Effect of saikosaponin A on maintenance of intravenous morphine self-administration

The therapeutic effects of saikosaponins on depression through the modulation of neuroplasticity: From molecular mechanisms to potential clinical applications

Depression is a major global health issue that urgently requires innovative and precise treatment options. In this context, saikosaponin has emerged as a promising candidate, offering a variety of therapeutic benefits that may be effective in combating depression. This review delves into the multifaceted potential of saikosaponins in alleviating depressive symptoms. We summarized the effects of saikosaponins on structural and functional neuroplasticity, elaborated the regulatory mechanism of saikosaponins in modulating key factors that affect neuroplasticity, such as inflammation, the hypothalamic-pituitary-adrenal (HPA) axis, oxidative stress, and the brain-gut axis. Moreover, this paper highlights existing gaps in current researches and outlines directions for future studies. A detailed plan is provided for the future clinical application of saikosaponins, advocating for more targeted researches to speed up its transition from preclinical trials to clinical practice.

Reducing effect of intragastrically administered saikosaponin A on alcohol and sucrose self-administration in rats

Saikosaponin A (SSA) is an active ingredient of the Asian medicinal herb, Bupleurum falcatum L. When administered via the intraperitoneal (i.p.) route, SSA suppressed multiple addictive-like behaviours, including operant alcohol self-administration, in rodents. It is unknown whether these effects are retained after intragastric (i.g.) administration, a desirable prerequisite for a compound with therapeutic potential. To fill this gap, i.g. SSA (0, 50, and 100 mg/kg) was tested in Sardinian alcohol-preferring (sP) rats trained to lever-respond for oral alcohol. SSA reduced lever-responding and amount of self-administered alcohol. However, when compared to i.p. SSA, i.g. SSA resulted to be markedly less potent and effective, suggestive of reduced bioavailability after i.g. treatment. Finally, and in agreement with previous data on the suppressing effect of i.p. SSA on behaviours motivated by highly palatable foods, i.g. SSA (0, 50, and 100 mg/kg) reduced oral sucrose self-administration in a separate set of sP rats.

In Vivo Evaluation of Self-assembled nano-Saikosaponin-a for Epilepsy Treatment

Saikosaponin-a (SSa) exhibits antiepileptic effects. However, its poor water solubility and inability to pass through the blood-brain barrier greatly limit its clinical development and application. In this study, SSa-loaded Methoxy poly (ethylene glycol)-poly(ε-caprolactone) (MePEG-SSa-PCL) NPs were successfully prepared and characterized. Our objective was to further investigate the effect of this composite on acute seizure in mice. First, we confirmed the particle size and surface potential of the composite (51.00 ± 0.25 nm and - 33.77 ± 2.04 mV, respectively). Further, we compared the effects of various MePEG-SSa-PCL doses (low, medium, and high) with those of free SSa, valproic acid (VPA - positive control), and saline only (model group) on acute seizure using three different acute epilepsy mouse models. We observed that compared with the model group, the three MePEG-SSa-PCL treatments showed significantly lowered seizure frequency in mice belonging to the maximum electroconvulsive model group. In the pentylenetetrazol and kainic acid (KA) acute epilepsy models, MePEG-SSa-PCL increased both clonic and convulsion latency periods and shortened convulsion duration more effectively than equivalent SSa-only doses. Furthermore, hematoxylin-eosin and Nissl staining revealed considerably less neuronal damage in the hippocampal CA3 area of KA mice in the SSa, VPA, and three MePEG-SSa-PCL groups relative to mice in the model group. Hippocampal gamma-aminobutyric acid-A (GABA-A) receptor and cleaved caspase-3 expression levels in KA mice were significantly higher and lower, respectively, in the three MePEG-SSa-PCL treatment groups than in the model group. Thus, MePEG-SSa-PCL exhibited a more potent antiepileptic effect than SSa in acute mouse epilepsy models and could alleviate neuronal damage in the hippocampus following epileptic seizures, possibly via GABA-A receptor expression upregulation.

