Aldehyde Reductase/antagonists & inhibitors; Diabetic Neuropathies/physiopathology; Galactosemias/physiopathology; Nerve Fibers, Myelinated/pathology; Neural Conduction; Sciatic Nerve/physiopathology; Aldehyde Reductase/pharmacology; Aldehyde Reductase/therapeutic use; Animals; Axons/drug effects; Axons/pathology; Axons/ultrastructure; Body Weight/drug effects; Fructose/metabolism; Galactitol/metabolism; Galactose/metabolism; Galactosemias/pathology; Galactosemias/prevention & control; Inositol/metabolism; Microscopy, Electron; Nerve Fibers, Myelinated/physiology; Nerve Fibers, Myelinated/ultrastructure; Nerve Regeneration; Neural Conduction/drug effects; Rats; Rats, Sprague-Dawley; Sciatic Nerve/drug effects; Sciatic Nerve/physiology; Sorbitol/metabolism; Sural Nerve/pathology; Sural Nerve/physiopathology