Synthesis of Allylthiopyridazine Derivatives and Inhibition of Aflatoxin B<Subscript>1</Subscript>-Induced Hepatotoxicity in Rats

Five kinds of allylthiopyridazine derivatives were synthesized and their chemoprotective activities examined in rats exposed to aflatoxin B1-toxicant. Rats were pretreated with five allylthiopyridazine derivatives at daily oral doses of 50 mg/kg for 10 consecutive days, and during this period with one or three repeated doses of the potent hepatotoxin, aflatoxin B1. The hepatoprotective effects of the allylthiopyridazine derivatives against aflatoxin B1 (1 mg/kg, three times at intervals of 3 days, i.p., or at 3 mg/kg, once at final days, i.p.) administration were showed the significantly normal as compared with control in body and liver weights. Aspartate aminotransferase and alanine aminotransferase levels were markedly elevated after aflatoxin B1 administration, and pretreatment with allylthiopyridazine derivatives, before aflatoxin B1 administration, resulted in decreased levels of these enzymes. In addition, the allylthiopyridazine derivatives, K6 (3-methoxy-), K8 (3-chloro-), K16 (3-ethoxy-) and K17 (3-n-propoxy), induced elevated hepatic GSH levels. Four kinds of allylthiopyridazine derivatives investigated were effective against aflatoxin B1-induced hepatotoxicity.     

Pharmacological characterisation of the agonist radioligand binding site of 5-HT<Subscript>2A</Subscript>, 5-HT<Subscript>2B</Subscript> and 5-HT<Subscript>2C</Subscript> receptors

In the present study we compared the affinity of various drugs for the high affinity agonist-preferring binding site of human recombinant 5-HT_2A, 5-HT_2B and 5-HT_2C receptors stably expressed in monoclonal mammalian cell lines. To ensure that the agonist-preferring conformation of the receptor was preferentially labelled in competition binding experiments, saturation analysis was conducted using antagonist and agonist radiolabels at each receptor. Antagonist radiolabels ([³H]-ketanserin for 5-HT_2A receptor and [³H]-mesulergine for 5-HT_2B and 5-HT_2C receptor) bound to a larger population of receptors in each preparation than the corresponding agonist radiolabel ([¹²⁵I]-DOI for 5-HT_2A receptor binding and [³H]-5-HT for 5-HT_2B and 5-HT_2C receptor binding). Competition experiments were subsequently conducted against appropriate concentrations of the agonist radiolabels bound to the agonist-preferring subset of receptors in each preparation. These studies confirmed that there are a number of highly selective antagonists available to investigate 5-HT₂ receptor subtype function (for example, MDL 100907, RS-127445 and RS-102221 for 5-HT_2A, 5-HT_2B and 5-HT_2C receptors respectively). There remains, however, a lack of highly selective agonists. (–)DOI is potent and moderately selective for 5-HT_2A receptors, BW723C86 has poor selectivity for human 5-HT_2B receptors, while Org 37684 and VER-3323 display some selectivity for the 5-HT_2C receptor. We report for the first time in a single study, the selectivity of numerous serotonergic drugs for 5-HT₂ receptors from the same species, in mammalian cell lines and using, exclusively, agonist radiolabels. The results indicate the importance of defining the selectivity of pharmacological tools, which may have been over-estimated in the past, and highlights the need to find more selective agonists to investigate 5-HT₂ receptor pharmacology.     

Isolation and quantitative analysis of B<Subscript>1</Subscript>, B<Subscript>2</Subscript>, B<Subscript>6</Subscript> AND B<Subscript>12</Subscript> vitamins using high-performance thin-layer chromatography

