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Biomedical subjects

F Cesselin

Publications and source records attributed to F Cesselin.

At least 109 records · Page 6Linked to original sources
PubMed1984

Simultaneous evaluation of the catecholamine pathway and three opioid peptide-producing systems in human pheochromocytomas.

Tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) activities, dopamine (DA), noradrenaline (NA), adrenaline (A), met 5-enkephalin (Met-Enk), leu5-enkephalin (Leu-Enk), dynorphin (Dyn) and beta-endorphin (beta-end) were measured simultaneously in ten human pheochromocytomas = 1 - TH activity was highly variable, from 22 to 2220 U/g tissue. 2 - DBH activity, in contrast, was rather constant, from 96 to 582 U/g. 3 - Catecholamines (A and NA) concentrations showed only small variations. 4 - The four opioid peptides were detected in all cases and exhibited a wide range of tissue concentrations (Enk much greater than Dyn greater than beta-end). 5 - Met-Enk and Leu-Enk concentrations were highly correlated; no correlation was observed with the other opioid peptides. 6 - A very strong correlation was observed between enkephalins concentrations and both catecholamines concentrations and DBH activities. These results are discussed in term of the significance of the co-localization of these various biologically active substances, principally with regard to the possible regulation of catecholamine synthesis by opioid peptides and conversely.

Adrenal Gland Neoplasms↗
PubMed1984

Basic and regulatory mechanisms of in vitro release of Met-enkephalin from the dorsal zone of the rat spinal cord.

Under control conditions, superfused slices of the dorsal half of the lumbar enlargement from adult rats released Met-enkephalin-like material (MELM) that behaved as authentic Met-enkephalin under two different chromatographic procedures (Bio-gel filtration, HPLC). MELM release increased markedly on exposure of slices to batrachotoxin (0.5 microM) or to an excess of K+ (28 and 56 mM instead of 5.6 mM). The K+-evoked release was totally dependent on the presence of Ca2+ in the superfusing fluid whereas the spontaneous efflux of MELM was only partially Ca2+-dependent. Further experiments performed with tissues of polyarthritic rats indicated that the increase in their MELM levels was associated with a lower fractional rate constant of MELM release, therefore suggesting that spinal Met-enkephalin turnover might be reduced in chronically suffering animals. Examination of the possible modulation of MELM release by various neuroactive compounds present within the dorsal horn revealed that cholecystokinin (10 microM), but not its desulphated derivative, substance P-sulphoxide (10 microM), and to a lesser extent substance P, enhanced the K+-evoked MELM release. In contrast, gamma-aminobutyric acid (10 microM) and (-)-baclofen (1 microM) partially prevented the stimulatory effect of K+ on MELM release. Other compounds such as serotonin, somatostatin, and neurotensin altered neither the spontaneous nor the K+-evoked release of MELM.

Animals↗
PubMed1984

Biochemistry of the hypothalamus in Parkinson's disease.

We assayed the content of neurotransmitters (or their synthesizing enzymes) and neuropeptides in the hypothalamus of control and parkinsonian brains post mortem. Only dopamine concentrations were lower than normal in Parkinson's disease, suggesting that deficiency in hypothalamic dopamine transmission may play a role in the autonomic and endocrine abnormalities of this disorder.

Aged↗
PubMed1984

[Possible functional significance of the simultaneous release of several putative neurotransmitters by the same neuron].

At least three criteria should be fulfilled before it can be concluded that one neurone may use more than one neurotransmitter (or neuromodulator) for synaptic transmission: Such putative neurotransmitters must be located in this particular neurone: They must be released from the neurone under physiological conditions, and: They must exert separately or together pre- and/or post-synaptic effects. Critical analysis of the literature reveals that the coexistence and corelease of neuroactive substances are rarely firmly established. However, more convincing data have been reported on the interaction at the pre- and/or post-synaptic levels between neurotransmitters possibly located in the same neuronal population. Thus, it has been shown that VIP coreleased with acetylcholine from the same parasympathetic fibres can facilitate the interaction of this neurotransmitter with muscarinic receptors on target cells. In contrast, substance P coreleased with serotonin from bulbo-spinal fibres can reduce the effect of the amine on specific presynaptic autoreceptors. The functional significance of such interactions between neurotransmitters coexisting in the same neurone seems extremely important. In particular, they might well be involved in the physiological control of hormone release from the adenohypophysis.

