Spinal cord and peripheral nerves

In the spinal cord, neuropil of laminae II, III, VI and X were moderately immunoreactive for glutaminase (Fig. 2o). Weakly immunoreactive neurons were found in laminae I, IV-IX, 

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The neuraxis is the rostrocaudal extension of the nervous system including forebrain, midbrain, brainstem, spinal cord, and peripheral nerves. 

Chicken (White Leghorn) once 2500 F 5000 F (increased incidence of unspecified spinal cord lesions) 10000 F (ataxia, increased incidence of unspecified spinal cord and peripheral nerve lesions) Mortensen and Ladefoged 1992 Fyrquel EHC... 

In the neurotoxicity study (OECD TG 424/EU Annex B.43), the animals are tested to allow the detection or the characterization of behavioral and/or neurological abnormalities. A range of behaviors that could be affected by neuro toxic ants is assessed during each observation period. At the end of the test, a subset of animals of each sex from each group are perfused in situ and sections of the brain, spinal cord, and peripheral nerves are prepared and examined. 

The nervous system consists of the brain, spinal cord, and peripheral nerves. Whereas the hormones generated by the endocrine system discussed in the preceding section direct longer-term activities of the body, the nervous system sends impulses very rapidly to direct movement and response of the body. At intervals that are generally of slightly less than 1 sec, a sequence of nerve impulses directs the heart to beat from before birth to death, 24 h each day, 7 days of the week. If just a few of these impulses fail, life ends. 

Application of in vitro test methods have become advantageous in specific cases, such as structurally defined compounds and delayed neuropathy, since target cell data and biochemical processes associated in delayed neuropathy are known. Microscopic studies reveal that cases of OPIDN have degeneration of axons followed by demyelination of the nervous system.25,26 Epidemiologic studies have indicated mild impairment of the brainstem, spinal cord, and peripheral nerve functions in Gulf War veterans.27 Such studies are consistent with the spectrum of OPIDN syndrome. The main nerve agents have been shown to inhibit NTE in vitro as well as in vivo. Sarin has been shown to produce delayed neurotoxicity when administered at higher doses in protected hens.25-27... 

No histological alterations were observed in the brains of rats exposed for 2 weeks to a dust of 4-nitrophenol sodium salt at concentrations of up to 2,119 mg 4-nitrophenol/m (Smith et al. 1988). Gross and histological examination of the brain, spinal cord, and peripheral nerves of rats exposed to up to 30 mg 4-nitrophenol dust/m for 4 weeks revealed no treatment-related effects (Hazleton 1983). However, since neurological tests were not performed in these studies, reliable NOAELs for neurological effects cannot be determined. 

A few OPs have been shown to cause OPIDN, a retrograde degeneration of long and large nerve fibers in the spinal cord and peripheral nerves of humans and experimental animals. Some OPs, such as GB, chlorpyrifos, and isofenphos, require very high doses to be acutely neuropathic (WHO 1986 Lotti 1991). Inhibition of approximately 70% or more of the carboxylesterase NTE often is associated with the disorder (WHO 1986 Lotti 1991). Onset of OPIDN is usually 10 days to several weeks after exposure. It is not clear whether OPIDN can occur after long-term exposure to low concentrations of OPs. 

Neurons are the core cell elements of the brain, spinal cord and peripheral nerves that process and hansmit information. Neurons are composed of a cell body (soma), dendritic hee (arbor. 

The limited neuropachologic information available from studies of affected persons deanonstrates that OP poisoning Induces degeneration of nerve fibers in spinal cord and peripheral nerves (122). 

Veronesi. B.,Arodentmodeloforganophosphateinduceddelayedneuropathy distribution of central (spinal cord) and peripheral nerve damage, Neuropathol. Appl. Neurobiol., 10, 357-368, 1984. 

The absorption, transport and metabolism of TOH in animals has been reviewed on several occasions (Bjomeboe et al., 1989 Drevon, 1991). TOH is transferred from circulating lipoproteins to the brain, spinal cord and peripheral nerves and muscle by unknown mechanisms (Sokol, 1989). There is no uniform distribution of TOH in the central and peripheral nervous system (Vatassery etal., 1984a). 

Spencer and Bischoff (1987) reported that, after skin penetration, musk ambrette (mainly used as a fragrance) causes the breakdown of cellular elements within the brain, spinal cord and peripheral nerves. These types of effects were also reported for the fragrance acetyl ethyl tetramethyl tetralin. 

Fischer E.D. (1892) Lead poisoning with special reference to the spinal cord and peripheral nerve lesionS Am. J. Med. Sci. 104, 51-54. 

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