A new, simple and accurate high-performance thin-layer chromatography (HPTLC) method has been developed for the separation and simultaneous analysis of B1, B2, B6 and B12 vitamins. Standard and sample solutions of vitamins were applied onto precoated aluminum-backed silica gel G 60 F254 HPTLC plate. The plates were developed with about thirty different solvent systems, and the ethanol – chloroform – acetonitrile – toluene – ammonia – water (7 : 4 : 4.5 : 0.5 : 1 : 1, v/v) mixture was chosen as the optimum mobile phase. UV detection was performed densitometrically at 254 nm. The retention factors of B1, B2, B6 and B12 vitamins were 0.36, 0.60, 0.85 and 0.46, respectively. The linearity range for indicated compounds was 10 – 2500 ng per spot and the correlation coefficients were R ² = 0.97 – 0.98. The limits of quantification (LOQ) were 141.72, 42.41, 100.31 and 11.50 ng and the limits of detection (LOD) were 42.52, 12.72, 30.09 and 3.45 ng for B1, B2, B6 and B12 vitamins, respectively. Analyses of standard solutions showed good precision and repeatability.     

Toxicity potentiation by H<Subscript>2</Subscript>O<Subscript>2</Subscript> with components of dental restorative materials on human oral cells

Toxicity potentiation of two monomers [bisphenol-A-glycidyldimethacrylate (BisGMA) and urethanedimethacrylate (UDMA)] as well as two comonomers [triethyleneglycoldimethacrylate (TEGDMA) and 2-hydroxyethylmethacrylate (HEMA)], each in combination with H₂O₂, was investigated on the viability on human gingival fibroblasts (HGF) and human pulpal fibroblasts (HPF). The applied concentration of H₂O₂ was 0.06 or 0.1 mmol/l, respectively, corresponding to the EC₀ of H₂O₂ in HGF or HPF. The cell viability was assessed by the XTT test. From this test the half maximum effect concentrations (EC₅₀) were calculated from fitted sigmoidale curves. EC₅₀ values were (HGF; mmol/l; mean ± s.e.m.; n = 5): HEMA 11.9 ± 0.9, TEGDMA 3.7 ± 0.3, H₂O₂ 0.36 ± 0.04, UDMA 0.27 ± 0.08, and BisGMA 0.11 ± 0.03. No significant (P < 0.05) differences in the EC₅₀ values were observed when HGF was exposed to substances, as compared to HPF. No significant decrease of the EC₅₀ values was found when HGF or HPF, respectively, was exposed to HEMA or BisGMA in addition with H₂O₂ up to the concentration of 0.1 mmol/l, as compared to those EC₅₀ values of each compound without H₂O₂ addition. A significant decrease of the TEGDMA EC₅₀ value from 3.7 to 2.1 or 0.4 mmol/l, respectively, was found when cells were exposed to TEGDMA in combination with H₂O₂ (0.06 or 0.1 mmol/l), as compared to that TEGDMA EC₅₀ value without H₂O₂ addition. A significant decrease of the UDMA EC₅₀ value from 0.27 to 0.11 or 0.08 mmol/l, respectively, was found when HGF or HPF was exposed to UDMA in combination with H₂O₂ (0.06 or 0.1 mmol/l), as compared to that UDMA EC₅₀ value without H₂O₂ addition. The addition of H₂O₂ (0.06 or 0.1 mmol/l) resulted in a toxicity potentiation of TEGDMA and UDMA, but not of HEMA and BisGMA, on HGF or HPF.     

HPLC法测定灵芝二维甲硫氨酸胶囊中甲硫氨酸、维生素B1及维生素B2含量

目的：建立用HPLC法同时测定灵芝二维甲硫氨酸胶囊中甲硫氨酸、维生素B1及维生素B2含量的方法。方法：采用Ultimate？ AQ-C18色谱柱（250 mm ×4.6 mm,5μm,Welch公司）,流动相：甲醇-0.07 mol·L-1庚烷磺酸钠溶液（加14 ml三乙胺并加水至1000 ml,用磷酸调节pH至3.5）,线性梯度洗脱,检测波长为220 nm,流速：1.0 ml·min-1。结果：甲硫氨酸、维生素B1、维生素B2分别在0.5270~1.5100 mg·ml-1（r=0.9999）、0.04552~0.13656 mg·ml-1（r=0.9999）、0.01010~0.06058 mg·ml-1（r =0.9999）范围内线性关系良好,平均回收率分别为100.5%、97.7%、101.5%,RSD 分别为0.5%、1.0%、1.4%（n=9）。结论：本法操作简便、结果准确、可靠,可用于灵芝二维甲硫氨酸胶囊中甲硫氨酸、维生素B1、维生素B2的含量测定。     

