BBB transport and rapid tissue binding of cyclofoxy: comparison of active and inactive enantiomers

The "rapid-phase" brain distribution of 3H-labeled enantiomers of the opiate receptor antagonist cyclofoxy (CF), receptor active (-) and inert (+) forms, was measured during 20- to 180-s intravenous infusion in rats. [14C]iodoantipyrine was coinfused during these experiments to obtain a simultaneous measure of blood flow. The influx clearance (K1) across the blood-brain barrier (BBB) and the rapid binding equilibrium constant (Keq) were estimated in different brain regions for both enantiomers (2-compartmental model); a possible receptor binding process (k3) was also examined for (-)-CF (3-compartment model). K1 (0.46-0.91 ml.min-1.g-1), the capillary permeability-surface area product (PS; 0.75 approximately 1.4 ml.min-1.g-1) and the tissue extraction fraction (E; 0.6-0.7) were found to be identical for both enantiomers in the nonreceptor binding model; Keq was identical in cerebellum but larger for (-)-CF in other brain structures. The difference in Keq between the enantiomers (2-compartment model) correlated with the rank order of opiate receptor density observed in vitro and in vivo. These results suggest that concomitant use of (-)-CF and (+)-CF will be useful for in vivo receptor binding analyses.

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Comparison of in vivo and in vitro parameters of opiate receptor binding in naive and tolerant/dependent rodents

Life Sciences ◽

10.1016/0024-3205(75)90284-2 ◽

1975 ◽

Vol 16 (12) ◽

pp. 1823-1828 ◽

Cited By ~ 84

Author(s):

V. Höllt ◽

J. Dum ◽

J. Bläsig ◽

P. Schubert ◽

A. Herz

Keyword(s):

Receptor Binding ◽

Opiate Receptor

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On the relationship between inhibition and receptor occupancy by nondepolarizing neuromuscular blocking drugs

Theoretical Biology and Medical Modelling ◽

10.1186/s12976-021-00147-w ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Hikaru Hoshino ◽

Eiko Furutani

Keyword(s):

Receptor Binding ◽

Receptor Occupancy ◽

Neuromuscular Blocking ◽

In Vitro Experiments ◽

Binding Model ◽

Neuromuscular Blocking Drugs ◽

The Relationship ◽

Nondepolarizing Neuromuscular Blocking Drugs

Abstract Background Nondepolarizing neuromuscular blocking drugs (NDNBs) are clinically used to produce muscle relaxation during general anesthesia. To better understand clinical properties of NDNBs, comparative in vitro pharmacologic studies have been performed. In these studies, a receptor binding model, which relies on the assumption that the inhibition, i.e., the effect of an NDNB, is proportional to the receptor occupancy by the drug, has been effectively used to describe obtained experimental data. However, it has not been studied in literature under which conditions the above assumption can be justified nor the assumption still holds in vivo. The purpose of this study is to explore the in vivo relationship between the inhibition and the receptor occupancy by an NDNB and to draw implications on how in vitro experimental results can be used to discuss the in vivo properties of NDNBs. Methods An ordinary differential equation model is employed to simulate physiologic processes of the activation of receptors by acetylcholine (ACh) as well as inhibition by an NDNB. With this model, the degree of inhibition is quantified by the fractional amount of receptors that are not activated by ACh due to the presence of an NDNB. The results are visualized by plotting the fractional amounts of the activated receptors as a function of the receptor occupancy. Results Numerical investigations reflecting in vivo conditions show that the degree of inhibition is not proportional to the receptor occupancy, i.e., there is a nonlinear relationship between the inhibition and the receptor occupancy. However, under a setting of high concentration of ACh reflecting a typical situation of in vitro experiments, the relationship between the inhibition and the receptor occupancy becomes linear, suggesting the validity of the receptor binding model. Also, it is found that the extent of nonlinearity depends on the selectivity of NDNBs for the two binding sites of the receptors. Conclusions While the receptor binding model may be effective for estimating affinity of an NDNB through in vitro experiments, these models do not directly describe in vivo properties of NDNBs, because the nonlinearity between the inhibition and the receptor occupancy causes the modulation of the resultant concentration-effect relationships of NDNBs.

