RESUMEN
Recent studies have shown that cell migration can be monitored in vivo by magnetic resonance imaging after intracellular contrast agent incorporation. This is due to the dephasing effect on proton magnetization of the local magnetic field created by a labelled cell. Anionic iron oxide nanoparticles (AMNP) are among the most efficient and non-toxic contrast agents to be spontaneously taken up by a wide variety of cells. Here we measured the iron load and magnetization of HeLa tumour cells labelled with AMNP, as a function of the external magnetic field. High-resolution gradient echo 9.4 T MRI detected individual labelled cells, whereas spin echo sequences were poorly sensitive. We then conducted a systematic study in order to determine the gradient echo sequence parameters (echo time, cell magnetization and resolution) most suitable for in vivo identification of single cells.
Asunto(s)
Células/citología , Células/metabolismo , Imagen por Resonancia Magnética/métodos , Supervivencia Celular , Compuestos Férricos/metabolismo , Células HeLa , Humanos , Hierro/metabolismo , Magnetismo , Factores de TiempoRESUMEN
The in vivo spectrum of regenerating muscles shows a specific cross-correlation signal assigned to the (n-3) fatty acyl chain, which peaks during the myoblast fusion phase. In order to identify the origin of this signal and to take all the lipid metabolites into account, we investigated the degeneration-regeneration process by 1H 2D NMR of lipid muscle extracts. We observed an increase in the total amount of lipids during the regeneration process, although the lipid profile did not show any drastic change during this process. The changes in the NMR signal observed in vivo and, in particular, the appearance of the specific (n-3) fatty acyl chain signal appears to arise from mobile lipid compartments located in fusing cells.
Asunto(s)
Músculo Esquelético/fisiología , Regeneración/fisiología , Animales , Extremidades/fisiología , Técnica del Anticuerpo Fluorescente , Hidrógeno , Lípidos/química , Lípidos/fisiología , Espectroscopía de Resonancia Magnética/métodos , Masculino , Ratones , Músculo Esquelético/química , Mioblastos/química , Mioblastos/fisiología , Valores de Referencia , Extractos de Tejidos/químicaRESUMEN
Localized in vivo NMR spectroscopy, chemical shift imaging or multi-voxel spectroscopy are potentially useful tools in small animals that are complementary to MRI, adding biochemical information to the mainly anatomical data provided by imaging of water protons. However the contribution of such methods remains hampered by the low spectral resolution of the in vivo 1D spectra. Two-dimensional methods widely developed for in vitro studies have been proposed as suitable approaches to overcome these limitations in resolution. The different homonuclear and heteronuclear sequences adapted to in vivo studies are reviewed. Their specific contributions to the spectral resolution of spectroscopic data and their limitations for in vivo investigations are discussed. The applications to experimental models of pathological processes or pharmacological treatment in mainly brain and muscle are presented. According to their combined sensitivity, acquisition duration and spatial resolution, the heteronuclear 2D experiments, which are mainly used for 1H detected-13C spectroscopy after administration of 13C-labeled compounds, appear to be less efficient than 1H detected-13C 1D methods at high field. However, the applications of 2D proton homonuclear methods show that they remain the best tools for in vivo studies when an improved resolution is required.
