Neuritogenic and chemical properties of guinea pig anterior and posterior root myelin

Distribution of P2 antigen in neural and non-neural bovine tissues

Rabbit antisera to bovine nerve preparations were used to study the tissue distribution in the ox of P2, an antigen specific for the peripheral nervous system. Double diffusion gel precipitation tests were able to demonstrate P2 in spinal nerves, trigeminal nerve, spinal cord, medulla oblongata, and pons, but not in higher centers of the CNS, optic nerve, or non-neural tissues. A highly sensitive inhibition of enzyme immunoassay was developed to detect and quantitate low levels of P2. By this assay, P2 was found to be most concentrated in peripheral nerves, with decreasing amounts found in the spinal cord, medulla oblongata, pons, cerebellum, and cerebral peduncle. No P2 was found in the thalamus, cerebrum, or optic nerve; however, low levels of P2 were detected in the adrenal medulla, a non-neural tissue composed largely of cells derived from the embryonic neural crest region.

Cholinesterase activities in the somatic nervous system of rabbits with experimental allergic neuritis

The allergic inflammatory disorders of the nervous tissue are associated with a complex series of cellular and humoral immune activities and they usually result at least in demyelination, but according to morphologic evidence also in secondary neuronal changes. Using the colorimetric method of Ellman et al. (G. L. Ellman, K. D. Courtney, V. Anders, and R. M. Featherstone, 1961, Biochem. Pharmacol. 7:88-95) the activities of enzymes splitting acetylthiocholine iodide (AThCh) were determined from various parts of the somatic nervous system of rabbits with experimental allergic neuritis (EAN), a primary demyelinating disease of the peripheral nerves. It was found that the total activity of AThCh-splitting enzymes was decreased already in an early phase of the disease in the dorsal root ganglia (DRG). In a well developed phase of the disease the activity of acetylcholinesterase (AChE) seemed to be decreased by 33% in the ventral roots and by a lesser amount in the DRG and the most proximal part of the sciatic nerves. The mechanism of the recorded changes may be related either to specific or to nonspecific immune events or to both. Proteolytic activity released by macrophages in the target tissue may, by inactivating the hydrolytic activity of AChE, at least partly explain these findings. Because the activity of AChE in the structures studied derives from a neuronal origin, our results provide biochemical evidence for the involvement of neurons in the sensory ganglia and of axolemma in the ventral roots in EAN.

Antigen-induced suppression of experimental allergic neuritis in the guinea pig

Treatment of guinea pigs suffering from a fatal form of experimental allergic neuritis (EAN) using P2 basic protein of PNS myelin reduced the clinical severity, the overall mortality and the incidence of respiratory problems. The large basic protein (MBP) common to the CNS and PNS had no suppressive effect on EAN. Cyanogen bromide cleavage of P2 destroyed its suppressive activity. P0 protein of PNS myelin had marginal suppressive activity but Cop 1, a synthetic copolymer effective in suppressing EAE, was without significant effect on EAN. The suppression with P2 protein of a milder form of EAN (induced with a reduced amount of PNS myelin) was less marked. Increasing the treatment period from 10 to 15 days did not increase the suppressive effect of P2 in the milder form of EAN.