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On the Relationship between Inhibition and Receptor Occupancy by Nondepolarizing Neuromuscular Blocking Drugs

10.21203/rs.3.rs-376415/v1 ◽

2021 ◽

Author(s):

Hikaru Hoshino ◽

Eiko Furutani

Keyword(s):

Receptor Binding ◽

Receptor Occupancy ◽

Neuromuscular Blocking ◽

In Vitro Experiments ◽

Binding Model ◽

Neuromuscular Blocking Drugs ◽

The Relationship ◽

Nondepolarizing Neuromuscular Blocking Drugs

Abstract Background: Nondepolarizing neuromuscular blocking drugs (NDNBs) are clinically used to produce muscle relaxation during general anesthesia. To better understand clinical properties of NDNBs, comparative in vitro pharmacologic studies have been performed. In these studies, a receptor binding model, which relies on the assumption that the inhibition, i.e., the e ect of an NDNB, is proportional to the receptor occupancy by the drug, has been effectively used to describe obtained experimental data. However, it has not been studied in literature under which conditions the above assumption can be justified nor the assumption still holds in vivo. The purpose of this study is to explore the in vivo relationship between the inhibition and the receptor occupancy by an NDNB and to draw implications on how in vitro experimental results can be used to discuss the in vivo properties of NDNBs. Methods: An ordinary di erential equation model is employed to simulate physiologic processes of the activation of receptors by acetylcholine (ACh) as well as inhibition by an NDNB. With this model, the degree of inhibition is quantified by the fractional amount of receptors that are not activated by ACh due to the presence of an NDNB. The results are visualized by plotting the fractional amounts of the activated receptors as a function of the receptor occupancy. Results: Numerical investigations reflecting in vivo conditions show that the degree of inhibition is not proportional to the receptor occupancy, i.e., there is a nonlinear relationship between the inhibition and the receptor occupancy. However, under a setting of high concentration of ACh reflecting a typical situation of in vitro experiments, the relationship between the inhibition and the receptor occupancy becomes linear, suggesting the validity of the receptor binding model. Also, it is found that the extent of nonlinearity depends on the selectivity of NDNBs for the two binding sites of the receptors. Conclusions: While the receptor binding model may be effective for estimating affinity of an NDNB through in vitro experiments, these models do not directly describe in vivo properties of NDNBs, because the nonlinearity between the inhibition and the receptor occupancy causes the modulation of the resultant concentration-effect relationships of NDNBs.

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The pharmacokinetics of [18F]UCB-H revisited in the healthy non-human primate brain

EJNMMI Research ◽

10.1186/s13550-021-00777-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sébastien Goutal ◽

Martine Guillermier ◽

Guillaume Becker ◽

Mylène Gaudin ◽

Yann Bramoullé ◽

...

Keyword(s):

