Precision Determination of the Neutral Weak Form Factor of ^{48}Ca

We report a precise measurement of the parity-violating (PV) asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{48}Ca. We measure A_{PV}=2668±106(stat)±40(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(q=0.8733  fm^{-1})=0.1304±0.0052(stat)±0.0020(syst) and the charge minus the weak form factor F_{ch}-F_{W}=0.0277±0.0055. The resulting neutron skin thickness R_{n}-R_{p}=0.121±0.026(exp)±0.024(model)  fm is relatively thin yet consistent with many model calculations. The combined CREX and PREX results will have implications for future energy density functional calculations and on the density dependence of the symmetry energy of nuclear matter.

New Measurements of the Beam-Normal Single Spin Asymmetry in Elastic Electron Scattering over a Range of Spin-0 Nuclei

We report precision determinations of the beam-normal single spin asymmetries (A_{n}) in the elastic scattering of 0.95 and 2.18 GeV electrons off ^{12}C, ^{40}Ca, ^{48}Ca, and ^{208}Pb at very forward angles where the most detailed theoretical calculations have been performed. The first measurements of A_{n} for ^{40}Ca and ^{48}Ca are found to be similar to that of ^{12}C, consistent with expectations and thus demonstrating the validity of theoretical calculations for nuclei with Z≤20. We also report A_{n} for ^{208}Pb at two new momentum transfers (Q^{2}) extending the previous measurement. Our new data confirm the surprising result previously reported, with all three data points showing significant disagreement with the results from the Z≤20 nuclei. These data confirm our basic understanding of the underlying dynamics that govern A_{n} for nuclei containing ≲50 nucleons, but point to the need for further investigation to understand the unusual A_{n} behavior discovered for scattering off ^{208}Pb.

Accurate Determination of the Neutron Skin Thickness of ^{208}Pb through Parity-Violation in Electron Scattering

We report a precision measurement of the parity-violating asymmetry A_{PV} in the elastic scattering of longitudinally polarized electrons from ^{208}Pb. We measure A_{PV}=550±16(stat)±8(syst) parts per billion, leading to an extraction of the neutral weak form factor F_{W}(Q^{2}=0.00616  GeV^{2})=0.368±0.013. Combined with our previous measurement, the extracted neutron skin thickness is R_{n}-R_{p}=0.283±0.071  fm. The result also yields the first significant direct measurement of the interior weak density of ^{208}Pb: ρ_{W}^{0}=-0.0796±0.0036(exp)±0.0013(theo)  fm^{-3} leading to the interior baryon density ρ_{b}^{0}=0.1480±0.0036(exp)±0.0013(theo)  fm^{-3}. The measurement accurately constrains the density dependence of the symmetry energy of nuclear matter near saturation density, with implications for the size and composition of neutron stars.

Autophagy in adipose tissue of patients with obesity and type 2 diabetes

BACKGROUND

Pathophysiology of obesity is closely associated with enhanced autophagy in adipose tissue (AT). Autophagic process can promote survival or activate cell death. Therefore, we examine the occurrence of autophagy in AT of type 2 diabetes (T2D) patients in comparison to obese and lean individuals without diabetes.

METHODOLOGY/PRINCIPAL FINDINGS

Numerous autophagosomes accumulated within adipocytes were visualized by electron transmission microscopy and by immunofluorescence staining for autophagy marker LC3 in obese and T2D patients. Increased autophagy was demonstrated by higher LC3-II/LC3-I ratio, up-regulated expression of LC3 and Atg5 mRNA, along with decreased p62 and mTOR protein levels. Increased autophagy occurred together with AT inflammation.

CONCLUSIONS

Our data suggest fat depot-related differences in autophagy regulation. In subcutaneous AT, increased autophagy is accompanied by increased markers of apoptosis in patients with obesity independently of T2D. In contrast, in visceral AT only in T2D patients increased autophagy was related to higher markers of apoptosis.

