Inhibition by ginsenosides Rb1 and Rg1 of cocaine-induced hyperactivity, conditioned place preference, and postsynaptic dopamine receptor supersensitivity in mice

Antimania-Like Effect of Panax ginseng Regulating the Glutamatergic Neurotransmission in REM-Sleep Deprivation Rats

Previous studies have shown the therapeutic properties of ginseng and ginsenosides on hyperactive and impulsive behaviors in several psychiatric diseases. Herein, we investigated the effect of Panax ginseng Meyer (PG) on hyperactive/impulsive behaviors in a manic-like animal model, sleep deprivation (SD) rats. Male rats were sleep-deprived for 48 h, and PG (200 mg/kg) was administered for 4 days, from 2 days prior to the start of SD to the end date of SD. The elevated plus maze (EPM) test showed that PG alleviated the increased frequency of entries into and spent time within open arms by SD. In order to investigate the molecular mechanism on this effect of PG, we assessed differentially expressed genes (DEGs) in the prefrontal cortex of PG-treated SD rats using RNA sequencing (RNA-seq) and performed gene-enrichment analysis for DEGs. The gene-enrichment analysis showed that PG most prominently affected the glutamatergic synapse pathway. Among the glutamatergic synapse pathway genes, particularly, PG enhanced the expressions of glutamate transporter Slc1a3 and Slc1a2 reduced in SD rats. Moreover, we found that PG could inhibit the SD-induced phosphorylation of the NR2A subunit of the NMDA receptor. These results suggested that PG might have a therapeutic effect against the manic-like behaviors, regulating the glutamatergic neurotransmission.

Dopamine D1 receptor antagonist reduces stimulant-induced conditioned place preferences and dopamine receptor supersensitivity

Repeated administration of stimulants induces conditioned place preference (CPP). Dopamine receptor supersensitivity is developed in stimulant-induced CPP animals; however, dopamine receptor subtypes associated with the development of supersensitivity in CPP animals are largely unknown. The present preclinical study aimed to examine whether dopamine D1 or D2 receptor antagonists exert inhibitory effects on stimulant-induced psychological behaviors. Additionally, the authors aimed to elucidate the role of dopamine receptor supersensitivity on the development of reward-related behavior. Sprague Dawley rats subjected to methamphetamine- and cocaine-induced CPP tests were treated with dopamine D1 (SCH23390) or D2 (sulpiride) receptor antagonists. Following the CPP experiment, rats were challenged with apomorphine (dopamine receptor agonist), and locomotor activity was measured. Methamphetamine- and cocaine-induced CPP was reduced with the administration of SCH23390, but not sulpiride. In addition, the apomorphine challenge evoked an increase in locomotor activity in stimulant-pre-treated rats, reflecting dopamine receptor supersensitivity. SCH23390 pre-treatment inhibited the development of dopamine receptor supersensitivity, while sulpiride demonstrated no inhibitory effects. These results suggest that the dopamine D1 receptor antagonist SCH23390 inhibits the development of dopamine receptor supersensitivity which is associated with the development of CPP.

Hepataprotective effects of ginsenoside Rg1 - A review

BACKGROUND AND ETHNOPHARMACOLOGICAL RELEVANCE

Ginseng has been used as efficient tonic and for the treatment of various diseases including hepatic disorders. Ginseng saponins, also known as ginsenosides, are principal constituents and have been treated to be responsible for disparate ginseng health benefits. The current review mainly focuses on ginsenoside Rg1, a compound isolated from traditional Chinese herbal medicine Panax ginseng Meyer.

AIMS

To summary the hepataprotective effects and related mechanisms of ginsenoside Rg1, we conclude this review by combining the literature and our own researches.

METHODS

As evidenced, we organized the pharmacological function of ginsenoside Rg1 by searching the pubmed. It has been deeply studied and summarized in the field of neurobiology, however, in this paper we described the pharmacological function of Rg1 in liver related to antioxidative stress and anti-inflammation. R&D: Individual ginsenoside could be used since it shows a wide array of beneficial functions in the regulation and disorders of acute and chronic hepatotoxicity, hepatitis, hepatic fibrosis and cirrhosis in various pathways and different mechanisms. Of note, the antioxidant hepatic protection of ginsenoside Rg1 is mainly through the induction of Keap1-Nrf2-ARE signaling pathway.

CONCLUSION

The multi-target actions of Rg1 substantiates it as a promising drug candidate for the treatment of hepatic impairment in different factors induced liver diseases.

