Variable responses of human microbiomes to dietary supplementation with resistant starch.

BACKGROUND: The fermentation of dietary fiber to various organic acids is a beneficial function provided by the microbiota in the human large intestine. In particular, butyric acid contributes to host health by facilitating maintenance of epithelial integrity, regulating inflammation, and influencing gene expression in colonocytes. We sought to increase the concentration of butyrate in 20 healthy young adults through dietary supplementation with resistant starch (unmodified potato starch-resistant starch (RS) type 2). METHODS: Fecal samples were collected from individuals to characterize butyrate concentration via liquid chromatography and composition of the microbiota via surveys of 16S rRNA-encoding gene sequences from the Illumina MiSeq platform. Random Forest and LEfSe analyses were used to associate responses in butyrate production to features of the microbiota. RESULTS: RS supplementation increased fecal butyrate concentrations in this cohort from 8 to 12 mmol/kg wet feces, but responses varied widely between individuals. Individuals could be categorized into three groups based upon butyrate concentrations before and during RS: enhanced, high, and low (n = 11, 3, and 6, respectively). Fecal butyrate increased by 67 % in the enhanced group (from 9 to 15 mmol/kg), while it remained ≥11 mmol/kg in the high group and ≤8 mmol/kg in the low group. Microbiota analyses revealed that the relative abundance of RS-degrading organisms-Bifidobacterium adolescentis or Ruminococcus bromii-increased from ~2 to 9 % in the enhanced and high groups, but remained at ~1.5 % in the low group. The lack of increase in RS-degrading bacteria in the low group may explain why there was no increase in fecal butyrate in response to RS. The microbiota of individuals in the high group were characterized by an elevated abundance of the butyrogenic microbe Eubacterium rectale (~6 % in high vs. 3 % in enhanced and low groups) throughout the study. CONCLUSIONS: We document the heterogeneous responses in butyrate concentrations upon RS supplementation and identify characteristic of the microbiota that appear to underlie this variation. This study complements and extends other studies that call for personalized approaches to manage beneficial functions provided by gut microbiomes.

Pharmacological characterization of 2-methyl-N-((2'-(pyrrolidin-1-ylsulfonyl)biphenyl-4-yl)methyl)propan-1-amine (PF-04455242), a high-affinity antagonist selective for κ-opioid receptors.

2-Methyl-N-((2'-(pyrrolidin-1-ylsulfonyl)biphenyl-4-yl)methyl)propan-1-amine (PF-04455242) is a novel κ-opioid receptor (KOR) antagonist with high affinity for human (3 nM), rat (21 nM), and mouse (22 nM) KOR, a ∼ 20-fold reduced affinity for human µ-opioid receptors (MORs; K(i) = 64 nM), and negligible affinity for δ-opioid receptors (K(i) > 4 µM). PF-04455242 also showed selectivity for KORs in vivo. In rats, PF-04455242 blocked KOR and MOR agonist-induced analgesia with ID(50) values of 1.5 and 9.8 mg/kg, respectively, and inhibited ex vivo [(3)H](2-(benzofuran-4-yl)-N-methyl-N-((5S,7R,8R)-7-(pyrrolidin-1-yl)-1-oxaspiro[4.5]decan-8-yl)acetamide ([(3)H]CI977) and [(3)H](2S)-2-[[2-[[(2R)-2-[[(2S)-2-amino-3-(4-hydroxyphenyl) propanoyl]amino]propanoyl]amino]acetyl]-methylamino]-N-(2-hydroxyethyl)-3-phenylpropanamide ([(3)H]DAMGO) binding to KOR and MOR receptors with ID(50) values of 2.0 and 8.6 mg/kg, respectively. An in vivo binding assay was developed using (-)-4-[(3)H]methoxycarbonyl-2-[(1-pyrrolidinylmethyl]-1-[(3,4-dichlorophenyl)acetyl]-piperidine ([(3)H]PF-04767135), a tritiated version of the KOR positron emission tomography ligand (-)-4-[(11)C]methoxycarbonyl-2-[(1-pyrrolidinylmethyl]-1-[(3,4-dichlorophenyl)acetyl]-piperidine ([(11)C]GR103545) in which PF-04455242 had an ID(50) of 5.2 mg/kg. PF-04455242 demonstrated antidepressant-like efficacy (mouse forced-swim test), attenuated the behavioral effects of stress (mouse social defeat stress assay), and showed therapeutic potential in treating reinstatement of extinguished cocaine-seeking behavior (mouse conditioned place preference). KOR agonist-induced plasma prolactin was investigated as a translatable mechanism biomarker. Spiradoline (0.32 mg/kg) significantly increased rat plasma prolactin levels from 1.9 ± 0.4 to 41.9 ± 4.9 ng/ml. PF-04455242 dose-dependently reduced the elevation of spiradoline-induced plasma prolactin with an ID(50) of 2.3 ± 0.1 mg/kg, which aligned well with the ED(50) values obtained from the rat in vivo binding and efficacy assays. These data provide further evidence that KOR antagonists have potential for the treatment of depression and addiction disorders.

