电针对吗啡戒断大鼠体质量和胃电图的影响

通过给大鼠连续注射递增量吗啡8d,建立吗啡戒断大鼠模型,停药后第2d开始给于强度为2mA,频率2～100Hz混频刺激.各组大鼠分别在实验前、实验第8d和实验第11d 18∶ 00测量体质量,在胃体、胃窦、体表投影处分别记录胃电图.观察电针足三里穴对其体质量和胃电图的影响.实验表明,模型组大鼠体质量与正常组比明显降低(P《0.01),胃电图频率、幅值改变,节律紊乱.电针组大鼠体质量与正常组比无显著差异,胃电图均有不同程度恢复.电针对吗啡戒断大鼠的体质量和胃肠功能紊乱具有良性调整作用.     

Testosterone modulation of reproductive indices vs. morphine antinociception in male rats

The purpose of this study was to determine whether testosterone (T) concurrently modulates reproductive and nociceptive systems in the adult male. Male Sprague-Dawley rats were orchidectomized, and then 28 days later implanted with capsules containing T or nothing (blanks). After 2, 7, 14 or 28 days' exposure to T-filled or blank capsules, rats were tested for male sexual and nociceptive behaviors in a counter-balanced design. As the duration of T exposure lengthened, the percentage of rats showing male sexual behaviors and the weights of steroid-sensitive organs systematically increased, and latencies to show sexual behaviors decreased. T treatment did not affect basal nociception on either the hotplate or tail withdrawal tests, but significantly increased morphine's antinociceptive potency on the tail withdrawal test -- however, this effect was small, and independent of duration of T exposure. Thus, T treatment that altered male sexual behavior and reproductive physiology in a systematic, duration-dependent manner did not similarly alter basal nociception or morphine antinociception. These findings suggest that in adult male rats, although T may modulate both male sexual behaviors and opioid antinociceptive sensitivity, these T effects do not occur in concert.     

The effect of cellular glucoprivation on skin temperature regulation in the rat

Studies were undertaken to determine the effects of cellular glucoprivation on temperature responses in morphine-addicted and placebo-treated rats and to compare these responses to those observed during naloxone-precipitated morphine withdrawal. Naloxone caused a tail skin temperature (TST) response of 5.7 +/- 0.5 degrees C in morphine-dependent rats. Intraperitoneal administration 2-deoxyglucose (2DG) caused TST responses in placebo-treated and morphine-dependent rats of 4.8 +/- 0.6 and 6.2 +/- 0.5 degrees C, respectively. These data indicate that the activation of the sympathetic nervous system by cellular glucoprivation causes a TST response which is equivalent in magnitude to that induced by precipitating withdrawal with naloxone. This effect of 2DG appears to be mediated by the brain, since icy administration of 2DG caused a TST response, similar to that induced by naloxone treatment of morphine-dependent rats. Collectively, these data suggest that a TST increase is a component of the response of rats to local brain glucoprivation induced by 2DG.     

Depression of Mesolimbic Dopamine Transmission and Sensitization to Morphine During Opiate Abstinence

To investigate the role of mesolimbic dopamine (DA) in the mechanism of drug dependence, extracellular DA was monitored by transcerebral dialysis in the caudal nucleus accumbens under basal conditions and after challenge with morphine (5 mg/kg s.c.) in control rats and in rats made dependent on and then deprived of morphine. Withdrawal from morphine resulted in a marked reduction of extracellular DA concentrations from control values at 1, 2, 3, and 5 days of withdrawal. After 7 days of withdrawal, DA output was less, but still significantly, reduced. Challenge with morphine resulted in stimulation of DA output in controls (maximum, 35%), no effect on the first day of withdrawal, and stimulation similar to controls' on days 2 and 7 of withdrawal. On day 5 and, particularly, on day 3 of withdrawal, morphine-induced stimulation of DA output was markedly potentiated (maximum, 100 and 160%, respectively). Changes in the sensitivity of DA transmission to morphine challenge were associated with changes in the behavioral stimulant effects of morphine, with tolerance on day 1 and marked sensitization on days 3 and 5 but also on day 7, when morphine-induced stimulation of transmission was no longer potentiated. The results indicate that repeated morphine administration induces a state of dependence in DA neurons and a short-lasting tolerance followed by an increased sensitivity to its stimulant effects on DA transmission. These changes might play an important role in the development of opiate addiction and in the maintenance of opiate self-administration in dependent subjects.     

