Toxic effects of subacute exposure to acrylamide on motor endplates of the gastrocnemius in rats

Protective effect of rutin on spinal motor neuron in rats exposed to acrylamide and the underlying mechanism

The present study aimed to investigate the protective effect of rutin on the injury of spinal motor neuron in rats exposed to acrylamide (ACR) the underlying mechanism. Fifty male Sprague-Dawley rats, aged 7-8 weeks, were randomly divided into control group, ACR group (20 mg/kg), low dose(100 mg/kg), medium dose (200 mg/kg) and high dose(400 mg/kg) rutin groups, ten rats in each group. The rats were given intragastric administration for 21 days. Every week, a neurobehavioral test was conducted. Nissl staining was used to observe the morphological changes in motor neurons in the L4-L6 segment of the spinal cord. Immunohistochemistry was used to identify AChE and ChAT in the rat spinal cord. Western blot was used to identify the expression of AChE, ChAT, P-ERK, ERK, and Nrf2 proteins in the rat spinal cord. The commercial kits were used to detect the presence of SOD, GSH, and LDH in the rat spinal cord. At the start of the second week, the medium and high dosage rutin group's rats' gait scores significantly decreased as compared to those of the ACR group. When rutin dosage was increased, the Nissl staining revealed that Nissl bodies was staining intensified compared to the ACR group. Immunohistochemistry and Western blot analysis revealed that AChE and ChAT expression changed when rutin dose was raised, but P-ERK and Nrf2 expression steadily increased in the spinal cord of rats in the medium and high dose groups compared to the ACR group. In the spinal cord of rats in each dosage group compared to the ACR group, the findings of the oxidative stress indices demonstrated that the expression levels of SOD and GSH rose with the increase of rutin dose, while the expression of LDH reduced with the rise of rutin dose. Rutin has an anti-oxidative impact through up-regulating the expression of P-ERK and Nrf2 proteins in the ERK/Nrf2 pathway, which may be connected to its protective action on motor neurons in the spinal cord of rats exposed to ACR.

Acrylamide Neurotoxicity as a Possible Factor Responsible for Inflammation in the Cholinergic Nervous System

Acrylamide (ACR) is a chemical compound that exhibits neurotoxic and genotoxic effects. It causes neurological symptoms such as tremors, general weakness, numbness, tingling in the limbs or ataxia. Numerous scientific studies show the effect of ACR on nerve endings and its close connection with the cholinergic system. The cholinergic system is part of the autonomic nervous system that regulates higher cortical functions related to memory, learning, concentration and attention. Within the cholinergic system, there are cholinergic neurons, anatomical cholinergic structures, the neurotransmitter acetylcholine (ACh) and cholinergic receptors. Some scientific reports suggest a negative effect of ACR on the cholinergic system and inflammatory reactions within the body. The aim of the study was to review the current state of knowledge on the influence of acrylamide on the cholinergic system and to evaluate its possible effect on inflammatory processes. The cholinergic anti-inflammatory pathway (CAP) is a neuroimmunomodulatory pathway that is located in the blood and mucous membranes. The role of CAP is to stop the inflammatory response in the appropriate moment. It prevents the synthesis and the release of pro-inflammatory cytokines and ultimately regulates the local and systemic immune response. The cellular molecular mechanism for inhibiting cytokine synthesis is attributed to acetylcholine (ACh), the major vagal neurotransmitter, and the α7 nicotinic receptor (α7nAChR) subunit is a key receptor for the cholinergic anti-inflammatory pathway. The combination of ACh with α7nAChR results in inhibition of the synthesis and release of pro-inflammatory cytokines. The blood AChE is able to terminate the stimulation of the cholinergic anti-inflammatory pathway due to splitting ACh. Accordingly, cytokine production is essential for pathogen protection and tissue repair, but over-release of cytokines can lead to systemic inflammation, organ failure, and death. Inflammatory responses are precisely regulated to effectively protect against harmful stimuli. The central nervous system dynamically interacts with the immune system, modulating inflammation through the humoral and nervous pathways. The stress-induced rise in acetylcholine (ACh) level acts to ease the inflammatory response and restore homeostasis. This signaling process ends when ACh is hydrolyzed by acetylcholinesterase (AChE). There are many scientific reports indicating the harmful effects of ACR on AChE. Most of them indicate that ACR reduces the concentration and activity of AChE. Due to the neurotoxic effect of acrylamide, which is related to the disturbance of the secretion of neurotransmitters, and its influence on the disturbance of acetylcholinesterase activity, it can be concluded that it disturbs the normal inflammatory response.