下丘脑视前正中核腺苷和5-羟色胺对大鼠睡眠—觉醒周期影响

【Abstract】wWw.shuoshilunwen.com ObjectiveAdenosine and 5-hydroxytryptamine are important neuro-hormonal factors which modulate sleep-wakefulness cycle. Median preoptic nucleus (MnPN) is an important area involving sleep regulation. The present study investigated the effects of adenosine and 5-hydroxytryptamine in MnPN on sleep-wakefulness cycle of rats by using brain stereotaxic, nucleus spile, microdialysis, microinjection, polysomnography.Methods1. Animal model Adult male SD rats (280-320 g and clean stage) were used in the experiments. Under pentobarbital anesthesia (40 mg/kg, i.p.), EEG and EMG electrodes were implanted for polysomnographic recordings, and a guide cannula was inserted into MnPN(AP:+0.24 mm、L/R:0.0 mm、H:7.8 mm)for drug application or microdialysis in rats. The EEG electrodes and the guide cannula were fixed to the skull with dental cement. After 7 days for recovery in a soundproof recording room, each animal was connected to an EEG/EMG recording cable and habituated for 1 day before polygraphic recording.2. Grouping The rats in the experiments were divided into four groups:? artificial cerebrospinal fluid group, AD group, S-(4-nitrobenzyl)-6-thioinosine (NBTI) group, and 5-HTP group.3. Microdialysis One week after surgery, a microdialysis probe was inserted through the guide cannula into the target structure and the tissue was allowed to stabilize for 24 h. Artificial cerebrospinal fluid (AC) was perfused before drug application, which was set at 21:00-23:00. AC, AD (300μmol/L), and NBTI(20μmol/L)were used in AC group, AD group and NBTI group. The flow rate was 2μl/min.4. Microinjection 5-HTP or AC was microinjected into the MnPN through the guide cannula about 1 min. The needle was kept in the guide cannula about 1 min to prevent the physic liquor flow out. False inject two days before the experiment start. Drug application was performed at 08:50-09:00.5. Polysomnography Polysomnography (PSG, including EEG and EMG) was started at 07:00 and sustained 24 hours. According to the PSG results, the sleep-wakefulness was divided into three stages: (1) Wakefulness (W) period was characterized by high frequency and low amplitude wes of EEG and relatively high tone EMG. (2) Non-rapid eye movement (NREM) period was characterized by low frequency, spindles, high amplitude andδslow wes of EEG, and significantly decreased EMG tone. (3) Rapid eye movement (REM) was characterized by high frequency and low amplitude wes of EEG, and lack of EMG tone except occasional muscle twitches. Total sleep time (TST) was composed of NREM and REM.6. Histological identification After sleep recording, a unipolar stainless steel electrode was inserted into MnPN through the guide cannula. Lesions were made by currents (2.5 mA for 10 s) to the microdialysis or microinjection site through an electrode. Only animals whose sites of lesion were located in the MnPN were used.7. Statistical analyses SPSS 12.0 software was used for statistical analyses. The data were presented as (x|ˉ)±S. Differences between the mean. The values were analyzed with Student’s t-test, and those at P < 0.05 were considered significant.Results1. Infusion of AD and NBTI significantly enhanced NREM sleep time and reduced wakefulness.2. Sleep time was increased in the second and third hour after infusion of AD, as well as in the third and fourth hour after infusion of NBTI.3. Microinjection of 5-HTP significantly increased wakefulness and reduced NREM sleep time. Conclusion1. AD is physiological sleep regulation factor. AD enhances sleep in MnPN, which may be mediated by A2A receptor.2. Infusion of NBTI in MnPN enhances sleep time by increasing extracellular AD level.3. 5-HT participates in sleep–wakefulness cycle regulation. 5-HT in MnPN enhances wakefulness, and its effect may be mediated by 5-HT1B receptor.