A Scutellaria baicalensis radix water extract inhibits morphine-induced conditioned place preference

CONTEXT

Scutellaria baicalensis Georgi (Lamiaceae) has been used as a traditional herbal preparation for the treatment of neuropsychiatric disorders in Asian countries for centuries.

OBJECTIVE

To evaluate the effects of S. baicalensis on morphine-induced drug dependence in rats.

MATERIALS AND METHODS

In order to evaluate the effect of S. baicalensis and baicalin on morphine-induced dependence-like behavior, a water extract of S. baicalensis [500 mg/kg, intraperitoneally (i.p.)] or baicalin (50 mg/kg, i.p., a flavonoid found in S. baicalensis) was administered prior to morphine injection [5 and 2.5 mg/kg, respectively, subcutaneously (s.c.)] to rats for 8 and 4 d, respectively. Morphine-induced conditioned place preference was assessed by measuring the time spent in a drug-paired chamber. The effect of S. baicalensis on dopamine receptor supersensitivity (locomotor activity) and dopamine agonist-induced climbing behavior due to a single apomorphine treatment (2 mg/kg, s.c.) was also measured.

RESULTS

At 50 mg/kg, a water extract of S. baicalensis decreased morphine (5 mg/kg)-induced conditioned place preference by 86% in rats. Apomorphine (2 mg/kg)-induced locomotor activity (dopamine receptor supersensitivity) in rats and climbing behavior in mice were attenuated after pretreatment with 500 mg/kg of S. baicalensis water extract by 41% and 56%, respectively. In addition, baicalin-reduced morphine-induced conditioned places preference by 86% in rats at 50 mg/kg.

DISCUSSION AND CONCLUSION

These results suggest that S. baicalensis can ameliorate drug addiction-related behavior through functional regulation of dopamine receptors.

Beneficial estrogen-like effects of ginsenoside Rb1, an active component of Panax ginseng, on neural 5-HT disposition and behavioral tasks in ovariectomized mice

Decreased 5-hydroxytryptamine (5-HT) concentration in the brain has been linked to central nervous system dysfunctions, especially in menopausal women. Ginsenoside Rb1, a potential phytoestrogen, has been shown to improve central nervous system dysfunctions, comparable to the estrogen treatment. To investigate the estrogen-like effects of ginsenoside Rb1 on neural 5-HT disposition and behavioral tasks, we quantified the concentrations of 5-HT and other related endogenous substances in the frontal cortex and striatum of ovariectomized mice. The activities of tryptophan hydroxylase (TPH), aromatic amino acid decarboxylase (AAAD) and monoamine oxidase (MAO) were also measured to evaluate the synthesis and metabolism of neural 5-HT. Our work shows that both ginsenoside Rb1 and estradiol increased the neural 5-HT concentration. Ginsenoside Rb1 and estradiol administration resulted in elevated TPH and depressed MAO activities, indicating that modulating the synthesis and metabolism of neural 5-HT successfully elevated 5-HT concentration. Ginsenoside Rb1 and estradiol also improved object recognition and decreased immobility time in the forced swimming test. However, a pretreatment with clomiphene (an estrogen receptor antagonist) blocked the beneficial effects of ginsenoside Rb1 and estradiol, suggesting that the estrogen-like effects of ginsenoside Rb1 were estrogen receptor-dependent.

Traditional medicine in the treatment of drug addiction

AIMS

To evaluate clinical trials and neurochemical mechanisms of the action of traditional herbal remedies and acupuncture for treating drug addiction.

METHODS

We used computerized literature searches in English and Chinese and examined texts written before these computerized databases existed. We used search terms of treatment and neurobiology of herbal medicines, and acupuncture for drug abuse and dependence.

RESULTS

Acupuncture showed evidence for clinical efficacy and relevant neurobiological mechanisms in opiate withdrawal, but it showed poor efficacy for alcohol and nicotine withdrawal or relapse prevention, and no large studies supported its efficacy for cocaine in well-designed clinical trials. Clinical trials were rare for herbal remedies. Radix Puerariae showed the most promising efficacy for alcoholism by acting through daidzin, which inhibits mitocochondrial aldehyde dehydrogenase 2 and leads to disulfiram-like alcohol reactions. Peyote also has some evidence for alcoholism treatment among Native Americans. Ginseng and Kava lack efficacy data in addictions, and Kava can be hepatotoxic. Thunbergia laurifolia can protect against alcoholic liver toxicity. Withania somnifera and Salvia miltiorrhiza have no efficacy data, but can reduce morphine tolerance and alcohol intake, respectively, in animal models.

