Protective Effects of Pelargonium graveolens Essential Oil on Methomyl-Induced Oxidative Stress and Spatial Working Memory Impairment in Association with Histopathological Changes in the Hippocampus of Male Wistar Rats

Abstract

Introduction: Methomyl (MET) is a carbamate insecticide, used in agriculture and public health to eliminate harmful insects. Besides its advantages in agriculture, it causes neurotoxic effects. The aim of this study was to evaluate the effect of MET on Spatial Working Memory (SWM), oxidative stress parameters, and histopathological changes in the hippocampus, as well as the possible protective role of Pelargonium graveolens Essential Oil (EO). Methods: Male Wistar rats were randomized into four groups of six animals: group I as the control that received the vehicle; group II received EO (75 mg/kg b.w), group III received MET (2 mg/kg b.w); and group IV received both MET and EO. The rats were administered the respective doses orally by gavage for 28 days. SWM was assessed using Y-maze on the day before the first treatment and day 28 after the last dose. They were sacrificed by decapitation and their brains were taken for assessing oxidative stress parameters and histopathological analysis. Results: MET treatment caused SWM deficits. Furthermore, drastic changes were observed in aspartate transaminase, alanine aminotransferase, and alkaline phosphatase activities. The level of malondialdehyde significantly increased, whereas antioxidant (glutathioneS-transferase and catalase) enzyme activities significantly decreased. The CA1 region of the hippocampus of rats exposed to MET revealed severe histological alterations. However, supplementation with EO improved SWM and partially restored the activities of antioxidant systems and prevented neuronal cell damage. Conclusion: P. graveolens EO has the potential in mitigating most of the adverse effects in the hippocampus and prevents SWM impairment induced by MET toxicity.

Neuroprotective Effect of White Nelumbo nucifera Gaertn. Petal Tea in Rats Poisoned with Mancozeb

“…The percentage of alternation of the Y-maze spontaneous alternation test showed no significant difference when compared to the control group at p < 0.05 (Figure 3). In contrast, a previous study showed male Wistar rats, after 28 days of exposure to methomyl (a type of pesticide), decreased the percentage of alternations of the Y-maze test due to alterations in synaptic plasticity [23]. Moreover, mancozeb was not reported to induce learning-memory behavior changes in adult rats at a dose of 500 mg/kg bw, but propylthiouracil (another fungicide) has been shown to impair learning and memory in rat offspring at doses as low as 1.6 mg/kg bw by disrupting brain development [47].…”

“…However, the hippocampus is sensitive to pesticides [22]. Pesticides are commonly used in agriculture and can lead to neurological and cognitive disorders [23,24]. Mancozeb is a manganese/zinc compound connected to ethylene-bis-dithiocarbamate and is commonly used in agriculture for controlling fungal infection of vegetables and ornamental plants [25].…”

Effects of ortho-eugenol on anxiety, working memory and oxidative stress in mice

“…Essential oils are volatile compounds extracted from various plant parts and whose composition encompasses a great complexity of bioactive metabolites (Machado and Fernandes Junior, 2011). Their use in therapies has been of increasing interest due to their ease of extraction, low cost of obtaining and great diversity of biological effects (Zhang et al, 2021), such as anxiolytic (Chioca et al, 2013), antioxidant (Barboza, 2018) and working memory improvement effects (Amine et al, 2020).…”