Design, synthesis, and evaluation of metabolism-based analogues of haloperidol incapable of forming MPP+-like species.

The long-term, irreversible, Parkinsonism-like side effects of haloperidol have been speculated to involve several mechanisms. More recently, it has been speculated that the metabolic transformation to MPP+-like species may contribute to the Parkinsonism-like side effects. Because BCPP+ and its reduced analogue have been shown to possess the potential to destroy dopamine receptors in the nigrostriatum, we have designed new analogues of haloperidol lacking the structural features necessary to form neurotoxic quaternary species but retaining their dopamine-binding capacity. The most potent agent at the D2 receptor, the homopiperidine analogue 11, was found to be equipotent to haloperidol. It was also of interest to identify analogues with DA binding profiles similar to that of clozapine at the dopamine receptor subtypes. Evaluation of the proposed agents shows that the ratio of D2 to D4 (2) binding of clozapine was mimicked by 7 [K(i)(D2) = 33, K(i)(D3) = 200, K(i)(D4) = 11 nM; K(i)(D2)/K(i)(D4) = 3] and 9 [K(i)(D2) = 44, K(i)(D3) = 170, K(i)(D4) = 24 nM; K(i)(D2)/K(i)(D4) = 2]. A preliminary in-vivo testing of compound 7 shows that its behavioral profile is similar to that of clozapine. This profile suggests that there is a need for further evaluation of these two synthetic agents and their enantiomers for efficacy and lack of catalepsy in animal models.

Ziprasidone: a novel antipsychotic agent with a unique human receptor binding profile.

Ziprasidone is a novel antipsychotic agent with a unique combination of pharmacological activities at human receptors. Ziprasidone has high affinity for human 5-HT receptors and for human dopamine D(2) receptors. Ziprasidone is a 5-HT(1A) receptor agonist and an antagonist at 5-HT(2A), 5-HT(2C) and 5-HT(1B/1D) receptors. Additionally, ziprasidone inhibits neuronal uptake of 5-HT and norepinephrine comparable to the antidepressant imipramine. This unique pharmacological profile of ziprasidone may be related to its clinical effectiveness as a treatment for the positive, negative and affective symptoms of schizophrenia with a low propensity for extrapyramidal side effects, cognitive deficits and weight gain.

Serotonergic effects and extracellular brain levels of eletriptan, zolmitriptan and sumatriptan in rat brain.

In vivo microdialysis was used to assess the central serotonergic effects and extracellular brain levels of the 5-HT(1B/1D) receptor agonists eletriptan, zolmitriptan and sumatriptan in rats after intravenous and intracerebral administration, while their binding affinities and functional potencies were determined at 5-HT(1B), 5-HT(1D) and 5-HT(1A) receptors. In vitro studies showed that all three triptans are high affinity, full agonists at 5-HT(1B/1D) receptors, but that sumatriptan is functionally less potent as a 5-HT(1B/1D) agonist than zolmitriptan and eletriptan. Local intracortical perfusion with the compounds via the dialysis probe decreased cortical 5-HT (5-hydroxytryptamine, serotonin) release with ED(50) values of approximately 0.1 microM for eletriptan and zolmitriptan and 0.5 microM for sumatriptan. At 3.2 mg/kg i.v., both eletriptan and zolmitriptan decreased 5-HT levels by about 35%, while sumatriptan had no effect, despite the fact that maximal sumatriptan concentrations in cortical dialysates were higher (8.8 nM at 20 min) than those of zolmitriptan (5.9 nM at 20 min) and eletriptan (2.6 nM at 40 min). The observation that eletriptan and zolmitriptan produce almost identical central serotonergic effects, after intracerebral as well as after systemic administration, is in agreement with their comparable functional 5-HT(1B/1D) receptor agonist potencies and their free levels in cortical dialysates after 3.2 mg/kg i.v. On the other hand, the lack of central serotonergic effects of 3.2 mg/kg i.v. sumatriptan is likely due to its weaker functional 5-HT(1B/1D) receptor agonist potency than eletriptan and zolmitriptan, rather than lower brain levels, consistent with sumatriptan's fivefold lower potency after intracerebral administration.

