The Role of Matricaria recutita L. and Asparagus officinalis L. against the Neurotoxicity of Diazinon in Rats

Abstract

Diazinon (DZN) is an organophosphate insecticide used mainly in agriculture and in sheep dips, and is designed as an irreversible acetylcholine esterase inhibitor [1,2]. It is classified as moderately hazardous class-II organophosphate insecticide [3]. Many systems could be affected by organophosphate intoxication are the immune system, urinary system, reproductive system, pancreas and haematological and biochemical changes [4-8]. In addition, showed that neonatal DZN exposure, at doses below the threshold for cholinesterase inhibition has been lasting effects on emotional responses, with preferential effects on males [9,10]. The microsomal enzymes in the liver oxidize DZN are generating more potent acetylcholinesterase inhibitors, such as diazoxon, hydroxydiazoxon and hydroxydiazinon [11]. Diazinon affects mitochondrial membrane transportation in rat liver [12]. Moreover, it interrupts cytochrome P450 system in human liver [13]. Oxidative stress can also be induced by pesticides, either by the overproduction of free radicals or by alteration in antioxidant defence mechanisms, including detoxification and scavenging enzymes [14]. Oxidative stress has been reported to play an important role in the toxicity of various pesticides, including organochlorines, carbamates and pyrethrods [15,16]. The higher oxidative stress in pesticide sprayers is evidenced by increased concentration of plasma and red blood cell thiobarbituric acid reactive substances (TBARS), changes in antioxidant status, and altered activities of cellular enzymes [17]. Treatment of rats with DZN significantly enhances renal lipid peroxidation, which is accompanied by a decrease in the activities of renal antioxidant enzymes (e.g. catalase (CAT), glutathione peroxidise, glutathione reductase (GSH-R), glucose- 6-phosphate dehydrogenase, glutathione-s-transferase (GST) and depletion in the level of glutathione reduced (GSH). In blood, normal erythrocyte function depends on the intactness of cell membrane, which is the target for many toxic factors, including pesticides. Erythrocyte GSH together with glutathione peroxidase (GSH-Px), GSH-R, GST, gamma-glutamyl transferase (γ-GT), superoxide dismutase (SOD) and CAT efficiently scavenge toxic free radicals and are partly responsible for protecting against lipid peroxidation due to acute/chronic pesticide exposure [18]. There is a relationship between pesticide exposure and the decrease of antioxidant enzymes [19]. Oxidative stress and genotoxic effects of DZN were documented through the changes in total antioxidant capacity (TAC), reduced GSH and oxidative DNA damage [20]. Exposure to low-level of pesticides is known to produce a variety of biochemical and molecular changes, some of which may be responsible for the adverse biological effects reported in human and experimental studies. Many studies have reported that DZN can induce molecular changes and alter gene expression. Jamshidi et al. have found that administration of DZN to rats at doses of 60 mg/ kg significantly decreased expression of glutamate dehydrogenase, the key enzyme of Langerhans islet for the secretion of insulin, gene 18- hour post-administration [21]. Other studies showed that DZN had affected the expression of neurotrophic factors that coordinate neuronal cell differentiation and brain assembly [22]. In addition, Timofeeva et al. found that persisting effect of developmental DZN cholinergic and serotonergic neurotransmitter systems and gene expression as well as behavioural function [9]. Matricaria recutita L. (family Asteraceae, commonly known as German chamomile) is one of the most widely used and welldocumented medicinal plants in the world [23]. Chamomile is also