Animals↗
PubMed1984

Angiotensin II in the central nervous system in the rat.

Characteristics and functional activity of Angiotensin II (AII) neuronal receptors were studied using binding and intracellular recording methods. Characteristics of AII binding allowed definition of two distinct classes of high and low affinity binding sites. The effects of AII on the electrophysiological membrane properties of neurones were investigated using cultured mouse spinal cord (SC). AII induced changes in membrane potential and input resistance which varied according to the applied concentration of peptide. These data agreed with binding results suggesting two classes of AII neuronal receptors. Although angiotensin II-like material is found in the rat brain by RIA and immunochemistry, the presence of authentic angiotensin II (AII) is a point for discussion. Using RIA and radio-receptor assay (RRA), we found AII like peptides. However, chromatographic separation by gel filtration has revealed that this material is not authentic AII but consists of compounds of higher molecular weight. The recognition of the same material, both by AII antibodies (RIA) and AII binding sites (RRA) suggests that precursors containing AII sequences exist in the rat brain. We incubated rat brain with 3H-angiotensin I (AI) at 37 degrees C and analysed the resulting 3H-peptides (HPLC). Authentic 3H-AII was not detected, but two smaller peptides appeared (peak alpha et beta). The same peaks appeared when rat brain was incubated with 3H-AII. We have only been able to reveal 3H-AII formation from 3H-AI by inhibiting AII angiotensinases with excess of AII or low temperature (22 degrees C or 12 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1983

Parkinson's disease affects differently Met5- and Leu5-enkephalin in the human brain.

When measured in post-mortem human control brains, the ratio of Met5-enkephalin levels to those of Leu5-enkephalin varied from 1 to 13 in the 11 areas examined. In parkinsonian brains a significant reduction in the levels of both peptides was found in the pallidum and putamen whereas only Met5-enkephalin levels were decreased in the substantia nigra and ventral tegmental area. Therefore, Met5-enkephalin and Leu5-enkephalin may be located (at least partly) in different neuronal populations in the human brain.

Brain↗
PubMed1983

Biochemical and functional alterations of central GABA receptors during chronic estradiol treatment.

The characteristics of GABA and benzodiazepine receptors were examined in the hippocampus, striatum and cerebral cortex of female rats at various times (up to 9 months) after the subcutaneous implantation of an estradiol pellet (10 mg). A significant decrease in the Bmax of the high-affinity binding of [3H]muscimol to membranes from these 3 regions was detected as soon as one week after the implantation. Although the characteristics of the high-affinity binding of [3H]flunitrazepam remained unaffected during the whole treatment, the stimulatory effect of GABA (and muscimol) on this binding was significantly reduced by estrogenization. The changes in GABA receptor binding appeared functionally relevant since the elevation of striatal acetylcholine levels normally induced by the peripheral administration of muscimol (5 mg/kg) was significantly lower in estradiol-treated than in control female rats. In contrast to that observed in intact female rats, the implantation of estradiol in hypophysectomized animals did not affect the characteristics of [3H]muscimol binding to hippocampal, striatal and cortical membranes. [3H]muscimol binding was also unchanged in female rats implanted with estradiol and treated chronically with bromocriptine for 3 weeks. Since both hypophysectomy and the chronic administration of bromocriptine suppressed the hyperprolactinemia normally induced by estrogenization, the down-regulation of central GABA receptors very likely involved prolactin in intact animals implanted with 17-beta-estradiol.

Acetylcholine↗
PubMed1983

Tyrosine hydroxylase and methionine-enkephalin in the human mesencephalon. Immunocytochemical localization and relationships.