Apolipoproteins D and E3 exert neurotrophic and synaptogenic effects in dorsal root ganglion cell cultures

Co-cultures of 3T3-L1 adipocytes with neurons from the rat dorsal root ganglia (DRG) showed enhanced neuritogenesis and synaptogenesis. Microarray analysis for upregulated genes in adipocyte/DRG co-cultures currently points to apolipoproteins D and E (ApoD, ApoE) as influential proteins. We therefore tested adipocyte-secreted cholesterol and the carrier proteins ApoD and ApoE3. Cholesterol, ApoD, and ApoE3 each increased neurite outgrowth and upregulated the expression of presynaptic synaptophysin and synaptotagmin, as well as the postsynaptic density protein 95. The neurotrophic effects of ApoD and ApoE3 were associated with an increased expression of the low-density lipoprotein receptor and apolipoprotein E receptor 2. Simultaneous treatment with receptor-associated protein, an apolipoprotein receptor antagonist, inhibited the neurotrophic function of both apolipoproteins. The application of ApoD, ApoE3, and cholesterol to DRG cell cultures corresponded with increased expression of the chemokine stromal cell-derived factor 1 and its receptor CXC chemokine receptor 4 (CXCR4). Surprisingly, the inhibition of CXCR4 by the antagonistic drug AMD3100 decreased the apolipoprotein/cholesterol dependent neurotrophic effects. We thus assume that apolipoprotein-induced neuritogenesis in DRG cells interferes with CXCR4 signaling, and that adipocyte-derived apolipoproteins might be helpful in nerve repair.

Analysis of the inter- and extracellular formation of platinum nanoparticles by Fusarium oxysporum f. sp. lycopersici using response surface methodology

Fusarium oxysporum fungal strain was screened and found to be successful for the inter- and extracellular production of platinum nanoparticles. Nanoparticle formation was visually observed, over time, by the colour of the extracellular solution and/or the fungal biomass turning from yellow to dark brown, and their concentration was determined from the amount of residual hexachloroplatinic acid measured from a standard curve at 456 nm. The extracellular nanoparticles were characterized by transmission electron microscopy. Nanoparticles of varying size (10-100 nm) and shape (hexagons, pentagons, circles, squares, rectangles) were produced at both extracellular and intercellular levels by the Fusarium oxysporum. The particles precipitate out of solution and bioaccumulate by nucleation either intercellularly, on the cell wall/membrane, or extracellularly in the surrounding medium. The importance of pH, temperature and hexachloroplatinic acid (H(2)PtCl(6)) concentration in nanoparticle formation was examined through the use of a statistical response surface methodology. Only the extracellular production of nanoparticles proved to be statistically significant, with a concentration yield of 4.85 mg l(-1) estimated by a first-order regression model. From a second-order polynomial regression, the predicted yield of nanoparticles increased to 5.66 mg l(-1) and, after a backward step, regression gave a final model with a yield of 6.59 mg l(-1).

New Pulsed Cold Neutron Beam Line for Fundamental Nuclear Physics at LANSCE

The NPDGamma collaboration has completed the construction of a pulsed cold neutron beam line on flight path12 at the Los Alamos Neutron Science Center (LANSCE). We describe the new beam line and characteristics of the beam. We report results of the moderator brightness and the guide performance measurements. FP12 has the highest pulsed cold neutron intensity for nuclear physics in the world.

Properties of a native cation channel activated by Ca2+ store depletion in vascular smooth muscle cells

Depletion of intracellular Ca(2+) stores activates capacitative Ca(2+) influx in smooth muscle cells, but the native store-operated channels that mediate such influx remain unidentified. Recently we demonstrated that calcium influx factor produced by yeast and human platelets with depleted Ca(2+) stores activates small conductance cation channels in excised membrane patches from vascular smooth muscle cells (SMC). Here we characterize these channels in intact cells and present evidence that they belong to the class of store-operated channels, which are activated upon passive depletion of Ca(2+) stores. Application of thapsigargin (TG), an inhibitor of sarco-endoplasmic reticulum Ca(2+) ATPase, to individual SMC activated single 3-pS cation channels in cell-attached membrane patches. Channels remained active when inside-out membrane patches were excised from the cells. Excision of membrane patches from resting SMC did not by itself activate the channels. Loading SMC with BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid), which slowly depletes Ca(2+) stores without a rise in intracellular Ca(2+), activated the same 3-pS channels in cell-attached membrane patches as well as whole cell nonselective cation currents in SMC. TG- and BAPTA-activated 3-pS channels were cation-selective but poorly discriminated among Ca(2+), Sr(2+), Ba(2+), Na(+), K(+), and Cs(+). Open channel probability did not change at negative membrane potentials but increased significantly at high positive potentials. Activation of 3-pS channels did not depend on intracellular Ca(2+) concentration. Neither TG nor a variety of second messengers (including Ca(2+), InsP3, InsP4, GTPgammaS, cyclic AMP, cyclic GMP, ATP, and ADP) activated 3-pS channels in inside-out membrane patches. Thus, 3-pS nonselective cation channels are present and activated by TG or BAPTA-induced depletion of intracellular Ca(2+) stores in intact SMC. These native store-operated cation channels can account for capacitative Ca(2+) influx in SMC and can play an important role in regulation of vascular tone.

