巴氯芬对慢性吗啡依赖后条件化位置偏好和戒断症状的抑制

小鼠连续7天腹腔注射吗啡(40mg/kg)建立条件化位置偏好模型,连续皮下递增注射吗啡(25、50、75、100、125、150mg/kg),成瘾后腹腔注射纳络酮(6mg/kg)诱导戒断症状(跳跃行为)建立戒断模型。腹腔注射GABAB受体激动剂巴氯芬(2mg/kg)可以有效地抑制吗啡诱导的条件化位置偏好和减轻纳络酮诱导的戒断症状,结果表明GABA系统参与动物成瘾后渴求和戒断过程,激动GABAB受体可以在一定程度上抑制成瘾的心理和生理戒断症状。     

侧脑室注射微量吗啡和纳络酮对小鼠记忆保持的影响

实验观察侧脑室注射微量吗啡和纳络酮对小鼠记忆保持的影响.结果表明:侧脑室注射吗啡后,小鼠从迷宫始点走到终点所需的时间显著延长,出现错误的次数增多,且具有一定的量效反应关系。这一作用可被纳络酮所阻断。而纳络酮对记忆的增强作用又可被吗啡所抵消。本实验提示中枢神经系统里的内源性阿片肽很可能参与记忆巩固的调制。     

面神经核背内侧区和腹内侧我注射吗啡和纳络酮对颏舌肌和 …

目的和方法：静脉注射氨基甲酸乙酯麻醉,断双这走神经,在４８只成年健康家兔,观察面神经核背内侧区（ｄＭＮＦ）和腹内侧区（ｖＭＮＦ）注射微量吗啡和阿片受体拮抗剂－－纳络酮对颏舌肌和膈肌肌电活动的影响。结果：在ｄＭＮＦ和ｖＭＮＦ内分别注射微量吗啡颏舌肌和膈肌肌电活动明显被抑制,表现为肌电积分幅度降低。注射微量纳络酮,颏舌肌和膈肌肌电活动明显增强,表现为肌电积分幅度升高,并且纳络酮对吗啡的抑制作用有反转效     

吗啡对培养海马神经元钙离子作用的机制研究

目的：研究吗啡对海马神经元[Ca^2 ]i影响的机制,为探索吗啡成瘾的神经生物学机制与可能的治疗途径。方法：荧光探针Fluo-4标记细胞内游离钙后,用激光共聚焦显微镜检测吗啡对大鼠原代培养海马神经元[Ca^2 ]i的影响。结果：吗啡急性刺激引起海马神经元[Ca^2 ]i升高,CTOP不能阻断吗啡引起的细胞内[Ca^2 ]i增加,而naltrindole能阻断吗啡引起的细胞内[Ca^2 ]i反应;Thapsigargin预处理阻断吗啡诱导的细胞内[Ca^2 ]i增加,Verapamil预处理不能完全抑制吗啡引起的细胞内[Ca^2 ]i增加;吗啡长时程作用后,海马神经元[Ca^2 ]i升高,加入纳络酮急性戒断后,不能阻断吗啡引起的细胞内[Ca^2 ]i升高,反而引起[Ca^2 ]i异常升高。结论：吗啡急性刺激引起的海马神经元内游离钙增加主要来源于δ2阿片受体介导的IP3敏感的钙库释放。     

多巴胺对吗啡成瘾大鼠海马区痛觉调制的研究进展

当今社会日益增长的吗啡等阿片类药物的非法滥用已经严重威胁到人类的健康。然而,迄今为止尚没有找到能够较为有效的防治阿片成瘾的方法。目前研究已知,阿片成瘾的形成所涉及的脑区及核团包括中脑腹侧被盖区(VTA)、伏隔核(NAc)、海马等,其成瘾涉及的神经递质系统包括多巴胺、5-羟色胺等。本文将就多巴胺及海马在痛觉调制及药物成瘾过程中的作用进行综述,为吗啡的成瘾与戒断的进一研究及治疗提供线索。     