A GABA<Subscript>B</Subscript> agonist reverses the behavioral sensitization to morphine in rats

Rationale In laboratory animals, repeated administration of drugs of abuse causes sensitization to their stimulant and rewarding effects. Neuroadaptations underlying sensitization could be related to those that contribute to addictive behaviors. An increased understanding of the molecular mechanisms of sensitization could lead to improved treatments for addiction. Objectives Since baclofen (BCF) co-administration has been reported to block the development and the expression of motor sensitization to morphine (MOR), the present study examined the hypothesis that a chronic treatment with BCF alone might reverse and/or prevent MOR-induced sensitization. Methods Rats were first sensitized to MOR (saline or 10 mg/kg MOR i.p.; days 1–10) and then chronically treated with BCF (saline or 2 mg/kg BCF i.p.; days 11–20). Finally, the motility effect of MOR (10 mg/kg i.p.) was assessed 3 and 30 days after the end of BCF treatment. The same rats were again challenged with MOR on day 70, after a further period of saline or MOR treatment (days 51–60). Results Behavioral sensitization to MOR was observed in control animals but not in rats chronically treated with BCF (days 23 and 50). Thus, BCF completely reversed MOR-induced sensitization, and its effect was long lasting. However, a previous repeated BCF treatment did not prevent the development of sensitization to MOR both in naive and desensitized rats. Conclusions The present results confirm that γ-aminobutyric acid (GABA)_B receptors play an important role in the expression of motor sensitization to MOR and suggest that GABA_B agonists could be useful for reversing the neuroadaptations related to drug addiction.     

Non-uniform blockade of intrastriatal D<Subscript>2</Subscript>/D<Subscript>3</Subscript> receptors by risperidone and amisulpride

Rationale Atypical antipsychotic drugs have been shown to preferentially affect extrastriatal (mesolimbic) D₂/D₃ receptors over those within the striatum (nigrostriatal). The striatum does not contain exclusively nigrostriatal dopamine tracts, however. The caudate nucleus and ventral parts of the striatum primarily contain limbic and associative dopamine pathways more relevant to psychosis. Objectives We tested the hypothesis that two pharmacologically distinct atypical antipsychotic drugs, amisulpride and risperidone, would preferentially occupy of D₂/D₃ dopamine receptors in limbic and associative regions of the striatum. Methods Eight amisulpride-treated patients, six risperidone-treated patients and six age- and sex-matched healthy controls were recruited. Dynamic SPET studies were performed after bolus injection of [¹²³I]epidepride. Binding potential (BP) images were generated using a modified Logan method and aligned between subjects. Regions of interest (ROIs) were placed around head of caudate and putamen bilaterally on an average BP map derived from aligned control images. These ROIs were then applied user-independently to the BP maps for each subject to calculate BP for head of caudate and putamen. Mean occupancy of D₂/D₃ receptors in each ROI was determined by reference to the drug-free healthy volunteer group. Occupancy values for head of caudate and putamen were compared using paired Student’s t test. Results D₂/D₃ receptor occupancy was 42% in caudate and 31% in putamen for risperidone (t=5.9, df=11, p=0.0001) and 51% in caudate and 37% in putamen for amisulpride (t=11.1, df=15, p<0.0001). Conclusions Amisulpride and risperidone both show selective occupancy for limbic and associative D₂/D₃ receptors within the striatum.     

