Differential susceptibility of peripheral nerves of the hen to triorthocresyl phosphate and to trauma

Abstract

The nerve fibres of largest diameter and of greatest length are considered to be the most vulnerable to triorthocresyl phosphate (TOCP). In this study, the differential vulnerability of the particular sciatic nerve branches was determined in the course of TOCP neuropathy and of Wallerian degeneration. The branch innervating the lateral gastrocnemius muscle, made up predominantly of large-diameter fibres, proved most susceptible to TOCP. By contrast, after proximal sciatic-nerve transection, degeneration commenced in the lateral nerve of the third digit, containing long nerve fibres of small diameter.

Mechanisms of Toxic Injury in the Peripheral Nervous System: Neuropathologic Considerations

“…Neuropathologic studies of experimental OPIDN induced by pentavalent phosphorus compounds (Type 1 OPIDN) have revealed a consistent pattern of lesions, which is felt to represent the morphologic substrate of the entity (56,61,88,104 (2,65). The proposed mechanism is that intra-axonal Ca2+ is thought to induce conformational and activity changes in the kinase that lead to cytoskeletal hyperphosphorylation, which contributes to the axonal degeneration.…”

Organophosphorus-Induced Delayed Neuropathy

“…Attention has been directed to the sensitivity of the nerve supplying the biventer cervicis muscle and the large-diameter myelinated fibers of the tibial nerve branch to the lateral head of the gastrocnemius muscle in this species (El-Fawal et al, 1988, 1990cKrinke et al, 1979). A similar neuropathologic pattern has been noted in cats exposed to neurotoxic doses of DFP or TOCP.…”

“…The test compounds most often used to elicit these lesions were TOCP or TOTP, its neurotoxic cyclic congener phenyl saligenin phosphate (PSP), DFP, or mipafox, with the chicken and cat being the major experimental animal subjects (Bischoff, 1967(Bischoff, , 1970Cavanagh, 1954Cavanagh, , 1964Cavanagh and Patangia, 1965;Ehrich and Jortner, 2001;Illis et al, 1966;Itoh et al, 1984Itoh et al, , 1985Jortner and Ehrich, 1987;Krinke et al, 1979;Prineas, 1969;Tanaka and Bursian, 1989). This body of work reveals that the primary lesion is a bilateral degenerative change in distal levels of axons and their terminals, primarily affecting larger/ longer myelinated central and peripheral nerve fibers, leading to breakdown of affected neuritic segments and secondarily of their myelin sheaths.…”

A ‘Best Practices’ Approach to Neuropathologic Assessment in Developmental Neurotoxicity Testing—for Today

“…In general, peripheral nerves in DNT studies are routinely taken from the hind limb and include the sciatic, tibial (internal popliteal), common peroneal (external popliteal, fibular), sural, and plantar nerves (Figure 4). In our experience, all these levels must be sampled due to inherent differences in the susceptibility of various regions of nerve from proximal to distal to toxicant-induced damage (Krinke et al, 1979(Krinke et al, , 2001. Some pathologists prefer to post-fix the nerves while they remain in the carcass, while others remove nerves immediately after perfusion fixation and staple them (through their ends) to a flat card to facilitate post-fixation.…”