Developmental Effects of Malathion Exposure on Recognition Memory and Spatial Learning in Males Wistar Rats

Abstract

<span style="font-family:Verdana;font-size:12px;">Most cognitive effects</span><span> </span><span style="font-family:Verdana;font-size:12px;">of Organophosphate</span><span> </span><span style="font-family:Verdana;font-size:12px;">Pesticides (OP) are induced after exposure to parathion, chlorpyrifos and diazinon, </span><span style="font-family:Verdana;font-size:12px;">which</span><span style="font-family:Verdana;font-size:12px;"> the us</span><span style="font-family:Verdana;font-size:12px;">age</span><span style="font-family:Verdana;font-size:12px;"> has been restricted because of</span><span> </span><span style="font-family:Verdana;font-size:12px;">overt signs of their toxicities. In this study, we investigate</span><span> </span><span style="font-family:Verdana;font-size:12px;">whether developmental exposure to Malathion could impair spatial learning and recognition memory in male rats.</span><span> </span><span style="font-family:Verdana;font-size:12px;">Ani</span><span><span style="font-family:Verdana;font-size:12px;">mals exposed by intragastric route, from </span><i><span style="font-family:Verdana;font-size:12px;">in utero</span></i><span style="font-family:Verdana;font-size:12px;"> to young adult stage, to incremental doses of Malathion</span></span><span> </span><span style="font-family:Verdana;font-size:12px;">dissolved in corn oil; 100, 200 and 300 mg/kg of body weight, and one control group are given corn oil. Then, cognitive and behave</span><span style="font-family:Verdana;font-size:12px;">ioral abilities are assessed using Barnes maze and object recognition memory task. Malathion administration at 300 mg/kg is toxic to pregnant dams, and pups are stillborns. Rats exposed to 200 mg/kg make</span><span> </span><span style="font-family:Verdana;font-size:12px;">a significant working mem</span><span style="font-family:Verdana;font-size:12px;">ory error, and require more time to find</span><span> </span><span style="font-family:Verdana;font-size:12px;">an escape box during the initial training phase of Barnes maze. However, fewer errors are made in rats exposed to 100 mg/kg.</span><span> </span><span style="font-family:Verdana;font-size:12px;">For reversal learning task,</span><span> </span><span style="font-family:Verdana;font-size:12px;">the high dose group shows</span><span> </span><span style="font-family:Verdana;font-size:12px;">great deficits in spatial strategy to locate the new position of the box. With respect to recognition task, both dose 100 and 200 mg/kg impair</span><span> </span><span style="font-family:Verdana;font-size:12px;">significant short-term</span><span> </span><span style="font-family:Verdana;font-size:12px;">(2</span><span> </span><span style="font-family:Verdana;font-size:12px;">h after habituation phase)</span><span> </span><span style="font-family:Verdana;font-size:12px;">object recognition memory, but long-term (24</span><span> </span><span style="font-family:Verdana;font-size:12px;">h after habituation phase) recognition memory </span><span style="font-family:Verdana;fon...

Effects of Dimethoate Exposure on Locomotor Activity and Anxiety-Like Behavior in Female Wistar Rat

“…Another study of developmental toxicity to Malathion also demonstrated a low body weight gain in young rats at stage (GD 6-PND 45) [21]. From a pathophysiological point of view, the low body weight gain in the exposed groups could be explained by the effect of overexpression of ACh molecules which increases gastric motility and decreases intestinal absorption [22].…”

“…The long-term developmental exposure (GD 6-PND 45) to Malathion induced a very significant inhibition of AChE associated with altered locomotors activity and high anxiety behavior [21], [27].…”

“…It is suggested that the level at which poisoning occurs, the duration of exposure and the degree of toxicity of the OPs should be considered. Indeed, a previous study showed that exposure to malathion during the critical brain period (GD 6-PND45) induced a highly significant alteration in anxiety level in rats of both sexes with more pronounced effects in female [21]. In addition, short-term exposure (4 days) at a dose of 1 mg/kg CPF resulted in a persistent increase in anxiety in female mice for the majority of postnatal periods tested (PND 1 -4, PND 5 -8 and PND 13 -16).…”

“…Indeed, the work of [21], showed an alteration of the cholinergic system of the hippocampus of intoxicated rats, but it has been shown that the cholinergic system plays a modulatory role in the control of the level of anxiety [48], [49].…”

Effect of Dimethoate on Object Recognition Memory in Wistar Rats and Essay of Treatment with Nettle

“…Another study of the developmental toxicity in Malathion also demonstrates a low physical weight gain for young rats to the (GD 6-PND 45) stage [16]. From the physio-pathological point of view, the low physical weight gain of the exposed groups could be attributed to the effect of overexpression of the ACh molecules which increases the gastric motility and decreases the intestinal absorption [17].…”