Ethanol suppression of naloxone-induced withdrawal in morphine-dependent rats

The technique of morphine pellet implantation was used to produce physical dependence on morphine in male rats. The number of “wet dog” shakes occurring within a period of 30 minutes during naloxone-precipitated (1.0 mg/kg, s.c.) withdrawal in four-day morphine implanted rats was determined after either acute or chronic treatment with ethanol. An acute dose of ethanol administered prior to withdrawal had no significant effect on the withdrawal response whereas chronic administration of ethanol during the development of dependence on morphine significantly suppressed the naloxone-precipitated withdrawal response to 44–57 percent of the control response. Analysis of brain and plasma for morphine concentration four days following dependence development showed no significant differences between morphine controls and those animals treated with both morphine and ethanol. Pentobarbital, another central nervous system depressant, demonstrated no effect on the withdrawal response, whether administered acutely or chronically during the development of dependence.     

Multiple 100 Hz electroacupuncture treatments produced cumulative effect on the suppression of morphine withdrawal syndrome: Central preprodynorphin mRNA and p-CREB implicated

Alleviating opiate withdrawal syndrome in addicts is a critical precondition to break away from drug and further to prevent reuse. Electroacupuncture (EA) was claimed to be effective for alleviating withdrawal syndrome, but the optimal protocol remained unclear. In the present study we found that (1) 100 Hz EA administered 12-24 h after the last morphine injection suppressed the withdrawal syndrome in rats, multiple sessions of EA were more effective than single session, with the after-effect lasting for at least 7 days. (2) A down-regulation of preprodynorphin (PPD) mRNA level was observed in spinal cord, PAG and hypothalamus 60 h after the last morphine injection, which could be reversed by multiple sessions, but not a single session of EA. (3) Accompanied with the decrease of PPD mRNA level, there was an up-regulation of p-CREB in the three CNS regions, which was abolished by 100 Hz EA treatment. The findings suggest that down-regulation of p-CREB and acceleration of dynorphin synthesis in spinal cord, PAG and hypothalamus may be implicated in the cumulative effect of multiple 100 Hz EA treatment for opioid detoxification.     

Morphine dependence is associated with changes in neuropeptide S receptor expression and function in rat brain

Neuropeptide S (NPS) is a newly identified ligand for the previously discovered G-protein coupled receptor 154 now named NPSR. Recently, it has been found that NPSR gene expression is altered during ethanol withdrawal. In this study we tried to elucidate if NPSR gene expression is modified in response to morphine withdrawal and its protracted abstinence. To induce opioid dependence Wistar rats were treated for 7 days with morphine. Twelve hours and 7 days after the last morphine administration brains were removed and the expression of NPSR mRNA was analyzed by in situ hybridization (ISH). Successful induction of opioid dependence was confirmed by the naloxone-precipitated withdrawal test 2 h after the last morphine administration. Moreover, 7 days after the last morphine dose animals were checked for signs of anxiety and for intracerebroventricular (ICV) NPS (0.3 and 1.0 nmol) induced anxiolytic effects by elevated plus maze (EPM). Results showed that in morphine treated rats strong somatic signs of naloxone-precipitated withdrawal occurred. ISH data revealed changes in NPSR gene expression in the ventral tegmental area as well as in the basolateral amygdaloid and bed nucleus of stria terminalis at 12 h and 7 days into abstinence, respectively. At 7 days into abstinence post dependent animals showed higher levels of anxiety than controls which were significantly attenuated by NPS. These results demonstrated that morphine dependence induction led to (i) changes in NPSR mRNA expression; (ii) increased anxiety; and (iii) more potent anxiolytic-like effect of NPS.     

