Rhodiola rosea L. extract and its active compound salidroside antagonized both induction and reinstatement of nicotine place preference in mice.

RATIONALE: Conventional pharmacological treatments for drug addiction aim to reduce three most important aspects: withdrawal syndrome, craving, and relapse. Pharmacological treatments currently available for the treatment of tobacco smoking are able to alleviate withdrawal symptoms but are not sufficiently effective in reducing craving and rarely effective to prevent relapse. Rhodiola rosea L., a well-known traditional oriental medicine with anxiolytic, antidepressive, antistress, and adaptogenic properties, has been recently shown to be effective in the prevention and treatment of nicotine-withdrawal symptoms. OBJECTIVES: The present study used the conditioned place preference (CPP) model to systematically investigate, in mice, the effects of a R. rosea L. extract (RHO) and its active compound salidroside (SDS), on the reinforcing properties of nicotine and their efficacy in the vulnerability to reinstatement. METHODS: To study the effects on the rewarding properties of nicotine, RHO (10, 15, and 20 mg/kg) and SDS (0.2 mg/kg) were tested both in the acquisition and expression of CPP induced by nicotine injection (0.5 mg/kg). Moreover, the efficacy of RHO and SDS in preventing relapse induced by nicotine priming (0.1 mg/kg, s.c.) and by restraint stress was also evaluated. RESULTS: Results showed the ability of RHO and salidroside to significantly reduce the rewarding properties of nicotine at all doses tested. RHO and SDS also suppressed both priming- and stress-induced reinstatement of CPP. CONCLUSIONS: The present study showed the positive effects of R. rosea L. in reducing rewarding properties and preventing relapse to nicotine and evidenced the important role of salidroside in the effects of the extract.

Rhodiola rosea Impairs Acquisition and Expression of Conditioned Place Preference Induced by Cocaine.

A novel approach to the treatment of adverse effects of drugs of abuse is one which makes use of natural products. The present study investigated the effect of Rhodiola rosea L. hydroalcoholic extract (RHO) on cocaine-induced hyperactivity and conditioned place preference (CPP) in mice. In a first experiment, mice received RHO (15, 20 or 25 mg/kg, IG), cocaine (25 mg/kg, i.p.) (COC), or a combination of both drugs (COC + RHO15, COC + RHO20, and COC + RHO25), and their locomotor activity was evaluated. In a second experiment, the effects of RHO on the acquisition, expression, and reinstatement of cocaine CPP (induced by drug priming or social defeat stress) were evaluated. RHO alone did not increase activity but potentiated the hyperactivity induced by cocaine. Rhodiola did not induce motivational effects by itself but attenuated the acquisition and expression of cocaine-induced CPP. Moreover, it was found that RHO did not block reinstatement. The results indicate that RHO is effective in reducing the rewarding properties of cocaine but is ineffective in preventing priming or stress-induced cocaine reinstatement. In light of these findings, the benefits of Rhodiola rosea L. as a treatment of cocaine addiction would seem to be limited.

Effects of a Rhodiola rosea L. extract on the acquisition, expression, extinction, and reinstatement of morphine-induced conditioned place preference in mice.

RATIONALE: Opioid addiction is a chronic, recurrent brain disease that is characterised by compulsive drug seeking and a high rate of relapse even after long periods of abstinence. Prevention of relapse is the primary goal of addiction treatment and is still the major limitation in drug therapy. OBJECTIVES: The present study investigated the effects of a Rhodiola rosea L. hydroalcoholic extract (RHO), a well-known traditional oriental medicine, on establishment and reinstatement of morphine-induced conditioned place preference (CPP) in mice. METHODS: CPP was induced by intraperitoneal injection of morphine (10 mg/kg) as an 8-day conditioning schedule. The effects of RHO on the rewarding properties of morphine were tested in mice receiving oral administration of RHO (10, 15, and 20 mg/kg) 60 min prior to each morphine injection (acquisition) or prior to the CPP test on day 9 (expression). Once established, CPP was extinguished by repeated testing, during which conditioned mice were injected daily with different doses of RHO. Finally, the efficacy of RHO in blocking reinstatement of CPP provoked by priming injections and physical stress was also evaluated. RESULTS: RHO administration showed dose dependency for prevention of establishment of CPP and was effective in facilitating extinction of morphine-induced CPP. RHO suppressed both priming- and stress-induced reinstatement of CPP in a dose-dependent manner. CONCLUSIONS: In conclusion, as RHO was effective for reducing craving and vulnerability to relapse, it might be a very effective natural remedy for the treatment of opioid addiction.