吗啡对大鼠海马神经元突触传递的作用及机制探讨

目的 :从离子通道角度研究吗啡对中枢神经系统兴奋性及抑制性突触传递的作用并探讨其机制。方法 :　原代培养新生Wistar大鼠的海马神经元。采用膜片钳技术研究吗啡对其兴奋性及抑制性突触后电流及谷氨酸诱发电流的影响。结果 :①吗啡可明显增强海马神经元兴奋性突触传递 ,加吗啡后自发兴奋性突触后电流 (sEPSC)的发放频率增加了 ( 2 0 7.8± 2 0 .9) %。此作用可被阿片受体阻断剂纳洛酮阻断 (P <0 .0 1) ;②吗啡对微小兴奋性突触后电流 (mEPSC)的发放频率及谷氨酸诱发电流的幅度没有明显影响 (P >0 .0 5 ) ;③吗啡可明显抑制神经元自发抑制性突触后电流 (sIPSC) ,纳洛酮可拮抗吗啡作用 (n =13 ,P <0 .0 1)。结论 :实验结果提示吗啡对海马神经元的兴奋作用不是由于吗啡直接作用于兴奋性氨基酸—谷氨酸突触传递过程 ,而是可能由于抑制了抑制性中间神经元 ,间接产生的兴奋作用。     

吗啡成瘾及戒断大鼠前额叶皮质蛋白质组变化的初步研究

目的：探讨与大鼠吗啡成瘾和戒断相关的前额叶皮质（PFC）蛋白。方法：以固相pH梯度等电聚焦为第一向和垂直SDS-PAGE为第二向,分别对吗啡成瘾和自然戒断大鼠及正常大鼠的PFC蛋白质样品进行二维分离,2-DE图谱经ImageMaster 2D Plat-inum v5.0软件分析,选取4个差异蛋白点用基质辅助激光解吸附离子化飞行时间质谱（MALDI-TOF-MS）进行鉴定。结果：通过对2-DE图谱蛋白斑点的匹配及对比分析,与吗啡成瘾和自然戒断相关的差异表达蛋白斑点为79个;经质谱鉴定出2个有意义的差异表达的蛋白斑点：Snap25亚型-βSnap25突触相关蛋白25,β-肌动蛋白。结论：PFC的某些蛋白可能与吗啡成瘾和戒断相关,其中尤其是神经毒性相关的蛋白可能与吗啡成瘾机制相关。     

基底外侧杏仁核对大鼠睡眠和行为的调节作用及机制研究

目的和方法 :本研究运用多导睡眠描记 (PSG)方法、大白鼠开阔实验法及强迫游泳实验观察杏仁核的基底外侧核 (BLN)内微量注射谷氨酸、吗啡和纳络酮对大鼠睡眠、觉醒和行为的影响。结果 :用谷氨酸选择性兴奋BLN内神经元胞体可增加觉醒 ,减少慢波睡眠 (SWS)和总睡眠时间 (TST) ,增加大鼠自主活动和缩短强迫游泳“不动”时间。吗啡作用与谷氨酸相似 ,而阿片受体阻断剂纳络酮引起的作用则与之相反 ,并可完全阻断吗啡的作用。结论 :BLN神经元兴奋可引起觉醒增加、SWS减少和自主活动增加效应 ,阿片受体激动剂是BLN调节睡眠、觉醒和行为的重要递质。     

