侧脑室注射东莨菪碱对吗啡依赖大鼠戒断反应的抑制作用

目的 观察非选择性毒蕈碱(M)受体拮抗剂东莨菪碱、选择性M1 受体拮抗剂哌拉唑嗪以及选择性M2受体拮抗剂美索四氨对吗啡戒断反应的影响。方法 采用吗啡依赖大鼠模型侧脑室注射上述药物, 并用腹腔注射纳洛酮诱发戒断反应, 记录60 min 内戒断症状。结果 侧脑室注射东莨菪碱(25, 50 μg)、哌拉唑嗪(20 μg)和美索四氨(25 μg)可明显抑制由纳洛酮诱发戒断反应, 东莨菪碱减轻吗啡戒断症状呈明显量效关系。结论 侧脑室注射东莨菪碱能减轻吗啡戒断反应, 提示中枢胆碱能神经毒蕈碱(M)受体在吗啡依赖和耐受过程中起重要作用。     

Image Quilting纹理合成算法的实现与改进

针对Image Quilting算法在合成结构性较强的纹理图片时产生局部纹理不连续的问题,提出了一种改进的方法。改进从以下两方面进行:通过图像变形增加样本图的采样空间以增大匹配的概率;改变匹配块的选择策略以提高合成质量。实验结果表明,改进后的算法有效地改善了纹理不连续现象,生成的纹理图像质量更高。     

Effects of chronic morphine treatment on responding for intracranial stimulation in female versus male rats.

Morphine was administered to Sprague-Dawley rats twice daily at 0, 3, 10, and 20 mg/kg injection during Weeks 1, 2, 3, and 4, respectively; responding for medial forebrain bundle stimulation was assessed 1, 2, and 3 hr after morning injections in female versus male rats. There were no sex differences in responding under control conditions (Week 1). Morphine's effect on response rate depended on dose, time post-injection, stimulation frequency, and day of treatment. Significant sex differences in morphine's effects occurred at 10 mg/kg, which decreased responding more in males at 1 hr and increased responding more in females at 2 hr, at some frequencies and on some test days. Similar trends were observed at other frequencies, test days, and doses. Morphine's differential effect in males versus females in this procedure suggests that sex comparisons of opioid effects in many animal models may be influenced by sex difference in opioid effects on behavior output. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

吗啡的结构与旋光方向

用螺旋理论分析了吗啡及其衍生物(可待因、海洛因)的螺旋结构与旋光方向。结果表明:对于骨架相同的分子,其螺旋结构相同,旋光方向相同,而取代基的不同只影响旋光度的大小。这进一步证实了螺旋理论预测分子旋光性的可靠性,反之,从旋光方向也可推测其结构。     

The Potential Role of Drug Onset Cues in Drug Dependence and Withdrawal: Reply to Bardo (2004), Bossert and Shaham (2004), Bouton (2004), and Stewart (2004).

In responding to commentaries (M. Bardo, see record 2004-10475-002; J. Bossert and Y. Shaham, see record 2004-10475-003; M. Bouton, see record 2004-10475-004; J. Stewart, see record 2004-10475-005) on their original article (see record 2004-10475-001), the authors agree that the basic mechanisms underlying intra-administration associations may be extensible to a much wider range of phenomena, including both other examinations of conditioned drug effects (e.g., conditioned place preference) and human psychological disorders. The authors also address the concerns of a number of the commenting authors regarding discrepancies in the literature concerning the effects of drug priming in both human and animal studies of reinstatement of drug self-administration. Finally, the authors accept and endorse the calls by several of these commenting authors for further studies required to generate additional support for their model of conditioned drug effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Once is too much: Conditioned changes in accumbens dopamine following a single saccharin-morphine pairing.

The present study tested whether presentation of a taste cue would support conditioned suppression of dopamine in the nucleus accumbens (NAcc) following a single taste-drug pairing. Nondeprived male Sprague-Dawley rats were given 20-min access to a 0.15% saccharin conditioned stimulus (CS). Immediately thereafter, experimental rats were injected with morphine (15 mg/kg ip); standard controls were injected with saline; and explicitly unpaired controls were injected with morphine, but approximately 24 hr later. All rats were then given one 20-min CS-only test. Microdialysis samples from the NAcc were measured over 20-min intervals before, during, and after CS access on the conditioning and test trial. The results showed that a single saccharin-morphine pairing led to a marked reduction in CS intake, and the reduction in intake was accompanied by a conditioned blunting of the accumbens dopamine response to the saccharin reward cue. In turn, a single exposure to the saccharin cue also blunted the unconditioned dopamine response to morphine. Reward comparison effects, then, are cross-modal, bidirectional, and immediate, resulting in both unconditioned and conditioned changes in brain and behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned Fos expression following morphine-paired contextual cue exposure is environment specific.

Environmental cues associated with drug administration elicit neural activation in circuits involved in cognitive processes and emotional regulation. An important question is whether the neural activation observed is specific to the drug-paired environment or is due to a generalized activation induced by previous drug treatment or changes in arousal state. Rats were treated with morphine (5 mg/kg ip) in one environment and saline in an alternative environment, and their brains were later examined for conditioned Fos expression after placement in one of these environments without drug administration. Increases in neural activation after drug-paired environmental exposure were dependent on exposure to the specifically paired environment; exposure to an alternative environment in morphine-treated rats did not elicit similar increases in Fos expression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brain injury and morphine withdrawal.

"A review of the literature indicates lack of agreement as to the presence or absence of opiate withdrawal symptoms following surgically imposed brain damage. The controversy is resolved when recourse is made to the temporal factor, i.e., the time at which withdrawal is carried out relative to the time an operation is performed. It is suggested that the withdrawal phenomenon is as complex as addiction itself, and that both are related to many peculiar effects that accrue to cerebral tissue destruction." 26 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amphetamine and morphine produce a conditioned taste and place preference in the house musk shrew (Suncus murinus).

Rats have been shown to avoid consuming a flavor, but prefer a location, previously paired with amphetamine or morphine. A series of 4 experiments evaluated the hedonic properties of amphetamine and morphine in the house musk shrew (Suncus murinus), an insectivore that (unlike rats) is capable of vomiting when exposed to toxins. Unlike rats, amphetamine (20 mg/kg) and morphine (20 mg/kg) produced both a conditioned sucrose (0.3 M) and saccharin (0.1%) preference in shrews (administered intraperitoneally), when measured by both a 1-and a 2-bottle test. At the same dose, both drugs also produced a place preference in shrews. These results suggest that the potential of rewarding drugs to produce taste avoidance may vary on the basis of the ability of the species to vomit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the Nature of the Intra-Administration Unconditioned Stimulus: Comment on McDonald and Siegel (2004).

R. V. McDonald and S. Siegel (see record 2004-10475-001) present convincing evidence that a small dose of morphine (5 mg/kg) may elicit withdrawal signs in rats previously injected on a number of occasions with a large dose of morphine (50 mg/kg), thus suggesting that intra-administration associations may be involved in drug withdrawal. This finding is important for basic and applied researchers studying drug reward mechanisms. Although R. V. McDonald and S. Siegel point out that the morphine conditional stimulus (CS) and unconditioned stimulus (US) making up the intra-administration association differ in onset and magnitude, the author of this comment argues that the CS and US may also differ in terms of pharmacologic activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)