The Role of Saponins in the Treatment of Neuropathic Pain

Neuropathic pain is a chronic pain caused by tissue injury or disease involving the somatosensory nervous system, which seriously affects the patient's body function and quality of life. At present, most clinical medications for the treatment of neuropathic pain, including antidepressants, antiepileptic drugs, or analgesics, often have limited efficacy and non-negligible side effects. As a bioactive and therapeutic component extracted from Chinese herbal medicine, the role of the effective compounds in the prevention and treatment of neuropathic pain have gradually become a research focus to explore new analgesics. Notably, saponins have shown analgesic effects in a large number of animal models. In this review, we summarized the most updated information of saponins, related to their analgesic effects in neuropathic pain, and the recent progress on the research of therapeutic targets and the potential mechanisms. Furthermore, we put up with some perspectives on future investigation to reveal the precise role of saponins in neuropathic pain.

Bupleurum chinense DC improves CUMS-induced depressive symptoms in rats through upregulation of the cAMP/PKA/CREB signalling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Bupleurum chinense DC. (B. chinense) is the dried root of B. chinense, belonging to the Umbelliferae family. B. chinense has been reported since ancient times for its effect of soothing the liver and relieving depression. Additionally, its important role in treating depression, depressed mood disorders and anti-inflammation has been proven in previous studies. However, its specific mechanism of action remains unknown.

AIM OF THE STUDY

The key targets and metabolites of the antidepressant effect of B. chinense were investigated based on the cAMP signalling pathway. The study examined the mechanism for the antidepressant effect of B. chinense by target prediction, analysis of related metabolites and potential metabolic pathways.

MATERIALS AND METHODS

A network pharmacology approach was used to predict the antidepressant targets and pathways of B. chinense. A depression rat model was established through the CUMS (chronic unpredictable mild stress) procedure. The depression model was assessed by body weight, sugar-water preference, water maze and enzyme-linked immunosorbent assay (ELISA) indicators (5hydroxytryptamine, etc.). The key metabolic pathways were screened by correlations between metabolites and key targets. Finally, a quantitative analysis of key targets and metabolites was experimentally validated.

RESULTS

B. chinense significantly ameliorated the reduction in body weight, sugar-water preference rate and cognitive performance in the water maze experiment in rats with depression induced by CUMS. ELISA, Western blotting (WB) and reverse transcription-polymerase chain reaction (RT-PCR) assays showed that B. chinense significantly improves the expression of protein kinase cyclic adenylic acid (cAMP)-activated catalytic subunit alpha (PRKACA), cAMP-response element-binding protein (CREB) and cAMP activation in the rat brain induced by CUMS. According to metabolic pathway analysis, B. chinense shows an antidepressant effect primarily by regulating the cAMP metabolic pathway.

CONCLUSION

B. chinense upregulated PRKACA and CREB expression and the level of the key metabolite cAMP in the cAMP/PKA/CREB pathway while reducing the inflammatory response to depression treatment. These new findings support future research on the antidepressant effects of B. chinense.

Aberrations in peripheral inflammatory cytokine levels in substance use disorders: a meta-analysis of 74 studies

AIMS

To characterize the peripheral inflammatory cytokine profile in people with substance use disorders (SUDs).

DESIGN

Systematic review and meta-analysis.

SETTING

Clinical studies that evaluated peripheral blood inflammatory cytokine levels in patients with SUDs and healthy controls PARTICIPANTS: SUD patients and healthy controls.

MEASUREMENTS

PubMed and Web of Science were systematically searched for relevant studies. Two investigators independently selected studies and extracted data. A total of 77 articles were included in the meta-analysis, containing 5649 patients with SUDs and 4643 healthy controls. Data were pooled using a random-effects model by the Comprehensive Meta-Analysis version 2 software.