Effects of Brugmansia arborea Extract and Its Secondary Metabolites on Morphine Tolerance and Dependence in Mice.

The aim of the present study was to investigate, in vivo, the effect of a Brugmansia arborea extract (BRU), chromatographic fractions (FA and FNA), and isolated alkaloids on the expression and the acquisition of morphine tolerance and dependence. Substances were acutely (for expression) or repeatedly (for acquisition) administered in mice treated with morphine twice daily for 5 or 6 days, in order to make them tolerant or dependent. Morphine tolerance was assessed using the tail-flick test at 1st and 5th days. Morphine dependence was evaluated through the manifestation of withdrawal symptoms induced by naloxone injection at 6th day. Results showed that BRU significantly reduced the expression of morphine tolerance, while it was ineffective to modulate its acquisition. Chromatographic fractions and pure alkaloids failed to reduce morphine tolerance. Conversely BRU, FA, and pure alkaloids administrations significantly attenuated both development and expression of morphine dependence. These data suggest that Brugmansia arborea Lagerh might have human therapeutic potential for treatment of opioid addiction.

Favourable involvement of α2A-adrenoreceptor antagonism in the I2-imidazoline binding sites-mediated morphine analgesia enhancement.

Aim of the present study was to obtain novel α(2)-adrenoreceptor (α(2)-AR) antagonists, possibly endowed with subtype-selectivity. Therefore, inspired by the non subtype-selective α(2)-AR antagonist idazoxan, we designed 1,4-dioxane derivatives bearing an aromatic area in position 5 or 6 and the imidazoline nucleus in position 2. Among the novel molecules 1-6, compound 2, with a trans stereochemical relationship between 5-phenyl and 2-imidazoline groups, was able to antagonize the sole α(2A)-subtype. Moreover, 2 showed an affinity at I(2)-imidazoline binding sites (I(2)-IBS) comparable to that at α(2A)-AR. In in vivo studies 2 strongly increased morphine analgesia. This interesting behaviour appeared to be induced by the favourable involvement of α(2A)-AR antagonism in the I(2)-IBS-mediated morphine analgesia enhancement.

Effects of a Rhodiola rosea L. extract on acquisition and expression of morphine tolerance and dependence in mice.

This study investigated the effect of Rhodiola rosea L. extract on acquisition and expression of morphine tolerance and dependence in mice. Therefore animals were injected with repeated administration of morphine (10 mg/kg, subcutaneous) twice daily for five or six days, in order to make them tolerant or dependent. Rhodiola rosea L. extract (0, 10, 15 and 20 mg/kg) was administered by the intragastric route 60 min prior to each morphine injection (for acquisition) or prior the last injection of morphine or naloxone on test day (for tolerance or dependence expression, respectively). Morphine tolerance was evaluated by testing its analgesic effect in the tail flick test at the 1st and 5th days. Morphine dependence was evaluated by counting the number of withdrawal signs (jumping, rearing, forepaw tremor, teeth chatter) after naloxone injection (5 mg/kg; intraperitoneal) on the test day (day 6). Results showed that Rhodiola rosea L. extract significantly reduced the expression of morphine tolerance, while it was ineffective in modulating its acquisition. Conversely, Rhodiola rosea L. extract significantly and dose-dependently attenuated both development and expression of morphine dependence after chronic or acute administration. These data suggest that Rhodiola rosea L. may have human therapeutic potential for treatment of opioid addiction.

Evaluation of Rhodiola rosea L. extract on affective and physical signs of nicotine withdrawal in mice.