In Vitro-In Vivo Evaluation of a Controlled Release Buccal Bioadhesive Device for Oral Drug Delivery

Purpose. To investigate the use of buccal bioadhesive device in targeting controlled drug delivery to the gastrointestinal tract. Methods. A three-leg crossover study was designed to evaluate the application of buccal bioadhesive device for providing controlled drug delivery to the gastrointestinal tract of a model drug cyanocobalamin in four healthy adult male beagle dogs. Results. In vitro dissolution studies using deionized water as the medium indicated that 100% of the drug was released within 15 min from a immediate release oral capsule formulation, whereas 90% of the drug was released within a period of 18 hrs from a buccal bioadhesive device formulation. Drug release from the buccal bioadhesive devices appeared to follow Higuchi's square root of time dependent model. The terminal half-life of the drug following I.V. administration in four dogs was found to be 16.4 ± 2.4 hrs. Following immediate release oral capsule administration of the drug C_max, t_max and bioavailability were 2333 ± 1469 ng/L, 2.5± 1.0 hrs and 14.1 ± 7.9%, respectively. Following buccal bioadhesive device administration of the drug C_max, t_max and bioavailability were 4154 ± 1096 ng/L, 11 ± 1.2 hrs and 35.8 ± 4.1%, respectively. Significantly higher bioavailability of the drug was observed with the buccal bioadhesive device administration when compared to the immediate release oral capsule. Conclusions. The buccal bioadhesive device appears to improve the oral bioavailability of cyanocobalamin by providing controlled delivery of the drug to the gastrointestinal tract.     

Cytotoxicity and apoptosis induced by fumonisin B<Subscript>1</Subscript>, beauvericin and ochratoxin A in porcine kidney PK15 cells: effects of individual and combined treatment

The objective of this study was to determine individual and combined effects of fumonisin B₁ (FB₁), beauvericin (BEA) and ochratoxin A (OTA) on porcine kidney epithelial PK15 cell survival by measuring lactate dehydrogenase (LDH) activity, apoptotic index and caspase-3 activity. Cells were treated with 0.05, 0.5 and 5 μg/ml of each mycotoxin or with the combinations of two or all three mycotoxins for 24 and 48 h. Changes in LDH and caspase-3 activity, and in apoptotic index showed that the cytotoxic and apoptotic effects of these mycotoxins were concentration- and time- dependent. Significant increase of LDH activity was observed after 48 h of exposure to the highest concentration of FB₁ (45%), BEA (84%) and OTA (77%), as compared to control. OTA increased caspase-3 activity after 24 h of treatment with 0.5 μg/mL (84%), while BEA (319%) and FB₁ (419%) significantly affected this enzyme activity after 48 h (P < 0.05). Increase of caspase-3 activity preceded significant morphological apoptotic changes, which were detected after 48 h of exposure to a single toxin. Combined treatment with FB₁, BEA and OTA resulted mostly in additive effects on LDH activity, and additive and synergistic effects on caspase-3 activity and apoptotic index.     

Reduced hypophagic effects of <Emphasis Type="Italic">d</Emphasis>-fenfluramine and the 5-HT<Subscript>2C</Subscript> receptor agonist <Emphasis Type="Italic">m</Emphasis>CPP in 5-HT<Subscript>1B</Subscript> receptor knockout mice

Rationale The possible role of compensatory changes in 5-HT_2C receptors in the reduced hypophagic action of d-fenfluramine in 5-HT_1B knockout (KO) mice was assessed by comparing their response to d-fenfluramine and the 5-HT_2C receptor agonist mCPP. In addition we measured 5-HT_2C/A receptor binding in 5-HT_1B KO and wild-type (WT) mice and examined the effects of 5-HT_1B receptor antagonists on d-fenfluramine-induced hypophagia in WT mice.Methods Hypophagic responses to d-fenfluramine (1–30 mg/kg) and mCPP (1–5.6 mg/kg) were measured using a behavioural satiety sequence paradigm. The effects of the 5-HT_1B receptor antagonists GR 127,935 and SB 224289 in opposing the hypophagic action of d-fenfluramine were evaluated in WT mice. The binding of [³H]-mesulergine was compared in the brains of both mouse strains.Results The hypophagic effects of moderate doses of d-fenfluramine and mCPP were attenuated in 5-HT_1B KO mice. Pretreatment of WT mice with the 5-HT_1B/1D receptor antagonist GR 127,935, or food-deprived WT mice with the 5-HT_1B receptor antagonist SB 224289, did not reproduce the reduction in sensitivity to the effects of d-fenfluramine on feeding behaviour observed in 5-HT_1B KO mice. Estimates of 5-HT_2C receptor binding were similar in 5-HT_1B KO and WT mice.Conclusions The hypophagic effect of d-fenfluramine in mice is unlikely to be mediated by the 5-HT_1B receptor. Instead, the evidence suggests that an adaptive change in 5-HT_2C receptor function occurs in 5-HT_1B receptor KO mice and contributes to their reduced response to d-fenfluramine.     