八肽胆囊收缩素对吗啡成瘾大鼠中枢痛觉的调制

目的:观察八肽胆囊收缩素(CCK-8)对正常及吗啡成瘾大鼠尾核中痛兴奋神经元(PEN)电活动的影响,从而进一步探讨中枢CCK-8和尾核在吗啡成瘾大鼠痛觉调制中的作用.方法:70只Wistar大鼠随机分为2组:正常对照组35只(又分为生理盐水组巧只和CCK-8组20只)及吗啡成瘾组35只、(又分为生理盐水组15只和CCK-8组20只).大鼠背部皮下注射递增剂量吗啡,依次为5、10、20、40、50、60mg/kg,3次/d(8:00,12:00,16:00),连续给药6d,建立吗啡成瘾大鼠的模型.正常对照组大鼠背部皮下注射生理盐水,时间、剂量均与吗啡成瘾组相同.第7天8:00观察大鼠的自然戒断症状30min后开始实验.实验以电脉冲刺激大鼠的坐骨神经作为伤害性痛刺激,用玻璃微电极记录尾核中PEN的放电,观察尾核内注入CCK-8对PEN电活动的影响.结果:实验结果表明:①CCK-8可提高正常大鼠尾核中PEN的兴奋性,即25个PEN平均秒净增值由注射CCK-8前(100%)增加到(224.34±10.81)5,潜伏期缩短到(54.69±5.62)%.②CCK-8使吗啡成瘾大鼠尾核中PEN的兴奋性也增高,22个PEN的平均秒净增值比注药前(100%)提高了(118.93±8.50)%,潜伏期缩短了(33.96±7.23)%.结论:CCK-8可使吗啡成瘾与正常大鼠尾核中PEN对电刺激的兴奋性增强,均呈易化疼痛作用,证明中枢CCK-8系统和尾核在吗啡成瘾过程和疼痛的调节中都起到了一定的作用.     

特异突触可塑性干扰肽在小鼠吗啡条件化位置偏爱表达过程中的作用

在作为成瘾检测手段的条件化位置偏爱模型中,环境背景和成瘾药物间的关联性学习起着关键的作用。突触可塑性作为学习记忆可能的物质基础,在药物成瘾方面的研究也越来越多,但其表现形式,长时程增强(LTP)或者长时程抑制(LTD)在成瘾过程中所发挥的具体作用尚不得而知。因此,本文利用生物信息学手段,设计并合成了旨在分别阻断LTP和LTD的干扰肽,研究其对小鼠吗啡条件化位置偏爱的影响。结果发现,干扰肽Pep-A2和Pep-A3能够分别特异地阻断海马CA1区的LTP和LTD,在测试前尾静脉注射具有穿膜特性的LTP/LTD特异性干扰肽（Tat-A2/Tat-A3）,均能阻断或损伤吗啡诱导的条件化位置偏爱的表达。此发现提示我们,LTP和LTD在成瘾性异常记忆的过程中均发挥着重要的作用。     

Intermittent administration of morphine alters protein expression in rat nucleus accumbens

Repeated exposure to drugs of abuse causes time-dependent neuroadaptive changes in the mesocorticolimbic system of the brain that are considered to underlie the expression of major behavioral characteristics of drug addiction. We used a 2-D gel-based proteomics approach to examine morphine-induced temporal changes in protein expression and/or PTM in the nucleus accumbens (NAc) of morphine-sensitized rats. Rats were pretreated with saline [1 mL/kg subcutaneously (s.c.)] or morphine (10 mg/kg, s.c.) once daily for 14 days and the animals were decapitated 1 day later. The NAc was extracted and proteins resolved by 2-DE. Several protein functional groups were found to be regulated in the morphine-treated group, representing cytoskeletal proteins, proteins involved in neurotransmission, enzymes involved in energy metabolism and protein degradation, and a protein that regulates translation.     

Behavioral sensitization to delta 9-tetrahydrocannabinol and cross-sensitization with morphine: differential changes in accumbal shell and core dopamine transmission

