Experimental neuropathy produced in rats with industrial solvents (thinner)

Thinner is a very potent neurotoxic compound which damages both the central and peripheric nervous system, as well as the rest of the organism, when it is used or inhaled spontaneously chronically. 20 Wistar rats were used. They inhaled 1.5 ml of thinner per day and were sacrificed by pairs upon days 7, 15, 30, 45, 60, 75, and 90. Four of them were sacrificed after suspending the inhalation 15, 30, 60 and 90 days later so as to study the process of recuperation. The hind legs were fixated in 10% formaldehyde for 15 days. Fragments of sciatic and crural nerves were included in paraffin and histological cuts were performed both in transversal and longitudinal sections of 5 to 7 micra. Techniques for myelin and argento-auric ones were performed. Incipient lesions are described as well as intermediate and terminal ones produced after having inhaled 45 ml of thinner for 30 days. The myelin sheath shows edema, ballooning and destruction due to lysis after inhaling 135 ml in 90 days. In a parallel manner the nerve fibers show edema, irregular thickening and after inhaling 135 ml in 90 days there is atrophy or disintegration. A partial regeneration is produced if inhalation is suspended after 30 days and 30 more days are allowed for recuperation, when some Schwann cells are still active. We believe that the lesions which begin to appear on the myelin sheath occur because thinner is a fat solvent, fats being important elements in their structure and the nerve fiber injury may be secondary to the demyelinization, or due to destruction of the central neuron from which they originate.