Ectoparasiticides: Antagonists and Modulators of Chloride Channels

Abstract

Lindane was isolated from the mixture of isomers in 1912. In 1943 lindane was identified as the insecticidal principle of hexachlorhexane. Insecticidal properties of chlordane, a cyclodiene, were at first identified in the 1940s. The action of lindane and cyclodienes to stimulate synaptic transmission was demonstrated 40 years ago. However, it was not until the early 1980s that the GABA-gated chloride channel complex was suggested to be their target site. In nerve and muscle preparations, lindane and cyclodiene insecticides antagonized GABA-stimulated 36 Cl uptake and competed with the TBPS (t-butylbicyclophosphorothioate) binding site at the GABA-gated chloride channel. Recent studies with cockroach neurones revealed that lindane and cyclodienes decrease the frequency of the GABA-gated chloride channel opening without changing the mean opening time. Dieldrin suppressed the GABA-induced current in a noncompetitive manner. Since picrotoxin attenuates the inhibitory effect of dieldrin, it is speculated that cyclodienes bind to the picrotoxin/TBPS binding site. It follows that lindane and cyclodienes are antagonists at GABA-gated chloride channels directly responsible for excitatory symptoms in poisoning of mammals and insects.Chlordane (cyclodiene compound) is a nonsystemic insecticide with contact, stomach, and respiratory action and long residual activity. It controls household insects as well as pests of domestic animals and man. The compound has impurities of different stereoisomers and heptachlor. Acute oral LD 50 for rats is 133-649 mg/kg (acute percutaneous LD 50 217 mg/kg). The compound accumulates in body fat and lipidcontaining organs. It shows serious chronic and cumulative toxicity. The compound is toxic to fish and bees. In mammals, chlordane is metabolized mainly to hydroxylated products. Bromocyclene is a nonsystemic insecticide with contact and stomach action. It is used against ectoparasites in sheep and against fleas on pets. Endosulfan (cyclodiene compound) is a nonsystemic insecticide with contact and stomach action. In animal and public health applications, it is used for the control of tsetse flies. Acute oral LD 50 for rats is 70-240 mg/kg depending on isomer and formulation (acute percutaneous

Comparison of the efficacy of tea tree (Melaleuca alternifolia) oil with other current pharmacological management in human demodicosis: A Systematic Review

“…Lindane, also known as γ hexachlorocyclohexane or benzene hexachloride, is an organochloride of the cyclohexane family. It acts on the GABA-gated chloride channels as a neurotoxin in arthropods, leading to paralysis and death of the parasite (Turberg, 2015).…”