Although cannabinoid-induced behavioral sensitization and cross-sensitization with opiates has been recently demonstrated, no information is available on the associated state and responsiveness of dopamine (DA) transmission in the nucleus accumbens (NAc) shell and core. In this study we investigate by means of dual probe microdialysis, the effect of exposure to a sensitizing regimen of Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and morphine on the extracellular concentrations of DA under basal conditions and after challenge with Delta(9)-THC and morphine in the NAc shell and core. Different groups of male Sprague-Dawley rats were administered twice daily for 3 days with increasing doses of Delta(9)-THC (2, 4, and 8 mg/kg i.p.), morphine (10, 20, and 40 mg/kg s.c.), and vehicle. After 14-20 days from the last injection, the animals were implanted with two microdialysis probes, one aimed at the NAc shell and the other at the core. The following day animals pre-treated with Delta(9)-THC and vehicle controls were challenged with 150 microg/kg i.v. of Delta(9)-THC or 0.5 mg/kg i.v. of morphine. Animals pre-treated with morphine and their vehicle controls were administered with 150 microg/kg i.v. of Delta(9)-THC. Rats pre-exposed to Delta(9)-THC showed behavioral sensitization associated with a reduced stimulation of DA transmission in the NAc shell and an increased stimulation in the NAc core in response to Delta(9)-THC challenge. Pre-exposure to Delta(9)-THC induced behavioral sensitization to morphine also, but only a reduced stimulation of DA transmission in the NAc shell was observed. Animals pre-treated with morphine showed behavioral sensitization and differential changes of DA in the NAc shell and core in response to Delta(9)-THC challenge with a decreased response in the shell and an increased response in the core. The results show that Delta(9)-THC-induced behavioral sensitization is associated with changes in the responsiveness of DA transmission in the NAc subdivisions that are similar to those observed in the sensitization induced by other drugs of abuse.     

Changes in the Properties of Glutamatergic Synapses in the Medial Prefrontal Cortex and Nucl. Accumbens in Rats with Behavioral Depression

In experiments on surviving rat forebrain slices, we studied the characteristics of glutamatergic synaptic transmission in the medial prefrontal cortex (MPFC) and nucl. accumbens. It was found that in rats with behavioral depression induced by zoosocial isolation (72 h), the mean amplitude of field EPSP (fEPSP) in the MPFC demonstrated no significant alterations. At the same time, the developments of rhythmic stimulation-caused long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission were suppressed, as compared with the control. In the nucl. accumbens of rats with behavioral depression, the mean fEPSP amplitude increased by nearly 25%, whereas rhythmic stimulation-induced LTD of transmission through synaptic connections between the cortex and nucl. accumbens weakened. Changes in the relay and plastic properties of glutamatergic synapses typical of behavioral depression were reproduced under conditions of chronic (for 3 days) i.p. injections of 1 mg/kg dexamethasone into the experimental animals. The influences exerted on brain slices in vitro by a synthetic glucocorticoid, dexamethasone, and a mineralocorticoid, deoxycorticosterone acetate, applied over 2 h in concentrations of 100 nM, did not significantly affect glutamatergic synaptic transmission in the MPFC and nucl. accumbens. In brain slices from animals with behavioral depression or from those subjected to chronic injection of dexamethasone, we observed a reduction of the modulatory effect of dexamethasone and a nonselective agonist of dopamine receptors, apomorphine hydrochloride, on glutamatergic synaptic transmission in the MPFC and nucl. accumbens. This is considered an indirect reflection of a decrease in the efficiency (down-regulation) of glucocorticoid and dopamine receptors in neurons of the brain structures under study. It is hypothesized that changes in the main properties of glutamatergic synapses in the forebrain structures (MPFC and nucl. accumbens), which were observed under conditions of behavioral depression, are determined by both direct effects of glucocorticoids on cortical and mesolimbic neurons and indirect effects mediated by the cerebral dopaminergic system.     

Effect of methamphetamine on the development of acute morphine tolerance and dependence in mice

The effect of methamphetamine on morphine analgesia (tail-flick assay) was studied in non-tolerant mice and in mice made acutely tolerant to morphine following a single injection of 100 mg/kg morphine. The analgesic potency of morphine was increased in non-tolerant and tolerant mice to the same extent by 3.2 mg/kg methamphetamine (3.3 and 4.4 fold increases, respectively). In contrast, the ED50's for morphine analgesia and naloxone-precipitated jumping in mice pretreated with either 100 mg/kg morphine or both morphine and 3.2 mg/kg methamphetamine were not significantly different, indicating that methamphetamine had no effect on the development of acute morphine tolerance and dependence. Although methamphetamine had no effect on the development of acute tolerance to morphine, 4-day pretreatment with methamphetamine produced cross-tolerance to morphine analgesia. However, cross-tolerance to morphine was not accompanied by enchanced sensitivity to naloxone.     

