The effects of simultaneous administration of alpha(2) -adrenergic agents with L-NAME or L-arginine on the development and expression of morphine dependence in mice

Both alpha(2)-adrenoceptors and the L-arginine/nitric oxide (NO) pathway have been implicated in the modulation of morphine dependence. This study examined the effects of simultaneous administration of the alpha(2)-adrenoceptor agonist clonidine or the antagonist yohimbine together with the NO precursor L-arginine or the NO synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on the induction and expression of morphine dependence as assessed by naloxone-precipitated withdrawal jumping and diarrhoea. Male NMRI mice weighing 20-30 g were used. In the induction phase, clonidine (0.01-0.1 mg/kg) intensified and yohimbine (0.5-2 mg/kg) attenuated the degree of morphine dependence. Yohimbine reversed the effect of clonidine. L-NAME (5 and 10 mg/kg) did not affect the development of morphine dependence, but significantly potentiated the effects of both subeffective (0.01 mg/kg) and effective (0.03 mg/kg) doses of clonidine. L-Arginine did not alter morphine dependence but inhibited the effect of clonidine. The effects of yohimbine in the induction phase were attenuated by L-NAME, but were not significantly affected by L-arginine. In the expression phase, clonidine attenuated and yohimbine intensified the signs of dependence. The effect of clonidine was inhibited by yohimbine. In the expression phase, L-NAME attenuated the withdrawal syndrome at 10 mg/kg and showed potentiation with clonidine in suppressing withdrawal signs. L-Arginine did not alter morphine dependence, but at 20 mg/kg inhibited and at 100 mg/kg potentiated the attenuating effect of clonidine on the expression of withdrawal syndrome. The effect of yohimbine on the expression phase was also attenuated by L-NAME, but was not significantly affected by L-arginine. In conclusion, alpha(2)-adrenergic and NO pathways seem to be functionally linked in the modulation of opioid dependence.     

川芎嗪对小鼠吗啡戒断症状的抑制作用

目的：研究川芎嗪对小鼠吗啡戒断症状的影响。方法：以剂量递增法形成吗啡依赖模型,用纳洛酮催促戒断。结果：ｓｃ给药,Ｌｉｇ２０ｍｇ／ｋｇ抑制“湿狗”样抖动,打洞,前爪震颤症状：Ｌｉｇ４０ｍｇ／ｋｇ抑制跳跃、“湿狗”样抖动、上睑下垂,前爪震颤、体重下降等症状。结论：Ｌｉｇ能抑制大部分吗啡戒断症状。     

Changes in benzodiazepine-receptor activity modify morphine withdrawal syndrome in mice

The effects of different benzodiazepine-receptor ligands on morphine withdrawal were studied: a benzodiazepine agonist, flunitrazepam; a benzodiazepine antagonist, flumazenil; a partial inverse benzodiazepine agonist, Ro 15-4513; and a partial benzodiazepine agonist, Ro 16-6028. Benzodiazepine-ligands were administered i.p. 30 min before naloxone-induced morphine withdrawal syndrome. Jumping behaviour was significantly increased by Ro 15-4513 at 10 and 20 mg/kg. Flunitrazepam decreased jumps at all the doses used. Wet dog shakes were decreased by flumazenil and Ro 15-4513 and increased by Ro 16-6028 (only at the highest dose) and flunitrazepam. Our results show that the activation of the benzodiazepine receptor by agonists or high doses of partial agonists decreases jumping and increases wet dog shake behaviour, while the antagonists or the partial inverse agonists enhance jumping and decrease wet dog shakes. These modifications could be interpreted as an attenuation in the severity of the morphine withdrawal syndrome by benzodiazepine agonists.     

Chronic morphine administration: Plasma levels and withdrawal syndrome in rats

Morphine, administered to Sprague-Dawley rats over a period of 65 hr either by the simultaneous implantation of two 75 mg pellets, or by a series of twice daily 20 or 30 mg/kg injections, produced dependence as indicated by the precipitation of the abstinence syndrome with the antagonist, naloxone. Plasma morphine levels, analyzed fluorometrically at various times during the treatment procedures, revealed peak concentrations that were 3 or 4 fold higher for injected animals than the maximum steady-state level established in the pellet-implanted animals. The calculated plasma concentration of the drug over time was not statistically different for the groups. It is noted that although the 2 methods of morphine administration produce a qualitatively identical dependent state, the pellet implantation technique causes greater weight loss and a higher incidence of jumping and wet-dog shakes during withdrawal.     