Asunto(s)
Algoritmos , Encéfalo/metabolismo , Perfilación de la Expresión Génica/métodos , Interpretación de Imagen Asistida por Computador/métodos , Espectroscopía de Resonancia Magnética/métodos , Proteínas Musculares/metabolismo , Músculo Esquelético/metabolismo , Animales , Ratones , RatasRESUMEN
How the myocardium is able to permanently coordinate its intracellular fluxes of ATP synthesis, transfer and utilization is difficult to investigate in the whole organ due to the cellular complexity. The adult myocardium represents a paradigm of an energetically compartmented cell since 50% of total CK activity is bound in the vicinity of other enzymes (myofibrillar sarcolemmal and sarcoplasmic reticulum ATPases as well as mitochondrial adenine nucleotide translocator, ANT). Such vicinity of enzymes is well known in vitro as well as in preparations of skinned fibers to influence the kinetic properties of these enzymes and thus the functioning of the subcellular organelles. Intracellular compartmentation has often been neglected in the NMR analysis of CK kinetics in the whole organ. It is indeed a methodological challenge to reveal subcellular kinetics in a working organ by a global approach such as NMR. To get insight in the energy transfer pathway in the perfused rat heart, we developed a combined analysis of several protocols of magnetization transfer associated with biochemical data and quantitatively evaluated which scheme of energetic exchange best describes the NMR data. This allows to show the kinetic compartmentation of subcellular CKs and to quantify their fluxes. Interestingly, we could show that the energy transfer pathway shifts from the phosphocreatine shuttle in the oxygenated perfused heart to a direct ATP diffusion from mitochondria to cytosol under moderate inhibition of ATP synthesis. Furthermore using NMR measured fluxes and the known kinetic properties of the enzymes, it is possible to model the system, estimate local ADP concentrations and propose hypothesis for the versatility of energy transfer pathway. In the normoxic heart, a 3-fold ADP gradient was found between mitochondrial intermembrane space, cytosol and ADP in the vicinity of ATPases. The shift from PCr to ATP transport observed when ATP synthesis decreases might result from a balance in the activity of two populations of ANT, either coupled or uncoupled to CK. We believe this NMR approach could be a valuable tool to reinvestigate the control of respiration by ADP in the whole heart reconciling the biochemical knowledge of mitochondrial obtained in vitro or in skinned fibers with data on the whole heart as well as to identify the implication of bioenergetics in the pathological heart.
Asunto(s)
Adenosina Trifosfato/metabolismo , Creatina Quinasa/metabolismo , Miocardio/metabolismo , Transferencia de Energía , Espectroscopía de Resonancia Magnética , Orgánulos/enzimología , Orgánulos/metabolismoRESUMEN
It is important to obtain high resolution images of joints for the study of disease, especially in rodent experimental models. We optimized (1)H magnetic resonance imaging three-dimensional sequences at 7 T, with lipid signal suppression, and T(1) and T(2) measurements for in-vivo experiments on rat joints, in order to assess the effectiveness of high-field MRI. The method was validated by applying it to the early diagnosis of arthritis. We studied the progress of rheumatoid arthritis in an arthritic rat model. We observed the rats' knees for 21 days after inducing arthritis. The images acquired over one hour had a high resolution of 1.75 x 10(-3) mm(3), (105 x 105 x 145 microm(3)) which allowed us to spot the early stages of joint degeneration, such as bone erosion, and to observe an apparent 'MRI' loss of cartilage thickness, attributed to dehydration of the cartilage tissue. The MR images obtained during the early stages of rheumatoid arthritis enabled us to study joint changes accurately before any histological signs of attack were visible.
Asunto(s)
Artritis/clasificación , Artritis/patología , Aumento de la Imagen/métodos , Imagenología Tridimensional/métodos , Articulación de la Rodilla/patología , Imagen por Resonancia Magnética/métodos , Animales , Progresión de la Enfermedad , Masculino , Ratas , Ratas Wistar , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Índice de Severidad de la EnfermedadRESUMEN
In the perfused rat heart NMR inversion transfer revealed the existence of a compartment of ATP not exchanging through creatine kinase (CK), as demonstrated by an apparent discrepancy between the forward (F(f)) and reverse (F(r)) CK flux if this compartment was neglected in the analysis [Joubert et al. (2000) Biophys. J. 79, 1-13]. To localize this compartment, CK fluxes were measured by inversion of PCr (inv-PCr) or gamma ATP (inv-ATP), and the distribution of metabolites between mitochondria and cytosol was studied by subcellular fractionation. Physiological conditions were designed to modify the concentration and distribution of CK metabolites (control, adenylate depletion, inhibition of respiration, KCl arrest). Depending on cardiac activity, mitochondrial ATP (mito-ATP) assessed by fractionation varied from 11% to 30% of total ATP. In addition, the apparent flux discrepancy increased together with mito-ATP (F(f)/F(r) ranged from 0.85 to 0.50 in inv-PCr and from 1.13 to 1.88 in inv-ATP). Under conditions masking the influence of the ATP-P(i) exchange on CK flux, the ATP compartment could be directly quantified by the apparent flux discrepancy; its size was similar to that of mito-ATP measured by fractionation. Thus NMR inversion technique is a potential tool to assess metabolite compartmentation in the whole organ.