Repeated administration of the 5-HT<Subscript>1B</Subscript> receptor antagonist SB-224289 blocks the desensitisation of 5-HT<Subscript>1B</Subscript> autoreceptors induced by fluoxetine in rat frontal cortex

Desensitisation of 5-HT_1A and 5-HT_1B autoreceptors is thought to be the mechanism underlying the therapeutic effects of fluoxetine and other selective serotonin re-uptake inhibitors (SSRIs) when these are administered chronically, while blockade of these autoreceptors occurring on administration of an SSRI together with an autoreceptor antagonist is responsible for the acute increase in 5-HT levels in vivo observed under these circumstances. The effects of repeated administration of SSRIs together with 5-HT_1B receptor antagonists on 5-HT levels and autoreceptor activity have not been studied previously with an in vivo method. In this work we found, using in vivo microdialysis that the effect of fluoxetine (5 mg/kg i.p. daily for 7 days) to desensitise 5-HT_1B autoreceptors in frontal cortex, as measured by the action of CP 93129 (10 M) to reduce 5-HT levels, was prevented by concomitant administration of the 5-HT_1B receptor antagonist SB 224289 (2.5 mg/kg s.c.). 5-HT_1B receptor activity in hypothalamus and 5-HT_1A autoreceptor activity, as determined by the effects of s.c. 8-OH-DPAT to reduce 5-HT levels, were not altered either by fluoxetine alone at this dose or by fluoxetine in the presence of SB 224289. We conclude that the effects obtained when 5-HT_1B autoreceptor antagonists are administered acutely together with SSRIs may not be maintained after repeated administration.     

高效液相色谱法测定赖氨肌醇维B12口服溶液中维生素B12及肌醇的含量

目的:建立赖氨肌醇维B12口服溶液中维生素B12和肌醇的含量测定方法.方法:采用高效液相色谱法,紫外及示差折光检测器,ODS柱和氨基柱分别测定维生素B12和肌醇含量.流动相分别为乙腈-0.05 mol·L-1磷酸二氢钾溶液(13∶87)用磷酸调节pH至3.0,乙腈-水(70∶30);检测波长分别为 361 nm 和 210 nm;流量:1.0 mL·min-1;进样体积:20 μL.结果:维生素B12和肌醇浓度分别在1.52～6.08 μg·mL-1和5.02～20.06 mg·mL-1范围内与峰面积呈良好的线性关系,平均回收率(n=9)分别为99.5%(RSD=0.76%)和99.4%(RSD=1.39%).结论:本法专属性强,结果准确,重现性好,适用于赖氨肌醇维B12口服溶液中维生素B12和肌醇的含量测定.     

A pharmacological differentiation between postjunctional (AT<Subscript>1A</Subscript>) and prejunctional (AT<Subscript>1B</Subscript>) angiotensin II receptors in the rabbit aorta