Similarities between morphine withdrawal in the rat and the menopausal hot flush

Skin temperature, cardiovascular and neuroendocrine responses to morphine withdrawal in the rat were evaluated in an effort to develop a potential animal model for the menopausal hot flush in women. Morphine dependency was produced by s.c. implantation of pellets containing morphine alkaloid. In response to precipitous, naloxone-induced withdrawal, rats showed surges in tail skin temperature (TST) which were similar in magnitude (4.8 to 7.2 degrees C) and duration (60 to 90 min.) to peripheral skin temperature increases reported during menopausal hot flushes. Additionally, a brief period of accelerated heart rate (59%) and a 9-fold hypersecretion of luteinizing hormone (LH) preceded the TST response to morphine withdrawal. These cardiovascular and neuroendocrine responses are observed to precede or coincide with the menopausal hot flush. Additionally, protracted morphine withdrawal subsequent to abstention, resulted in TST instability characterized by spontaneous, high amplitude TST fluctuations. Thus, the alteration in skin temperature, heart rate and LH secretion during precipitated morphine withdrawal in the rat are similar in magnitude, duration and in their temporal relationship to those observed during the hot flush. These data suggest a possible opioid etiology in this vasomotor disturbance. Acute withdrawal in the morphine addicted rats may serve as an animal model by which to study the neural mechanism underlying the menopausal hot flush.     

慢性吗啡给予、戒断及再给药过程中大鼠海马感觉门控的动态变化

药物成瘾被认为是药物长期作用于脑而产生的一种慢性复吸性脑疾病,长期反复的药物（如吗啡）滥用会导致一系列严重后果,如药物依赖、药物耐受、强迫性药物寻求等。本实验利用条件化位置偏好（conditioned place preference,CPP）模型来检测大鼠对吗啡依赖和心理渴求等过程;采用双声刺激听觉诱发电位来研究大鼠在慢性吗啡给予、戒断以及再给药过程中海马感觉门控（N40）的动态变化。吗啡组大鼠注射吗啡（10mg／kg,i．p．）12d,经历第一次戒断12d,再次注射吗啡（2．5mg／kg,i．P．）1d,之后经历第二次戒断2d;对照组大鼠注射同体积生理盐水,其余实验条件与吗啡组相同。CPP实验表明,这种药物给予方法促使大鼠对吗啡产生药物依赖和心理渴求。双声刺激诱发电位实验表明,吗啡组大鼠在吗啡给予期间海马感觉门控受到损伤;第一次戒断期的第1～2天海马感觉门控能力减弱,第3天增强,第4～12天逐渐恢复到正常水平;再次给予吗啡后海马感觉门控能力与对照组相比显著降低,并且随后2d的戒断期内海马感觉门控能力也一直保持较低水平,表明再次给药使大鼠海马感觉门控对吗啡更加敏感化。结果提示,长期反复的吗啡给予及再给药干扰了海马的感觉门控能力,吗啡成瘾对大脑可能产生长期影响。     

Wild ginseng attenuates anxiety- and depression-like behaviors during morphine withdrawal

The purpose of this study was to evaluate whether wild ginseng (WG) administration could attenuate anxiety- and depression-like behaviors and expression of corticotrophin-releasing factor (CRF) and neuropeptide Y (NPY) following withdrawal from repeated morphine administration in rats. Male rats were administered daily doses of WG (50, 100, or 200 mg/kg, i.p.) for 5 days, 30 min before morphine injection (40 mg/kg, s.c). The anxiety- and depression-like behavioral responses were measured 72 h after the last morphine injection using an elevated plus maze (EPM) and forced swimming test (FST), respectively. Changes in hypothalamic CRF and NPY expressions were also examined by analyzing their immunoreactivities in the hypothalamus. Daily administration of WG significantly reduced anxiety-and depression-like behavior, and elicited the suppression of CRF expression and the stimulation of NPY expression in the hypothalamus. Our results demonstrated that WG extract might be effective at inhibiting the anxiety and depression responses due to morphine withdrawal by possibly modulating the hypothalamus CRF and NPY systems. Furthermore, these findings imply that WG extract can be used for developing new medication to cure or alleviate morphine withdrawal symptoms and to prevent relapses of morphine use.     