The immunocytochemical localization of tyrosine hydroxylase (TH) and methionine-enkephalin (met-enkephalin) was determined at two representative caudal and rostral levels of the human mesencephalon. Four main groups of catecholaminergic neurons were delineated, situated in the substantia nigra and the lateral, ventromedial and dorsomedial tegmentum, extending over several cytoarchitectonic divisions. They matched fairly well the dopaminergic cell groups described in monkey midbrain. TH-like immunoreactivity and neuromelanin were closely related in neurons of substantia nigra, but less so in the other groups. A widespread met-enkephalinergic innervation was observed in most areas containing catecholaminergic neurons. It followed a characteristic pattern: homogeneous and very dense in the lateral and posterior portions of substantia nigra; patchy and less dense in the other areas, the medio-ventral and periaqueductal gray being only sparsely innervated, in contrast to observations in rodents. Dopaminergic cell bodies surrounded by met-enkephalinergic varicosities were seen in most groups, particularly in the lateral substantia nigra and medioventral tegmentum. The topography of met-enkephali-like immunoreactive terminals in the substantia nigra was reminiscent of the distribution of neostriatal and pallidal afferents.

Aged↗
PubMed1983

Different localizations of Met-enkephalin-like immunoreactivity in rat forebrain and spinal cord using hydrogen peroxide and Triton X-100. Light microscopic study.

The histological distribution of met-enkephalin-like immunoreactivity was studied in the forebrain (particularly the striatum) and the spinal cord of the rat using the indirect peroxidase-labelled antibody method. In most experiments, vibratome sections of formaldehyde-fixed tissues and purified antibodies were used. The search for optimal conditions for the immunohistochemical reaction lead us to establish that met-enkephalin-containing perikarya of both untreated and colchicinized animals were better demonstrated when tissue were pre-treated with diluted hydrogen peroxide only. The additional treatment of these sections with Triton X-100 (or some other detergents) resulted in the near disappearance of the perikaryal immunoreactivity; on the contrary, numerous met-enkephalin containing nerve fibres and varicosities were then demonstrated in the same region. Using only the hydrogen peroxide treatment, we found numerous met-enkephalin-containing perikarya in the medial and ventral regions of the neostriatum. This distribution was prolonged caudally by the existence of a prominent group of stained somata in the ventral putamen-central nucleus of the amygdala. When intraventricular injections of colchicine were used, positive perikarya were more numerous within the striatum (the globus pallidus excepted) but their distribution was largely the same as in non injected animals. However, some new groups of somata were stained in this case in the forebrain (in the lateral septum, the olfactory tubercle and the hypothalamus particularly). In control animals only few met-enkephalin-containing perikarya were observed in the dorsal horn of the spinal cord when H2O2 pretreatment was used alone and they were numerous only when intraspinal injections of colchicine were performed. Met-enkephalin-containing fibres and varicosities, which were scattered in the whole neostriatum in the conditions used above, became very numerous when the tissue sections were incubated in the presence of Triton X-100. Their density increased markedly from the latero-dorsal to the medio-ventral regions but, in addition, an organization under the form of islands of stronger immunoreactivity was also evidenced. These islands were more numerous ventrally in the anterior neostriatum and in the central region of the "putamen." The dense plexus of immunoreactive nerve fibers forming "tube-like structures" which was always observed in the paleostriatum and in the cranial medial forebrain bundle (islands of Calleja) appeared more diffuse when detergents were used.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1983

Met-enkephalin-like immunoreactivity in rat forebrain and spinal cord using hydrogen peroxide and Triton X-100. Ultrastructural study.