The aim of the present study was to investigate the effects of a Rhodiola rosea L. extract on the prevention of the development of nicotine dependence and for the reduction of abstinence suffering following nicotine cessation in mice. Dependence was induced in mice by subcutaneous injections of nicotine (2 mg/kg, 4 times/day) for eight days. Spontaneous abstinence syndrome was evaluated 20 h after the last nicotine administration, by analysis of withdrawal signs, as affective (anxiety-like behaviour) and physical (somatic signs and locomotor activity). Rhodiola rosea L. extract was administered orally during nicotine treatment (10, 15 and 20 mg/kg) or during nicotine withdrawal (20 mg/kg). Results show that both affective and somatic signs (head shaking, paw tremors, body tremors, ptosis, jumping, piloerection and chewing) induced by nicotine withdrawal are abolished by administration of Rhodiola rosea L. extract in a dose-dependent fashion, during both nicotine exposure and nicotine cessation. In conclusion, our data encourage additional studies to define the use of R. rosea L. as a therapeutic approach in the treatment of smoking cessation.

Fruitful adrenergic α(2C)-agonism/α(2A)-antagonism combination to prevent and contrast morphine tolerance and dependence.

The functional in vitro study of the enantiomers of imidazolines 4-7 highlighted the role played by the nature of the ortho phenyl substituent in determining the preferred α(2C)-AR configuration. Indeed, the (S) enantiomers of 4-6 or (R) enantiomer of 7 behave as eutomers and activate this subtype as full agonists; the corresponding distomers are partial agonists. Because in clinical pain management with opioids α(2C)-AR agonists, devoid of the α(2A)-AR-mediated side effects, may represent an improvement over current therapies with clonidine like drugs, 4 and its enantiomers, showing α(2C)-agonism/α(2A)-antagonism, have been studied in vivo. The data suggest that partial α(2C)-activation is compatible with effective enhancement of morphine analgesia and reduction both of morphine tolerance acquisition and morphine dependence acquisition and expression. On the contrary, full α(2C)-activation appears advantageous in reducing morphine tolerance expression. Interestingly, the biological profile displayed by 4 (allyphenyline) and its eutomer (S)-(+)-4 has been found to be very unusual.

Novel highly potent and selective sigma 1 receptor antagonists related to spipethiane.

Conservative chemical modifications of the core structure of the lead spipethiane (1) afforded novel potent sigma(1) ligands. sigma(1) affinity and sigma(1/)sigma(2) selectivity proved to be favored by the introduction of polar functions (oxygen atom or carbonyl group) in position 3 or 4 (4-6) or by the elongation of the distance between the two hydrophobic portions of the molecule with the simultaneous presence of a carbonyl group in position 4 (8 and 9). The observed cytostatic effect against the human breast cancer cell line MCF-7/ADR, highly expressing sigma(1) receptors, and not against MCF-7, as well as the enhancement of morphine analgesia highlighted the sigma(1) antagonist profile of this series of compounds. In particular, due to its high sigma(1) affinity (pK(i) = 10.28) and sigma(1)/sigma(2) selectivity ratio (29510), compound 9 might be a novel valuable tool for sigma receptor characterization and a suitable template for the rational design of potential therapeutically useful sigma(1) antagonists.

Might adrenergic alpha2C-agonists/alpha2A-antagonists become novel therapeutic tools for pain treatment with morphine?

The imidazoline nucleus linked in position 2 via an oxyethylene bridge to a phenyl ring carrying an ortho substituent of moderate steric bulk provided alpha(2)-adrenergic (AR) ligands endowed with significant alpha(2C)-agonism/alpha(2A)-antagonism. Similar behavior was displayed by cirazoline (12). For their positive morphine analgesia modulation (due to alpha(2C)-AR stimulation) and sedation overcoming (due to alpha(2A)-AR antagonism), 8 and 11 might be useful as adjuvant agents in the management of pain with morphine.

Novel ligands rationally designed for characterizing I2-imidazoline binding sites nature and functions.

