Effects Of Rx781094 And M5050 Complex On Regaining Consciousness Activity And On The Content Of β-endorphin In Rats

Abstract:Several studies have been demonstrated that 13 -endorphin, an endogenous opioid peptide with profound analgesic effect when administered to the central nerval system, is involved in the progress of analgesic and anesthetic. From the point of antagonist we concurrently treated anesthetic of xylazine and DHE or untreated rats with Rx78 1094 and MS 050 to investigate their effects on pain threshold and regain consciousness activities and on the content of ir- 13-endorphin in the blood plasma, hypothalamus and pituitary of rats. On the basis of the data obtained, we tentatively explored the correlation between the algesia and regain consciousness activity and changes in the content of 13 -endorphin in rats, and explored the mechanism of analgesic and anesthetic. Method: Sequential analysis was employed to determine the regain consciousness ED50 value of the Rx78 1094 and M5050 when rats were pretreated with xylazine and DHE intraperitoneally. The pain threshold (shown as percent maximal possible effect, %MPE) of anesthetic or untreated rats to noxious thermal stimuli was determined at different time when drugs were given intraperitoneally. Rate of recover of righting reflex in anesthetic was selected to measure the extent of muscle tension. Radioimmuoactive assay was used to measure the content of fB -endorphin in anesthetic or untreated rats?blood plasma, hypothalamus and pituitary. Results:The regain consciousness ED50 value of Rx78 1094 and M5050 was 9.935 mg/kg, and the regain consciousness dose of the complex is 15mg/kg. The rate of recover of righting reflex was 94.74% in anesthetic rats, significantly higher than that of Rx78 1094, M5050 or saline. This dose also made the pain threshold of anesthetic rats significantly decrease in 5mm and last for 60mm. It also made esthetic rats significantly decrease at 5mm and reach the lowest level (-37.24%) at I 0mm and then increase and last for 60mm. The content of 13 -endorphin in the blood plasma of anesthetic rats treated with Rx78 1094 and M5050 group recovered faster than that of saline control, which started at 5mm and lasted for 60mm, and the content of esthetic rats significantly decreased at 5mm and got to the lowest level at 10mm (8.92ng/mL) and then increased and lasted for 60mm. The content of 13 -endorphin in the pituitary of anesthetic rats in Rx78 1094 and M5050 group increased faster than that of saline control, which started at 5mm and lasted for 60mm. However, the content of esthetic rats still significantly37decreased at 5mm and reached the lowest level (131 .43ng/mg) at 10mm and then increased. The content of fB -endorphin in the hypothalamus of anesthetic rats in Rx78 1094 and M5050 group decreased faster than that of saline control, which started at 5mm and lasted for 60mm, and the content of esthetic rats significantly decreased at 5mm and got to the lowest level at 10mm (9.32ng/mg) and then increased and lasted 60mm. Conclusion: The results showed that Rx78 1094 and M5050 is a profound complex anesthetic antagonist compared with Rx78 1094 or M5050 at our experimental dosage. Synergistic effect on decrease pain threshold or enhancing regain consciousness activity and on the content of ir- 13 -endorphin in the blood plasma, hypothalamus and pituitary of rats were exerted by Rx78 1094 and M5050 in the complex. Blood circular f3-endorphin is derived from pituitary. 13 -endorphin, an endogenous opioid peptide, was evoked and involved in the process of anesthesia and analgesia caused by the complex of alpha-2 adrenergic receptor agonist xylazine and opiate receptor agonist DHE.