Central nervous system , neurotoxicity

Soukup J +, Anaesthesist 45(1 I), 1024 Central Nervous System Neurotoxicity... 

The distribution of endosulfan and endosulfan sulfate was evaluated in the brains of cats given a single intravenous injection of 3 mg/kg endosulfan (Khanna et al. 1979). Peak concentrations of endosulfan in the brain were found at the earliest time point examined (15 minutes after administration) and then decreased. When tissue levels were expressed per gram of tissue, little differential was observed in distribution among the brain areas studied. However, if endosulfan levels were expressed per gram of tissue lipid, higher initial levels were observed in the cerebral cortex and cerebellum than in the spinal cord and brainstem. Loss of endosulfan was most rapid from those areas low in Upid. Endosulfan sulfate levels peaked in the brain at 1 hour postadministration. In contrast, endosulfan sulfate levels in liver peaked within 15 minutes postadministration. The time course of neurotoxic effects observed in the animals in this study corresponded most closely with endosulfan levels in the central nervous system tissues examined. 

The central nervous system is a major target of endosulfan-induced toxicity in both humans and animals (Blanco-Coronado et al. 1992 Boyd and Dobos 1969 Boyd et al. 1970 Garg et al. 1980 Kiran and Varma 1988 Terziev et al. 1974). Therefore, individuals with seizure disorders, such as epilepsy, may be particularly susceptible because exposure to endosulfan may reduce the threshold for tremors, seizures, and other forms of neurotoxicity, as demonstrated in studies in rats (Gilbert and Mack 1995 Gilbert 1992). 

Organometallic compounds such as alkylmercury fungicides, and tetraethyl lead, used as an antiknock in petrol, are neurotoxic, especially to the central nervous system of vertebrates (Wolfe et al. 1998, Environmental Health Criteria 101, and Chapter 8,... 

The inhibition of two cholinesterase activities in blood can also be used to confirm exposure to certain organophosphate ester compounds. Red blood cell acetylcholinesterase is the same cholinesterase found in the gray matter of the central nervous system and motor endplates of sympathetic ganglia. Synonyms for this enzyme include specific cholinesterase, true cholinesterase, and E-type cholinesterase. Plasma cholinesterase is a distinct enzyme found in intestinal mucosa, liver, plasma, and white matter of the central nervous system. Synonyms for this enzyme include nonspecific cholinesterase, pseudocholinesterase, butyrylcholinesterase, and S-type cholinesterase (Evans 1986). Nonspecific cholinesterase is thought to be a very poor indicator of neurotoxic effects. 

Understand the mechanisms by which National Institute of lead (Pb2+) exerts neurotoxic effects in Environmental Health the central nervous system particularly Sciences in the developing brain... 

The long-term consequences of neonatal exposure to triethyllead were examined with respect to the development of the central nervous system of rats138. The studies of the developmental exposure to triethyllead lead to the conclusion that this compound causes permanent hippocampus damage (neurotoxicity) in rats. 

In a study where both peripheral and central nervous system effects were measured in rats co-exposed to u-hexane and toluene (Pryor and Rebert 1992), toluene exposure at 1,400 ppm for 14 hours a day for 9 weeks prevented the peripheral neurotoxicity (decreased grip strength and nerve conduction velocities) caused by exposure to 4,000 ppm 77-hcxanc alone. There was no reciprocal action of 77-hexane on the motor syndrome (shortened and widened gait and widened landing foot splay) and hearing loss caused by toluene. Brainstem auditory response amplitudes were decreased by 77-hcxanc, co-exposure to toluene did not block this effect. 

There are a number of electrophysiological techniques available which can be used to detect and/or assess neurotoxicity. These techniques can be divided into two broad general categories those focused on central nervous system (CNS) function and those focused on peripheral nervous system function, (Seppalainer, 1975). 

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