CONCLUSIONS

Traditional herbal treatments can compliment pharmacotherapies for drug withdrawal and possibly relapse prevention with less expense and perhaps fewer side effects with notable exceptions. Both acupuncture and herbal treatments need testing as adjuncts to reduce doses and durations of standard pharmacotherapies.

Fermented ginseng improves the first-night effect in humans

STUDY OBJECTIVES

The goal of this study was to clarify whether ginseng fermented by lactic acid bacteria (fermented ginseng, FG), can improve the first-night effect (FNE) in humans.

DESIGN

Behavioral tests and quantification of mRNA expression related to GABAergic neurotransmission in brain (glutamic acid decarboxylase 1, gamma-aminobutyrate aminotransferase [Abat], gamma-aminobutyric acid transporter 1 [GAT1], gamma-aminobutyric acid transporter 4, gamma-aminobutyric acid A receptor subunit alpha 1 and gamma-aminobutyric acid A receptor subunit alpha 2) were carried out in FG-treated mice. We also performed double-blind sleep recordings of human subjects given FG or placebo.

SETTING

A university-based sleep laboratory.

PATIENTS OR PARTICIPANTS

Sixteen healthy male volunteers (aged 20.69 +/- 0.44 years) were observed in the human study.

INTERVENTIONS

At the end of administration, 2 consecutive all-night polysomnography recordings were performed. Subjects also completed psychological questionnaires, and urine and saliva samples were taken to analyze stress-sensitive markers.

MEASUREMENTS AND RESULTS

The light-dark transition test demonstrated that FG had some anxiolytic effect in mice, but other anxiety measures were unaffected. The hippocampal mRNA expression showed a decrease of Abat and GAT1 suggesting an increase of GABA. Other regions (amygdala and cerebellum) showed no differences. Furthermore, there was some evidence (using simple pairwise comparisons but not supported in the full ANOVA model) that administration of FG tended to diminish decreases in total sleep time and sleep efficiency (seen as first night effects in the placebo group) without affecting sleep architecture.

CONCLUSIONS

Our results suggest the administration of FG could improve the FNE in humans. The improvement may be related to an anxiolytic effect of FG which acts via GABAergic modification.

Measuring reward with the conditioned place preference (CPP) paradigm: update of the last decade

Conditioned place preference (CPP) continues to be one of the most popular models to study the motivational effects of drugs and non-drug treatments in experimental animals. This is obvious from a steady year-to-year increase in the number of publications reporting the use this model. Since the compilation of the preceding review in 1998, more than 1000 new studies using place conditioning have been published, and the aim of the present review is to provide an overview of these recent publications. There are a number of trends and developments that are obvious in the literature of the last decade. First, as more and more knockout and transgenic animals become available, place conditioning is increasingly used to assess the motivational effects of drugs or non-drug rewards in genetically modified animals. Second, there is a still small but growing literature on the use of place conditioning to study the motivational aspects of pain, a field of pre-clinical research that has so far received little attention, because of the lack of appropriate animal models. Third, place conditioning continues to be widely used to study tolerance and sensitization to the rewarding effects of drugs induced by pre-treatment regimens. Fourth, extinction/reinstatement procedures in place conditioning are becoming increasingly popular. This interesting approach is thought to model certain aspects of relapse to addictive behavior and has previously almost exclusively been studied in drug self-administration paradigms. It has now also become established in the place conditioning literature and provides an additional and technically easy approach to this important phenomenon. The enormous number of studies to be covered in this review prevented in-depth discussion of many methodological, pharmacological or neurobiological aspects; to a large extent, the presentation of data had to be limited to a short and condensed summary of the most relevant findings.

Inhibitory effects of paeonol on morphine-induced locomotor sensitization and conditioned place preference in mice

The inhibitory effects of paeonol, a major compound of Paeoniae radix, on the development of locomotor sensitization, conditioned place preference (CPP) and dopamine receptor supersensitivity induced by the repeated administration of morphine were investigated through behavioral experiments. A single administration of morphine produces hyperlocomotion. Repeated administration of morphine develops sensitization (reverse tolerance), a progressive enhancement of locomotion, which is used as a model for studying the drug-induced drug-seeking behaviors, and CPP, which is used as a model for studying drug reinforcement. Paeonol inhibited morphine-induced hyperlocomotion, sensitization and CPP. In addition, paeonol inhibited the development of postsynaptic dopamine receptors supersensitivity, which may be an underlying common mechanism that mediates the morphine-induced dopaminergic behaviors such as sensitization and CPP. Apomorphine (a dopamine agonist)-induced climbing behaviors also were inhibited by a single direct administration of paeonol. These results provide evidence that paeonol exerts anti-dopaminergic activity, and it is suggested that paeonol may be useful for the prevention and therapy of these adverse actions of morphine.

