The effect of nerve preservation methods on rat sciatic nerve structures studied with Synchrotron small-angle X-ray scattering (SAXS)

ABSTRACT

BACKGROUND: Synchrotron small-angle X-ray scattering (SAXS) is a very useful technique for experimental study of the nano-structure of the nervous system of animals. The study was designed to evaluate nerve preservation methods for the measurement of SAXS patterns. METHODS: Normal sciatic nerves extracted from male Sprague- Dawley rats were preserved in saline (N = 2), formalin (N = 2) or liquid nitrogen (N = 2) for 1 day, followed by measurement of SAXS patterns. SAXS patterns of normal sciatic nerves (N = 3) extracted just before the initiation of the experiment were used as controls. The study was carried out using the 4C1 beamline at Pohang Accelerator Laboratory in Korea. Incoming X-rays were monochromatized at 11 keV using a double multilayer (WB4C) monochromator with beam size of approximately 0.5 (V) × 0.8 (H) mm2. The exposure time was set at 60 sec, and 8 to 12 images per sample were acquired at a 0.5 mm interval. RESULTS: The periodic peaks of interfibrillar space between collagen fibrils were undetectable. The periodic peaks of the myelin sheath and collagen fibers were weakly detected or undetected in the nerves preserved in normal saline or formalin. The periodic peaks and intensity of the myelin sheath, collagen fibers, and interfibrillar space between collagens in the nerves preserved in liquid nitrogen were comparable to those of nerves in the ex vivo state. CONCLUSIONS: The study results indicated that preservation of nerves in liquid nitrogen is adequate for measurements with SAXS. However, saline and formalin preservation techniques were inadequate for SAXS measurement.