脊髓水平nNOS和iNOS在吗啡戒断反应中的作用差异

目的:观察鞘内注射选择性一氧化氮合酶(nNOS)和诱导型一氧化氮合酶(iNOS)抑制剂对吗啡依赖大鼠纳洛酮催促戒断反应、脊髓Fos蛋白表达和脊髓神经元nNOS和iNOS表达的影响,以探讨nNOS和iNOS在吗啡依赖和戒断反应中的作用。方法:在大鼠吗啡依赖和戒断模型上,采用行为学、免疫组织化学和Western blot方法观察鞘内应用nNOS抑制剂7-硝基吲哚(7-Ni)和iNOS抑制剂氨基胍(AG)对吗啡依赖大鼠纳洛酮催促戒断反应、脊髓Fos蛋白表达和脊髓神经元nNOS和iNOS表达的影响。结果:①鞘内注射7-Ni、AG可明显减轻吗啡依赖大鼠戒断症状,戒断组戒断症状评分为28.6±4.89,7-Ni组为16.2±3.99(P<0.01),AG组为22.94±4.0(P<0.05);戒断组TEA评分为13.5±2.55,7-Ni、AG组分别为7.5±2.56、10.5±2.71(P<0.05);②鞘内注射7-Ni、AG可减少脊髓背角Fos阳性神经元的数目,7-Ni、AG组为228.2±49.5、296.8±50.6,低于戒断组(380±71,P<0.05);③7-Ni、AG组nNOS和iNOS阳性神经元的数目分别为169±32、10.2±2.85,均低于戒断组(239±45,16.8±5.1,P<0.05),两给药组脊髓NOS蛋白的表达也显著减少。结论:nNOS和iNOS抑制剂能减轻吗啡依赖及戒断大鼠的戒断症状和在脊髓水平抑制nNOS和iNOS的表达,nNOS起主要作用而iNOS可能起辅助作用。     

Mechanisms mediating the thermal response to morphine withdrawal in rats

Studies were undertaken to evaluate the role of peripheral adrenergic mechanisms and the adrenal gland in the thermal responses which accompany morphine withdrawal in the rat. Ovariectomized rats were addicted to morphine and subsequently withdrawn by administration of naloxone. This treatment resulted in a significant rise (5-6 degrees C) in tail skin temperature (TST) and fall in colonic temperature (2-4 degrees C). Systemic administration of clonidine (0.5 mg/kg) completely suppressed this surge in TST and significantly attenuated the fall in core temperature. Similar results were observed following the systemic administration of ST-91, another alpha 2-adrenergic agonist which does not cross the blood-brain barrier. Central administration of ST-91 (50 micrograms/5 microliters, icv) was also successful in attenuating these temperature changes in the morphine-dependent rat. Adrenalectomy and peripheral administration of propranolol (10 mg/kg sc) both resulted in a significant attenuation of the surge in TST and the fall in core temperature in the morphine-dependent rat which suggest some peripherally mediated event is necessary to produce the full skin temperature surge. Collectively, the data suggest a role for the adrenal gland and adrenergic receptors in producing the surge in TST in morphine-dependent rats. It also suggests that the blocking effects of the alpha 2-adrenergic agonist can be mediated both centrally and peripherally.     

Reduced tolerance to morphine thermoregulatory effects in senescent rats

Age-related differences in the thermoregulatory response to morphine have been shown in rats. To determine if these age-related differences would be reflected in the acquisition of tolerance, we studied morphine tolerance induced by either a single morphine dose or implantation of a morphine pellet. precipitated withdrawal was also analyzed by inducing withdrawal with naloxone in morphine-pelleted rats. Senescent (26 or 27 month old), mature (10 or 11 month old) and young (3 or 4 month old) male Fischer 344 rats were restrained and changes in rectal temperature were monitored for six hours after morphine administration. Only mature and young rats exhibited increased hyperthermic responses to a second low dose of morphine (5 mg/kg s.c.). Only young rats became tolerant after a single higher morphine dose (25 mg/kg s.c.). All age groups showed tolerance three days after morphine pellet implantation. Hypothermia was equivalent in all age groups when withdrawal was induced by naloxone in morphine-pelleted rats. These results indicate that older rats were more resistant to the acquisition of tolerance to the thermic effects of morphine; however; with continued morphine treatment, rats became tolerant regardless of age.     