Effect of p-chloroamphetamine on morphine withdrawal syndrome

Adult male rats were injected four times a day with increasing doses of morphine sulfate until a dose of 405 mg/kg/day was tolerated. After 5 days of maintenance at that dose, withdrawal signs were observed at 24, 48, and 72 hr of withdrawal. Given 4 or 18 hr after last morphine injection, a single administration (3–12 mg/kg) of p-chloroamphetamine (PCA) blocked withdrawal “wet shakes” and ptosis during the following withdrawal period. Dose-dependent reduction in withdrawal hypothermia was observed only at 24 hr of withdrawal. Writhing was blocked only at higher doses. Morphine-withdrawal aggression measured at 72 hr of withdrawal and loss in body weight were not blocked by any delayed action of PCA. However, withdrawal aggression was blocked by PCA when given 1 hr before measurement at a dose of 3 mg/kg. Mice that were made morphine dependent by repeated injections of morphine given in large doses, exhibited withdrawal jumping either after cessation of morphine injections, or on injection of naloxone. PCA (3–12 mg/kg) given 2 hr before naloxone blocked this jumping in a dose-dependent manner. It also blocked withdrawal jumping in morphine-deprived mice when injected 2 hr, but not 14 or 17 hr before measurement. Jumping induced by α-naphthyloxyacetic acid (α-NOAA) was not blocked. The effect of PCA on different signs of morphine withdrawal is time dependent and may be related to its similarly time-dependent effect on brain serotonin and dopamine.     

The effect of chronic administration of L-arginine and L-NAME on morphine-induced antinociception in ovariectomized rats

Objective:

The role of ovarian hormones and nitric oxide on morphine-induced antinociception and their interaction have been widely investigated. The results of previous study showed that nitric oxide synthase inhibition differently affects morphine-induced antinociception in male and female rats. The present study was carried out to evaluate the different effects of chronic administration of L-arginine (LA) and L-NAME (LN) on morphine-induced antinociception in ovariectomized (OVX) and naive female rats.

Materials and Methods:

Sixty female rats were randomly divided into six groups (n = 10) as follows: (1) sham, (2) OVX, (3) sham-LA (4) sham-LN (5) OVX-LA, and (6) OVX-LN. The animals of sham-LA and OVX-LA groups received daily injection of 200 mg/kg LA (i.p.) during 6 weeks, while in sham-LN and OVX-LN groups, the animals were treated with 10 mg/kg LN (i.p.). The animals of sham and OVX groups received 2 ml/kg saline (i.p.) instead of LA and LN. Finally, all the animals were tested on the hot plate test (52 ± 0.2°C; cut-off time 80 seconds) for evaluating the antinociceptive effects of morphine. The hot plate test was performed as three base records with a 15-min interval before the injection of morphine (10 mg/kg; s.c.) following which it was repeated every 15 min after injection. Analgesic effect of morphine was quantified as maximal percent effect (MPE). Base reaction latency times (seconds) before the injection of morphine and MPE after the injection of morphine were compared using repeated-measure analysis of variance (ANOVA) followed by post-hoc Tukey''s test. Differences were considered statistically significant when P < 0.05.

Results:

Before injection of morphine, there was no significant difference observed between sham and OVX groups in three recorded base reaction latency times. The base reaction latency times in sham-LA group were significantly higher than those of sham group (P < 0.001). In sham-LN group, the base reaction latency times were nonsignificantly lower than those of sham group (P = 0.095). There was no significant difference between OVX-LA group and OVX group. In OVX-LN group, three base reaction latency times were nonsignificantly lower than those of OVX group (P = 0.077). MPE in sham-LN group was higher than that of sham group (P < 0.05); however, there was no significant difference between sham-LA and sham groups.

Conclusion:

It is concluded that NO has a role in pain perception and the analgesic effect of morphine. The effect of NO might be differing in the presence or absence of ovarian hormones, but further investigations need to be done.     