The effects of angiotensin II and angiotensin III were compared at prejunctional and postjunctional AT₁ receptors of the rabbit thoracic aorta. Furthermore, the influence of PD123319, losartan and eprosartan on these effects was also compared. To study prejunctional effects, the tissues were preincubated with (³H)-noradrenaline, superfused and electrically stimulated (1 Hz, 2 ms, 50 mA, 5 min). To study postjunctional effects, non-cumulative concentration–response curves were determined. Both angiotensin II and angiotensin III were more potent prejunctionally than postjunctionally. In the case of angiotensin II, the EC₅₀ was 12 times lower at the prejunctional than at the postjunctional level, while that of angiotensin III was 30 times lower prejunctionally. Furthermore, whereas angiotensin II was about 33 times more potent than angiotensin III postjunctionally, it was only 12 times more potent than angiotensin III prejunctionally. Eprosartan did not differentiate between prejunctional and postjunctional effects of both angiotensins. In contrast, PD123319 and losartan did differentiate; however, whereas PD123319 concentration-dependently antagonised the facilitation of tritium release caused by angiotensin II and angiotensin III and had no influence on the contraction of the aortic rings elicited by the peptides, losartan did the opposite: it concentration-dependently antagonised the contractions caused by the peptides on the aortic rings and exerted no influence on the facilitatory effect of angiotensin II and angiotensin III. These results show that prejunctional and postjunctional receptors for angiotensin II and angiotensin III are different and underline the hypothesis that postjunctional AT₁ receptors belong to the AT_1A subtype, while prejunctional AT₁ receptors belong to the AT_1B subtype.     

Differential sensitivity to the motor and hypothermic effects of the GABA<Subscript>B</Subscript> receptor agonist baclofen in various mouse strains

Rationale Comparison of different mouse strains can provide valuable information about the genetic control of behavioural and molecular phenotypes. Recent evidence has demonstrated the importance of GABA_B receptors in anxiety and depression. Investigation of the phamacogenetics of GABA_B receptor activation may aid in the understanding of mechanisms underlying the role of GABA_B in affect.Objectives The aim of current study was to determine the relative sensitivity of different mouse strains to GABA_B receptor agonism in two models of GABA_B receptor function, namely hypothermia and motor incoordination.Methods Mice each from 11 strains (BALB/cByJIco, DBA/2JIco, OF1, FVB/NIco, CD1, C3H/HeOuJIco, 129/SvPasIco, NMRI, C57BL/6JIco, A/JOlaHsd and Swiss) were trained to walk on a rotarod for 300 s. On the following day, mice received 0, 3, 6 or 12 mg/kg of l-baclofen PO. Rectal temperature and rotarod performance were measured at 0, 1, 2 and 4 h after drug application.Results l-Baclofen produced a significant dose-dependent hypothermia and ataxia in most, but not all, mouse strains examined. The magnitude and duration of response was influenced by strain, with mice of the 129/SvPasIco strain showing largest hypothermic response to 12 mg/kg l-baclofen and C3H/HeOuJIco the lowest, whereas the BALB/cByJIco strain demonstrated greatest ataxic response on the rotarod, and NMRI the least. Interestingly, some strains (notably C3H/HeOuJIco) had marked differential hypothermic and ataxic responses, with minimal body temperature responses to l-baclofen but significant ataxia on the rotarod observed.Conclusion There is differential genetic control on specific GABA_B receptor populations that mediate hypothermia and ataxia. Further, these studies demonstrate that background strain is an important determinant of GABA_B receptor mediated responses, and that hypothermic and ataxic responses may be influenced by independent genetic loci.     

<Emphasis Type="BoldItalic">In vitro</Emphasis> Interactions Between the Oral Absorption Promoter,Sodium Caprate (C<Subscript>10</Subscript>) and <Emphasis Type="BoldItalic">S. typhimurium</Emphasis> in Rat Intestinal Ileal Mucosae

Purpose The medium chain fatty acid, sodium caprate (C₁₀), is a promising oral drug delivery agent that may promote permeability of peptides through increasing paracellular permeability of the intestinal epithelium. One safety concern is that it may permit co-absorption of by-stander agents including pathogens. The purpose of this in vitro study was to examine the effects of C₁₀ on rat intestinal ileal mucosae in the presence of co-administered Salmonella typhimurium in a low volume vertical Ussing chamber. Methods C₁₀ or S. typhimurium was added to rat ileal mucosae mounted in chambers and the flux of the paracellular flux of [¹⁴C]-mannitol examined. S. typhimurium adherence and uptake by ileal mucosae was also examined by counting. Bacterial growth curves were assessed in the presence of C₁₀. Minimum inhibitory- and bacteriocidal concentrations of C₁₀ were determined against a range of bacteria. Results Apical addition of either C₁₀ or S. typhimurium to rat ileal mucosae mounted in modified diffusion chambers significantly increased the flux of [¹⁴C]-mannitol in a concentration-dependent fashion. Co-exposure with increasing concentrations of C₁₀ attenuated the Salmonella-induced increase in mannitol flux. Histological evaluation revealed that C₁₀ inhibited both adhesion and invasion of S. typhimurium to intestinal mucosae. Short term bacterial growth studies in the presence of C₁₀ showed evidence of concentration-dependent inhibition. C₁₀ was bacteriocidal in mM concentrations against S. typhimurium and selected gram positive and negative bacteria. Conclusions C₁₀ does not promote the permeation of a common bacterium across isolated intestinal tissue upon acute co-exposure. It prevents S. typhimurium attachment to epithelia and impedes growth of a range of different bacterial strains.     