5-HT(1A) receptor activation contributes to ziprasidone-induced dopamine release in the rat prefrontal cortex.

BACKGROUND: Ziprasidone (Zeldox) is a novel antipsychotic with a unique combination of antagonist activities at monoaminergic receptors and transporters and potent agonist activity at serotonin 5-HT(1A) receptors. 5-HT(1A) receptor agonism may be an important feature in ziprasidone's clinical actions because 5-HT(1A) agonists increase cortical dopamine release, which may underlie efficacy against negative symptoms and reduce dopamine D(2) antagonist-induced extrapyramidal side effects. This study investigated the in vivo 5-HT(1A) agonist activity of ziprasidone by measuring the contribution of 5-HT(1A) receptor activation to the ziprasidone-induced cortical dopamine release in rats. METHODS: Effects on dopamine release were measured by microdialysis in prefrontal cortex and striatum. The role of 5-HT(1A) receptor activation was estimated by assessing the sensitivity of the response to pretreatment with the 5-HT(1A) antagonist, WAY-100635. For comparison, the D(2)/5-HT(2A) antagonists clozapine and olanzapine, the D(2) antagonist haloperidol, the 5-HT(2A) antagonist MDL 100,907 and the 5-HT(1A) agonist 8-OHDPAT were included. RESULTS: Low doses (<3.2 mg/kg) of ziprasidone, clozapine, and olanzapine increased dopamine release to approximately the same extent in prefrontal cortex as in striatum, but higher doses (> or =3.2 mg/kg) resulted in an increasingly preferential effect on cortical dopamine release. The 5-HT(1A) agonist 8-OHDPAT produced a robust increase in cortical dopamine (DA) release without affecting striatal DA release. In contrast, the D(2) antagonist haloperidol selectively increased striatal DA release, whereas the 5-HT(2A) antagonist MDL 100,907 had no effect on cortical or striatal DA release. Prior administration of WAY-100635 completely blocked the cortical DA increase produced by 8-OHDPAT and significantly attenuated the ziprasidone- and clozapine-induced cortical DA increase. WAY-100635 pretreatment had no effect on the olanzapine-induced DA increase. CONCLUSIONS: The preferential increase in DA release in rat prefrontal cortex produced by ziprasidone is mediated by 5-HT(1A) receptor activation. This result extends and confirms other in vitro and in vivo data suggesting that ziprasidone, like clozapine, acts as a 5-HT(1A) receptor agonist in vivo, which may contribute to its activity as an antipsychotic with efficacy against negative symptoms and a low extrapyramidal side effect liability.

Clozapine increases dopamine release in prefrontal cortex by 5-HT1A receptor activation.

Clozapine (1-10 mg/kg s.c.) produces a selective increase in dopamine release in rat prefrontal cortex which is, in large part (approximately 50%), mediated via activation of 5-HT1A receptors. Clozapine is a moderately potent, partial 5-HT1A receptor agonist and activation of 5-HT1A receptors may contribute to its efficacy against negative symptoms and reduced extrapyramidal side effect liability. Agonist affinity for 5-HT1A receptors could thus be a desirable feature in the design of new antipsychotics.

CP-154,526: a potent and selective nonpeptide antagonist of corticotropin releasing factor receptors.

Here we describe the properties of CP-154,526, a potent and selective nonpeptide antagonist of corticotropin (ACTH) releasing factor (CRF) receptors. CP-154,526 binds with high affinity to CRF receptors (Ki < 10 nM) and blocks CRF-stimulated adenylate cyclase activity in membranes prepared from rat cortex and pituitary. Systemically administered CP-154,526 antagonizes the stimulatory effects of exogenous CRF on plasma ACTH, locus coeruleus neuronal firing and startle response amplitude. Potential anxiolytic activity of CP-154,526 was revealed in a fearpotentiated startle paradigm. These data are presented in the context of clinical findings, which suggest that CRF is hypersecreted in certain pathological states. We propose that a CRF antagonist such as CP-154,526 could affirm the role of CRF in certain psychiatric diseases and may be of significant value in the treatment of these disorders.