Comparison of selective and complete inhibitors of enkephalin-degrading enzymes on morphine withdrawal syndrome

We investigated the effects of thiorphan, a selective inhibitor of endopeptidase 24.11 'enkephalinase', kelatorphan ((R)-3-(N-hydroxy-carboxamido-2-benzylpropanoyl)-L-alanine), and RB 38 A ((R)-3-(N-hydroxycarboxamido-2-benzylpropanoyl)-L-phenylalanine) two almost complete inhibitors of enkephalin metabolism, on the naloxone-precipitated morphine withdrawal syndrome in rats. Inhibitors administered intracerebroventricularly reduced several symptoms of the withdrawal syndrome. Jumping, chewing and tooth chattering were decreased by all drugs. The rise in plasma corticosterone and the hypothermia were reduced by kelatorphan and RB 38 A whereas rhinorrhea was blocked by thiorphan, tremor by kelatorphan and diarrhoea by RB 38 A. Other signs remained unchanged. These data suggest that an increase in opioid receptor occupancy by endogenous opioid peptides, protected from biotransformation specially by mixed inhibitors reduced the severity of the morphine abstinence symptoms in rats.     

Comparison of the effect of levodopa and bromocriptine on naloxone-precipitated morphine withdrawal symptoms in mice

In this study, the effect of l-dopa and bromocriptine on morphine withdrawal syndrome was compared. Both l-dopa (125, 250 mg/kg, i.p.) and low doses of bromocriptine (0.04, 0.08 mg/kg, i.p.) potentiated naloxone-induced morphine withdrawal symptoms such as jumping, climbing and rearing in mice. Higher doses of bromocriptine (0.16, 0.32 mg/kg, i.p.) attenuated these naloxone-induced symptoms. SKF 83566, D(1) dopamine antagonist (0.4, 0.8 mg/kg, i.p.) and sulpiride, D(2) dopamine antagonist (5, 10 mg/kg, i.p.) when used alone, also produced inhibitory effects on naloxone-induced morphine withdrawal symptoms. Pretreatment with sulpiride (5, 10 mg/kg, i.p.) and SKF 83566 (0.4, 0.8 mg/kg, i.p.) attenuated the potentiating effects of l-dopa on withdrawal symptoms significantly. Pretreatment with sulpiride also decreased the potentiating effect of bromocriptine and reinforced the inhibitory action of it, but SKF 83566 pretreatment just reinforced the effect of higher doses of bromocriptine. Concurrent pretreatment of animals with sulpiride (10 mg/kg, i.p.) and SKF 83566 (0.8 mg/kg, i.p.) markedly decreased the potentiating effects of l-dopa and bromocriptine and reinforced the inhibitory action of bromocriptine on the naloxone-induced morphine withdrawal syndrome. Prazosin, alpha(1) antagonist (1, 2 mg/kg, i.p.) decreased the naloxone-induced morphine withdrawal syndrome significantly. Pretreatment with yohimbine, alpha(2)-antagonist (5 mg/kg, i.p.) reversed the inhibitory effects of bromocriptine (0.16, 0.32 mg/kg, i.p.) on naloxone-induced morphine withdrawal syndrome significantly. In conclusion, our results show that bromocriptine at lower doses (0.04, 0.08 mg/kg, i.p.) acts similar to l-dopa, but at higher doses (0.16, 0.32 mg/kg, i.p.) shows different effects on naloxone-induced morphine withdrawal syndrome which may be due to the interaction of bromocriptine with alpha-adrenoceptors. Copyright 2000 John Wiley & Sons, Ltd.     

The mechanisms of morphine dependence and it's withdrawal syndrome: study in mutant mice

To investigate the involvement of catecholamines and/or the cyclic AMP (cAMP) systems in the development of drug dependence, we examined whether morphine dependence was developed in tyrosine hydroxylase (TH) heterozygous (TH+/-) and cAMP response element binding protein (CREB) binding protein (CBP) heterozygous (CBP+/-) mice. Morphine (10 mg/kg) induced place preference in the wild-type mice. In the TH+/- and CBP+/- mice, however, we could not find any morphine-induced place preference. When the wild-type mice pretreated with morphine (10 mg/kg) twice a day for 5 days were challenged with naloxone (5 mg/kg), they showed increased numbers of jumping, rearing and forepaw tremor as a sign of withdrawal symptom and increased level of cAMP in the thalamus/hypothalamus, but not in the striatum. However, increased numbers of jumping and forepaw tremor in the TH+/- and CBP+/- mice and increased level of cAMP in the thalamus/hypothalamus of TH+/- mice were not observed. These results suggest that catecholamines and CBP are involved in the development of morphine dependence, and that some changes in the catecholaminergic and/or cAMP system induced by repeated morphine treatment play an important role in the addiction of morphine.     