Ca(2+)-dependent Cl(-) channels in mouse and rabbit aortic smooth muscle cells: regulation by intracellular Ca(2+) and NO

Ca(2+)-dependent Cl(-) (Cl(-)(Ca)) channels and their regulation by intracellular Ca(2+) concentration ([Ca(2+)](i)) and nitric oxide (NO) were characterized in mouse and rabbit aortic smooth muscle cells (SMC) using patch clamp and fura 2 imaging. Single channels (1. 8 pS) and whole cell Cl(-)(Ca) currents were activated by caffeine-induced Ca(2+) release. Single Cl(-)(Ca) channels were also activated by >/=200 nM Ca(2+) in inside-out membrane patches and remained active for >5 min in </=1 microM Ca(2+) but showed rapid rundown in 2 mM Ca(2+). Authentic NO or S-nitroso-N-acetylpenicillamine (SNAP) did not affect their activation or rundown in inside-out patches. In the whole cell, SNAP (100 microM) and 8-(4-chlorophenylthio)-guanosine 3',5'-cyclic monophosphate (50 microM) did not affect Cl(-)(Ca) current, but at a higher concentration SNAP (1 mM) induced a sustained [Ca(2+)](i) rise, accompanied by a dramatic decrease in caffeine-induced Ca(2+) release and Cl(-)(Ca) current. These results indicate that 1) mouse and rabbit aortic SMC possess 1.8-pS Cl(-)(Ca) channels that are activated by Ca(2+) release from the stores, 2) both activation and rundown of single Cl(-)(Ca) channels depend on [Ca(2+)](i), and 3) NO does not affect Cl(-)(Ca) channels directly or via cGMP but can inhibit their activation indirectly by decreasing Ca(2+) release from the stores.

Mechanism of nitric oxide-induced vasodilatation: refilling of intracellular stores by sarcoplasmic reticulum Ca2+ ATPase and inhibition of store-operated Ca2+ influx

The precise mechanisms by which nitric oxide (NO) decreases free [Ca2+]i, inhibits Ca2+ influx, and relaxes vascular smooth muscle are poorly understood. In rabbit and mouse aorta, agonist-induced contractions and increases in [Ca2+]i were resistant to nifedipine, suggesting Ca2+ entry through non-L-type Ca2+ channels. Relaxations to NO were inhibited by thapsigargin (TG) or cyclopiazonic acid (CPA) indicating the involvement of sarcoplasmic reticulum ATPase (SERCA). Studies of the effect of NO on [Ca2+]i and the rate of Mn2+ influx with fura-2 fluorometry in rabbit aortic smooth muscle cells in primary culture were designed to test how SERCA is involved in mediating the response to NO. When cells were stimulated with angiotensin II (AII), NO accelerated the removal of Ca2+ from the cytoplasm, decreased [Ca2+]i, and inhibited Ca2+ and Mn2+ influx. Inhibition of SERCA abolished all the effects of NO. In contrast, inhibition of the Na+/Ca2+exchanger or the plasma membrane Ca2+ ATPase had no influence on the ability of NO to decrease [Ca2+]i. NO maximally decreased [Ca2+]i within 5 s, whereas significant inhibition of AII-induced Ca2+ and Mn2+ influx required more than 15 s. The inhibition of cation influx strictly depended on [Ca2+]o and functional SERCA, suggesting that during the delay before NO inhibits Ca2+ influx, the influx of Ca2+ and the uptake into intracellular stores are required. In the absence of [Ca2+]o, NO diminished the AII-induced [Ca2+]i transient by a SERCA-dependent mechanism and increased the amount of Ca2+ in the stores subsequently released by ionomycin. The present study indicates that the initial rapid decrease in [Ca2+]i caused by NO in vascular smooth muscle is accounted for by the uptake of Ca2+ by SERCA into intracellular stores. It is proposed that the refilling of the stores inhibits store-operated Ca2+ influx through non-L-type Ca2+ conducting ion channels and that this maintains the decrease in [Ca2+]i and NO-induced relaxation.