Pharmacological action of Panax ginseng on the behavioral toxicities induced by psychotropic agents

Morphine-induced analgesia has been shown to be antagonized by ginseng total saponins (GTS), which also inhibit the development of analgesic tolerance to and physical dependence on morphine. GTS is involved in both of these processes by inhibiting morphine-6-dehydrogenase, which catalyzes the synthesis of morphinone from morphine, and by increasing the level of hepatic glutathione, which participates in the toxicity response. Thus, the dual actions of ginseng are associated with the detoxification of morphine. In addition, the inhibitory or facilitated effects of GTS on electrically evoked contractions in guinea pig ileum (mu-receptors) and mouse vas deferens (delta-receptors) are not mediated through opioid receptors, suggesting the involvement of non-opioid mechanisms. GTS also attenuates hyperactivity, reverse tolerance (behavioral sensitization), and conditioned place preference induced by psychotropic agents, such as methamphetamine, cocaine, and morphine. These effects of GTS may be attributed to complex pharmacological actions between dopamine receptors and a serotonergic/adenosine A2A/ delta-opioid receptor complex. Ginsenosides also attenuate the morphine-induced cAMP signaling pathway. Together, the results suggest that GTS may be useful in the prevention and therapy of the behavioral side effects induced by psychotropic agents.

Anxiolytic-like effects of ginsenosides on the elevated plus-maze model in mice

In a previous study, we reported that ginseng extract has anxiolytic-like effects in the elevated plus-maze model and that the ginseng saponin fraction plays an important role. This experiment was performed to investigate the anxiolytic-like effects of ginsenosides Rb1, Rg1, Rg3-R, and Rg3-S, and the Rg5 and Rk mixture isolated from the ginseng saponin fraction in the elevated plus-maze. Furthermore, the anxiolytic-effects of Rb1, Rg1, Rg3-R, Rg3-S, and the Rg5 and Rk mixture were compared with those of a well-known active anxiolytic drug (diazepam). The oral administration of ginsenoside Rb1 significantly increased the number of open arm entries and the time spent on the open arm compared with those in the vehicle-treated group. Ginsenoside Rg1 and the Rg5 and Rk mixture also significantly increased the number of open arm entries and the time spent on the open arm. However, ginsenosides Rg3-R and Rg3-S did not increase the number of open arm entries or the time spent on the open arm. On the other hand, ginsenoside Rb1 and the Rg5 and Rk mixture decreased locomotor activity in a manner similar to diazepam. These data indicate that ginsenosides Rb1, Rg1, and the Rg5 and Rk mixture have anxiolytic-like effects, but ginsenosides Rg3-R and Rg3-S do not in this model. We provide evidence that some ginsenosides may be useful for the treatment of anxiety.

Calcium-independent CaMKII activity is involved in ginsenoside Rb1-mediated neuronal recovery after hypoxic damage

Recent studies have indicated that Ginsenoside Rb1, one of the major components of ginseng root, may play an important role in protecting cells from damage. Here, we investigated the neuroprotective activity of Rb1 after hypoxic injury in young rats. About 50% animals were dead by exposing hypoxic condition three times in three consecutive days. Then, the pretreatment with Rb1 prior to hypoxic stimulation reduced animal death to 12%, and also significantly reduced the recovery time from hypoxia-related, compromised symptoms in survived animals. Rb1 also significantly reduced levels of lactate dehydrogenase (LDH) release from primary hippocampal neurons which were maintained at low oxygen concentration, indicating increased neuronal survival by Rb1. Ca(2+)/calmodulin-dependent kinase II (CaMKII) activity in the hippocampal tissues of hypoxia-induced rats was decreased to about 50% of the control animal. Then Rb1-treatment prior to hypoxic stimulation significantly elevated Ca(2+)-independent kinase II activity when measured 48 hr after hypoxic stimulation. Thus, the present data suggest that calcium independent CaMKII activity may be involved in the process of ginsenoside Rb1-mediated recovery of neuronal cells after hypoxic damage.

