Reactive oxygen species (ROS) have been implicated in the development of behavioral sensitization following repeated cocaine exposure. We hypothesized that increased ROS following cocaine exposure would act as signaling molecules in the mesolimbic dopamine (DA) system, which might play an important role in mediating the reinforcing effects of cocaine. The aim of this study was to evaluate cocaine enhancement of brain metabolic activity and the effects of ROS scavengers on cocaine self-administration behavior, cocaine-induced ROS production in the nucleus accumbens (NAc) and cocaine enhancement of DA release in the NAc. Metabolic neural activity monitored by temperature and oxidative stress were increased in NAc following cocaine exposure. Systemic administration of the ROS scavenger N-tert-butyl-?-phenylnitrone (PBN) or 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL), either pre- or post-treatment, significantly decreased cocaine self-administration without affecting food intake. Infusion of TEMPOL into the NAc inhibited cocaine self-administration. Increased oxidative stress was found mainly on neurons, but not astrocytes, microglia or oligodendrocytes, in NAc of rats self-administering cocaine. TEMPOL significantly attenuated cocaine-induced enhancement of DA release in the NAc, compared to saline controls. TEMPOL had no effect on the enhancement of DA release produced by the DA transporter inhibitor GBR12909. Taken together, these findings suggest that enhancement of ROS production in NAc neurons contributes to the reinforcing effect of cocaine.
In the previous study, acupuncture at HT7 has shown to attenuate the self-administration of morphine at a low dose (0.1mg/kg). In this study, it was further investigated whether acupuncture at HT7 could attenuate the morphine self-administration at a high dose (0.5mg/kg). Male Sprague-Dawley rats weighing 270-300g were used. After surgery of catheterization, animals were trained to self-administer morphine solution (0.5mg/kg) using daily 1h session under fixed ratio 1 schedule for 3 weeks. Animals that had shown stable morphine-taking (establish baseline: variation less than 20% of the mean of three consecutive days) were subjected to the acupuncture treatment. Bicuculline and SCH 50911 were used to investigate the possible relation between the effect of acupuncture and the GABA receptor system. Acupuncture at HT7, but not at control acupoint, LI5, suppressed spontaneous morphine-taking behavior significantly. In addition, the effect of acupuncture was blocked by both GABA receptor antagonists. The results of this study suggest that acupuncture at HT7 suppresses morphine-taking behavior through the mediation of GABA receptor system.
The role of neuropeptide Y (NPY) in the central nucleus of amygdala (CeA) in the preventive effects of acupuncture against ethanol withdrawal-induced anxiety was investigated. Rats were treated with 3g/kg/day of ethanol for 28 days, followed by 3 days of withdrawal. Bilateral acupuncture treatment at HT7 (Shen-Men), PC6 (Nei-Guan) or a non-acupoint was respectively added to the rats during the withdrawal once a day for three days. Enzyme-linked immunosorbent assays and real-time polymerase chain reaction analyses showed there was a significant decrease in NPY protein and mRNA expression in the CeA during ethanol withdrawal, which was reversed by acupuncture at HT7 but neither at PC6 nor at a non-acupoint. Acupuncture at HT7 also greatly inhibited the decrease in cAMP response element-binding protein (CREB) phosphorylation in the CeA. In elevated plus maze tests, a selective NPY Y1 receptor antagonist BIBP 3226 into the CeA before the acupuncture abolished almost completely the anxiolytic effect of acupuncture at HT7. These results suggest that acupuncture at HT7 rescues the depletion of amygdaloid NPY and reverses the decrease in CREB phosphorylation to produce anxiolytic effects during ethanol withdrawal.