Immunological stimulation of single rat basophilic leukemia RBL-2H3 cells co-activates Ca(2+)-entry and K(+)-channels

The relationship between type 1 Fc epsilon-receptor (Fc epsilon RI) mediated cell stimulation, Ca(2+)-signals and membrane currents was studied in rat mucosal mast cells, subline RBL-2H3 by combining patch-clamp, Fura-2, 45Ca(2+)-uptake and secretory response measurements. Cells were stimulated by Fc epsilon RI clustering either with IgE and antigen or by an IgE specific monoclonal antibody. Both stimuli induced a biphasic increase in the free intracellular Ca(2+)-concentration ([Ca2+]i). Fc epsilon RI clustering in Ca(2+)-free solution induces a transient increase in [Ca2+]i reflecting Ca2+ release from the Ins(1,4,5)P3 sensitive stores. Mn2+ applied to a nominally Ca(2+)-free solution, causes quenching of the Fura-2 emission during Fc epsilon RI clustering, indicating activation of a transmembrane pathway for the entry of extracellular calcium ions. Whole-cell current-voltage relationship of resting cells showed strong inward rectification. The inward current component at a potential of -100 mV is increased by 23 +/- 11% (n = 14) upon Fc epsilon RI clustering, whereas the outward component at +50 mV was enhanced by 45 +/- 6%. The Fc epsilon RI activated current was identified as due to K+ ions, because it reversed close to the K(+)-equilibrium potential, was blocked by Ba2+ or Cs+ containing or K(+)-free bath solutions. It was also inhibited by TEA and quinidine, while DIDS had no effect. Moreover, an inwardly rectifying K(+)-channel with a conductance of 28 pS was recorded in single channel measurements. The open probability of this channel increased by 39 +/- 16% (n = 8) upon Fc epsilon RI clustering. Superfusion of the cells with nominally K(+)-free solution also significantly inhibited both the Fc epsilon RI mediated 45Ca2+ uptake and the secretory response of the cells. We conclude that activation of K(+)-channels upon Fc epsilon RI clustering is functionally involved in the control and the maintenance of the secretory response of RBL-2H3 mast cells.

Inhibition of capacitative Ca2+ entry by a Cl- channel blocker in human endothelial cells

We have used the patch clamp technique in combination with intracellular calcium measurements to measure simultaneously Ca2+ entry and ionic currents activated by emptying of intracellular Ca2+ stores (capacitative Ca2+ entry and Ca2+ release-activated Ca2+ currents, CRAC) in human endothelial cells from umbilical veins. Intracellular stores were depleted of Ca2+ by preincubating endothelial cells for 20 minutes with 2 microM thapsigargin in Ca(2+)-free solution. Reapplication of 10 mM [Ca2+]e evoked an increase in [Ca2+]i indicating Ca2+ influx after the thapsigargin-induced store depletion (capacitative Ca2+ entry), however no measurable CRAC could be detected. The increase in [Ca2+]i after [Ca2+]e resubmission was substantially reduced in the presence of 50 microM NPPB (5-nitro-2-(3-phenylpropylamino)-benzoic acid) from 0.77 +/- 0.25 microM to 0.2 +/- 0.06 microM (n = 6) at a holding potential of -40 mV. Estimates of the capacitative Ca2+ entry at various membrane potentials from the first time derivative of the Ca2+ transients showed a highly inwardly rectifying I-V curve with a Ca2+ inward current amplitude of 1.0 +/- 0.3 pA (membrane capacitance 59 +/- 9 pF, n = 8) at -80 mV. This current amplitude was decreased to 0.32 +/- 0.12 pA (n = 6) in the presence of 50 microM NPPB. This corresponds to a decrease in the Ca2+ permeability of the endothelial cell membrane from 0.15 x 10(-8) cm/s (control) to 0.06 x 10(-8) cm/s (50 microM NPPB).

