| Autor: |
Fan BW; Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China., Liu YL; Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China., Zhu GX; Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China., Wu B; Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China., Zhang MM; Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China., Deng Q; Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China., Wang JL; Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China., Chen JX; Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China., Han RW; Laboratory of Fear and Anxiety Disorders, Institute of Life Science, Nanchang University, Nanchang, China., Wei J; Department of Physiology, Medical College of Nanchang University, Bayi Road 461, Nanchang, Jiangxi, 330006, China. |
| Abstrakt: |
G (1-5)-NH 2 , G (1-7)-NH 2 , and G (1-9) are the active fragments of ghrelin. The aim of this study was to investigate the antinociceptive effects, their ability to cross the blood-brain barrier, and the receptor mechanism(s) of these fragments using the tail withdrawal test in male Kunming mice. The antinociceptive effects of these fragments (2, 6, 20, and 60 nmol/mouse) were tested at 5, 10, 20, 30, 40, 50, and 60 min after intravenous (i.v.) injection. These fragments induced dose- and time-related antinociceptive effects relative to saline. Using the near infrared fluorescence imaging experiments, our results showed that these fragments could cross the brain-blood barrier and enter the brain. The antinociceptive effects of these fragments were completely antagonized by naloxone (intracerebroventricular, i.c.v.); however, naloxone methiodide (intraperitoneal, i.p.), which is the peripheral restricted opioid receptor antagonist, did not antagonize these antinociceptive effects. Furthermore, the GHS-R1α antagonist [D-Lys 3 ]-GHRP-6 (i.c.v.) completely antagonized these antinociceptive effects, too. These results suggested that these fragments induced antinociceptive effects through central opioid receptors and GHS-R1α. In conclusion, our studies indicated that these active fragments of ghrelin could cross the brain-blood barrier and enter the brain and induce antinociceptive effects through central opioid receptors and GHS-R1α after intravenous injection. |