Slow Component ◽

Specific Binding ◽

Compartment Model ◽

Brain Regions ◽

Volume Of Distribution ◽

Pharmacokinetic Data ◽

Limited Information ◽

Positron Emission ◽

Human Primate

Abstract Background Positron Emission Tomography (PET) imaging of the Synaptic Vesicle glycoprotein (SV) 2A is a new tool to quantify synaptic density. [18F]UCB-H was one of the first promising SV2A-ligands to be labelled and used in vivo in rodent and human, while limited information on its pharmacokinetic properties is available in the non-human primate. Here, we evaluate the reliability of the three most commonly used modelling approaches for [18F]UCB-H in the non-human cynomolgus primate, adding the coupled fit of the non-displaceable distribution volume (VND) as an alternative approach to improve unstable fit. The results are discussed in the light of the current state of SV2A PET ligands. Results [18F]UCB-H pharmacokinetic data was optimally fitted with a two-compartment model (2TCM), although the model did not always converge (large total volume of distribution (VT) or large uncertainty of the estimate). 2TCM with coupled fit K1/k2 across brain regions stabilized the quantification, and confirmed a lower specific signal of [18F]UCB-H compared to the newest SV2A-ligands. However, the measures of VND and the influx parameter (K1) are similar to what has been reported for other SV2A ligands. These data were reinforced by displacement studies using [19F]UCB-H, demonstrating only 50% displacement of the total [18F]UCB-H signal at maximal occupancy of SV2A. As previously demonstrated in clinical studies, the graphical method of Logan provided a more robust estimate of VT with only a small bias compared to 2TCM. Conclusions Modeling issues with a 2TCM due to a slow component have previously been reported for other SV2A ligands with low specific binding, or after blocking of specific binding. As all SV2A ligands share chemical structural similarities, we hypothesize that this slow binding component is common for all SV2A ligands, but only hampers quantification when specific binding is low.

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Physiology, Pharmacology, and Topography of Cholinergic Neocortical Oscillations In Vitro

Journal of Neurophysiology ◽

10.1152/jn.1997.77.5.2427 ◽

1997 ◽

Vol 77 (5) ◽

pp. 2427-2445 ◽

Cited By ~ 61

Author(s):

Heath S. Lukatch ◽

M. Bruce Maciver

Keyword(s):

Current Source ◽

Brain Slices ◽

Receptor Activation ◽

Brain Regions ◽

Oscillatory Activity ◽

Cortical Layers ◽

Eeg Activity ◽

Layer 2

Lukatch, Heath S. and M. Bruce MacIver. Physiology, pharmacology, and topography of cholinergic neocortical oscillations in vitro. J. Neurophysiol. 77: 2427–2445, 1997. Rat neocortical brain slices generated rhythmic extracellular field [microelectroencephalogram (micro-EEG)] oscillations at theta frequencies (3–12 Hz) when exposed to pharmacological conditions that mimicked endogenous ascending cholinergic and GABAergic inputs. Use of the specific receptor agonist and antagonist carbachol and bicuculline revealed that simultaneous muscarinic receptor activation and γ-aminobutyric acid-A (GABAA)-mediated disinhibition werenecessary to elicit neocortical oscillations. Rhythmic activity was independent of GABAB receptor activation, but required intact glutamatergic transmission, evidenced by blockade or disruption of oscillations by 6-cyano-7-nitroquinoxaline-2,3-dione and (±)-2-amino-5-phosphonovaleric acid, respectively. Multisite mapping studies showed that oscillations were localized to areas 29d and 18b (Oc2MM) and parts of areas 18a and 17. Peak oscillation amplitudes occurred in layer 2/3, and phase reversals were observed in layers 1 and 5. Current source density analysis revealed large-amplitude current sinks and sources in layers 2/3 and 5, respectively. An initial shift in peak inward current density from layer 1 to layer 2/3 indicated that two processes underlie an initial depolarization followed by oscillatory activity. Laminar transections localized oscillation-generating circuitry to superficial cortical layers and sharp-spike-generating circuitry to deep cortical layers. Whole cell recordings identified three distinct cell types based on response properties during rhythmic micro-EEG activity: oscillation-on (theta-on) and -off (theta-off) neurons, and transiently depolarizing glial cells. Theta-on neurons displayed membrane potential oscillations that increased in amplitude with hyperpolarization (from −30 to −90 mV). This, taken together with a glutamate antagonist-induced depression of rhythmic micro-EEG activity, indicated that cholinergically driven neocortical oscillations require excitatory synaptic transmission. We conclude that under the appropriate pharmacological conditions, neocortical brain slices were capable of producing localized theta frequency oscillations. Experiments examining oscillation physiology, pharmacology, and topography demonstrated that neocortical brain slice oscillations share many similarities with the in vivo and in vitro theta EEG activity recorded in other brain regions.