Characterization of CP-122,721; a nonpeptide antagonist of the neurokinin NK1 receptor.

CP-122,721 [(+)-(2S,3S)-3-(2-methoxy-5-trifluoromethoxybenzyl)amino-2 -phenylpiperidine] interacts with high affinity (pIC50 = 9.8) at the human NK1 receptor expressed in IM-9 cells. In the presence of CP-122,721, there was a reduction in Bmax of [125I]BH-SP binding with no change in affinity suggesting that CP-122,721 does not interact with the NK1 receptor in competitive manner. In an in vitro functional assay. CP-122,721 blocked SP-induced excitation of locus ceruleus cells in guinea pig brain slices with a IC50 value of 7 nM. In vivo, CP-122,721 potently blocked plasma extravasation in guinea pig lung elicited by aerosolized capsaicin (1 mM) with an ID50 = 0.01 mg/kg, p.o. Orally administered CP-122,721 antagonized Sar9, Met (O2)11-SP-induced locomotor activity in guinea pigs with an ID50 = 0.2 mg/kg suggesting good entry into the central nervous system. In addition, consistent with insurmountable blockade observed in vitro, CP-122,721 (0.01, 0.03 0.3 mg/kg, p.o.) produced a rightward shift in the dose response curve for SP-induced hypotension in the awake dog that was accompanied by a decrease in the maximal response. Thus, in vitro and in vivo CP-122,721 appears to behave functionally as a non-competitive antagonist producing an insurmountable blockade of the actions of SP.

3-Benzisothiazolylpiperazine derivatives as potential atypical antipsychotic agents.

A series of substituted phenethyl derivatives of 3-benzisothiazolylpiperazine incorporating potent D2 and 5-HT2A antagonist activity was investigated as an approach to a novel atypical antipsychotic agent. The in vitro profile of 8e from this series is a combination of D2 receptor affinity comparable to the typical antipsychotic agent haloperidol and a 5-HT2A/D2 ratio comparable to the atypical agent clozapine. In vivo 8e possesses activity consistent with an efficacious antipsychotic agent with less tendency to induce extrapyramidal side effects in man.

Ziprasidone (CP-88,059): a new antipsychotic with combined dopamine and serotonin receptor antagonist activity.

Ziprasidone (CP-88,059) is a combined 5-HT (serotonin) and dopamine receptor antagonist which exhibits potent effects in preclinical assays predictive of antipsychotic activity. Whereas the compound is a dopamine antagonist in vitro and in vivo, its most potent action is antagonism of 5-HT2A receptors, where its affinity is an order of magnitude greater than that observed for dopamine D2 sites. Laboratory and clinical findings have led to a hypothesis that antagonism of 5-HT2A receptors in the brain limits the undesirable motor side effects associated with dopamine receptor blockade and improves efficacy against the negative symptoms of schizophrenia. Ziprasidone possesses an in vitro 5-HT2A/dopamine D2 receptor affinity ratio higher than any clinically available antipsychotic agent. In vivo, ziprasidone antagonizes 5-HT2A receptor-induced head twitch with 6-fold higher potency than for blockade of d-amphetamine-induced hyperactivity, a measure of central dopamine D2 receptor antagonism. Ziprasidone also has high affinity for the 5-HT1A, 5-HT1D and 5-HT2C receptor subtypes, which may further enhance its therapeutic potential. The prediction of antipsychotic efficacy without severe motor side effects is supported by the relatively weak potency of ziprasidone to produce catalepsy in animals, contrasted with its potent antagonism of conditioned avoidance responding and dopamine agonist-induced locomotor activation and stereotypy. The compound is well tolerated in animals at doses producing effective dopamine antagonism in the brain. Ziprasidone should be a valuable addition to the treatment of psychotic disorders.

The substance P receptor antagonist CP-96,345 interacts with Ca2+ channels.

