Melatonin attenuates the intensity of β-endorphin immunoreactivity in the arcuate nucleus of rat hypothalamus
10.3321/j.issn:0371-0874.2000.03.020
- VernacularTitle:褪黑素减弱大鼠下丘脑弓状核β-内啡肽免疫反应的强度
- Author:
Chang-Xi YU
1
;
Gen-Cheng WU
;
Shao-Fen XU
;
Chong-Hong CHEN
Author Information
1. 上海医科大学
- Keywords:
melatonin;
β-endorphin;
arcuate nucleus;
immunohistochemistry;
image processing;
rat;
analgesia
- From:
Acta Physiologica Sinica
2000;52(3):263-266
- CountryChina
- Language:Chinese
-
Abstract:
The present study was undertaken to observe the effect of exogenously administered melatonin on the intensity of β-endorphin (β-Ep) immunoreactivity of the neuron in the arcuate nucleus of rat hypothalamus with an aim to explore the possible mechanisms of the analgesic effect of melatonin. The experimental rats were divided into two groups, one injected intraperitoneally with melatonin (110 mg/kg) and the other with only a vehicle. One hour after injection, the brain was processed for coronal sections, which were stained with immunohistochemical ABC technique. The integral optical density (IOD) and mean optical density (OD) of the stained sections were measured with a computer-assisted image-processing and analytical system. β-Ep immunoreactivity was much decreased in the sections treated with melatonin and the IOD and OD were also decreased significantly (P<0.01; P<0.05). The above results suggest that melatonin may result in a decrease of β-Ep content in the arcuate nucleus, as a result of increased β-Ep release induced by administration of melatonin. It is likely that the analgesic effect of melatonin may be in part mediated by the release of β-endorphin from the arcuate nucleus.