FINDINGS

Concentrations of interleukin (IL)-6) in 32 studies, tumor necrosis factor (TNF)-α in 28 studies, IL-10 in 20 studies, IL-8 in 17 studies, C-reactive protein in 14 studies, IL-4 in 10 studies, IL-12 in seven studies, monocyte chemoattractant protein (MCP)-1 in 6 studies, TNF-receptor 2 (TNF-R2) in four studies and granulocyte-macrophage colony-stimulating factor (GM-CSF) in three studies were significantly higher in patients with SUDs compared with healthy controls, while concentrations of leptin in 14 studies were significantly lower in patients with SUDs compared with healthy controls. The findings were inconclusive for the associations between interferon-γ, IL-1β, IL-2, IL-1 receptor antagonist (IL-1RA), transforming growth factor (TGF)-β1, G-CSF, C-C motif chemokine 11, TGF-α and SUDs.

CONCLUSIONS

People with substance use disorders (SUDs) appear to have higher peripheral concentrations of IL-4, IL-6, IL-8, IL-10, IL-12, TNF-α, C-reactive protein, MCP-1, TNF-R2 and GM-CSF and lower peripheral concentrations of leptin than people without SUDs. This strengthens the view that SUD is accompanied by an inflammatory response.

Differential Effects of Saikosaponins A, B2, B4, C and D on Alcohol and Chocolate Self-Administration in Rats

AIMS

Treatment with saikosaponin A (SSA)-an ingredient of the medicinal herb, Bupleurum falcatum-has been reported to suppress several addictive-like behaviors, including morphine, cocaine, alcohol and chocolate self-administration in male rats. The aim of this investigation was to investigate whether saikosaponins of B. falcatum other than SSA affect alcohol and chocolate self-administration in rats.

METHODS

Ovariectomized female Sardinian alcohol-preferring (sP) and Wistar rats were trained to self-administer alcohol (15%, v/v) and a chocolate solution [5% (w/v) Nesquik® in water], respectively, under fixed ratio schedules of reinforcement. The following saikosaponins were compared to SSA: saikosaponin D (SSD; epimer of SSA), saikosaponin C (SSC), saikosaponin B2 (SSB2) and saikosaponin B4 (SSB4). All saikosaponins were tested acutely at the doses of 0, 0.25, 0.5 and 1 mg/kg (i.p.).

RESULTS

Treatment with SSA and SSD resulted in highly similar, marked reductions in alcohol self-administration; SSC failed to alter lever-responding for alcohol, while SSB2 and SSB4 produced intermediate reductions. Only SSA and SSD reduced chocolate self-administration, with SSC, SSB2 and SSB4 being ineffective.

CONCLUSIONS

The wide spectrum of efficacy of saikosaponins in reducing alcohol and chocolate self-administration suggests that even relatively small structural differences are sufficient to produce remarkable changes in their in vivo pharmacological profile. Together, these results confirm that roots of B. falcatum may be an interesting source of compounds with anti-addictive potential.

Saikosaponin d causes apoptotic death of cultured neocortical neurons by increasing membrane permeability and elevating intracellular Ca2+ concentration

Saikosaponins (SSs) are a class of naturally occurring oleanane-type triterpenoid saponins found in Radix bupleuri that has been widely used in traditional Chinese medicine. As the main active principals of Radix bupleuri, SSs have been shown to suppress mouse motor activity, impair learning and memory, and decrease hippocampal neurogenesis. In the present study, we investigated the effect of five SSs (SSa, SSb1, SSb2, SSc, and SSd) on neuronal viability and the underlying mechanisms in cultured murine neocortical neurons. We demonstrate that SSa, SSb1 and SSd produce concentration-dependent apoptotic neuronal death and induce robust increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) at low micromolar concentrations with a rank order of SSd > SSa > SSb1, whereas SSb2 and SSc have no detectable effect on both neuronal survival and [Ca²⁺]_i. Mechanistically, SSd-induced elevation in [Ca²⁺]_i is the primary result of enhanced extracellular Ca²⁺ influx, which likely triggers Ca²⁺-induced Ca²⁺ release through ryanodine receptor activation, but not SERCA inhibition. SSd-induced Ca²⁺ entry occurs through a non-selective mechanism since blockers of major neuronal Ca²⁺ entry pathways, including L-type Ca²⁺ channel, NMDA receptor, AMPA receptor, Na⁺-Ca²⁺ exchanger, and TRPV1, all failed to attenuate the Ca²⁺ response to SSd. Further studies demonstrate that SSd increases calcein efflux and induces an inward current in neocortical neurons. Together, these data demonstrate that SSd elevates [Ca²⁺]_i due to its ability to increase membrane permeability, likely by forming pores in the surface of membrane, which leads to massive Ca²⁺ influx and apoptotic neuronal death in neocortical neurons.