Asunto(s)
Creatina Quinasa/metabolismo , Mitocondrias Cardíacas/enzimología , Miocardio/enzimología , Adenosina Trifosfato/metabolismo , Animales , Técnicas In Vitro , Líquido Intracelular/enzimología , Líquido Intracelular/metabolismo , Masculino , Mitocondrias Cardíacas/metabolismo , Modelos Biológicos , Contracción Miocárdica , Miocardio/metabolismo , Resonancia Magnética Nuclear Biomolecular/métodos , Ratas , Ratas Wistar , Partículas Submitocóndricas/enzimología , Partículas Submitocóndricas/metabolismoRESUMEN
The combination of localized 2D 1H MR correlation spectroscopy and Hadamard encoding allows the simultaneous acquisition of multiple volumes of interest without an increase in the experimental duration, compared to single-voxel acquisition. In the present study, 2D correlation spectra were acquired simultaneously within 20 to 40 min in two voxels located in each hemisphere of the rat brain. An intervoxel distance of 20% of the voxel size was sufficient to limit spatial contamination. The following cerebral metabolites gave detectable crosspeaks: N-acetylaspartate, the glutamate/glutamine pool, aspartate, phosphoethanolamine, glucose, glutathione, taurine, myo-inositols, lactate, threonine, gamma-aminobutyric acid, and alanine. Most of the metabolites were measured without contamination of other resonances.
Asunto(s)
Daño Encefálico Crónico/fisiopatología , Isquemia Encefálica/fisiopatología , Dominancia Cerebral/fisiología , Metabolismo Energético/fisiología , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Espectroscopía de Resonancia Magnética , Animales , Encéfalo/fisiología , Aumento de la Imagen , Ácido Láctico/metabolismo , Fantasmas de Imagen , Ratas , Valores de ReferenciaRESUMEN
To study the relation among mitochondrial energy supply, cardiac performance, and energy transfer through creatine kinase (CK), two acute models of inhibition of ATP synthesis were compared in the isovolumic acetate-perfused rat heart. Similar impairments of mechanical performance (rate-pressure product, RPP) were achieved by various stepwise decreases in O(2) supply (PO(2) down to 20% of control) or by infusing CN (0.15-0.25 mM). The forward CK flux measured by saturation-transfer (31)P NMR spectroscopy was 6.1 +/- 0. 4 mM/s in control hearts. Only after severe hypoxia (PO(2) < 40% of control) did CK flux drop (to 1.9 +/- 0.2 mM/s at PO(2) = 25% of control) together with impaired systolic activity and a rise in end-diastolic pressure. In contrast, in mild hypoxia CK flux remained constant and similar to control (5.3 +/- 0.5 mM/s, not significant) despite a twofold reduction in systolic activity. Similarly in all CN groups, constant CK flux was maintained for a threefold reduction in RPP, showing the absence of a relation between cardiac performance and global NMR-measured CK flux during mild ATP synthesis inhibition.
Asunto(s)
Adenosina Trifosfato/biosíntesis , Creatina Quinasa/metabolismo , Corazón/fisiología , Miocardio/enzimología , Animales , Hipoxia/metabolismo , Cinética , Masculino , Oxígeno/metabolismo , ATPasas de Translocación de Protón/metabolismo , Ratas , Ratas WistarRESUMEN
Muscle degeneration and regeneration were studied by 2D 1H magnetic resonance spectroscopy (MRS) and histological examination, in an experimental model of muscle injury using a myotoxic snake venom, notexin. The injured muscles produced a very specific MRS signal, corresponding to a tri-unsaturated fatty acid (linolenic acid-like) signal, from day 2 to day 9 after injury. The combination of MRS with histology showed that this signal was associated with a mechanism occurring during myoblast fusion to form myotubes. 2D 1H MRS is thus a useful non-invasive tool for detecting muscle regeneration in vivo.
