J Korean Soc Study Obes 2000; 9(2): 92-100
Published online July 1, 2000
Copyright © Korean Society for the Study of Obesity.
Tai Hee Lee1,Myung Soo Kim1,Jae Woo Lee2,Naoko Okane,Akiko Kobayashi,Toshimasa Osaka,Shuji Inoue
Department of Internal Medicine, Chonnam University Medical School,1 Chosun University Graduate School,2 Kwangju, Korea, and National Institute of Health and Nutrition, Tokyo, Japan
The effects of adrenodemedullation and propranolol, ruthenium red on thermoregulation by capsaicin analogue resiniferatoxin were studied in male Wistar rats.
Thermoregulation was observed by the measurements of oxygen consumption and temperature of colon and skin, simultaneously every 5 minutes for 300 minutes after subcutaneous injection of resiniferatoxin (50 μg/kg). The rats were studied at one to four weeks after adrenodemedullation.
Propranolol treatments were 2 times of intraperitoneal injections (5 mg/kg) before 30 minutes and at the same time of resiniferatoxin injection. Ruthenium red (10 μg/kg) was injected subcutaneously before 15 minutes and after 45 minutes of resiniferatoxin injection.
The results were as follows.
1. After resiniferatoxin (50 μg/kg s.c.) administration, oxygen consumption showed double-peak response. It reached to the peak level (12.8±0.5 mL/min/kg 0.75) at 50 minutes, then began to decrease. At 100 minutes, it began to increase and maintained elevated level till 300 minutes. After
resiniferatoxin injection, colon temperature showed biphasic pattern; it decreased by 0.2℃ at 30
minutes, and then increased. Skin temperature began to increase immediately after resiniferatoxin
injection, reached to 30.38±0.45℃ at 50 minutes. Then it decreased slowly, but maintained elevated level till 300 minutes.
2. After resiniferatoxin (50 μg/kg) administration in adrenodemedullated rats, oxygen consumption was reduced in early-increasing response of double-peak response but was not changed in late-increasing response. The temperature of colon and skin was not chaned after adrenodemedullation, too.
3. Increments of oxygen consumption by resiniferatoxin administration was abolished by the treatment of propranolol till 300 minutes. Changes of skin temperature by resiniferatoxin administration were not affected by propranolol (The peak level of skin temperature was 30.4± 0.8℃ at 40 minutes. The temperature of colon was slightly decreased to 36.0±0.2℃ at 50 minutes).
4. Ruthenium red enhanced the increments of oxygen consumption to 14.7±0.8 and 14.9±0.5 mL/min/㎏0.75 at 50 and 100 minutes after resiniferatoxin administration respectively while the decrement of oxygen consumption after the first peak was attenuated by ruthenium red treatment to 14.3±0.6 mL/min/㎏0.75 at 70 minutes. There were no significant changes of skin temperature and colon temperature. Elevation of colon temperature was enhanced to the peak of 37.5±0.2℃ from 140 to 160 minutes.
These results suggest that thermogeneses of resiniferatoxin may be caused by catecholamine secreted from the adrenal medulla and β adrenergic receptor binding in peripheral region, and inhibition system of thermogenesis such as VN2 receptor system also may be involved by resiniferatoxin.
Keywords: Resiniferatoxin, Thermogenesis, Catecholamine