Effects of calcitonin on morphine tolerance and withdrawal syndrome in morphine physically dependent rats

We investigated the effect of acute or chronic peripheral administration of [Asu1.7]eel-calcitonin on the development of tolerance to the analgesic effect of morphine and on the naloxone-precipitated withdrawal syndrome in morphine-dependent rats. Neither the analgesic effect of acute morphine nor the development of tolerance to the antinociceptive effect of this drug was modified by calcitonin. However, the chronic but not the acute administration of calcitonin attenuated some signs and symptoms of morphine withdrawal.     

预先应用咪哒唑仑抑制小鼠和大鼠吗啡戒断反应

目的:研究咪哒唑仑对小鼠和大鼠吗啡戒断反应的影响.方法:实验中采用急性和慢性吗啡依赖和纳洛酮催促戒断模型.使用放免法测定cAMP含量,免疫组织化学方法观察Fos蛋白表达变化.结果:合用咪哒唑仑和吗啡可抑制小鼠急性和慢性吗啡依赖的发展.在急性吗啡依赖小鼠,咪哒唑仑-吗啡组纳络酮催促跳跃的ED_(50)(10.4,8.5-12.3 mg/kg)明显大于生理盐水-吗啡组(3.0,1.9-4.3 mg/kg)(P<0.01).在慢性吗啡依赖小鼠,咪哒唑仑-吗啡组纳络酮催促跳跃的发生率和跳跃次数明显低于生理盐水-吗啡组(P<0.01).预先使用咪哒唑仑抑制吗啡戒断大鼠脊髓Fos蛋白表达,但不能抑制脊髓cAMP含量的增加.结论:咪哒唑仑通过抑制脊髓神经元敏感化减轻吗啡戒断反应,cAMP信号转导通路不参与介导这一效应.     

Dextromethorphan attenuates morphine withdrawal syndrome in neonatal rats passively exposed to morphine

We had previously found that co-injection of dextromethorphan, an antitussive drug and a non-competitive NMDA receptor antagonist, with morphine into dam rats throughout the pregnancy period could attenuate the naloxone-precipitated morphine withdrawal syndrome in their offspring. In the present study, we further tested whether postnatal injection of dextromethorphan into the neonatal rats or a 3-day co-injection of dextromethorphan with morphine into the dam rats before delivery is also effective. Female Sprague-Dawley rats were bi-daily injected with escalating doses of morphine from a week before mating till the first postnatal week. Withdrawal syndrome of morphine in the offspring, manifested mainly as abdominal stretching, was generated by injection of naloxone on postnatal day 5. Direct injection of dextromethorphan into the offspring effectively reduced the severity of naloxone-precipitated abdominal stretching in a dose-dependent manner. A 3-day co-treatment with dextromethorphan given to the dam rat before delivery also had a similar attenuating effect, but the efficacy was lower than that produced by postnatal injection. Thus, the results from the present study support that dextromethorphan is of potential in treating or preventing neonatal morphine withdrawal syndrome.     

Lack of sex-related differences in the prevention by baclofen of the morphine withdrawal syndrome in mice

In previous studies we have demonstrated a possible interaction between the GABAergic and opioid systems involved in the antinociceptive effect of the GABA(B) agonist, baclofen (BAC). On the other hand, sex differences have been observed for the antinociceptive effect of morphine (MOR). In the present study, we analyzed sex-related differences in the MOR abstinence syndrome and its prevention with BAC. Prepubertal male and female Swiss-Webster albino mice (27-33 g) were rendered dependent by intraperitoneal (i.p.) injection of MOR (2, 4 and 8 mg/kg), twice daily for 9 days. On the tenth day the dependent animals were divided into two groups: one received naloxone (NAL) (6 mg/kg, i.p.) 60 min after the last dose of MOR, to precipitate the abstinence syndrome; the other group received BAC (2 mg/kg, i.p.) followed by NAL (6 mg/kg, i.p.), injected 30 and 60 min after the last dose of MOR, respectively. Behavioral signs were recorded in the open field for 30 min. Although there were sex differences in the MOR withdrawal syndrome, we found a lack of sex differences in the prevention of the MOR abstinence syndrome by BAC.     

