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The action of bradykinin fragments on the arachidonate cascade of brain microvessels
210 attention, perception, memory, emotion and behaviour occur under different circumstances of arousal so, it is argued, do changes in need states. Further, whereas certain core characteristics are acknowledged as constituting what is generally referred to as ‘personality’, the notions of ‘mutability’ and ‘pathology’ can also be seen to be accommodated within the same framework. In fact the paper argues, and the models demonstrate, that there is not just a thin line between, for instance creativity and ‘madness’ but that the ‘line’ may be extremely thin and sometimes broken. The new perspective raises criticisms of current diagnostic practices and argues for descriptions and categories which also relate to ‘normal’ states. Certain questions of mind - body interaction are touched on, especially with reference to the immune system; and some specific possibilities of ‘biological alternatives’ in terms of the roles people play are also suggested. Finally, it offers a simple ‘model of regression’ which can be seen to apply at macro as well as micro levels: to groups and societies, as well as individuals. Reference
1. Gear, I., Perception and the Evolution of Style: a new model of mind, Routledge, London (in press).
THE ACTION OF BRADYKININ FRAGMENTS ON THE ARACHIDONATE CASCADE OF BRAIN MICROVESSELS A. Geese, Zs. Mezei, G Telegdy Department of Pathophysiology Albert Szent-Gyorgyi Medical University Szeged, Hungary Cerebral cortical microvessels were specifically studied, because arachidonate interactions might occur with other cells (circulating blood cells, platelets, endothelial cells or neural elements) and peptides that come into contact with the endothelial lining of microvessels. The locally synthesized and released arachidonate metabolites might modify the endothelial cell functions resulting in an altered cerebral microcirculation, blood-brain-barrier function with consequences in the neural functions. Studies were undertaken to explore the possible role played in the regulation of the cyclooxygenase and
lipoxygenase pathways of the arachidonate cascade by peptides - bradykinin fragments - synthesized and/or released in the nervous system. The brains of male rats of CFY strain, weighing 160-180 g were perfused with NaCl (0.9%0 under light ether anaesthesia. Isolation of blood free brain microvessels were prepared by a micromethod (Hwang et al., 1980), with modifications. The cerebral cortex was freed of myelin and pial membranes. The chopped tissue was homogenized in 9 volume of 3 mM HEPES buffers (containing 0.32 M sucrose, pH 7.3) with 10 strokes (1000 revolution/min), then centrifuged at 1000 g for 10 min at 2°C. The pellet was resuspended in the above mentioned buffers and was centrifuged at 100 g for 15 sec. and the pellet was diluted with 1 volume of 3 mM HEPES buffers followed by a centrifugation at 100 g for 15 sec. The supematants of the last two centrifugation were collected and centrifuged at 200 g for 1 min. The pellet was resuspended in 2.5 volume of TC Medium 199 @H 7.4) and centrifuged at 200 g for 1 min. The pellet was taken up in 1 volume of TC Medium 199 and centrifuged again at 200 g for 1 min. The pellet which contained the microvessels were resuspended in TC Medium 199. An aliquot was examined for purity using light and phasecontrast microscope. The contamination was less than 6% and the microvessels were free of blood cells. The microvessels were preincubated in TC Medium 199 at 37°C for 10 min, then one peptide - bradykinin fragment - was added to the incubation mixture. Ten minutes later the enzyme reaction was started adding 1-W-arachidonic acid to the incubation mixture (1 ml). Ten minutes later the enzyme reaction was quenched by bringing the pH to 3 with formic acid. The samples were extracted with ethylacetate then evaporated to dryness under nitrogen. The residues were reconstituted in ethylacetate and quantitatively applied to Silica gel-G t.1.c. plates, which were developed in the organic phase of ethylacetate:acetic acid: 2,2,4trimethyl pentane:water (110:20:30:100) applying an overpressure layer chromatograph. The radioactivity was determined in a Beckman LS 1800 liquid scintillation counter. The radiolabelled products of arachidonic acid were identified with unlabelled authentic standards which were detected with anisaldehyde reagent (Kiefer et al., 1975). The quantity of each released arachidonate metabolite was expressed as % of total DPM of cyclooxygenase and lipoxygenase products.