A comprehensive review and perspectives on pharmacology and toxicology of saikosaponins

BACKGROUND

Radix Bupleuri (RB) has been widely used in Chinese Traditional Medicine for over 2000 years and is currently marketed in China as Chai-Hu-Shu-Gan tablets and Xiao-Yao-Wan tablets. Saikosaponins (SSs, especially SSa, SSc and SSd), as the major bioactive compounds in RB, represent anti-inflammatory, anti-tumor, anti-oxidant, anti-viral and hepatoprotective effects.

PURPOSE

To summarize recent findings regarding to the extraction, detection, biosynthesis, metabolism, pharmacological/toxicological effects of SSs.

METHODS

Online academic databases (including PubMed, Google Scholar, Web of Science and CNKI) were searched using search terms of "Saikosaponin", "Radix Bupleuri", "Bupleurum" and combinations to include published studies of SSs primarily from 2003 to 2018. Several critical previous studies beyond this period were also included.

RESULTS

354 papers were found and 165 papers were reviewed. SSs have drawn great attention for their anti-inflammation, anti-viral and anti-cancer effects and contradictory roles in the regulation of cell apoptosis, oxidative stress and liver fibrosis. Meanwhile, increased risks of overdose-induced acute or accumulation-related chronic hepatotoxicity of SSs and RB have also been reported. However, underlying mechanisms of SSs bioactivities, the metabolism of SSs and bioactivities of SSs metabolites are largely unknown.

CONCLUSION

This comprehensive review of SSs provides novel insights and perspectives on the limitations of current studies and the importance of metabolism study and the dose-pharmacological/toxic relationship of SSs for the future discovery of SSs-based therapeutic strategies and clinical safe practice.

A comprehensive review and perspectives on pharmacology and toxicology of saikosaponins

BACKGROUND

Radix Bupleuri (RB) has been widely used in Chinese Traditional Medicine for over 2000 years and is currently marketed in China as Chai-Hu-Shu-Gan tablets and Xiao-Yao-Wan tablets. Saikosaponins (SSs, especially SSa, SSc and SSd), as the major bioactive compounds in RB, represent anti-inflammatory, anti-tumor, anti-oxidant, anti-viral and hepatoprotective effects.

PURPOSE

To summarize recent findings regarding to the extraction, detection, biosynthesis, metabolism, pharmacological/toxicological effects of SSs.

METHODS

Online academic databases (including PubMed, Google Scholar, Web of Science and CNKI) were searched using search terms of "Saikosaponin", "Radix Bupleuri", "Bupleurum" and combinations to include published studies of SSs primarily from 2003 to 2018. Several critical previous studies beyond this period were also included.

RESULTS

354 papers were found and 165 papers were reviewed. SSs have drawn great attention for their anti-inflammation, anti-viral and anti-cancer effects and contradictory roles in the regulation of cell apoptosis, oxidative stress and liver fibrosis. Meanwhile, increased risks of overdose-induced acute or accumulation-related chronic hepatotoxicity of SSs and RB have also been reported. However, underlying mechanisms of SSs bioactivities, the metabolism of SSs and bioactivities of SSs metabolites are largely unknown.

CONCLUSION

This comprehensive review of SSs provides novel insights and perspectives on the limitations of current studies and the importance of metabolism study and the dose-pharmacological/toxic relationship of SSs for the future discovery of SSs-based therapeutic strategies and clinical safe practice.