吗啡与丁丙诺啡的蛛网膜下腔与皮下联合给药的相互作用(英文)

目的:观察大鼠吗啡与丁丙诺啡(或吗啡)的蛛网膜下腔与皮下联合给药的相互作用。方法:SD大鼠,置入蛛网膜下腔导管。辐射热诱发鼠腿撤退试验测痛阈。分别蛛网膜下腔给予吗啡、皮下注射丁丙诺啡(或吗啡)、蛛网膜下腔给予吗啡与皮下注射丁丙诺啡(或吗啡)的联合给药。结果:单独和联合给药均剂量依赖性地提高鼠痛阈。联合给药的量效曲线的斜率均显著大于吗啡单独给药的曲线斜率。等效线图显示联合给药的ED_(50)均位于理论推测的叠加效应线的左侧。结论:吗啡与丁丙诺啡(或吗啡)的蛛网膜下腔与皮下联合给药呈协同效应。     

Precipitation of morphine withdrawal syndrome in rats by administration of mu-, delta- and kappa-selective opioid antagonists

The acute effects of opioid drugs are generally hypothesized to be mediated by multiple receptors, for which three types of binding sites have been established. In order to evaluate the selective participation of each type of opioid receptor in opiate withdrawal, the opiate withdrawal syndrome, precipitated by the intraventricular acute administration of mu-, delta- and kappa-selective opioid antagonists was investigated. After implantation of the cannula into the lateral ventricle, rats were made physically dependent by subcutaneous insertion of two 75-mg pellets of morphine (base). -Phe-Cys-Tyr- -Trp-Arg-Thr-Pen-Thr-NH₂ (CTAP) (5–5000 ng), a mu-selective opioid antagonist, naltrindole (62–2000 ng), a delta-selective antagonist or nor-binaltorphimine (nor-BNI) (600–20,000 ng), a kappaselective antagonist, were administered 72 hr after implantation of the pellets. All three drugs elicited some signs of morphine withdrawal but they differed in both their potency and their efficacy. The most efficacious and the most potent was CTAP, eliciting 8 of the 14 withdrawal signs at doses of 5–5000 ng. Nor-BNI was less efficacious and less potent, eliciting a significant increase in 5 of the 14 withdrawal signs in a dose range of 600–20,000 ng. Naltrindole was the least potent and least efficacious of the three drugs, eliciting a significant increase of only 2 withdrawal signs after intraventricular administration of 2000 ng. In a second experiment, the withdrawal syndrome was precipitated by the combined administration of CTAP + naltrindole or CTAP + nor-BNI. The severity of withdrawal, obtained with these two combinations, was similar to that observed with CTAP alone. These results support the importance of the mu receptor in the expression of central opiate dependence and suggest a minor role for delta and kappa receptors.     

Cardiovascular changes during morphine administration and spontaneous withdrawal in the rat

Morphine maintenance doses of 10 mg kg(-1) day(-1), 20 mg kg(-1) day(-1) and 30 mg kg(-1) day(-1) were administered to three groups of rats via miniosmotic pumps for 7 days to induce physical dependence. They were then allowed to undergo spontaneous withdrawal. Radiotelemetric blood pressure measurements showed that morphine increased systolic and diastolic blood pressure on the first day of morphine treatment and produced a dose dependent decrease in heart rate, systolic and diastolic blood pressure thereafter. After the peak depressive effect, development of tolerance to morphine was observed in systolic and diastolic blood pressure, but not in the heart rate. During spontaneous withdrawal, both systolic and diastolic blood pressure increased beyond pre-morphine levels for all doses and there was a rebound increase in heart rate at the 30 mg kg(-1) day(-1) dose. These results suggest that the improved sensitivity of telemetric measures combined with the use of minipumps for morphine treatment provide an animal model of spontaneous opioid withdrawal.     

