Masazumi Kawamoto

Study on Application of Static Magnetic Field for Adjuvant Arthritis Rats

In order to examine the effectiveness of the application of static magnetic field (SMF) on pain relief, we performed a study on rats with adjuvant arthritis (AA). Sixty female Sprague–Dawley (SD) rats (age: 6 weeks, body weight: approximately 160 g) were divided into three groups [SMF-treated AA rats (Group I), non-SMF-treated AA rats (Group II) and control rats (Group III)]. The SD rats were injected in the left hind leg with 0.6 mg/0.05 ml Mycobacterium butyrium to induce AA. The rats were bred for 6 months as chronic pain model. Thereafter, the AA rats were or were not exposed to SMF for 12 weeks. We assessed the changes in the tail surface temperature, locomotor activity, serum inflammatory marker and bone mineral density (BMD) using thermography, a metabolism measuring system and the dual-energy X-ray absorptiometry (DEXA) method, respectively. The tail surface temperature, locomotor activity and femoral BMD of the SMF-exposed AA rats were significantly higher than those of the non-SMF-exposed AA rats, and the serum inflammatory marker was significantly lower. These findings suggest that the pain relief effects are primarily due to the increased blood circulation caused by the rise in the tail surface temperature. Moreover, the pain relief effects increased with activity and BMD of the AA rats.

Central and peripheral sympathetic controls on catecholamine release in male 2-month-old SHRSP and WKY investigated by means of 6-hydrodydopamine injections

In order to investigate the role of central and peripheral sympathetic activities in stroke-prone spontaneously hypertensive rats (SHRSP), maximum dose of 6-OHDA was injected into a lateral cerebral ventricle (i.c.v.) or a peritoneal cavity (i.p.), and changes of catecholamine metabolites in the brain, adrenal glands, plasma, and urine were measured and analyzed. 6-OHDA i.c.v. showed no changes in blood pressure, but showed a tendency to lower heart rates, and a significant decrease in NE in the brain and plasma in SHRSP. On the other hand, 6-OHDA i.p. showed a significant decline of blood pressure, an increase in heart rate, and a decrease of Ep in plasma without effects on NE level in SHRSP. These findings indicate that (1) 6-OHDA i.p. treatment destroys the accessory or extra-adrenal glands besides peripheral sympathetic nerves; (2) Ep is released from the extra-secretary organs, and contributes to maintaining the hypertension in SHRSP; (3) 6-OHDA i.c.v. destroys the central sympathetic nerves and inhibits temporally the peripheral sympathetic activity, adrenal glands and the accessory or extra-adrenal glands; and (4) peripheral sympathetic nerve function works to maintain hyper-sympathetic states in SHRSP.