Calcium entry activated by store depletion in human umbilical vein endothelial cells

We have used the patch clamp technique combined with simultaneous measurement of intracellular Ca2+ to record ionic currents activated by depletion of intracellular Ca(2+)-stores in endothelial cells from human umbilical veins. Two protocols were used to release Ca2+ from intracellular stores, i.e. loading of the cells via the patch pipette with Ins(1,4,5)P3, and extracellular application of thapsigargin. Ins(1,4,5)P3 (10 microM) evoked a transient increase in [Ca2+]i in cells exposed to Ca(2+)-free extracellular solutions. A subsequent reapplication of extracellular Ca2+ induced an elevation of [Ca2+]i. These changes in [Ca2+]i were very reproducible. The concomitant membrane currents were neither correlated in time nor in size with the changes in [Ca2+]i. Similar changes in [Ca2+]i and membrane currents were observed if the Ca(2+)-stores were depleted with thapsigargin. Activation of these currents was prevented and holding currents at -40 mV were small if store depletion was induced in the presence of 50 microM NPPB. This identifies the large currents, which are activated as a consequence of store-depletion, as mechanically activated Cl- currents, which have been described previously [1,2]. Loading the cells with Ins(1,4,5)P3 together with 10 mM BAPTA induced only a very short lasting Ca2+ transient, which was not accompanied by activation of a detectable current, even in a 10 mM Ca(2+)-containing extracellular solution. Also thapsigargin does not activate any membrane current if the pipette solution contains 10 mM BAPTA (ruptured patches). The contribution of Ca(2+)-influx to the membrane current during reapplication of 10 mM extracellular calcium to thapsigargin-pretreated cells was estimated from the first time derivative of the corresponding Ca2+ transients at different holding potentials. These current values showed strong inward rectification, with a maximal amplitude of 1.0 +/- 0.3 pA at -80 mV (n = 8; membrane capacitance 59 +/- 9 pF).(ABSTRACT TRUNCATED AT 250 WORDS)

Conversion of homothallic yeast to heterothallism through HO gene disruption

A simple method was developed for the conversion of homothallic Saccharomyces cerevisiae yeast strains to heterothallism through HO gene disruption. An integrative ho::neo disrupted allele was constructed by cloning a dominant selectable marker, the bacterial neo gene, within the HO gene. Transformation of a homothallic diploid S. cerevisiae strain with plasmid DNA containing the ho::neo allele yielded G418-resistant yeast transformants in which one of the HO alleles was replaced by the disrupted ho::neo allele. Meiotic tetrad analysis of four-spored asci from these G418-resistant transformants gave rise to haploid heterothallic and diploid homothallic tetrad progeny. The presence of the ho::neo and HO alleles in the heterothallic and homothallic progeny was confirmed by Southern-blot analysis.

Thapsigargin discharges intracellular calcium stores and induces transmembrane currents in human endothelial cells

We have measured the effects of thapsigargin, a specific inhibitor of endoplasmic Ca(2+)-adenosine 5'-triphosphatase (Ca(2+)-ATPase), on membrane currents and on the intracellular Ca2+ concentration ([Ca2+]i) in single endothelial cells from the human umbilical cord vein. Currents were recorded by means of the patch-clamp technique in the whole-cell mode and [Ca2+]i was measured using Fura II. Application of thapsigargin at concentrations between 0.2 and 2 mumol/l induced a slow increase in [Ca2+]i to a peak value of 400 +/- 110 nmol/l above a resting level of 120 +/- 35 nmol/l, and then slowly declined to a new steady-state level of 315 +/- 90 nmol/l (n = 33). The thapsigargin-induced increase in [Ca2+]i depended on the extracellular Ca2+ concentration ([Ca2+]o: it declined after removal of extracellular Ca2+, but increased again when [Ca2+]o was augmented, indicating that the response depends on a transmembrane influx of Ca2+ ions. The peak amplitude of the histamine-induced Ca2+ transient was reduced in the presence of thapsigargin. This reduction was more pronounced when histamine was applied at the peak of the increase in [Ca2+]i induced by thapsigargin than during the rising phase of the changes in [Ca2+]i. The decline of the Ca2+ transient induced by histamine after washing out the agonist was also affected by thapsigargin. Before application of thapsigargin, this decline could be described by a single exponential with a time constant tau equal to 24.5 +/- 5 s (n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Thimerosal induced changes of intracellular calcium in human endothelial cells