Asunto(s)
Músculo Esquelético/fisiología , Resonancia Magnética Nuclear Biomolecular , Regeneración/fisiología , Animales , Masculino , Ratones , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/patologíaRESUMEN
To study the dependence of the forward flux of creatine kinase (CK) on its substrates and products we designed an acute normoxic model of steady-state depletion of phosphocreatine (PCr) and adenylate in the isovolumic acetate-perfused rat heart. Various concentrations of PCr and ATP were induced by prior perfusion with 2 deoxy-D-glucose in the presence of insulin. The apparent rate constant (k(f)) and the forward CK flux were measured under metabolic and contractile steady state by progressive saturation-transfer 31P nuclear magnetic resonance (NMR). At high adenylate content CK flux was constant for a twofold reduction in PCr concentration ([PCr]); CK flux was 6.3 +/- 0.6 mM/s (vs. 6.5 +/- 0.2 mM/s in control) because of a doubling of k(f). Although, at the lowest ATP concentration and [PCr], CK flux was reduced by 50%, it nevertheless always remained higher than ATP synthesis estimated by parallel oxygen consumption measurement. NMR-measured flux was compared with the flux computed under the hypothesis of CK equilibrium. CK flux could not be fully predicted by the concentrations of CK metabolites. This is discussed in terms of metabolite and CK isozyme compartmentation.
Asunto(s)
Adenosina Trifosfato/metabolismo , Creatina Quinasa/metabolismo , Corazón/fisiología , Miocardio/metabolismo , Fosfocreatina/metabolismo , Animales , Desoxiglucosa/metabolismo , Corazón/efectos de los fármacos , Insulina/farmacología , Cinética , Espectroscopía de Resonancia Magnética , Masculino , Modelos Cardiovasculares , Modelos Químicos , Contracción Miocárdica , Perfusión , Ratas , Ratas Wistar , Análisis de RegresiónRESUMEN
The proton NMR spectra of regenerating muscle shoe high resolution fatty acid signals as the spectra of other stressed cells such as ischemic cardiac cells, stimulated immune cells or malignant cells. We report here the in vitro study, by 2D 1H NMR, of the fusion of myogenic cells. High resolution fatty acid signals are only detected during cell fusion, demonstrating a higher mobility of the acyl chains.
Asunto(s)
Lípidos/análisis , Espectroscopía de Resonancia Magnética/métodos , Músculo Esquelético/citología , Músculo Esquelético/metabolismo , Animales , Fusión Celular , Células Cultivadas , Ácido Láctico/química , Metabolismo de los Lípidos , Lípidos/química , Ratones , Ratones Endogámicos C3H , Músculo Esquelético/fisiología , Regeneración , Taurina/químicaRESUMEN
The suitability of two-dimensional (2D) proton spectroscopy for monitoring, in vivo, the changes in levels of brain metabolites induced by cerebral ischemia was investigated in an experimental model of 30-min reversible ischemia induced by four-vessel occlusion in the rat. The resulting data were compared with those obtained by one-dimensional (1D) proton and phosphorus spectroscopy. Phosphorus spectra obtained during ischemia showed significant drops in levels of phosphocreatine (-73%), beta-ATP (-60%), and intracellular pH (to 6.30) and an increase in inorganic phosphate level (905%). 1D and 2D proton spectra showed decreases in the N-acetylaspartate/creatine-phosphocreatine ratio that were not significantly different [-21% (1D) and -32% (2D)]. Similarly, the increases in lactate/creatine-phosphocreatine ratio were not significantly different [2,546% (1D) and 3,020% (2D)]. 2D spectroscopy also indicated a decrease in aspartate (-66%) and an increase in the inositol-choline derivative (+124%) pools during ischemia and an increase in alanine pool (+516%) during reperfusion. The glutamate-glutamine pool and taurine content did not change significantly during ischemia but decreased during reperfusion. The glucose level transiently decreased (-67%) during ischemia and increased immediately after (+261%). The levels of all the metabolites investigated returned to control values within 175 min after ischemia. 2D spectroscopy seems to be a reliable method of monitoring the changes in levels of cerebral compounds known to be involved in ischemia.
Asunto(s)
Isquemia Encefálica/fisiopatología , Prosencéfalo/irrigación sanguínea , Daño por Reperfusión/fisiopatología , Animales , Hidrógeno , Espectroscopía de Resonancia Magnética , Masculino , Isótopos de Fósforo , Protones , Ratas , Ratas WistarRESUMEN
Mammals react to acute hypoxia with an initial augmentation and a secondary depression of the respiratory rhythm generated by brain stem neuronal networks. To investigate the cytosolic level of energy rich phosphorus metabolites during these responses, we developed 31P nuclear magnetic resonance spectroscopy of the brain stem. Moderate hypoxia (paO2 = 40 mmHg, 2 min) caused a reversible 62 +/- 15% respiratory rhythm depression and decreased cytosolic phosphocreatine levels by 43 +/- 11% (p < 0.01, n = 7) without affecting adenosine triphosphate levels. Cellular metabolic depletion therefore contributes to the brain stem response to hypoxia, and appears to reflect adaptive mechanisms to limited oxygen availability in the brain stem.
