| Nowadays,the social competition is becoming more and more intense,and the high-intensity and high-pressure living condition is followed,people's physical and mental health is becoming more and more serious.Clinical studies have found that insomnia,depression,anxiety and other central nervous system diseases gradually increase and seriously affect people's daily lives.At present,western medicine is the main therapeutic method of central nervous system diseases.However,due to the long-term dependence and various side effects of western medicine,in the clinical applications,it has some limitations.Therefore develop a safe and effective drug for the treatment of central nervous system diseases has become a research focus for people to study.In recent years,looking for new treatments for psychiatric disorders from medicinal plants has become a trend.A large number of studies have shown that many of the constituents in medicinal plants with good efficacy and little side effects,they may be as a lead compound for further modification and eventually applied to clinical.In the previous study,we isolated a purine alkaloid compound-1,3,7,9-Tetramethyluric acid(theacrine)from Camellia assamica var.kucha,and extracted a iridiod compound-loganin from Cornus officinalis Sieb.et Zucc..In this study,we will develop the characteristics of sedative and hypnotic effect of theacrine,and further discuss mechanism of sedative and hypnotic effect of theacrine.In the other hand,we will explore the pharmacological activity of central nervous system of loganin.For the clinical cure,this research may provide a preliminary theoretical basis.[Objective]1.To confirm the sedative and hypnotic effects of theacrine,and to explore the characteristics of sedative and hypnotic effect of theacrine.2.To investigate the possible mechanism of sedative and hypnotic effects of theacrine.3.To clarify the relationship between the hypnotic effect of theacrine and adenosine receptors.4.A preliminary study of the pharmacological activity of loganin on central nervous system.[Methods]1.Locomotor activity test and pentobarbital-induced sleep test were carried out to confirm the sedative and hypnotic effects of theacrine,and further investigated the most efficacious dose of sedative and hypnotic effect of theacrine.2.EEG and EMG recordings were performed to observe the influence of theacrine on sleep phase of normal rats.This section was to ulteriorly illuminate the pharmacological activity of theacrine on the sedative and hypnotic effects,and also to specify the characteristics of sedative and hypnotic effect of theacrine.3.Based on the adenosine system,serotonin system and the dopamine system,the antagonist or the agonist of each receptor were used to explore the possible mechanism of sedative and hypnotic effects of theacrine.4.Combined with the antagonists and agonists of selective adenosine A1 receptor and the antagonists and agonists of selective adenosine A2A receptor to observe the relationship between the hypnotic effect of theacrine and the adenosine A1 or A2A receptor.5.Two groups of rats of theacrine(2.0 mg/kg)and the control were sacrificed by decapitation at 20 min after administration.The hypothalamus,prefrontal cortex and hippocampus tissues were isolated from the rat brain.HPLC-UV was used to detect the adenosine levels and the adenosine deaminase activity in the rats brain tissues.6.We adopted the locomotor activity test and pentobarbital-induced sleep test to observe whether loganin had the effect of sedative and hypnotic.EEG and EMG recordings were proceeded to verify the sedative and hypnotic activities of loganin,on the other hand it contributed to specify the characteristics of sedative and hypnotic effect of loganin.7.Forced swimming test and tail suspension test were conducted to evaluate the anti-depression of loganin.8.Hot plate test and acetic acid stretching experiment were observed to discover whether loganin has the activity of analgesia.9.Use the pentylenetetrazole to establish the convulsion model,and on account of this model,we could estimate the effect of anticonvulsion of loganin.[Results]1.Locomotor activity test suggested that theacrine showed an inhibiting effect on normal mice.The inhibitory effect of theacrine in the test was from 5 min to 30 min after administration.5 min after treatment with theacrine,the sedative effect appeared promptly.When the mice were treated with a sub-hypnotic dose of pentobarbital(23 mg/kg,i.p.),theacrine increased the rate of sleep onset signally at the dose of 3.0 mg/kg.Meanwhile theacrine significantly potentiated pentobarbital(45 mg/kg,i.p.)-induced the hypnotic effects at the same dose.It reflected that theacrine(3.0 mg/kg,i.g.)could reduce sleep latency and prolong sleeping time.2.The EEG and EMG recordings in freely moving rats showed that theacrine prolonged total sleeping time and shortened sleep latency obviously at 6 h after intragastric administration.Theacrine significantly increased the ratio of NREM sleep and reduced the ratio of wakefulness.However on the ratio of REM sleep,theacrine almost had no significant influence.3.Theacrine(3.0 mg/kg,i.g.)obviously attenuated the insomnia effect of caffeine(an antagonists adenosine receptor)in pentobarbital-treated mice,which was reflected by increasing sleeping time.Furthermore,in the pentobarbital-induced sleep test,the selective adenosine A1 receptor antagonist DPCPX and the selective adenosine A2A receptor antagonist SCH 58261 prolonged sleep latency and decreased sleeping time.When used in combination with theacrine(3.0 mg/kg,i.g.),theacrine exhibited the antagonism effect of decreasing sleep latency and increasing sleeping time.At the same time,theacrine revealed a synergistic effect with the selective adenosine A1 receptor agonist CCPA and the selective adenosine A2A receptor agonist CGS 21680.In addition,theacrine markedly augmented the adenosine content in hippocampus at 20 min after intragastric administration.And theacrine also increased the contents of adenosine in hypothalamus and frontal cortex,however there was no significant difference in statistics.And theacrine also inhibited the adenosine deaminase activities in hypothalamus,frontal cortex and hippocampus of rats,however there was no significant difference in statistics.4.In the locomotor activity test,it suggested that loganin exhibited an inhibiting effect on normal mice.The inhibitory effect of loganin in the test was from 5 min to 180 min after administration.5 min after treatment with loganin,the sedative effect appeared promptly.In the sub-hypnotic dose of pentobarbital-induced sleep test,loganin(50 mg/kg,i.p.)increased the rate of sleep onset signally,and in the hypnotic dose of pentobarbital-induced sleep test,loganin(50 mg/kg,i.p.)could prolong the sleeping time.The EEG and EMG recordings in freely moving rats showed that loganin prolonged total sleeping time and shortened sleep latency obviously at 6 h after intragastric administration.Loganin significantly increased the ratio of NREM sleep and reduced the ratio of wakefulness.Forced swimming test and tail suspension test results showed that loganin(50 mg/kg,i.p.)could decrease the duration of immobility of the mice and suggested that loganin had a potent anti-depressant effect.And at this dose,loganin exhibited the activity of analgesia in the hot plate test and acetic acid stretching experiment.But loganin did not have a protective effect on the pentylenetetrazole-induced convulsion model.[Conclusion]1.Theacrine had an obvious sedative and hypnotic effect,and theacrine could prolong the NREM sleep to improve sleep quality.The pharmacological mechanism of hypnotic activity of theacrine might relate to the adenosine system.And theacrine could act on both adenosine A1 receptors and adenosine A2A receptors to induce sleep at the same time.2.Behavioral experiment suggested that loganin had the pharmacological activity of sedative and hypnotic effect,anti-depressant effect and analgesia effect,which played an important role on the central nervous system. |
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