Chronic deep brain stimulation in the rat nucleus accumbens and its effect on morphine reinforcement.

In order to explore a novel method for the treatment of drug abuse, we evaluated the effect of chronic deep brain stimulation (DBS) of the rat nucleus accumbens (NAc) on morphine reinforcement, using a DBS apparatus and an implant method we developed. Thirty-two adult rats weighing 240-260 g were divided into three groups, which included a DBS group (n = 10, administration of surgery, morphine and DBS), a sham DBS group (n = 12, administration of surgery and morphine) and a control group (n = 10, administration of physiological saline). The DBS electrode was stereotaxically implanted into the core of unilateral NAc and connected to an implantable pulse generator. Then, they were fixed to the rat skull. One week later, the rats in each group were intraperitoneally injected with morphine at an increasing dose (10-60 mg/kg) once daily. The rats in the DBS group were administered a 130-Hz high-frequency stimulation (HFS) once daily. A 900-second conditioned place preference (CPP) paradigm was used for determining the effect of electrical stimulation on morphine reinforcement in rats. The data showed that 7-10 days later, the preference score of the DBS group was significantly lower than that of the sham DBS group. The results suggest that chronic HFS of the rat NAc can block CPP induced by morphine and attenuate morphine reinforcement.     

Short-term tolerance to morphine: effects of diazepam, phenobarbital, and amphetamine

Short-term tolerance to morphine, which can be demonstrated in as little as 3 hours after a single administration of the opiate, was examined in animals chronically pretreated with diazepam, phenobarbital, or amphetamine. Tail-flick latency in mice and changes in plasma corticosterone in rats were the parameters tested in these experiments. Rats primed with either saline or morphine, 10 mg/kg, were injected 3 hours subsequently with morphine, 5 mg/kg. Those primed with saline showed the characteristic plasma corticosterone elevation following morphine, when serial blood samples were examined, whereas those previously treated with morphine did not. Mice were primed with saline or either of two doses of morphine, 30 or 100 mg/kg, 3.5 hours prior to estimation of tail-flick latency and ED50 determinations. Mice primed with either dose of morphine had significantly higher ED50's than those primed with saline. Chronic treatment with diazepam or amphetamine in either species did not significantly alter short-term tolerance development by either parameter. However, with phenobarbital pretreatment, the plasma corticosterone response was attenuated and short-term tolerance to morphine's analgesic effects did not occur. Further studies in morphine-pelleted mice showed that analgesic tolerance occurred similarly in all groups. This suggests that barbiturates may delay the process.     

Cellular distribution of AMPA receptor subunits and mGlu5 following acute and repeated administration of morphine or methamphetamine

Ionotropic AMPA receptors (AMPAR) and metabotropic glutamate group I subtype 5 receptors (mGlu5) mediate neuronal and behavioral effects of abused drugs. mGlu5 stimulation increases expression of striatal‐enriched tyrosine phosphatase isoform 61 (STEP₆₁) which internalizes AMPARs. We determined the rat brain profile of these proteins using two different classes of abused drugs, opiates, and stimulants. STEP₆₁ levels, and cellular distribution/expression of AMPAR subunits (GluA1, GluA2) and mGlu5, were evaluated via a protein cross‐linking assay in medial prefrontal cortex (mPFC), nucleus accumbens (NAc), and ventral pallidum (VP) harvested 1 day after acute, or fourteen days after repeated morphine (8 mg/kg) or methamphetamine (1 mg/kg) (treatments producing behavioral sensitization). Acute morphine decreased GluA1 and GluA2 surface expression in mPFC and GluA1 in NAc. Fourteen days after repeated morphine or methamphetamine, mGlu5 surface expression increased in VP. In mPFC, mGlu5 were unaltered; however, after methamphetamine, STEP₆₁ levels decreased and GluA2 surface expression increased. Pre‐treatment with a mGlu5‐selective negative allosteric modulator, blocked methamphetamine‐induced behavioral sensitization and changes in mPFC GluA2 and STEP₆₁. These data reveal (i) region‐specific distinctions in glutamate receptor trafficking between acute and repeated treatments of morphine and methamphetamine, and (ii) that mGlu5 is necessary for methamphetamine‐induced alterations in mPFC GluA2 and STEP₆₁.     

