Kutlu Selim, Canpolat Sinan, Sandal Suleyman, Ozcan Mete, Sarsilmaz Mustafa, Kelestimur Haluk
Firat University, The Institute of Health Science, Department of Neuroendocrinology, Elazig, Turkey.
Neuro Endocrinol Lett. 2003 Jun-Aug;24(3-4):193-6.
This study was planned to investigate the effects of exogenous leptin on the pain threshold.
Adult male Wistar rats weighing 250-300 g and mice weighing 25-30 g were used in this study. Leptin was intracerebroventricularly (i. c. v.) injected in a dose of 3.5 micro g/rat. Mice were intraperitoneally (i. p.) injected with leptin in a dose of 25 micro g/mouse. Control animals were injected with the respective vehicle. The pain threshold test was performed using hot plate analgesia meter. The experiments were performed during the day and at night. The data were statistically analysed by Mann-Whitney U test. Level of significance was set at p<0.05.
During the day, there were no significant changes in hot plate latencies half an hour after i.c.v. injection of vehicle or leptin in the control and leptin-treated rats, respectively. At night, like during the day, i.c.v. injection of neither vehicle nor leptin caused any significant change in pain sensitivity. In mice, i.p. injection of leptin decreased latencies significantly (p<0.05) during the day and at night. Thus, leptin caused an increase in pain sensitivity during the day and at night.
These results clearly demonstrated that leptin has a decreasing-effect on pain threshold if it is peripherally administered in mice.
本研究旨在探讨外源性瘦素对痛阈的影响。
本研究使用体重250 - 300 g的成年雄性Wistar大鼠和体重25 - 30 g的小鼠。瘦素以3.5μg/只大鼠的剂量进行脑室内注射。小鼠以25μg/只小鼠的剂量腹腔注射瘦素。对照动物注射相应的溶剂。使用热板镇痛仪进行痛阈测试。实验在白天和晚上进行。数据采用曼-惠特尼U检验进行统计学分析。显著性水平设定为p<0.05。
白天，在对照大鼠和瘦素处理的大鼠中，分别脑室内注射溶剂或瘦素后半小时，热板潜伏期均无显著变化。在晚上，与白天一样，脑室内注射溶剂或瘦素均未引起痛觉敏感性的任何显著变化。在小鼠中，腹腔注射瘦素在白天和晚上均显著缩短潜伏期（p<0.05）。因此，瘦素在白天和晚上均导致痛觉敏感性增加。
这些结果清楚地表明，如果在小鼠外周给予瘦素，它对痛阈有降低作用。