211 Reserved-phase high-performance liquid chromatography (HPLC) was performed on a column (4.6 * 250 mm) packed with LiChrosorbR Cl8 (7 pm particles). Statistical analysis was performed utilizing a Student’s t test.. The lipoxygenase pathway dominated the arachidonate cascade in the microvessels isolated from the brain cortex of male rats. More than 65% of the arachidonate cascade metabolites was HPETE or HETE. The main cyclooxygenase products were the PGD2 and TxB2 followed by PGF2alpha, PGE2 and 6-oxo-PGFlalpha in magnitude of order. Exposure of rat brain microvessels to bradykinin (10-7 M) resulted in a decreased liberation of lipoxygenase products. The synthesis of PGD2 was significantly reduced in cerebral cortex microvessels when 10-6 M bradykinin was present in the incubation mixture. The transformation of amchidonic acid to activate metabolites was significantly elevated as a result of lo-6 M bradykinin. The bradykinin fragment acetyl-Ser-Pro-Phe-Arg (10-6, 10-7 and 10-s M) did not modify the ratio of lipoxygenase and cycloexygenase products in the microvessels. The synthesis of vasoconstrictor cyclooxygenase metabolites was stimulated with acetyl-serProqhe-Arg. Bradykinin l-5 pentapeptide was without any effect on the arachidonate cascade in the microvessels. The dipeptide had no effect on the ratio of the vasoconstrictor and vasodilator cyclooxygenase metabolites. These results confirm our earlier findings (Geese et al., 1982), that the arachidonate cascade might be concentrated in the brain microvessels and not in the neural and glial cells of brain and cortex. This is in accordance with the results of Maurer et al. (1980), Gerritsen et al. (1980). These results in rat microvessels confirm our earlier observation (Geese et al., 1987) obtained in guinea pig capillaries, that the bradykinin inhibits the lipoxygenase pathway of arachidonate cascade and the synthesis of PGD2. Our findings suggest that some of the effects of peptides (bradykinin, bradykinin l-5, acetyl-Ser-ProPhe-Arg) may be mediated through the cyclooxygenase and/or lipoxygenase pathways of arachidonate cascade in the central nervous system. References
S.M. Hwang, S. Weiss, S. Segal (1980) Uptake of
L-(35s) cystine by isolated rat brain capillaries. J. Neurochemistry 35:417-427 C.A. Kiefer, C.R. Johnson, K.L. Arora (1975) Colorimetric identification of prostaglandins in subnanomole amounts. Anal. B&hem. 68:336340 A. Geese, A. Ott&z, Zs. Mezei, G. Telegdy, F. Jo6, E. Dux, I. Karnushina (1982) Prostacyclin and protaglandin synthesis in isolated brain capillaries, Prostaglandins 23:287-297 P. Maurer, M.A. Moskovitz, L. Levine, E. Melamed (1980) The synthesis of prostaglandins by bovine cerebral microvessels. Prostaglandins Med. 4: 153161 M.E. Gerritsen, T.P. Parks, M.P. Printz (1980) Pmtaglandin endoperoxide metabolism by bovine cerebral microvessels. B&hem. Biophys. Acta 619: 196-206 A. Geese, Zs. Mezei, G. Telegdy (1987) Neuropeptides and arachidonate cascade in the central nervous system. In: Neuropeptides and brain function, G. Telegdy ed., Karger, Base1 This work was partly supported by the Scientific Research Council, Ministry of Social And Health, Hungary.