Morphine inhibits TRH-induced gastric contractile activity.

This study investigated the effect of centrally and peripherally administered thyrotropin releasing hormone (TRH) on gastric contractile activity of rats 14, 21, 28 and adult (greater than or equal to 50) days (D) of age, and the effect of morphine pretreatment on that response. Rats were anesthetized with urethane, then a tension transducer was implanted on the anterior gastric corpus. Following baseline recording, rats were pretreated with intraperitoneal morphine (2 mg/kg). TRH (5 micrograms) in saline or saline alone (0.6 microliters) was then injected into the cisternum magnum. Additionally, dose response to TRH was examined in 14- and 50-day-old rats. Intracisternal TRH induced a dose-related increase in gastric contractile activity in both 14- and 50-day-old rats. Higher doses of TRH (10 and 30 micrograms) prolonged the response as compared to low doses. Peripheral morphine pretreatment blocked the TRH-induced increase in gastric contractile activity in all age groups although a higher morphine dose (10 mg/kg) was needed to block the effect in 28D rats. Intravenous TRH (5, 10, 30 micrograms) produced an increase in gastric contractile activity in 14D rats which was blocked by vagotomy.     

Intravenous morphine infusion (IMF) to drug-naive, conscious rats evokes bradycardic, hypotensive effects, but pressor actions are elicited after IMF to rats previously given morphine

Hemodynamic (blood pressure and heart rate) responses of conscious drug-naive rats were studied following intravenous (i.v.) infusion of sterile saline, morphine sulphate, and then naloxone hydrochloride, as well as of other groups previously injected with morphine sulphate. Those groups chronically given morphine sulphate received twice daily injections of morphine sulphate (5 mg/kg, s.c. per injection) for 3 or 6 days before testing with the i.v. infusion of morphine sulphate. Drugs were infused (135 microL/min) through an indwelling femoral venous catheter via a Harvard infusion pump, and blood pressure was recorded from the abdominal aorta via a femoral arterial catheter. Other pretreatment studies were done to determine the receptor mechanisms mediating the blood pressure responses of drug-naive and chronic morphine-treated rats, whereby equimolar doses (0.32 mumol) of specific receptor antagonists were given as a bolus i.v. injection 5 min after saline but before subsequent infusion with morphine sulphate. Intravenous infusion of morphine sulphate (7.5 mg/kg total over 15 min) to drug-native rats caused a transient but precipitous fall in mean arterial pressure and mean heart rate with an associated rise in mean pulse pressure; these effects were blocked in other groups pretreated with atropine. Interestingly, however, rats chronically injected with morphine sulphate for 3 days previously evoked a transient pressor response when subsequently infused i.v. with morphine sulphate, actions that were blocked in other groups when pretreated i.v. with 0.32 mumol of phentolamine, yohimbine, prazosin, or guanethidine. A greater and persistent pressor response occurred following morphine infusion to groups of rats previously injected over 6 days with morphine sulphate, which was associated with tachycardia during the later stages of the 15-min morphine sulphate infusion period. The prolonged pressor and tachycardic responses of this 6-day chronically injected group were completely blocked in another group pretreated i.v. with both phentolamine and propranolol (0.32 mumol). The results suggest that morphine sulphate infusion to conscious, drug-naive rats evokes classical hypotensive effects due to decreases in mean heart rate caused by activation of parasympathetic vagal activity. With 3 or 6 days of chronic morphine sulphate administration beforehand, subsequent i.v. infusion of morphine sulphate evoked pressor actions felt to be caused by a progressive activation of the sympathetic nervous system.(ABSTRACT TRUNCATED AT 400 WORDS)