Using two immunocytochemical methods, we have shown in light microscopy that the met-enkephalin-like immunoreactivity within striatum and spinal cord of the rat is differentially distributed in either perikarya or nerve terminals according to the technical conditions used [1]. The present electron microscopic study has been undertaken in order to elucidate the subcellular localization of immunoprecipitates according to the same technical conditions. In the neostriatum, numerous met-enkephalin-containing perikarya were stained (principally at the level of rough endoplasmic reticulum) when tissue sections were treated with hydrogen peroxide (H2O2) only, prior to the immunocytochemical procedure. However, injections of colchicine were required to demonstrate perikarya in the dorsal horn of the spinal cord. At variance with previous results, numerous dendritic profiles and nerve terminals were also reactive in this condition. Neurotubules, mitochondria, large granular vesicles (LGVs) and small synaptic vesicles were stained within these structures. The addition of a low concentration of Triton-X-100 (0.02%) in the first incubation medium often resulted in the disappearance of most perikarya and in the staining of only LGVs in nerve terminals. The addition of a higher concentration of Triton-X-100 (0.1%) produced diffusion of immunoprecipitates at the level of nerve terminals, which was probably responsible for the increased intensity of staining and, subsequently, for the better demonstration of fibre varicosities in light microscopy. On the contrary, the disappearance of reactive perikarya seemed to result from the diffusion of the non-protected peptide out of the cytoplasm. The diverse ultrastructural localizations of met-enkephalin-like immunoreactivity in striatum and spinal cord are finally discussed in light of intrinsic connections or afferents described in the literature.

Animals↗
PubMed1983

Localization of Met-enkephalin-like immunoreactivity within pain-related nuclei of cervical spinal cord, brainstem and midbrain in the cat.

Met-enkephalin immunoreactivity was investigated with an indirect immunoperoxidase technique in the cervical spinal cord, brainstem and midbrain of the cat, paying special attention to pain-related nuclei. Different technical conditions were used to reveal preferentially met-enkephalin-containing fibres and terminals or perikarya. Immunoreactive fibres and terminals were revealed optimally in sections from control animals incubated with detergent (Triton X-100). Immunoreactive perikarya were revealed in colchicine treated animals. Comparison between different routes of administration showed that local injections of colchicine are needed to reveal optimally immunoreactive perikarya in nuclei located far from the ventricles. Met-enkephalin-containing fibres and terminals are widely distributed in the posterior brain and spinal cord. The densest network of immunoreactive fibers are observed in the superficial layers of the cervical spinal cord and the caudal trigeminal nucleus, in the nucleus of the solitary tract, the nucleus of the facial nerve, the nucleus of the prepositus hypoglossi, the nucleus raphe pallidus, the medial vestibular nucleus, the interpedoncular nucleus and the substantia nigra. A moderate staining of fibres is observed in various nuclei including the ventral horn of the spinal cord and caudal trigeminal nucleus, the brainstem and midbrain reticular formation, the inferior olivary complex, the nucleus of the descending trigeminal tract and the periaqueductal grey. Met-enkephalin-containing perikarya are present in all the nuclei cited before, except in the inferior olivary complex. The densest aggregation of enkephalin-like perikarya is observed in the nucleus raphe magnus, nucleus raphe obscurus, nucleus raphe pallidus, nucleus reticularis gigantocellularis pars alpha and nucleus reticularis lateralis. The general distribution of enkephalin-containing structures in the cervical spinal cord, brainstem and midbrain of the cat appears very similar to that of the rat except in the substantia nigra where met-enkephalin cell bodies are found in the cat but not in the rat. In particular the pain-related nuclei present a similar distribution of the peptide in the two species; however, met-enkephalin-containing cell bodies are much more numerous in the cat than in the rat (notably in the reticular formation). Similar types of met-enkephalin innervation occur in the dorsal and intermediate grey of the spinal cord and of the caudal trigeminal nucleus supporting further that the functional organizations of these regions are closely related.

Animals↗
PubMed1983

Modifications of the high and low affinity pituitary domperidone-binding sites in chronic estrogenized rats.