PREDOMINANT IMPLICATION OF THE RIGHT HEMISPHERE IN THE PROCESSING OF DEVIANT STIMULI IN AN AUDITORY STIMULUS TRAIN: A TOPOGRAPHIC ERP STUDY M.H. Giard, F. Perrin and J. Pemier INSERM-Unite 280, 15 1 Cours Albert Thomas 9003 LYON - FRANCE
Introduction
Human event-related potential (ERP) recordings have shown that a physically deviant stimulus in a sequence of homogenous (standard) stimuli elicits a negative wave called “mismatch negativity” (MMN) (Nat&ten et al., 1982, 1986). It has been regarded by Nltitinen as reflecting a fully automatic, preperceptual cerebral process that does not involve a conscious discrimination of the task, and is independent of attention. It has been suggested that this process occurs at the modality-specific cortex (Simson et al., 1977),
1. Gear, I., Perception and the Evolution of Style: a new model of mind, Routledge, London (in press).
THE ACTION OF BRADYKININ FRAGMENTS ON THE ARACHIDONATE CASCADE OF BRAIN MICROVESSELS A. Geese, Zs. Mezei, G Telegdy Department of Pathophysiology Albert Szent-Gyorgyi Medical University Szeged, Hungary Cerebral cortical microvessels were specifically studied, because arachidonate interactions might occur with other cells (circulating blood cells, platelets, endothelial cells or neural elements) and peptides that come into contact with the endothelial lining of microvessels. The locally synthesized and released arachidonate metabolites might modify the endothelial cell functions resulting in an altered cerebral microcirculation, blood-brain-barrier function with consequences in the neural functions. Studies were undertaken to explore the possible role played in the regulation of the cyclooxygenase and
lipoxygenase pathways of the arachidonate cascade by peptides - bradykinin fragments - synthesized and/or released in the nervous system. The brains of male rats of CFY strain, weighing 160-180 g were perfused with NaCl (0.9%0 under light ether anaesthesia. Isolation of blood free brain microvessels were prepared by a micromethod (Hwang et al., 1980), with modifications. The cerebral cortex was freed of myelin and pial membranes. The chopped tissue was homogenized in 9 volume of 3 mM HEPES buffers (containing 0.32 M sucrose, pH 7.3) with 10 strokes (1000 revolution/min), then centrifuged at 1000 g for 10 min at 2°C. The pellet was resuspended in the above mentioned buffers and was centrifuged at 100 g for 15 sec. and the pellet was diluted with 1 volume of 3 mM HEPES buffers followed by a centrifugation at 100 g for 15 sec. The supematants of the last two centrifugation were collected and centrifuged at 200 g for 1 min. The pellet was resuspended in 2.5 volume of TC Medium 199 @H 7.4) and centrifuged at 200 g for 1 min. The pellet was taken up in 1 volume of TC Medium 199 and centrifuged again at 200 g for 1 min. The pellet which contained the microvessels were resuspended in TC Medium 199. An aliquot was examined for purity using light and phasecontrast microscope. The contamination was less than 6% and the microvessels were free of blood cells. The microvessels were preincubated in TC Medium 199 at 37°C for 10 min, then one peptide - bradykinin fragment - was added to the incubation mixture. Ten minutes later the enzyme reaction was started adding 1-W-arachidonic acid to the incubation mixture (1 ml). Ten minutes later the enzyme reaction was quenched by bringing the pH to 3 with formic acid. The samples were extracted with ethylacetate then evaporated to dryness under nitrogen. The residues were reconstituted in ethylacetate and quantitatively applied to Silica gel-G t.1.c. plates, which were developed in the organic phase of ethylacetate:acetic acid: 2,2,4trimethyl pentane:water (110:20:30:100) applying an overpressure layer chromatograph. The radioactivity was determined in a Beckman LS 1800 liquid scintillation counter. The radiolabelled products of arachidonic acid were identified with unlabelled authentic standards which were detected with anisaldehyde reagent (Kiefer et al., 1975). The quantity of each released arachidonate metabolite was expressed as % of total DPM of cyclooxygenase and lipoxygenase products.