To help the clinicians prescribe acupoints easily and effectively, we developed one simple flow chart to select acupoints. This study aimed to evaluate the usefulness of flow chart to select acupoints in dogs. Total 102 dogs showing intervertebral disc disease (IVDD) (n = 12), vomiting (n = 11), diarrhea (n = 2), abdominal pain (n = 5), cough (n = 66), or epilepsy (n = 6) received acupuncture treatment according to the chart, and its outcomes were evaluated as regards clinical symptoms, duration, treatment numbers, and recovery time. Dogs (8/8) with IVDD from grades I to III recovered over periods of 5 days to 6 weeks after 1-12 treatments, while 1/4 dogs with grade IV recovered over 7 weeks after 15 treatments. Vomiting dogs with acute/subacute (n = 8) and chronic symptoms (n = 3) required about 1 and 7 treatments to recover fully, respectively. All dogs (n = 5) with abdominal pain showed fast relief within 24 hours after acupuncture. Two diarrhea cases recovered over 2-9 days after 1-2 treatments. Fifty-four of 66 coughing dogs were recovered by 1-2 treatments. And 5 of 6 epilepsy dogs under a regular acupuncture treatment had no epileptic episode during followup of 12 months. These results suggest that this flow chart can help the clinicians prescribe acupoints effectively.
In a previous study, acupuncture at acupoint HT7 attenuated ethanol withdrawal-induced anxiety-like behavior in rats by normalizing amygdaloid catecholamines. In the present study, the involvement of amygdaloid corticotropin-releasing factor (CRF) in the anxiolytic effect of acupuncture was investigated during ethanol withdrawal. Rats were intraperitoneally treated with 3 g /kg/day of ethanol for 28 days, and the CRF mRNA levels in the central nucleus of the amygdala (CEA) were measured by using a RT-PCR analysis 72 hours after the last dose of ethanol. During ethanol withdrawal, the rats were bilaterally treated with acupuncture at acupoints HT7, PC6 or at a non-acupoint (Tail) for one min/day for three days. Also, rats were bilaterally injected with CRF into the CEA five minutes after the third acupuncture treatment, after which followed by the elevated-plus maze (EPM) test and the plasma corticosterone radioimmunoassay (RIA) were administered. The RT-PCR analysis showed a significant increase in the amygdaloid CRF mRNA levels in the ethanol-withdrawn rats compared with both the saline-treated rats and the rats treated with acupuncture at HT7, but neither acupuncture at PC6 nor acupuncture at a non-acupoint significantly inhibited the increased mRNA expression. The EPM test and the RIA also showed that the post-acupuncture infusion of CRF greatly reduced the anxiolytic effect of acupuncture at HT7. These results suggest that during ethanol withdrawal, the anxiolytic effect of acupuncture may be mediated through the modulation of amydaloid CRF during ethanol withdrawal.
Morphine causes physical and psychological dependence for individuals after repeated-use. Above all, our previous study showed that acupuncture attenuated reinstatement of morphine-seeking behavior induced by pharmacological cue. In this study, we investigated whether acupuncture could suppress the reinstatement of morphine-seeking behavior induced by the combination of environmental and pharmacological cues and the possible neuronal involvement. Male Sprague-Dawley rats were trained to self-administer morphine (1.0 mg/kg) for 3 weeks. Following the withdrawal phase (7 days), the effects of acupuncture on reinstatement of morphine-seeking behavior were investigated. For the investigation of neuronal involvement, the GABAA receptor antagonist bicuculline and the GABAB receptor antagonist SCH 50911 were pre-treated. Morphine-seeking behavior induced by combination of re-exposure to the operant chamber and morphine injection was suppressed perfectly by acupuncture at SI5, but not at the control acupoint LI5 and this effect was blocked by pre-treatment with the GABA receptor antagonists. This study suggests that acupuncture at SI5 can be considered as a predominant therapy for the reinstatement of morphine-seeking behavior in humans.