Characterization of dopamine D<Subscript>1</Subscript> and D<Subscript>2</Subscript> receptor function in socially housed cynomolgus monkeys self-administering cocaine

Rationale Social rank has been shown to influence dopamine (DA) D₂ receptor function and vulnerability to cocaine self-administration in cynomolgus monkeys. The present studies were designed to extend these findings to maintenance of cocaine reinforcement and to DA D₁ receptors.Objective Examine the effects of a high-efficacy D₁ agonist on an unconditioned behavior (eyeblinking) and a low-efficacy D₁ agonist on cocaine self-administration, as well as the effects of cocaine exposure on D₂ receptor function across social ranks, as determined by positron emission tomography (PET).Methods Effects of the high-efficacy D₁ agonist SKF 81297 and cocaine (0.3–3.0 mg/kg) on spontaneous blinking were characterized in eight monkeys during 15-min observation periods. Next, the ability of the low-efficacy D₁ agonist SKF 38393 (0.1–17 mg/kg) to decrease cocaine self-administration (0.003–0.1 mg/kg per injection, IV) was assessed in 11 monkeys responding under a fixed-ratio 50 schedule. Finally, D₂ receptor levels in the caudate and putamen were assessed in nineteen monkeys using PET.Results SKF 81297, but not cocaine, significantly increased blinking in all monkeys, with slightly greater potency in dominant monkeys. SKF 38393 dose-dependently decreased cocaine-maintained response rates with similar behavioral potency and efficacy across social rank. After an extensive cocaine self-administration history, D₂ receptor levels did not differ across social ranks.Conclusions These results suggest that D₁ receptor function is not substantially influenced by social rank in monkeys from well-established social groups. While an earlier study showed that dominant monkeys had higher D₂ receptor levels and were less sensitive to the reinforcing effects of cocaine during initial exposure, the present findings indicate that long-term cocaine use changed D₂ receptor levels such that D₂ receptor function and cocaine reinforcement were not different between social ranks. These findings suggest that cocaine exposure attenuated the impact of social housing on DA receptor function.     

Naringenin-Loaded Nanoparticles Improve the Physicochemical Properties and the Hepatoprotective Effects of Naringenin in Orally-Administered Rats with CCl<Subscript>4</Subscript>-Induced Acute Liver Failure

Purpose  A novel naringenin-loaded nanoparticles system (NARN) was developed to resolve the restricted bioavailability of naringenin (NAR) and to enhance its hepatoprotective effects in vivo on oral administration. Materials and methods  Physicochemical characterizations of NARN included assessment of particle size and morphology, powder X-ray diffraction, fourier transform infrared spectroscopy, and dissolution study. In addition, to evaluate its bioactivities and its oral treatment potential against liver injuries, we compared the hepatoprotective, antioxidant, and antiapoptotic effects of NARN and NAR on carbon tetrachloride (CCl₄)-induced hepatotoxicity in rats. Results  NARN had a significantly higher release rate than NAR and improved its solubility. NARN also exhibited more liver-protective effects compared to NAR with considerable reduction in liver function index and lipid peroxidation, in conjunction to a substantial increase in the levels of the antioxidant enzymes (P < 0.05). Moreover, NARN was able to significantly inhibit the activation of caspase-3, -8, and -9 signaling, whereas NAR only markedly inhibited caspase-3 and -9 (P < 0.05). Conclusion  NARN effectively improved the release of NAR which resulted in more hepatoprotective effects mediated by its antioxidant and antiapoptotic properties. These observations also suggest that nanoformulation can improve the free drug’s bioactivity on oral administration. Feng-Lin Yen and Tzu-Hui Wu contributed equally to this work.     

