Turkish Neurosurgery
1999 , Vol 9 , Num 1-2
EFFECT OF BETA-ENDORPHIN ON PAIN THRESHOLD IN HYPOPHYSECTOMIZED RATS
1Departments of Neurosurgery, Gülhane Medical School, Ankara2Departments of Nuclear Medicine, Gülhane Medical School, Ankara
3Departments of Pathology, Gülhane Medical School, Ankara Beta-endorphin (B-EP) is a 31 amino acid polypeptide secreted by the pituitary, brain, and various other tissues. It has potent opiate-like activity, can produce analgesia, and may play a physiological role in adapting the immune system to stress by affecting lymphocyte and complement binding activity. To investigate the effect of B-EP on pain threshold, we analyzed cerebrospinal fluid (CSF) and plasma concentrations of B-EP in 12 intact and 12 hypophysectomized (HYP) rats. Plasma and CSF samples were obtained from both intact and HYP rats 24 hours postsurgery. Pain threshold values were then assessed using the tail-flick test. Results showed a decrease in the plasma concentration of B-EP (p < 0.001), but no significant difference in the level in CSF. Keywords : Beta-endorphin, hypophysectomy, pain threshold, tail-flick test