A single dose of liposome-encapsulated oxymorphone or morphine provides long-term analgesia in an animal model of neuropathic pain

An extended-release formulation of oxymorphone was produced by encapsulation into liposomes, using a novel technique. Liposome-encapsulated morphine was produced, using a standard technique These preparations were tested in an animal model of neuropathic pain. Male Sprague-Dawley rats (approx. 300 g) were allotted to control (non-loaded liposomes) and treatment (liposome-encapsulated oxymorphone or morphine) groups. Drugs were administered subcutaneously to all rats immediately prior to sciatic nerve ligation. Thermal withdrawal latencies were measured at baseline and daily for seven days after sciatic nerve ligation. A second experiment involved subcutaneous administration of non-loaded liposomes, morphine, or oxymorphone to rats that did not undergo sciatic nerve ligation. Thermal withdrawal latencies in sciatic nerve-ligated rats given non-loaded liposomes decreased significantly by day four, with maximal decrease at day seven after surgery, indicating development of full hyperalgesia. In contrast, ligated rats given liposome-encapsulated morphine or liposome-encapsulated oxymorphone had no decrease in thermal withdrawal latency by day four, indicating that these long-acting preparations prevented development of hyperalgesia after a single injection. This treatment effect persisted to day seven. Non-ligated rats treated with vehicle or liposome-encapsulated morphine had no change in thermal withdrawal latencies. Non-ligated rats treated with liposome-encapsulated oxymorphone had a small, but significant increase in thermal withdrawal latency from day four through day seven. One subcutaneous injection of liposome-encapsulated oxymorphone or morphine was effective in preventing hyperalgesia in this pain model for up to seven days. These results suggest that liposome-encapsulation of oxymorphone offers a novel, convenient, and effective means to provide long-term analgesia.     

Co-administration of dextromethorphan during pregnancy and throughout lactation significantly decreases the adverse effects associated with chronic morphine administration in rat offspring.

In this study, we have focused our investigation of the facts whether co-administration of a NMDA antagonist dextromethorphan (DM) with morphine during pregnancy and throughout lactation could prevent the adverse effects associated with chronic morphine administration in rat offspring. Adult female Sprague-Dawley rats were randomly separated into four groups and were received subcutaneous injection of either saline, morphine, morphine + dextromethorphan or dextromethorphan twice a day and progressively increased 1 mg/kg at 7-day intervals from a beginning dose of 2 mg/kg for both morphine and dextromethorphan. The rats were mated between days 7 and 8. Administration of drugs was continued during pregnancy. After rat offspring were born, the doses of morphine or dextromethorphan injected into the maternal rats were increased by 1 mg/kg every two weeks till the offspring were 30 day old. The results showed that mortality of morphine group is much higher than control group. The offspring of morphine group weighed significantly less than control group on postnatal day 14 (p14), p30 or p60. The antinociceptive effect of morphine on p14 rats was reduced in the morphine group and indicated the development of morphine tolerance. The hippocampal NMDA receptor densities have been shown decreased on p14 rats. The precipitated withdrawal symptoms were assessed on p7 rats. Rats in morphine group showed greater frequency of abdominal stretch and wet dog shake in 2 hr than control group. On the other hand, co-administration of DM with morphine effectively prevented all these adverse effects of morphine to the offspring rats. DM co-administered with morphine also partially prevented the development of morphine tolerance in maternal rats. If this effect of dextromethorphan is applied to clinical pregnant patients with morphine addiction or chronic pain, it will have a great value for the benefit of their children.     

Acupuncture at Both ST25 and ST37 Improves the Pain Threshold of Chronic Visceral Hypersensitivity Rats

Previous studies demonstrated the efficacy of electro-acupuncture (EA) in relieving chronic visceral hypersensitivity (CVH) in IBS rats. However, ST25 which is a key acupoint for patients with IBS has not been reported in these experiments. Eight CVH rats were treated by EA at both ST25 and ST37 for 20 min, once daily for seven consecutive days, model rats (n = 8) and normal rats (n = 8) as controls. After the first EA treatment, the abdominal withdrawal reflex scores were investigated to evaluate the pain threshold. After seven EA treatments, the concentrations of 5-hydroxytryptamine (5-HT), 5-HT3 receptor (5-HT3R) and 5-HT4 receptor (5-HT4R) in colon tissue were assayed quantitatively by enzyme-linked immunosorbent assay. The results showed that EA improved the pain threshold of CVH rats, reduced the 5-HT concentration and increased the 5-HT4R concentration, but had no effect on the 5-HT3R concentration. Further studies are needed to optimize the choice of two-matching points for EA in the treatment of CVH rats.     