A comprehensive review and perspectives on pharmacology and toxicology of saikosaponins

BACKGROUND

Radix Bupleuri (RB) has been widely used in Chinese Traditional Medicine for over 2000 years and is currently marketed in China as Chai-Hu-Shu-Gan tablets and Xiao-Yao-Wan tablets. Saikosaponins (SSs, especially SSa, SSc and SSd), as the major bioactive compounds in RB, represent anti-inflammatory, anti-tumor, anti-oxidant, anti-viral and hepatoprotective effects.

PURPOSE

To summarize recent findings regarding to the extraction, detection, biosynthesis, metabolism, pharmacological/toxicological effects of SSs.

METHODS

Online academic databases (including PubMed, Google Scholar, Web of Science and CNKI) were searched using search terms of "Saikosaponin", "Radix Bupleuri", "Bupleurum" and combinations to include published studies of SSs primarily from 2003 to 2018. Several critical previous studies beyond this period were also included.

RESULTS

354 papers were found and 165 papers were reviewed. SSs have drawn great attention for their anti-inflammation, anti-viral and anti-cancer effects and contradictory roles in the regulation of cell apoptosis, oxidative stress and liver fibrosis. Meanwhile, increased risks of overdose-induced acute or accumulation-related chronic hepatotoxicity of SSs and RB have also been reported. However, underlying mechanisms of SSs bioactivities, the metabolism of SSs and bioactivities of SSs metabolites are largely unknown.

CONCLUSION

This comprehensive review of SSs provides novel insights and perspectives on the limitations of current studies and the importance of metabolism study and the dose-pharmacological/toxic relationship of SSs for the future discovery of SSs-based therapeutic strategies and clinical safe practice.

A comprehensive review and perspectives on pharmacology and toxicology of saikosaponins

BACKGROUND

Radix Bupleuri (RB) has been widely used in Chinese Traditional Medicine for over 2000 years and is currently marketed in China as Chai-Hu-Shu-Gan tablets and Xiao-Yao-Wan tablets. Saikosaponins (SSs, especially SSa, SSc and SSd), as the major bioactive compounds in RB, represent anti-inflammatory, anti-tumor, anti-oxidant, anti-viral and hepatoprotective effects.

PURPOSE

To summarize recent findings regarding to the extraction, detection, biosynthesis, metabolism, pharmacological/toxicological effects of SSs.

METHODS

Online academic databases (including PubMed, Google Scholar, Web of Science and CNKI) were searched using search terms of "Saikosaponin", "Radix Bupleuri", "Bupleurum" and combinations to include published studies of SSs primarily from 2003 to 2018. Several critical previous studies beyond this period were also included.

RESULTS

354 papers were found and 165 papers were reviewed. SSs have drawn great attention for their anti-inflammation, anti-viral and anti-cancer effects and contradictory roles in the regulation of cell apoptosis, oxidative stress and liver fibrosis. Meanwhile, increased risks of overdose-induced acute or accumulation-related chronic hepatotoxicity of SSs and RB have also been reported. However, underlying mechanisms of SSs bioactivities, the metabolism of SSs and bioactivities of SSs metabolites are largely unknown.

CONCLUSION

This comprehensive review of SSs provides novel insights and perspectives on the limitations of current studies and the importance of metabolism study and the dose-pharmacological/toxic relationship of SSs for the future discovery of SSs-based therapeutic strategies and clinical safe practice.