Inhibitory effects of glycine on morphine-induced hyperactivity, reverse tolerance and postsynaptic dopamine receptor supersensitivity in mice

The effects of glycine on morphine-induced hyperactivity, reverse tolerance and postsynaptic dopamine receptor supersensitivity in mice was examined. A single administration of morphine (10 mg/kg, s.c.) induced hyperactivity as measured in mice. The morphine-induced hyperactivity was inhibited by pretreatment with glycine (100, 200 and 400 mg/kg, i.p.). In addition, it was found repeated administration of morphine (10 mg/kg, s.c.) to mice daily for 6 days caused an increase in motor activity which could be induced by a subsequent morphine dose, an effect known as reverse tolerance or sensitization. Glycine (100, 200 and 400 mg/kg, i.p.) also inhibited morphine-induced reverse tolerance. Mice that had received 7 daily repeated administrations of morphine also developed postsynaptic dopamine receptor supersensitivity, as shown by enhanced ambulatory activity after administration of apomorphine (2 mg/kg, s.c.). Glycine inhibited the development of postsynaptic dopamine receptor supersensitivity induced by repeated administration of morphine. It is suggested that the inhibitory effects of glycine might be mediated by dopaminergic (DAergic) transmission. Accordingly, the inhibition by glycine of the morphine-induced hyperactivity, reverse tolerance and dopamine receptor supersensitivity suggests that glycine might be useful for the treatment of morphine addiction.

Neurotransmitter levels in brains of chronically Jiawey Siwu-treated rats

Levels of monoamines and metabolites, excitatory amino acids, and gamma-aminobutyric acid (GABA) were investigated in discrete brain areas of chronic Jiawey Siwu (JS)-treated rats. Male Sprague-Dawley rats were dosed orally for 3 months with normal saline or JS at 0.21, 1.05 or 4.2 g/kg/day. Body weights of these four groups were similar over 3 months. Most effects of JS revealed a dose dependency with levels of neurotransmitters. Levels of norepinephrine (NE) and epinephrine (EPI) in cerebral cortex; EPI, vanillylmandelic acid (VMA), dopamine (DA) and 5-hydroxytryptamine (5-HT) in medulla oblongata; DA in midbrain; NE and 5-HT in amygdala; and 5-HT in hypothalamus had decreased in JS-treated rats. 3-Methoxytyramine (3-MT) in cerebral cortex; 5-hydroxyindole-3-acetic acid (5-HIAA) in medulla oblongata; NE, 3-MT and homovanillic acid (HVA) in pons; EPI and 3-MT in midbrain; 3-MT and HVA in amygdala; 3-MT, 3,4-dihydroxyphenylacetic acid (DOPAC), HVA and 5-HIAA in cerebellum; HVA in hypothalamus; and DOPAC and HVA in hippocampus had all increased in JS-treated rats. In pons, 5-HT increased with low and decreased with high JS doses. Ratios of DA/3-MT in pons and midbrain; DA/HVA in pons and cerebellum; and 5-HT/5-HIAA in medulla oblongata, cerebellum and hypothalamus had decreased. Furthermore, aspartate (ASP) and glutamate (GLU) levels had decreased in cerebral cortex, midbrain, hypothalamus and hippocampus or amygdala, and increased in pons. GABA levels were reduced in cerebral cortex, and higher in medulla oblongata, pons, amygdala, cerebellum, hippocampus and striatum of JS-treated rats. These results indicate that the synthesis and (or) metabolism of NE, DA, EPI and 5-HT, and the levels of ASP, GLU and GABA in rat brains were differentially regionally altered by JS, which may contribute to the central manifestations of JS treatment.

Dual effects of dextromethorphan on cocaine-induced conditioned place preference in mice

Dextromethorphan (DM) at supra-antitussive doses might produce psychotomimetic effects in humans. In order to understand the underlying mechanisms responsible for the behavior induced by DM, we examined the effects of DM on cocaine-induced conditioned place preference (CPP) and locomotor pattern in mice, and Fos-related antigen immunoreactivity (FRA-IR) in the striatal complex (nucleus accumbens and striatum) of the mouse brain. The effects of DM (20 and 40 mg/kg, i.p.) on the CPP for 2.5, 5, 10, and 20 mg cocaine/kg, i.p. were assessed. Pretreatment with DM dose-dependently decreased the CPP for 20 mg cocaine/kg. Similarly, pretreatment with DM appeared to reduce the CPP for 10 mg cocaine/kg, but increase the CPP for 5 mg cocaine/kg. This finding was more pronounced for 2.5 mg cocaine/kg; DM significantly increased the CPP for 2.5 mg cocaine/kg in a dose-related manner. Furthermore, these results were correlated with alterations in the locomotor pattern (marginal activity) and FRA-IR in the striatal complex. Thus, our results suggest that DM exhibits a biphasic effect on the cocaine-induced CPP and locomotor pattern.