The nonpeptide substance P receptor antagonist CP-96,345 was found to displace binding to Ca2+ channel binding sites labelled with either [3H]desmethoxyverapamil or [3H]diltiazem and to enhance [3H]nitrendipine binding. Unlike the substance P receptor antagonist activity of CP-96,345, these effects on Ca2+ channel binding sites were neither stereoselective nor species-dependent. It is concluded that CP-96,345 may act as an antagonist of L-type Ca2+ channels in addition to being a potent NK1 receptor (substance P) antagonist.

Separation of alpha 1 adrenergic and N-methyl-D-aspartate antagonist activity in a series of ifenprodil compounds.

Ifenprodil (1) represents a new class of N-methyl-D-aspartate (NMDA) antagonist. This drug also possesses potent activity at several other brain receptors (most notably alpha 1 adrenergic receptors). We have prepared the enantiomers and diastereomers of ifenprodil along with a series of partial structures in order to explore the basic structure activity relations within this class of compounds. From this study, it is clear that alpha 1 adrenergic and NMDA receptor activities may be separated by selection of the threo relative stereochemistry. Examination of the optical isomers of threo-ifenprodil (2) reveals that no further improvement in receptor selectivity is gained from either antipode. Individual removal of most of the structural fragments from the ifenprodil molecule generally results in less active compounds although fluorinated derivative 9 with threo relative stereochemistry is somewhat more potent and substantially more selective for the NMDA receptor. Finally a minimum structure for activity in this series (14) has been identified. This stripped-down version of ifenprodil possesses nearly equivalent affinity for the NMDA receptor with no selectivity over alpha 1 adrenergic receptors.

1-Naphthylpiperazine derivatives as potential atypical antipsychotic agents.

The design and synthesis of a series of potential atypical antipsychotic agents based on the structure of 1-naphthylpiperazine are described. The incorporation of dopamine antagonist activity into the parent structure was achieved with heterocyclic surrogates for the catechol moiety of dopamine. Compound 4b from this series showed a biochemical profile that translated to behavioral activity in the rat predictive of an antipsychotic agent with a low propensity to cause extrapyramidal side effects in man.

Quantitative molecular analysis predicts 5-hydroxytryptamine3 receptor binding affinity.

A quantitative molecular model was derived to predict drug affinities for 5-hydroxytryptamine3 (5-HT3) receptors. The model was based on the molecular characteristics of a "learning set" of 40 pharmacological agents that had been analyzed previously in radioligand binding studies. Molecules were analyzed for various structural features, i.e., the presence of a benzenoid ring and nitrogen atom, substitutions on the benzenoid ring, the location of the substitutions on the nitrogen, and the molecular characteristics of the most direct pathway from the benzenoid ring to the nitrogen. Weighting factors, based on published 5-HT3 receptor affinity data, were then assigned to each of 10 molecular characteristics. The derived computational model predicts accurately the affinities of the learning set for the 5-HT3 receptor (r = 0.98; p less than 0.001). The computational model was then used to predict the receptor affinities of a "test set" of 40 pharmacological agents. The predicted values for these agents also correlate significantly (r = 0.83; p less than 0.001) with drug affinities for the 5-HT3 receptor, as determined by radioligand binding assays. This first line screening approach allows for the accurate prediction of drug affinities based on molecular characteristics with minimal dependence upon animal tissues or radioactivity.

On the behavior of instantaneous frequency estimators implemented on Doppler flow imagers.

Analytical and experimental results have been used to examine the behavior of the "autocorrelator" or instantaneous frequency detector (IFD) applied to color-coded Doppler flow mapping. Two effects were studied. The first was the influence of noise, as modified by a stationary echo canceler, on the Doppler frequency detector. Our theoretical considerations predict that uncorrelated input noise signals become partially correlated after cancellation, and bias the response to flow signals. This effect was confirmed by experiment. The canceler introduces a constant negative bias into the denominator of the algorithm implemented by the estimator, thus changing the indicated frequency. The second phenomenon, examined through processing computer simulated Doppler signals added to real noise, is related to the possible ambiguity, called aliasing, of measurements of the mean frequency for wide-band Doppler spectra. We show that aliasing cannot be observed with these spectra unless the signal is first processed by a canceler. Thus, regions of apparent reversed flow direction on two-dimensional flow images of turbulence must usually be due to real reversal of the flow direction.