Asunto(s)
Tronco Encefálico/metabolismo , Metabolismo Energético/fisiología , Hipoxia Encefálica/metabolismo , Espectroscopía de Resonancia Magnética , Respiración/fisiología , Enfermedad Aguda , Adenosina Trifosfato/metabolismo , Anestésicos , Animales , Masculino , Fosfocreatina/metabolismo , Fósforo , Ratas , Ratas Sprague-DawleyRESUMEN
Itaconate biosynthesis was studied in intact cells of high-yield (RC4') and low-yield (CM85J) strains of the fungus Aspergillus terreus by methods (tracers, nuclear magnetic resonance spectroscopy, and mass spectroscopy) that did not interfere with metabolism. Itaconate formation in RC4' required de novo protein biosynthesis. Krebs cycle intermediates increased in both strains during the production of itaconic acid. The Embden-Meyerhof-Parnas pathway and the Krebs cycle were shown to be involved in this biosynthesis by using 14C- and 13C-labelled substrates and nuclear magnetic resonance spectroscopy. A metabolic pathway for itaconate formation from glucose in A. terreus is proposed.
Asunto(s)
Aspergillus/metabolismo , Succinatos/metabolismo , Aspergillus/enzimología , Aspergillus/crecimiento & desarrollo , Isótopos de Carbono , Radioisótopos de Carbono , Cromatografía Líquida de Alta Presión , Ciclo del Ácido Cítrico , Glucosa/metabolismo , Espectroscopía de Resonancia Magnética , Vía de Pentosa Fosfato , Inhibidores de la Síntesis de la Proteína/farmacologíaRESUMEN
The dynamic effects of the non-competitive NMDA receptor antagonist, MK-801 on brain metabolism were investigated over 105 minutes in unanesthetized rats by proton and phosphorus NMR spectroscopy. MK-801 (0.5 and 5 mg/kg, i.p) induced no changes in intracellular pH, and in phosphocreatine, ATP, and inorganic phosphate levels, indicating that the drug preserved energy and intracellular pH homeostasis. There were transient increases in lactate after both doses of MK-801, suggesting early activation of glycolysis, which was not immediately matched by enhanced oxidative metabolism or by enhanced blood flow. Thereafter, lactate control level was not restored after 0.5 mg/kg whereas it was restored after 5 mg/kg in spite of a sustained metabolic activation. The low dose of MK-801 also caused a continuous decrease in cerebral aspartate level (-38%) which is thought to match the enhanced energy demand, whereas the high dose caused shorter and smaller changes. The intracerebral glucose level rose after MK-801 injection, indicating that brain tissue had an adequate or even excessive supply of glucose. Glucose time course seemed to closely match the changes in blood flow elicited by MK-801. This is the first study giving the metabolic pattern of a pharmacological activation. We demonstrate an excess of glycolysis over oxidative metabolism in the early time similar to that following physiological and pathophysiological states such as photic stimulation and seizures. The difference between the effects of the two doses of MK-801 suggests that the adjustment of cerebral metabolism to MK-801 activation is faster and greater with the high dose than with the low dose.
Asunto(s)
Encéfalo/metabolismo , Maleato de Dizocilpina/farmacología , Fosfatos/metabolismo , Animales , Ácido Aspártico/análogos & derivados , Ácido Aspártico/metabolismo , Encéfalo/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Electroencefalografía/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Glucosa/metabolismo , Concentración de Iones de Hidrógeno , Cinética , Espectroscopía de Resonancia Magnética/métodos , Masculino , Fosfocreatina/metabolismo , Fósforo , Ratas , Ratas Wistar , Receptores de N-Metil-D-Aspartato/antagonistas & inhibidores , Factores de TiempoRESUMEN
The cerebral metabolic changes elicited by kainate-induced seizures in the rat were investigated by in vivo combined NMR spectroscopy of 31P and 1H. Systemic injection of kainate induced no significant changes in cerebral ATP or PCr levels during up to 90 min of continuous, generalised seizures, and the cerebral 31P spectra showed only a transient mild cerebral acidosis 30 min after kainate administration. In parallel with the changes in intracellular cerebral pH, the 1H spectra showed a significant increase in lactate, which remained elevated throughout the seizures. These findings indicate that oxidative metabolism does not completely match the increased glycolysis during seizures though the energy homeostasis is maintained. This suggests that oxidative metabolism has a limited capacity to satisfy the brain's energy needs during the kainate-induced seizures, but that the different pathways of energy production in the brain cells can overcome this limitation. Thus the brain damage associated with this experimental model of epilepsy is not due to extended major failure of the energy supply.