The study of two series of 2-aryl-ethylen-imidazolines 3-7 and 8-12 inspired by I2-IBS ligands phenyzoline (1) and diphenyzoline (2), respectively, confirmed the interesting "positive" or "negative" morphine analgesia modulation displayed by their corresponding leads and demonstrated that these effects might be correlated with morphine tolerance and dependence, respectively. By comparative examination of rationally designed compounds, some analogies between binding site cavity of I2-IBS proteins and alpha 2C-adrenoreceptor emerged.

Thiorphan-induced survival and proliferation of rat thymocytes by activation of Akt/survivin pathway and inhibition of caspase-3 activity.

The activity of substance P (SP) in the rat thymus seems to be tightly controlled by its bioavailability. In this study, we provide evidence for the expression of the SP-degrading enzyme, neutral endopeptidase (NEP)/CD10, by rat thymocyte subsets, and we illustrate its involvement in the in vivo SP/neurokinin-1 receptor (NK(1)R)-mediated regulation of thymocyte survival and proliferation. NEP/CD10 was expressed at both mRNA and protein levels on a substantial portion (45.5%) of CD5(+) thymocytes, namely on the CD4(+)CD8(+) (double positive; DP) and CD4(+) subsets. Continuous administration of thiorphan, a specific NEP/CD10 inhibitor, by means of miniosmotic pumps, enhanced rat thymocyte preprotachykinin-A (PPT-A) and NK(1)R mRNA expression as well as SP and NK(1)R protein levels in an NK(1)R-dependent manner. Thiorphan increased CD10(+)CD4(+) and CD10(+)DP thymocyte numbers, and an NK(1)R antagonist, (S)1-{2-[3(3-4-dichlorophenyl)-1-(3-iso-propoxyphenylacetyl)-piperidine-3-yl]ethyl}-4-pheny-1-azoniabicyclo[2.2.2]octane, chloride (SR140333), abrogated these stimulatory effects. In addition, the NEP/CD10 inhibitor stimulated interleukin (IL)-2 production, IL-2 receptor alpha chain expression, and concanavalin A-induced proliferation of CD5(+) thymocytes, and it inhibited spontaneous and NK(1)R-dependent thymocyte apoptosis. The thiorphan-protective antiapoptotic and proliferative effects involved the activation of Akt serine-threonine kinase, subsequent up-regulation of survivin mRNA, down-regulation of procaspase-3 mRNA levels, and suppression of caspase-3 activity, which were inhibited by SR140333 and mimicked by exogenous SP administration. Overall, our findings suggest that by controlling SP availability, NEP/CD10 negatively regulates thymocyte homeostasis and development.

Synthesis, docking studies and anti-inflammatory activity of 4,5,6,7-tetrahydro-2H-indazole derivatives.

A regioselective synthesis of 2,3-disubstituted tetrahydro-2H-indazols, mediated by alpha-zirconium sulfophenylphosphonate-methanephosphonate, was reported. Docking studies into the catalytic site of COX-2 were used to identify potential anti-inflammatory lead compounds. Two lead derivatives were chosen endowed with good binding energies and good ADME profiling. The biological in vivo evaluation of these compounds in two different experimental models (Freund's adjuvant-induced arthritis and carrageenan-induced oedema) proved the presence of anti-inflammatory activity. Noteworthy, both compounds evidenced the lack of any gastric injury even at high doses in gastric ulcerogenic assays.

Rhodiola rosea L. extract reduces stress- and CRF-induced anorexia in rats.