Reducing Effect of Saikosaponin A, an Active Ingredient of Bupleurum falcatum, on Intake of Highly Palatable Food in a Rat Model of Overeating

Recent lines of experimental evidence have indicated that saikosaponin A (SSA)-a bioactive ingredient of the medicinal plant, Bupleurum falcatum L.-potently and effectively reduced operant self-administration of chocolate and reinstatement of chocolate-seeking behavior in rats. The present study was designed to assess whether the protective properties of SSA on addictive-like, food-related behaviors generalize to a rat model of overeating of palatable food. To this end, rats were habituated to feed on a standard rat chow for 3 h/day; every 4 days, the 3-h chow-feeding session was followed by a 1-h availability of highly palatable, calorie-rich Danish butter cookies or Oreo chocolate cookies. Even though fed, rats consumed large amounts of cookies; intake of calories from cookies (consumed in 1 h) was even larger than that of calories from chow (consumed in 3 h). SSA (0, 0.25, 0.5, and 1 mg/kg, i.p.) was administered 10 min before cookie presentation. Treatment with SSA resulted in a dose-related decrease in intake of both butter and chocolate cookies. Administration of the cannabinoid CB₁ receptor antagonist/inverse agonist, rimonabant (0, 0.3, 1, and 3 mg/kg, i.p.; tested as reference compound), produced a similar reduction in intake of butter cookies. These results (a) contribute to the set-up and validation of a rat model of overeating, characterized by the intake of large amounts of unnecessary calories and (b) provide an additional piece of evidence to the anorectic profile of SSA in rats.

A systematic review of the active saikosaponins and extracts isolated from Radix Bupleuri and their applications

CONTEXT

Radix Bupleuri has been used in traditional Chinese medicine for over 2000 years with functions of relieving exterior syndrome, clearing heat, regulating liver-qi, and lifting yang-qi. More natural active compounds, especially saikosaponins, have been isolated from Radix Bupleuri, which possess various valuable pharmacological activities.

OBJECTIVE

To summarize the current knowledge on pharmacological activities, mechanisms and applications of extracts and saikosaponins isolated from Radix Bupleuri, and obtain new insights for further research and development of Radix Bupleuri.

METHODS

PubMed, Web of Science, Science Direct, Research Gate, Academic Journals and Google Scholar were used as information sources through the inclusion of the search terms 'Radix Bupleuri', 'Bupleurum', 'saikosaponins', 'Radix Bupleuri preparation', and their combinations, mainly from the year 2008 to 2016 without language restriction. Clinical preparations containing Radix Bupleuri were collected from official website of China Food and Drug Administration (CFDA).

RESULTS AND CONCLUSION

296 papers were searched and 128 papers were reviewed. A broad spectrum of in vitro and in vivo research has proved that Radix Bupleuri extracts, saikosaponin a, saikosaponin d, saikosaponin c, and saikosaponin b₂, exhibit evident anti-inflammatory, antitumor, antiviral, anti-allergic, immunoregulation, and neuroregulation activities mainly through NF-κB, MAPK or other pathways. 15 clinical preparations approved by CFDA remarkably broaden the application of Radix Bupleuri. The main side effect of Radix Bupleuri is liver damage when the dosage is excess, which indicates that the maximum tolerated dose is critical for clinical use of Radix Bupleuri extract and purified compounds.

Suppressing effect of saikosaponin A, an active ingredient of Bupleurum falcatum, on chocolate self-administration and reinstatement of chocolate seeking in rats

Recent lines of experimental evidence have indicated that saikosaponin A (SSA) - a bioactive ingredient of the medicinal plant, Bupleurum falcatum L. - suppressed alcohol, morphine, and cocaine self-administration in rats. The present paper was designed to assess whether the protective properties of SSA on addiction-related behaviors generalize to a hyperpalatable food such as a chocolate-flavored beverage (CFB). To this end, rats were initially trained to lever-respond for CFB [5% (w/v) Nesquik^® powder in water] under fixed ratio (FR) 10 (FR10) schedule of reinforcement. Once lever-responding reached stable levels, rats were treated acutely with two different dose ranges of SSA (0, 0.25, 0.5, and 1mg/kg; 0, 1, 2.5, and 5mg/kg; i.p.) and exposed to the FR10 and progressive ratio (PR) schedules of reinforcement in four independent experiments. The effect of acutely administered SSA (0, 0.25, 0.5, and 1mg/kg; i.p.) on cue-induced reinstatement of seeking behavior for CFB was also assessed. Under the FR and PR schedules of reinforcement, treatment with SSA diminished lever-responding for CFB, amount of self-administered CFB, and breakpoint for CFB. All variables were virtually completely suppressed after treatment with 5mg/kg SSA. Treatment with SSA also suppressed reinstatement of CFB-seeking behavior. No dose of SSA altered rat motor-performance, evaluated exposing all rats to an inverted screen test immediately after the self-administration session. These results demonstrate that acute treatment with SSA potently suppressed several addictive-like behaviors motivated by highly hedonic nourishment. These data extend to a highly rewarding natural stimulus the anti-addictive properties of SSA recently disclosed in rats self-administering alcohol, morphine, and cocaine.