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Role of the ligand in intracellular receptor function: receptor affinity determines activation in vitro of the latent dioxin receptor to a DNA-binding form

Molecular and Cellular Biology ◽

10.1128/mcb.11.1.401-411.1991 ◽

1991 ◽

Vol 11 (1) ◽

pp. 401-411

Author(s):

S Cuthill ◽

A Wilhelmsson ◽

L Poellinger

Keyword(s):

Dna Binding ◽

Cellular Response ◽

Molecular Mechanisms ◽

Nuclear Translocation ◽

Rank Order ◽

Receptor Ligands ◽

Free System ◽

Dioxin Receptor

To reconstitute the molecular mechanisms underlying the cellular response to soluble receptor ligands, we have exploited a cell-free system that exhibits signal- (dioxin-)induced activation of the latent cytosolic dioxin receptor to an active DNA-binding species. The DNA-binding properties of the in vitro-activated form were qualitatively indistinguishable from those of in vivo-activated nuclear receptor extracted from dioxin-treated cells. In vitro activation of the receptor by dioxin was dose dependent and was mimicked by other dioxin receptor ligands in a manner that followed the rank order of their relative affinities for the receptor in vitro and their relative potencies to induce target gene transcription in vivo. Thus, in addition to triggering the initial release of inhibition of DNA binding and presumably allowing nuclear translocation, the ligand appears to play a crucial role in the direct control of the level of functional activity of a given ligand-receptor complex.

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IgG modulation in male mice with reproductive failure after prenatal inflammation

Reproduction ◽

10.1530/rep-20-0386 ◽

2021 ◽

Author(s):

Marina Izvolskaia ◽

Vasilina Ignatiuk ◽

Ayshat Ismailova ◽

Viktoria Sharova ◽

Liudmila Zakharova

Keyword(s):

Positive Impact ◽

Brain Structures ◽

Peritoneal Macrophages ◽

The Body ◽

Male Rats ◽

Male Mice ◽

Prenatal Inflammation ◽

Exposure In Vivo

Sexual performance in adult male rats is highly sensitive to prenatal stress which can affect the functionality of the reproductive system and various brain structures involved in modulating sexual behavior. The immunomodulatory effect of mouse IgG on reproductive maturity in male offspring after LPS exposure in vivo and in vitro was studied. Prenatal IgG injection (20 µg / mouse) had a positive impact on the puberty of male mice whose mothers were exposed to LPS (100 µg / kg) on the 12th day of pregnancy. The number of Sertoli cells were increased, whereas the body weight and the number of symplastic spermatids were decreased in offspring as compared to LPS-treated animals. Besides, IgG had a positive effect on altered hormone levels: reduced estradiol level on the 5th and 14th postnatal days and increased testosterone level on the 30th postnatal day in blood that led to an increased number of mounting attempts in sexually mature males. The cAMP-dependent pathway may be involved in the regulation of the LPS-induced inflammation. IgG reduced the increased level of cAMP in mouse peritoneal macrophages activated by LPS in vitro. IgG is able to modulate inflammation processes, but its exposure time is important.

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Abstract 1340: Disruption of a Hepatocyte Growth Factor/c-Met Receptor Autocrine Loop Severely Impairs the Potency of Pluripotent Adipose Stromal Cells

Circulation ◽

10.1161/circ.116.suppl_16.ii_274-c ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Liying Cai ◽

Brian H Johnstone ◽

Zhong Liang ◽

Dmitry Traktuev ◽

Todd G Cook ◽

...