Rhodiola rosea L. is one of the most popular adaptogen and anti-stress plants in European and Asiatic traditional medicine. Its pharmacological properties appear to depend on its ability to modulate the activation of several components of the complex stress-response system. Exposure to both physical and psychological stress reduces feeding in rodents. The aim of this work was thus to determine whether in rats an hydroalcoholic R. rosea extract standardized in 3% rosavin and 1% salidroside (RHO) reverses hypophagia induced by (1) physical stress due to 60 min immobilization; (2) intracerebroventricular injection of corticotrophin-releasing factor (CRF, 0.2 microg/rat), the major mediator of stress responses in mammals; (3) intraperitoneal injection of Escherichia coli Lipopolysaccharide (LPS, 100 microg/kg); (4) intraperitoneal administration of fluoxetine (FLU, 8 mg/kg). The effect of the same doses of the plant extract was also tested in freely-feeding and in 20 h food-deprived rats. RHO was administered acutely by gavage to male Wistar rats 1 h before the experiments. The results show that at 15 and 20 mg/kg, RHO reversed the anorectic effects induced both by immobilization and by intracerebroventricular CRF injection. Moreover, at the same doses, RHO failed to reduce the anorectic effect induced both by LPS and FLU, and did not modify food intake in both freely-feeding and food-deprived rats. These findings strongly demonstrated that RHO is able selectively to attenuate stress-induced anorexia, providing functional evidence of claimed adaptogen and anti-stress properties of Rhodiola rosea L.

Adaptogenic and central nervous system effects of single doses of 3% rosavin and 1% salidroside Rhodiola rosea L. extract in mice.

Rhodiola rosea L., or 'golden root', is a popular plant in traditional medicine in Eastern Europe and Asia, with a reputation for improving depression, enhancing work performance, eliminating fatigue and treating symptoms of asthenia subsequent to intense physical and psychological stress. Due to these therapeutic properties, R. rosea is considered to be one of the most active adaptogenic drugs. To confirm and extend results obtained in the few preclinical and clinical studies available in English language journals, the purpose of the present study was to re-investigate the effects produced by a single oral administration of an R. rosea hydroalcohol extract (containing 3% rosavin and 1% salidroside) on the central nervous system in mice. The extract was tested on antidepressant, adaptogenic, anxiolytic, nociceptive and locomotor activities at doses of 10, 15 and 20 mg/kg, using predictive behavioural tests and animal models. The results show that this R. rosea extract significantly, but not dose-dependently, induced antidepressant-like, adaptogenic, anxiolytic-like and stimulating effects in mice. This study thus provides evidence of the efficacy of R. rosea extracts after a single administration, and confirms many preclinical and clinical studies indicating the adaptogenic and stimulating effects of such R. rosea extracts. Moreover, antidepressant-like and anxiolytic-like activities of R. rosea were shown in mice for the first time.

Involvement of I2-imidazoline binding sites in positive and negative morphine analgesia modulatory effects.

Some studies, suggesting the involvement of I(2)-imidazoline binding sites (I(2)-IBS) in morphine analgesia modulation, prompted us to examine on mice antinociceptive assays the effect produced by 1 (phenyzoline), that in view of its high I(2)-IBS affinity and high I(2)-IBS selectivity with regard to I(1)-IBS, alpha(2)-adrenoreceptors and mu-opioid receptors might be considered the first interesting I(2)-IBS ligand. The study was also applied to its ortho phenyl derivative 2 (diphenyzoline), designed and prepared in order to produce a possible modification of the biological profile of 1. Diphenyzoline (2) retains a significant I(2)-IBS selectivity with regard to I(1)-IBS, alpha(2)-adrenoreceptors and mu-opioid receptors. Moreover, by the functional assays 1 and 2 proved inactive at all alpha(2)-adrenoreceptors subtypes up to 10(-3) M. As expected, phenyzoline and diphenyzoline, which are structurally related, highlighted an interesting "positive" or "negative", respectively, morphine analgesia modulatory effect. In fact, 1 (s.c. 10 mg/kg) enhanced morphine analgesia (60% and 40% in mouse tail-flick and mouse hot-plate, respectively), while 2 (s.c. 10 mg/kg) decreased it (-41% and -20%, respectively). The ability to decrease morphine analgesia had never been observed before in I(2)-IBS ligands. These effects were not affected by i.p. treatment of animals with yohimbine (a selective alpha(2)-adrenoreceptor antagonist, 0.625 mg/kg) or efaroxan (an I(1)-IBS/alpha(2)-adrenoreceptor antagonist, 1.0 mg/kg). In contrast, they were completely reversed by i.p. treatment of animals with idazoxan (an I(2)-IBS/alpha(2)-adrenoreceptor antagonist, 2 mg/kg). Moreover, compound 2, in mouse tail-flick test, was able to potentiate by 23% the naloxone-induced decrease of morphine analgesia. Therefore, the results of this study indicate the crucial involvement of I(2)-IBS in the morphine analgesia modulatory effects of 1 and 2.