211 Reserved-phase high-performance liquid chromatography (HPLC) was performed on a column (4.6 * 250 mm) packed with LiChrosorbR Cl8 (7 pm particles). Statistical analysis was performed utilizing a Student’s t test.. The lipoxygenase pathway dominated the arachidonate cascade in the microvessels isolated from the brain cortex of male rats. More than 65% of the arachidonate cascade metabolites was HPETE or HETE. The main cyclooxygenase products were the PGD2 and TxB2 followed by PGF2alpha, PGE2 and 6-oxo-PGFlalpha in magnitude of order. Exposure of rat brain microvessels to bradykinin (10-7 M) resulted in a decreased liberation of lipoxygenase products. The synthesis of PGD2 was significantly reduced in cerebral cortex microvessels when 10-6 M bradykinin was present in the incubation mixture. The transformation of amchidonic acid to activate metabolites was significantly elevated as a result of lo-6 M bradykinin. The bradykinin fragment acetyl-Ser-Pro-Phe-Arg (10-6, 10-7 and 10-s M) did not modify the ratio of lipoxygenase and cycloexygenase products in the microvessels. The synthesis of vasoconstrictor cyclooxygenase metabolites was stimulated with acetyl-serProqhe-Arg. Bradykinin l-5 pentapeptide was without any effect on the arachidonate cascade in the microvessels. The dipeptide had no effect on the ratio of the vasoconstrictor and vasodilator cyclooxygenase metabolites. These results confirm our earlier findings (Geese et al., 1982), that the arachidonate cascade might be concentrated in the brain microvessels and not in the neural and glial cells of brain and cortex. This is in accordance with the results of Maurer et al. (1980), Gerritsen et al. (1980). These results in rat microvessels confirm our earlier observation (Geese et al., 1987) obtained in guinea pig capillaries, that the bradykinin inhibits the lipoxygenase pathway of arachidonate cascade and the synthesis of PGD2. Our findings suggest that some of the effects of peptides (bradykinin, bradykinin l-5, acetyl-Ser-ProPhe-Arg) may be mediated through the cyclooxygenase and/or lipoxygenase pathways of arachidonate cascade in the central nervous system. References
S.M. Hwang, S. Weiss, S. Segal (1980) Uptake of
L-(35s) cystine by isolated rat brain capillaries. J. Neurochemistry 35:417-427 C.A. Kiefer, C.R. Johnson, K.L. Arora (1975) Colorimetric identification of prostaglandins in subnanomole amounts. Anal. B&hem. 68:336340 A. Geese, A. Ott&z, Zs. Mezei, G. Telegdy, F. Jo6, E. Dux, I. Karnushina (1982) Prostacyclin and protaglandin synthesis in isolated brain capillaries, Prostaglandins 23:287-297 P. Maurer, M.A. Moskovitz, L. Levine, E. Melamed (1980) The synthesis of prostaglandins by bovine cerebral microvessels. Prostaglandins Med. 4: 153161 M.E. Gerritsen, T.P. Parks, M.P. Printz (1980) Pmtaglandin endoperoxide metabolism by bovine cerebral microvessels. B&hem. Biophys. Acta 619: 196-206 A. Geese, Zs. Mezei, G. Telegdy (1987) Neuropeptides and arachidonate cascade in the central nervous system. In: Neuropeptides and brain function, G. Telegdy ed., Karger, Base1 This work was partly supported by the Scientific Research Council, Ministry of Social And Health, Hungary.
PREDOMINANT IMPLICATION OF THE RIGHT HEMISPHERE IN THE PROCESSING OF DEVIANT STIMULI IN AN AUDITORY STIMULUS TRAIN: A TOPOGRAPHIC ERP STUDY M.H. Giard, F. Perrin and J. Pemier INSERM-Unite 280, 15 1 Cours Albert Thomas 9003 LYON - FRANCE
Introduction
Human event-related potential (ERP) recordings have shown that a physically deviant stimulus in a sequence of homogenous (standard) stimuli elicits a negative wave called “mismatch negativity” (MMN) (Nat&ten et al., 1982, 1986). It has been regarded by Nltitinen as reflecting a fully automatic, preperceptual cerebral process that does not involve a conscious discrimination of the task, and is independent of attention. It has been suggested that this process occurs at the modality-specific cortex (Simson et al., 1977),