Relationship between chronic treatment with morphine and sex-dependent low molecular weight protein excretion

Chronic administration of morphine caused a marked decrease in the urinary excretion of low molecular weight proteins (LMWP) including α₂u-globulin (E.L. Stanley and O.W. Neuhaus, Biochim. Biophys. Acta, $\text{257}$, 461–470, 1972), which exist only in male rats. Levels of urinary high molecular weight proteins, such as albumin and γ-globulin, however, were not significantly changed by morphine treatment. The amount of excreted LMWP was observed to decrease 3 days after giving morphine, 0.5 mg/g food, and to recover to the control level within 6 days after withdrawal of morphine. These findings suggest that the decrease of excreted LMWP may be related to the development of morphine dependence in male rats.     

Dosing time-dependent nephrotoxicity of cyclosporin A during 21-day administration to Wistar rats

The incidence of cyclosporine A (CsA) nephrotoxicity with reference to the temporal stage of administration was studied during a chronic 21-day treatment in male Wistar rats. Oral administration (20 mg/kg/day) was given at four different times: 1, 7, 13, or 19 hours after light onset (HALO). Plasma creatinine and blood urea nitrogen (BUN) levels were determined at regular intervals over the 24 h: before treatment (day 0); 7, 14, and 21 days after the beginning of treatment (days 7, 14, and 21); and 7 and 14 days after CsA withdrawal (days 28 and 35). At the same times, creatinine clearance and g-glutamyl transferase urinary excretion were determined in the groups of animals treated at 7 and 19 HALO. Residual concentrations of CsA in the renal tissue were measured at the end of the treatment period (day 21) in all groups. Nephrotoxicity of CsA was dependent on the temporal stage of administration. The renal vasoconstriction showed by the increase in plasma creatinine and BUN levels and the decrease in creatinine clearance was maximal when the CsA was given at 7 and 19 HALO and was correlated to the tissue concentrations of CsA. Tubular injury seems to occur earlier and the return to normal function less rapidly in animals treated at 19 HALO compared with animals treated at 7 HALO.     

Monoamine Metabolism in the Locus Coeruleus Measured Concurrently with Behavior During Opiate Withdrawal: An In Vivo Microdialysis Study in Freely Moving Rats

Abstract: Using microdialysis, changes in monoamine metabolism were monitored in the locus coeruleus of freely moving rats during opiate withdrawal concomitantly with behavioral symptoms. Rats were infused with morphine (2 mg/kg/h, s.c.) or saline for 5 days and challenged with naltrexone (100 mg/kg, s.c.) on day 6. Following naltrexone challenge, the classic behavioral symptoms of morphine withdrawal were observed in rats treated with morphine but not in saline-infused rats. In morphine-dependent rats, naltrexone induced a marked increase (280%) in dialysate concentrations of 3,4-dihydroxyphenylacetic acid, an index of the functional activity of the noradrenergic neurons in the locus coeruleus. The local concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid were also increased (70%) during morphine withdrawal. Taken together, these results (a) confirm in unanesthetized rats the hypothesis of an activation by opiate withdrawal of noradrenergic neurons in the locus coeruleus and (b) suggest an increase in serotonergic transmission in the same nucleus during morphine withdrawal.     

Long-term enhancement of morphine hypalgesia as a result of periodic blockade of opiate receptors using naloxone

A significant enhancement of the analgetic effect of morphine (6 mg/kg, subcutaneously; tail withdrawal reflex at 60 degrees C) was observed in rats 3-4 hours after single naloxone (1 mg/kg) administration. Periodical naloxone injection (0.5 mg/kg, subcutaneously, 3 times per day at 3.5-hour intervals for 3 days) led to a prominent and long-term (testing on the 20th and 105th hour after the last naloxone administration) enhancement of morphine analgesia (2.6 mg/kg subcutaneously) and insignificant inhibition of stress analgesia during two-hour immobilization of animals. These modifications of morphine and stress analgetic effects are considered a result of adaptive changes of opiate receptors after their blockade.