Effect of the cannabinoid CB1 receptor antagonist SR-141716A on ethanol self-administration and ethanol-seeking behaviour in rats.

RATIONALE: It has been suggested that endocannabinoid mechanisms are involved in the control of ethanol consumption. OBJECTIVES: The aims of the present study were (1) to evaluate the role of the endocannabinoid system in the control of operant ethanol self-administration and in the reinstatement of ethanol seeking, when induced by stress or conditioned stimuli and (2) to offer new insights on the specificity of such a role. METHODS: Rats were administered intraperitoneally with the selective cannabinoid CB1 receptor antagonist, SR-141716A, 30 min before operant self-administration or reinstatement sessions. Two schedules of reinforcement, the fixed-ratio 1 (FR1) and the progressive ratio (PR), were used to study 10% (w/v) alcohol and 5.0% sucrose self-administration. NaCl (2% w/v) intake in sodium-depleted rats was studied only under the FR1 program. RESULTS: Treatment with SR-141716A (0.3-3.0 mg/kg) significantly attenuated FR1 alcohol self-administration and lowered the break point for ethanol under PR. SR-141716A also markedly inhibited the reinstatement of alcohol seeking elicited by presentation of cues predictive of drug availability. Conversely, the cannabinoid antagonist did not prevent the reinstatement of alcohol seeking induced by foot-shock stress. Lever pressing for sucrose under FR1 and PR schedules was also significantly decreased by SR-141716A treatment, whereas the drug modestly and only at the highest dose decreased 2% NaCl self-administration. CONCLUSIONS: Results emphasize that endocannabinoid mechanisms play a major role in the control of ethanol self-administration and in the reinstatement of conditioned ethanol seeking. However, these effects extend to the control of operant behaviours motivated by natural rewards (i.e. sucrose). On the other hand, SR-141716A only weakly reduces NaCl self-administration in sodium-depleted rats, in which salt intake is largely controlled by homeostatic mechanisms. Overall, these observations demonstrate that the inhibition of operant behaviour following blockade of CB1 receptors by SR-141716A is linked to a reduction of reward-related responding and is not related to drug-induced motor deficits.

Reduction of ethanol intake by chronic treatment with Hypericum perforatum, alone or combined with naltrexone in rats.

Acute treatment with extracts of Hypericum perforatum, the common plant usually called St. John's Wort, reduces voluntary ethanol intake in Marchigian Sardinian alcohol-preferring (msP) rats and acts synergistically with opioid receptor antagonists to further attenuate ethanol consumption. The present study evaluated the effect of chronic (once a day for 12 days) intragastric administration of a CO2 Hypericum perforatum extract (HPCO2), given alone or combined with naltrexone (NTX), on ethanol intake offered 2h/day in msP rats. Chronic treatment with HPCO2 markedly reduced ethanol intake at the dose of 125, but not at 7 mg/kg; the effect of 125 mg/kg was observed since the first day of treatment and remained constant across the 12 days. The same dose of HPCO2 slightly reduced the simultaneous intake of food only on day 3 and day 11 of treatment. Treated rats promptly recovered baseline ethanol intake when treatment did not precede access to ethanol (on day 8) or after the end of treatment (day 13 and day 14), suggesting that HPCO2 administrations did not induce conditioned aversion to alcohol. Chronic intraperitoneal treatment with NTX reduced ethanol intake at 3, but not at 0.5mg/kg. The synergistic effect on ethanol intake of HPCO2 and NTX was evident also in conditions of chronic treatment. HPCO2, 7 mg/kg, and NTX, 0.5mg/kg, evoked a pronounced and statistically significant reduction of ethanol intake, while being inactive. The effect on ethanol intake of the combined treatment remained stable over the 12 days of treatment; food intake was slightly reduced only on day 3 and on day 7 in response to 125 mg/kg of HPCO2 combined with NTX 0.5mg/kg, but no difference in body weight between controls and treated rats was observed at the end of treatment. Following 12-day treatment with 125 mg/kg of HPCO2, no difference was observed in the responsivity of msP rats to the effect on ethanol intake of several doses of the extract. In conclusion, the present results provide evidence for a selective and pronounced effect of HPCO2, alone or combined with naltrexone, on ethanol intake in conditions of chronic treatment, without development of tolerance. These findings further support the view that clinical trials for extracts of Hypericum perforatum in the treatment of alcoholism should be considered.