The effect of chronic estrogen treatment on the anterior pituitary domperidone-binding sites was studied in female rats. The rats were implanted from 1-6 months with a Silastic capsule containing 17 beta-estradiol. The Feldman analysis of [3H]domperidone binding to anterior pituitary membranes of control or estrogenized rats revealed the presence of two sites. The binding characteristics of the higher affinity site were identical for both groups (Kd of the high affinity site, 0.30-0.45 nM; maximum number of binding sites of the high affinity site, 74-95 fmol/mg protein); however, those of the lower affinity site were affected by the estrogen treatment: the Kd of the low affinity site increased from 17.4 +/- 3.2 to 41.5 +/- 9 (+/- SE) nM, and the maximum number of binding sites of the low affinity site increased from 214 +/- 22 to 343 +/- 35 fmol/mg protein. Thus, in chronic estrogenized rats, the total number of binding sites was increased by 54%. These changes, induced by chronic estrogenization, were reversible, since 2 weeks after removal of the 17 beta-estradiol pellet, the binding characteristics were no longer different from those observed in control rats. In contrast to chronic estrogen treatment, ovariectomy reduced markedly the total number of [3H]domperidone-binding sites in anterior pituitary membranes (-70%). Feldman analysis revealed that this reduction resulted from the complete disappearance of the low affinity sites in those membranes. No significant change in the binding characteristics of the high affinity site was detected in ovariectomized rats. Since estradiol induces a decrease in the anterior pituitary content of dopamine, a denervation supersensitivity-like mechanism might be responsible for the increase in pituitary domperidone-binding sites in estrogenized rats. Conversely, a hyposensitivity mechanism could be implicated in the decrease in the total number of the pituitary domperidone-binding sites in ovariectomized rats, since pituitary dopamine levels are increased in those animals. Whether the antidopaminergic properties of estrogen are also involved in this modulation after chronic estradiol treatment requires further investigation.

Animals↗
PubMed1983

[Study of angiotensin II].

Radioisotopic competition of angiotensin II (A II) together with the use of structural analogues of this peptide are the two main methods of investigating the physiopathology of this hormone. Of great theoretical interest, the results of radioimmunological assay of plasma A II should be interpreted with caution because of the methodological difficulties related to its measurement and to the metabolic situation of A II. The values of the plasma A II alone do not provide additional information compared to PRA and are not representative of the pressor and biological effects of the hormone. The inhibitors of A II, although they too have a certain agonist activity, represent a method of precise investigation of the peripheral role of the hormone.

Angiotensin II↗
PubMed1982

In vivo modulations by GABA-related drugs of met-enkephalin release in basal ganglia of the cat brain.

The influence of the intrapallidal application of GABA-related compounds on the release of Met-enkephalin in the globus pallidus and the caudate nucleus in the two hemispheres was investigated in vivo in the cat. For this purpose, the 4 structures were continuously superfused with an artificial CSF through implanted push-pull cannulae and Met-enkephalin released in superfusates was determined using a specific radioimmunoassay. GABA (10-500 microM) reduced the local release of Met-enkephalin during its application but once the amino acid was removed from the superfusing fluid, an increase in the peptide release was observed. Diazepam (10 microM) induced only an inhibitory effect whereas muscimol (1 microM) stimulated Met-enkephalin release. Opposite changes in Met-enkephalin release were also seen with the GABA antagonists, bicuculline methiodide (1 microM) and picrotoxin (10 microM), suggesting that the local regulation of Met-enkephalin release by GABA related compounds may be mediated by at least two types of GABA receptors. In several cases, the unilateral pallidal application of GABA agonists and antagonists induced significant changes in Met-enkephalin release at distant structures. The most striking effect was observed with diazepam which markedly reduced the peptide release in both caudate nuclei and pallida. These data suggest that GABAergic systems can contribute to some bilateral regulation of striato-pallidal enkephalinergic neurones.

Animals↗
PubMed1982

CCK-8-Immunoreactivity distribution in human brain: selective decrease in the substantia nigra from parkinsonian patients.

The regional distribution of immunoassayable CCK-8 was determined in 12 regions of control and parkinsonian human brain, with specific attention to the possible regional coexistence of CCK-8 with dopamine. In Parkinson's disease, CCK-8-I levels were only decreased in the substantia nigra where dopamine cell bodies lie, and not in striatal and corticolimbic dopamine projecting areas. Our results suggest that the major proportion of dopaminergic neurones degenerated in Parkinson's disease may not contain the CCK-8 peptide.

Appetite Depressants↗