‑ iological experiments and a possible mechanism of action for menthol is via activation of octopamine receptors. The project was supported by the National Science Center, Po‑ land under grant: NCN 014/15/N/NZ9/03868.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2018
• Tom: 78
• Numer: Suppl.1
• Opis fizyczny: p.9

Twórcy

autor

Jankowska M.

• Nicolaus Copernicus University, Torun, Poland

autor

Stankiewicz M.

• Nicolaus Copernicus University, Torun, Poland