Influence of omega-conotoxin on morphine analgesia and withdrawal syndrome in rats.

The effect of omega-conotoxin on opiate analgesia and withdrawal syndrome was investigated in rats. omega-Conotoxin given i.c.v. and i.p. caused weak analgesia in the tail-flick test. When the toxin (20 ng/rat) was given i.c.v. immediately before morphine (1.5 micrograms/rat i.c.v.) the resultant analgesic effect was additive. In contrast, the analgesia elicited by morphine (3 micrograms/rat i.c.v.) was greatly reduced after 24-h pretreatment with the toxin (20 ng/rat i.c.v.). The systemic administration of the toxin (10 micrograms/kg i.p.) did not affect morphine analgesia whether omega-conotoxin was coadministered with morphine (2.5 mg/kg i.p.) or was given 24 h before the opiate (5 mg/kg i.p.). omega-Conotoxin i.c.v. injected in morphine-dependent rats 15 min before naloxone challenge significantly attenuated the abstinence syndrome. On the contrary systemic administration of omega-conotoxin failed to suppress the morphine withdrawal syndrome. The present results suggest that omega-conotoxin affects both acute and chronic effects of morphine.     

Conditioned withdrawal in environments associated with the presence or absence of morphine.

An experiment designed to compare conditioned withdrawal in environments associated with the presence or absence of morphine was conducted in hamsters. For some animals, morphine administration was paired with distinctive environmental cues. For other animals, naloxone-precipitated withdrawal was paired with the distinctive environmental cues. For still other animals, naloxone-precipitated withdrawal and the distinctive environmental cues were unpaired. Following 12 days of training, animals were observed for signs of withdrawal (e.g., wet-dog shakes, etc.) in the distinctive environment following vehicle injections. Results indicated that more conditioned withdrawal responses occurred in the environment paired with the absence of morphine (naloxone-precipitated withdrawal) than in the environment paired with morphine administration.     

Suppression of the drug-induced morphine withdrawal syndrome by cyproheptadine

In rats treated with gradually increasing amounts of morphine hydrochloride until they tolerated fatal doses, levallorphan precipitated acute body weight loss and elicited a variety of other typical withdrawal symptoms. Cyproheptadine markedly reduced this b.w. loss and abolished the drug-induced withdrawal syndrome. Fenfluramine also suppressed the major signs of the levallorphan-induced morphine withdrawal; however the combination of the three drugs proved to be very toxic. Since both agents interfere with different hypothalamic feeding mechanisms these results are accordant with the hypothesis of Kerr and Pozuelo (1971) that morphine dependence and tolerance are due to a functional disorganization of the hypothalamic centers concerned wit the regulation of food intake.     

Effects of adenosine receptor agents on the expression of morphine withdrawal in mice

Effects of different doses of adenosine receptor agonists and antagonists on naloxone-induced jumping and diarrhea in morphine-dependent mice were studied. The adenosine A1 receptor agonists, N6-cyclohexyladenosine (CHA: 0.1, 0.25 and 0.5 mg kg(-1)) and R-isomer of N6-phenylisopropyladenosine (R-PIA: 0.1, 0.3 and 1 mg kg(-1)), decreased jumping and diarrhea induced by naloxone in morphine-dependent mice. The adenosine A1 receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX: 0.3-9 mg kg(-1)), increased jumping but decreased diarrhea. The adenosine A2 receptor agonist, 5'-(N-cyclopropyl)-carboxamidoadenosine (CPCA), decreased jumping and diarrhea. However, the adenosine A2 receptor antagonist, 3,7-dimethyl-1-propargylxanthine (DMPX: 0.5 and 1 mg kg(-1)), did not elicit any response in this respect. DPCPX (0.3 and 3 mg kg(-1)), decreased the inhibition of jumping and diarrhea induced by CHA (0.5 mg kg(-1)), while DMPX (0.5 and 1 mg kg(-1)), decreased the inhibition of diarrhea induced by CPCA (0.1 mg kg(-1)). It is concluded that jumping induced by naloxone in morphine-dependent mice may be modified by the adenosine A receptor mechanism(s) and diarrhea induced by the opioid receptor antagonist could be mediated by the adenosine A1 and A2 receptors.