We have measured the effects of the -SH oxidizing agent thimerosal on the intracellular calcium concentration in single endothelial cells from human umbilical cord vein. Application of 1 microM thimerosal after a 10 s prepulse of 10 microM evoked oscillations of intracellular calcium. Concentrations higher than 10 microM induced a few oscillations which were followed by a long lasting increase in intracellular calcium between 120 and 980 nM at 10 microM thimerosal, between 250 and 1290 nM at 100 microM. The plateau level of the thimerosal induced increase in intracellular calcium depended on the extracellular calcium concentration, and was clearly decreased in calcium free solution. It was also reduced if the extracellular potassium concentration was increased to 140 mM. Nickel (5 mM) did not block the elevation of intracellular calcium. Thimerosal induced quenching of the Fura-2 fluorescence in Ca2+ free solutions containing 1 mM Mn2+. These effects indicate that thimerosal opens a pathway for Ca2+ entry from the extracellular side. The amount of calcium which could be released by histamine was drastically reduced after initiation of the thimerosal response. If refilling of Ca2+ stores was prevented by incubation of the cells in Ca2+ free solution, histamine still induced a transient, but not maintained, increase in [Ca2+]i. After application of thimerosal in Ca2+ free solutions to prevent refilling of the stores, a transient increase in [Ca2+]i could still be recorded but the histamine response on [Ca2+]i almost disappeared indicating a discharge of Ca2+ stores by thimerosal.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonselective ion pathways in human endothelial cells

Four probably different transmembrane pathways are described in human endothelial (EN) cells that are all nonselective for cations. i) A nonselective cation channel that is more permeable for Na+ and K+ than for Ca2+ can be gated by agonists such as histamine. This channel provides an agonist-gated entry route for Ca2+ into EN cells with a single-channel conductance of 25 pS for Na+, K+, and approximately 4 pS for Ca2+ (110 mM). ii) Another Ca(2+)-permeable pathway can be activated by shear stress. This supposedly mechanically activated channel is more permeable for divalent than for monovalent cations and provides mechano-sensing properties to EN cells. iii) A third ionic current, activated by the selective Ca(2+)-ATPase blocker thapsigargin, seems to be related to Ca(2+)-release from Ca(2+)-stores in the endoplasmic reticulum. In EN cells, this Ca(2+)-entry route is cation selective, but cannot differentiate between Na+ and K+. Activation of this nonselective current is associated with an increase in intracellular Ca2+. We therefore assume a Ca(2+)-entry through this thapsigargin-activated pathway. iv) A nickel-blockable, Ca(2+)-permeable, nonselective leak is described that is present in nonstimulated EN cells. It will be discussed whether agonist-gated channels and leak channels might be related to the Ca(2+)-release activated Ca(2+)-entry mechanism.

Kinetic differences between Ca(2+)-dependent K+ channels in smooth muscle cells isolated from normal and atherosclerotic human aorta

The properties of large conductance Ca(2+)-dependent K+ channels in smooth muscle cells (SMC) isolated from normal and atherosclerotic human aorta were studied using the patch-clamp technique. It was shown that SMC from normal human aorta possess a homogeneous population of normal Ca(2+)-dependent K+ channels. In atherosclerotic aorta two kinetically different types of these channels could be distinguished: along with normal 'long' (L)-type channels there appeared channels of 'short' (s)-type. Under similar conditions s-type channels had about a four times shorter mean open time. About five times higher [Ca2+]in was necessary for s-type channels to reach the probability of the channels being open equal to L-type channels. No differences in conductance and voltage dependency were found between the two channel types. Channels of the s-type resembled those previously described in SMC isolated from foetal human aorta. Thus, it can be suggested that during the development of atherosclerosis a population of SMC with s-type Ca(2+)-dependent K+ channels appears in human aorta.

The influence of tifluadom on cholecystokinin-induced antinociception

The effects of tifluadom, a benzodiazepine-kappa-opioid-receptor agonist, on cholecystokinin-octapeptide (CCK-8)-induced antinociception were investigated in the mouse writhing test. When given alone, tifluadom produced pronounced, dose-dependent analgesia. The antinociceptive effect of intracerebroventricularly injected CCK-8 was potentiated by high doses of tifluadom. In contrast, when tifluadom was applied at low doses which did not induce antinociception, the antinociceptive effect of CCK-8 was completely antagonized. It is concluded that tifluadom acts both as kappa-opioid receptor agonist and as an antagonist at CCK receptors mediating CCK-induced antinociception.