Administration of cocaine increases locomotor activity by enhancing dopamine transmission. To explore the peripheral mechanisms underlying acupuncture treatment for drug addiction, we developed a novel mechanical acupuncture instrument (MAI) for objective mechanical stimulation. The aim of this study was to evaluate whether acupuncture inhibition of cocaine-induced locomotor activity is mediated through specific peripheral nerves, the afferents from superficial or deep tissues, or specific groups of nerve fibers. Mechanical stimulation of acupuncture point HT7 with MAI suppressed cocaine-induced locomotor activity in a stimulus time-dependent manner, which was blocked by severing the ulnar nerve or by local anesthesia. Suppression of cocaine-induced locomotor activity was elicited after HT7 stimulation at frequencies of either 50 (for Meissner corpuscles) or 200 (for Pacinian corpuscles) Hz and was not affected by block of C/A?-fibers in the ulnar nerve with resiniferatoxin, nor generated by direct stimulation of C/A?-fiber afferents with capsaicin. These findings suggest that HT7 inhibition of cocaine-induced locomotor activity is mediated by A-fiber activation of ulnar nerve that originates in superficial and deep tissue.
Repeated morphine administration increases extracellular dopamine levels in the nucleus accumbens, which results in behavioral sensitization that can be suppressed by acupuncture at Shenmen (HT7) points. The present study was conducted to investigate the effects of acupuncture at HT7 on morphine withdrawal syndrome as well as to explore the role of GABA receptors in mediating the effects of HT7 acupuncture. We induced morphine withdrawal by injecting naloxone to rats that self-administer morphine and evaluated the effects of acupuncture and/or GABA receptor antagonists on their withdrawal symptoms. Acupuncture at HT7, but not at the control point LI5, significantly decreased symptoms of morphine withdrawal. HT7 inhibition of the withdrawal syndrome was blocked by pretreatment with either the GABA(A) receptor antagonist bicuculline or the GABA(B) antagonist SCH 50911. These findings suggest that the effects of acupuncture on suppression of morphine withdrawal syndrome are mediated, at least in part, through GABA receptors.
In the present study, functional roles of GABA receptors in the nucleus accumbens on morphine self-administration behavior were investigated. Male Sprague-Dawley rats were trained to press lever for morphine (0.1 mg/kg per infusion) during daily 1-h self-administration session. After establishing stable baseline responses, rats were given microinjections of the GABA(A) receptor agonist muscimol (0, 250 and 500 ng/microl, bilateral) or the GABA(B) receptor agonist baclofen (0, 100 and 250 ng/microl, bilateral) into the nucleus accumbens immediately before the morphine self-administration. Microinjection of muscimol (250 and 500 ng/microl) into the nucleus accumbens, but not baclofen, decreased morphine self-administration responses. These results suggest that activation of GABA(A) receptors, but not GABA(B) receptors, in the nucleus accumbens plays a critical role in modulating the reinforcing effects of morphine.
Our previous studies have shown that acupuncture attenuates morphine self-administration and sensitization behavior as well as withdrawal signs. The present study was designed to investigate the role of acupuncture in the reinstatement of morphine seeking. Male Sprague-Dawley rats weighing 270-300 g were subjected to intravenous catheterization after food training. The animals were trained to self-administer morphine (1.0mg/kg, 3 weeks), followed by extinction (1 week). Extinction conditions were introduced by substituting saline for morphine. The rats were then tested for reinstatement of morphine self-administration by a priming injection of morphine (0.25mg/kg). To see whether acupuncture can reduce morphine reinstatement, acupuncture was performed at SI5 or LI5 for 1 min immediately before a morphine injection. To further test the involvement of gamma aminobutyric acid (GABA) receptors in acupuncture effects, GABA receptor antagonists were injected before acupuncture. In the present results, acupuncture at SI5, but not at control acupoint LI5 attenuated the reinstatement of morphine seeking behavior, which was blocked by the GABA receptor antagonists. It suggests that acupuncture can reduce the reinstatement of morphine seeking, possibly due to the mediation of GABA receptor system.
Cocaine addiction is associated with high rates of relapse, and stress has been identified as a major risk factor. We have previously demonstrated that acupuncture reduces drug self-administration and dopamine release in the nucleus accumbens (NAc), a brain structure implicated in stress-induced reinstatement of drug-seeking behavior.
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