Keyword(s):

Growth Factor ◽

Hepatocyte Growth Factor ◽

Rank Order ◽

Residual Activity ◽

Autocrine Loop ◽

Major Mode ◽

Factor C ◽

Hepatocyte Growth

Background Paracrine stimulation of endogenous repair, rather than direct tissue regeneration, is increasingly accepted as a major mode of therapeutic stem and progenitor cell action; yet, this principle has not been fully established in vivo . Adipose-derived stem cells (ASCs) secrete many factors and promote reperfusion and tissue repair in ischemia models. RNA interference was used to silence the expression of the abundant protein, hepatocyte growth factor (HGF), to determine its contribution to ASC potency in vivo . Methods and Results Dual-cassette lentiviral vectors, expressing GFP and either a small hairpin RNA (shRNA) specific for HGF mRNA (shHGF) or a control sequence (shCtrl), were used to stably transduce ASCs (ASC-shHGF or ASC-shCtrl). ASC-shHGF secreted 5-fold less HGF, which resulted in a reduced ability of these cells to promote survival, proliferation and migration of mature and progenitor endothelial cells in vitro ( p <0.01). HGF knockdown also severely impaired the ability of ASCs to promote reperfusion in a mouse hindlimb ischemia model. Perfusion of the ischemic leg at 15 d in mice treated with ASC-Ctrl was 84±4%, compared to only 69±5% for ASC-shHGF ( p <0.05). Even so, ASC-shHGF retained residual activity as indicated by greater reperfusion ( p <0.05) than with saline treatment (58±6%). Capillary densities in ischemic tissues from each group followed a similar rank order (ASC-Ctrl>ASC-shHGF>saline) ( p <0.05 between each group). While there was no difference in total GFP + cells in ischemic limbs at 5 d after infusion, indicating similar homing potentials, 3-fold fewer ASC-shHGF were present in ischemic tissues at 15 d compared to ASC-shCtrl ( p <0.01). This was accompanied by an increase in TUNEL-positive ASC-shHGF cells (61 ± 0.1%) compared to ASC-Ctrl (41% ± 3.2%) in ischemic tissues at 5 d ( p <0.01); suggesting that attenuated potency of ASC-shHGF was related to reduced survival in ischemic tissues. Conclusions These results indicate that secretion of HGF is critically important for ASC potency. In addition to promoting endogenous repair, the data suggest that an important effect of HGF is autocrine promotion of ASC survival in ischemic tissue. Enhanced donor cell survival is an important goal for increasing the efficacy of cell therapy.

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Effects of costimulation of dopamine D1- and D2-like receptors on renal function

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1998.275.4.r986 ◽

1998 ◽

Vol 275 (4) ◽

pp. R986-R994 ◽

Cited By ~ 14

Author(s):

Pedro A. Jose ◽

Laureano D. Asico ◽

Gilbert M. Eisner ◽

Felice Pocchiari ◽

Claudio Semeraro ◽

...

Keyword(s):

Dopamine Receptor ◽

Sodium Transport ◽

Sodium Excretion ◽

Rank Order ◽

Sch 23390 ◽

Urine Flow ◽

Dopamine Receptor Agonist ◽

Vasodilatory Effect

In vitro studies have suggested that dopamine D1- and D2-like receptors interact to inhibit renal sodium transport. We used Z-1046, a dopamine receptor agonist with the rank-order potency D3 ≥ D4 > D2 > D5 > D1, to test the hypothesis that D1- and D2-like receptors interact to inhibit renal sodium transport in vivo in anesthetized rats. Increasing doses of Z-1046, administered via the right renal artery, increased renal blood flow (RBF), urine flow, and absolute and fractional sodium excretion without affecting glomerular filtration rate. For determination of the dopamine receptor involved in the renal functional effects of Z-1046, another group of rats received Z-1046 at 2 μg ⋅ kg−1 ⋅ min−1( n = 10) in the presence or absence of the D2-like receptor antagonist domperidone and/or the D1-like antagonist SCH-23390. Domperidone alone had no effect but blocked the Z-1046-mediated increase in urine flow and sodium excretion; it enhanced the increase in RBF after Z-1046. SCH-23390 by itself decreased urine flow and sodium excretion without affecting RBF and blocked the diuretic, natriuretic, and renal vasodilatory effect of Z-1046. We conclude that the renal vasodilatory effect of Z-1046 is D1-like receptor dependent, whereas the diuretic and natriuretic effects are both D1- and D2-like receptor dependent.

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