Effect of Hypericum perforatum CO2 extract on the motivational properties of ethanol in alcohol-preferring rats.

AIMS: Extracts of Hypericum perforatum (HPE) attenuate voluntary ethanol intake in different lines of alcohol-preferring rats. The present study evaluated the effect of the intragastric (IG) administration of a CO(2) Hypericum perforatum extract (HPCO(2)) on operant ethanol self-administration, as well as on voluntary ethanol intake, after a period of ethanol deprivation in genetically selected Marchigian Sardinian alcohol-preferring rats. METHODS: HPCO2 was administered by means of an indwelling IG catheter, 1 h before the tests. For the self-administration experiments, the rats were trained to self-administer 10% (v/v) ethanol in 30-min daily sessions under a fixed ratio 1 schedule of reinforcement. HPCO2 was also tested on 0.2% w/v saccharin self-administration. For the ethanol deprivation experiments, rats that had a previous experience with voluntary ethanol drinking were deprived of ethanol for 9 days, whereas water and food were freely available; HPCO2 was given by IG injection 1 h before the ethanol re-presentation. RESULTS: HPCO2 in doses of 31 or 125 mg/kg but not 7 mg/kg, significantly reduced ethanol self-administration, while it did not modify saccharin self-administration. The same doses of the extract abolished the increased ethanol intake following ethanol deprivation. CONCLUSIONS: These findings provide evidence that HPCO2 markedly reduces the reinforcing properties of ethanol in the self-administration paradigm, as well as the increase of ethanol intake following ethanol deprivation. These findings further support the view that the use of HPE may represent an interesting pharmacological approach in the treatment of alcohol abuse and alcoholism.

Neonatal capsaicin treatment affects rat thymocyte proliferation and cell death by modulating substance P and neurokinin-1 receptor expression.

Herein we provide evidence that substance P (SP) and its neurokinin-1 receptor (NK-1R) expressed on thymocytes counteract thymus depletion induced by neonatal capsaicin (CPS) treatment by affecting thymocyte proliferation and apoptotic death. SP administration reversed the CPS-mediated inhibitory effects on the total thymocyte number and subset distribution, namely CD4+ and CD4- CD8- cells, through its interaction with NK-1R as shown by concomitant NK-1R (SR140333) antagonist administration. SP-induced enhancement of thymus cellularity parallels its ability of inhibiting the thymocyte apoptotic program. Indeed, exogenously administered SP completely nullified CPS-induced apoptosis, and SR140333 abrogated the SP-mediated protective effect. SP administration also stimulated concanavalin A (Con A)-induced thymocyte proliferation of CPS-treated rats, completely reversing the CPS-induced inhibition. The SP-mediated stimulation of Con A-induced thymocyte proliferation was NK-1R dependent as shown by concomitant administration of SP and SR140333 to CPS-treated rats. Our results also demonstrate that CPS treatment induces a marked decrease of thymocyte PPT-A mRNA level and endogenous SP content as evaluated by quantitative RT-PCR, in situ hybridization and cytofluorimetric analysis. By contrast, NK-1R mRNA levels were increased in thymocytes from CPS-treated rats. Exogenous SP administration augmented PPT-A, SP and NK-1R thymocyte expression in CPS-treated rats, and this enhancement was antagonized by SR140333 administration. Overall, our results strongly suggest that the immunomodulatory effects of neonatal CPS treatment on rat thymocyte functions are dependent on vanilloid-mediated regulation of SP and NK-1R functional expression by neuronal and immune cells.