Reducing effect of saikosaponin A, an active ingredient of Bupleurum falcatum, on alcohol self-administration in rats: Possible involvement of the GABAB receptor

Recent studies demonstrated that treatment with saikosaponin A (SSA) - an active ingredient of the medicinal herb, Bupleurum falcatum L. - selectively suppressed, likely via a GABAB receptor-mediated mechanism, intravenous self-administration of morphine and cocaine in rats [Yoon et al., 2012; 2013]. The present study was designed to investigate whether the capacity of SSA to suppress morphine and cocaine self-administration extends to oral alcohol self-administration. To this end, selectively bred Sardinian alcohol-preferring (sP) rats were trained to lever-respond on a Fixed Ratio (FR) 4 (FR4) schedule of reinforcement for alcohol (15%, v/v) in daily 30-min sessions. Once responding had stabilized, rats were tested under the FR4 (measure of alcohol reinforcing properties) and Progressive Ratio (PR; measure of alcohol motivational properties) schedules of reinforcement. The possible involvement of the GABAB receptor system was investigated testing the effect of (a) pretreatment with the GABAB receptor antagonist, SCH50911, and (b) combined treatment with the positive allosteric modulator of the GABAB receptor, GS39783. Treatment with SSA (0, 0.25, 0.5, and 1mg/kg, i.p.) markedly reduced lever-responding for alcohol, amount of self-administered alcohol, and breakpoint for alcohol (defined as the lowest response requirement not achieved in the PR experiment). Pretreatment with 2mg/kg SCH50911 (i.p.) resulted in a partial blockade of the reducing effect of 0.5mg/kg SSA on lever-responding for alcohol and amount of self-administered alcohol. Combination of per se ineffective doses of GS39783 (5mg/kg, i.g.) and SSA (0.1mg/kg, i.p.) reduced lever-responding for alcohol and amount of self-administered alcohol. These results (a) extend to alcohol self-administration the capacity of SSA to suppress morphine and cocaine self-administration in rats and (b) suggest that the GABAB receptor system is likely part of the neural substrate underlying the reducing effect of SSA on alcohol self-administration.

Endogenous opiates and behavior: 2013

This paper is the thirty-sixth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2013 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

Effects of saikosaponin A on cocaine self-administration in rats

We have previously demonstrated that saikosaponin A (SSA) attenuated morphine self-administration behavior. In the present study, we evaluated the effects of SSA on cocaine-maintained responding using self-administration procedure. Rats self-administered cocaine (0.25mg/kg per infusion) under a fixed ratio 1 schedule of reinforcement during daily 3-h session. Once stable basal responses were obtained, rats were pretreated with each doses of SSA (1.0, 2.5, 5.0mg/kg) or its vehicle (5% Tween-80) by an intraperitoneal injection 30min before the start of self-administration testing. Additionally, different groups of rats received either the selective GABAB antagonist SCH 50911 or the GABAA antagonist bicuculline before systemic administration of SSA at dose of 2.5mg/kg. Results showed that SSA significantly reduced cocaine self-administration without affecting food consumption. SSA inhibition of cocaine reinforced-responding was blocked by SCH 50911, but not bicuculline. Results suggest that SSA may attenuate cocaine-reinforced behavior through activation of GABAB receptors.