Asunto(s)
Encéfalo/metabolismo , Ácido Kaínico/toxicidad , Convulsiones/metabolismo , Acidosis , Adenosina Trifosfato/metabolismo , Animales , Presión Sanguínea , Dióxido de Carbono/sangre , Metabolismo Energético , Análisis de Fourier , Glucólisis , Homeostasis , Hidrógeno , Concentración de Iones de Hidrógeno , Técnicas In Vitro , Lactatos/metabolismo , Espectroscopía de Resonancia Magnética/métodos , Oxígeno/sangre , Presión Parcial , Fosfocreatina/metabolismo , Fósforo , Ratas , Convulsiones/inducido químicamente , Convulsiones/fisiopatología , Factores de TiempoRESUMEN
We have previously demonstrated that 2D 1H NMR is suitable for studying cerebral metabolism. The same technique was used to study the hind leg muscle of normal (C57BL10) and dystrophic (mdx) mice. The results were compared to preliminary results for cultured muscle cells to determine the origin of fatty acid signals.
Asunto(s)
Fusión Celular , Ácidos Grasos/análisis , Músculos/fisiología , Distrofia Muscular Animal/metabolismo , Envejecimiento/fisiología , Animales , Células Cultivadas , Hidrógeno , Espectroscopía de Resonancia Magnética/métodos , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes Neurológicos , Músculos/metabolismoRESUMEN
Homonuclear 1H 2D NMR spectroscopy (COSY experiments at 400 and 600 MHz) were used to study the rat brain in vivo and the rabbit spinal cord and sciatic nerve in vitro. The following metabolites were identified: lactate, alanine, threonine, GABA, glutamine/glutamate, N-acetyl aspartate, aspartate, taurine, inositol derivatives, choline derivatives, and glucose. The sciatic nerve spectra showed characteristic COSY graphs of saturated and unsaturated fatty acids, and linoleic and linolenic type structures were identified.
Asunto(s)
Química Encefálica , Espectroscopía de Resonancia Magnética/métodos , Nervio Ciático/química , Médula Espinal/química , Animales , Ácidos Grasos/química , Ácidos Grasos/metabolismo , Conejos , RatasRESUMEN
Intracerebral glucose resonance was directly detected and resolved in vivo by two-dimensional shift-correlated (COSY) 1H NMR spectroscopy in anesthetized rats (n = 4). The relative changes in brain glucose concentration were measured by volume integration of the alpha-D-glucose cross peak in the 2D COSY spectra. This report demonstrates the possibility of monitoring the variations in cerebral glucose following iv injection of glucose.
Asunto(s)
Encéfalo/metabolismo , Glucosa/metabolismo , Espectroscopía de Resonancia Magnética , Animales , Ácido Aspártico/análogos & derivados , Ácido Aspártico/metabolismo , Glucemia/análisis , Glucosa/administración & dosificación , Glutamatos/metabolismo , Ácido Glutámico , Glutamina/metabolismo , Hidrógeno , Inositol/metabolismo , Espectroscopía de Resonancia Magnética/métodos , Masculino , Monitoreo Fisiológico , Ratas , Ratas WistarRESUMEN
Bioactivity-guided purification of a crude alkaloid extract of Psychotria oleoides has afforded a new alkaloid, psycholeine [1], together with quadrigemine C [2], a tetrameric pyrrolidinoindoline compound of unknown stereochemistry. A comparison study of nmr and cd spectra of quadrigemine C and hodgkinsine [3], a trimeric pyrrolidinoindoline substance, led us to suggest the stereochemistry of quadrigemine C. The structure and configuration of psycholeine was determined by spectroscopic means and chemical correlation with quadrigemine C. Psycholeine interacts with somatostatin receptors and exhibits a somatostatin antagonistic activity on GH secretion by pituitary cells in primary culture.