Ameliorative effects of jojoba oil on fipronil-induced hepatorenal- and neuro-toxicity: the antioxidant status and apoptotic markers expression in rats

Jojoba (Simmondsia chinensis) is an economically important plant due to its high oil content in the seeds. Fipronil is an extensively used phenylpyrazole insecticide. The present investigation aimed to assess the possible ameliorative effect of jojoba oil on fipronil induced toxicity in rats. Animals orally received the insecticide dissolved in corn oil by stomach tube at 1/10th LD₅₀ for 28 days. Fipronil induced hepatorenal toxic effects evidenced by elevated serum ALT, AST, ALP, and LDH activities, and urea and creatinine levels, with histomorphological changes in the liver and kidney. Brain GABA was elevated with histopathological alterations in the brain tissue. Oxidative stress was demonstrated in liver, brain, and kidney as indicated by elevated MDA and NO levels with reduction in GSH level and activities of SOD and CAT. In addition, caspase-3 gene expression was enhanced, while Bcl2 gene expression was downregulated in the three organs. Increased DNA fragmentation was recorded in the liver and kidney. Cotreatment of jojoba oil with fipronil ameliorated the toxic effects of fipronil on various organs with improvement of the antioxidant status, the rate of apoptosis and the histopathological alterations. In conclusion, jojoba oil provided significant protection against fipronil induced hepatorenal- and neuro-toxicity, by its antioxidant and antiapoptic effects, making it a possible beneficial protective of natural origin.

Neurotranmission systems as targets for toxicants: a review

Neurotransmitters are chemicals that transmit impulses from one nerve to another or from nerves to effector organs. Numerous neurotransmitters have been described in mammals, amongst them acetylcholine, amino acids, amines, peptides and gases. Toxicants may interact with various parts of neurotransmission systems, including synthetic and degradative enzymes, presynaptic vesicles and the specialized receptors that characterize neurotransmission systems. Important toxicants acting on the cholinergic system include the anticholinesterases (organophosphates and carbamates) and substances that act on receptors such as nicotine and the neonicotinoid insecticides, including imidacloprid. An important substance acting on the glutamatergic system is domoic acid, responsible for amnesic shellfish poisoning. 4-Aminobutyric acid (GABA) and glycine are inhibitory neurotransmitters and their antagonists, fipronil (an insecticide) and strychnine respectively, are excitatory. Abnormalities of dopamine neurotransmission occur in Parkinson's disease, and a number of substances that interfere with this system produce Parkinsonian symptoms and clinical signs, including notably 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, which is the precursor of 1-methyl-4-phenylpyridinium. Fewer substances are known that interfere with adrenergic, histaminergic or seroninergic neurotransmission, but there are some examples. Among peptide neurotransmission systems, agonists of opioids are the only well-known toxic compounds.

Toxicology of insecticides to mammals

Many insecticides target structures or functions in non-target species, including mammals. This is particularly true of those that target the insect nervous system, such as the organochlorines, anticholinesterases and GABA antagonists. Another group of insecticides target structures or functions not present in mammals, and this group of insecticides has considerable target species specificity, but there are often potential targets in mammals. Octopamine is closely related to adrenaline and amitraz (an octopamine receptor agonist) and acts in mammals at α2-adrenergic receptors. Although there are potential targets in mammals for juvenile hormone mimics and ecdysone receptor agonists, there is no evidence that the mammalian toxicity of either group is related to their insecticidal activity. Nor do chitin synthesis inhibitors have high mammalian toxicity.