Occupancy of dopamine D<Subscript>1</Subscript>, D<Subscript>2</Subscript> and serotonin<Subscript>2A</Subscript> receptors in schizophrenic patients treated with flupentixol in comparison with risperidone and haloperidol

Rationale Flupentixol (FLX) has been used as a neuroleptic for nearly 4 decades. In vitro data show comparable affinity to dopamine D₂, D₁ and 5-HT_2A receptors and recently, FLX showed to be not inferior to risperidone in schizophrenic patients with predominant negative symptomatology, which was implicated with flupentixol’s interaction with 5-HT_2A and/or D₁ receptors. Objectives To assess in vivo receptor occupancy (RO) in patients clinically treated with FLX (n = 13, 5.7 ± 1.4 mg/day) in comparison with risperidone (RIS, n = 11, 3.6 ± 1.3 mg/day) and haloperidol (HAL, n = 11, 8.5 ± 5.5 mg/day). Materials and methods Each patient underwent two PET scans with 3-N-[¹¹C]methylspiperone (target: frontal 5-HT_2A), [¹¹C]SCH23390 (striatal D₁) or [¹¹C]raclopride (striatal D₂). RO was calculated as the percentage reduction of specific binding in comparison with healthy controls. Results D₂-RO under FLX was between 50% and 70%, indicating an ED₅₀ of about 0.7 ng/ml serum. 5-HT_2A and D₁-RO was 20 ± 10% and 20 ± 5% (mean, SEM). Under HAL, D₁-RO was 14 ± 6% and under RIS not significantly different from zero. Conclusions We were able to demonstrate a moderate 5-HT_2A and D₁ occupancy under clinically relevant doses of flupentixol, albeit lower than expected from in vitro data and clearly below saturation. Therefore, if flupentixol’s efficacy on negative symptoms is based on its interaction with 5-HT_2A and/or D₁ receptors, it should be highly dependent on serum concentration and thus on dosage and metabolism. However, these data suggest that mechanisms other than D₁ or 5-HT_2A antagonism may contribute to flupentixol’s efficacy on negative symptoms.     

Effects of ethanol and GABA<Subscript>B</Subscript> drugs on working memory in C57BL/6J and DBA/2J mice

Rationale It has been suggested that GABA_B receptors may be part of a neural substrate mediating some of the effects of ethanol.Objective The purpose of this experiment was to investigate, in mice, the effects of ethanol on working memory in a delayed matching-to position (DMTP) task, and additionally to determine if these effects were modulated by GABA_B receptors.Methods Female C57BL/6J and DBA/2J mice were trained in the DMTP task, and after asymptotic levels of performance accuracy were achieved, injections (IP) of ethanol, baclofen, or phaclofen were administered. Baclofen or phaclofen were then co-administered with ethanol. Each test was repeated twice.Results Ethanol caused deficits in working memory at 2.0 g/kg and higher. The highest dose (2.5 g/kg) produced additional non-specific effects, indicative of sedation. Baclofen increased performance accuracy (2.5 mg/kg), while decreasing the total number of trials completed. When combined with ethanol (1.5 g/kg), baclofen increased memory deficits at the highest dose (7.5 mg/kg). Phaclofen increased performance accuracy at 10 and 30 mg/kg but had no effect on the total number of trials completed. When combined with ethanol (2.5 g/kg), phaclofen did not significantly alter ethanol-induced deficits in performance.Conclusions Analyses of performance accuracy, total trials completed and variables indexing bias and motor impairment indicated that GABA_B drugs modulate working memory in a behaviorally specific manner. Overall, these receptors may be part of a neural substrate that modulates some of the effects of ethanol.