Biomedical subjects

F Vandesande

Publications and source records attributed to F Vandesande.

At least 73 records · Page 4Linked to original sources

PubMed1994

Alterations in GAP-43 and synapsin immunoreactivity provide evidence for synaptic reorganization in adult cat dorsal lateral geniculate nucleus following retinal lesions.

Growth-associated protein-43 (GAP-43) and synapsin were used as molecular markers for synaptic reorganization in the adult cat visual system following sensory deprivation. Small binocular retinal lesions (central 10 degrees) were made with a xenon light photocoagulator in adult cats. One, 3, 5 and 7 weeks after induction of the lesion, the neuropil levels of synapsin and GAP-43 in the dorsal lateral geniculate nucleus (dLGN) and area 17 were determined by immunocytochemistry. GAP-43 displayed a moderately low basal level in the dLGN of normal adult cats. The parvocellular C layers and the interlaminar plexi were characterized by higher immunoreactivity for GAP-43. Lesion-induced alterations were observed in all layers: GAP-43 immunoreactivity increased in the part of the dLGN representing central vision. This increase was maximal 3 weeks after the lesion. Under our experimental conditions, sensory deprivation did not significantly alter GAP-43 levels in the visual cortex. The changes in synapsin immunoreactivity were also restricted to the dLGN. In this nucleus, synapsin immunoreactivity decreased in all layers in the part subserving central vision 1 week after lesion. By 3 weeks after lesion, the level of synapsin had already returned to normal. This study provides evidence for a capacity for structural remodelling in primary sensory brain areas such as the dLGN throughout adult life. The observed changes in GAP-43 and synapsin in the dLGN suggest that synaptic reorganization is induced by retinal lesions. Normalization of synaptic density and activity could be important for the survival of the partially deafferented geniculate neurons.

Animals↗

PubMed1994

A simple method for the immunocytochemical processing of large numbers of floating sections and its application in screening for monoclonal antibodies.

A technically simple modification of routine (non-adsorbent) multi-well plates, permitting the simultaneous immunocytochemical processing of hundreds of free-floating sections is described. The adaptations consist of (1) making a 1.5 mm wide perforation in the bottom of each well of the multi-well plate, (2) placing a 6 mm wide 50 microns mesh nylon filter on the bottom of each well and (3) preincubating the plate with excess inert protein in order to prevent adsorption of protein reagents. During the incubation of the floating sections with the immunocytochemical reagents, the fluid is retained in the well by capillarity, provided the detergent concentrations within the well do not exceed 0.005% (v/v). The wells can be emptied simply and quickly by blotting the plate bottom with a piece of laboratory paper toweling: the fragile sections are gently caught on the filter, without the risk of loss or damage. Sections start floating again as soon as the next reagent is added to the well. The present method drastically reduces the time needed for rinsing and reagent exchange, making immunocytochemistry on free-floating sections feasible as a primary screening method during hybridoma production.

Amino Acid Sequence↗

PubMed1994

Immunocytochemical localization of mammalian GnRH (gonadotropin-releasing hormone) and chicken GnRH-II in the brain of the European silver eel (Anguilla anguilla L.).

Using specific antibodies for the two molecular forms of gonadotropin-releasing hormone (GnRH) present in the European eel, Anguilla anguilla, (mammalian GnRH, mGnRH, and chicken GnRH II, cGnRH-II), we employed immunocytochemistry to determine the distribution of these two peptides in the brain and in the pituitary. The results indicate that mGnRH and cGnRH-II are localized in different neurons: mGnRH-immunoreactive (ir) perikaria were observed in the olfactory bulbs, the junction between olfactory bulbs and telencephalon (nucleus olfactoretinalis), the telencephalon, the preoptic region and the mediobasal hypothalamus. These cell bodies are located along a continuum of ir-fibers that could be traced from the olfactory nerve to the pituitary. Mammalian GnRH-ir fibers were detected in many parts of the brain (olfactory bulbs, ventral telencephalon, hypothalamus, optic tectum, mesencephalon) and in the pituitary. Chicken GnRH-II-ir cell bodies were detected in the nucleus of the medial longitudinal fasciculus of the midbrain tegmentum, but only scattered fibers could be detected in different parts of the brain. The pituitary exhibited very few cGnRH-II-ir fibers, contrasting with an extensive mGnRH innervation. These results are in agreement with our previous data obtained in the same species using specific radioimmunoassays for mGnRH and cGnRH-II. They demonstrate a differential distribution of the two forms of GnRH in the brain of the eel, as in the brain of some other vertebrate species, and suggest differential physiological roles for the two GnRH forms in the eel. They also provide information concerning the evolution of the GnRH systems in vertebrates.

Anguilla↗

PubMed1994

Partial colocalization of the GABAA receptor with parvalbumin and calbindin D-28K in neurons of the visual cortex and the dorsal lateral geniculate nucleus of the cat.

Monoclonal antibodies to a synthetic peptide fragment of the beta 1-subunit of the bovine central GABAA/benzodiazepine receptor were used to investigate immunocytochemically the distribution of this receptor in the visual system of the cat. Labeled neurons were observed in all layers of the visual cortex and the dorsal lateral geniculate nucleus. About half of the total cortical or geniculate neuronal population was found to be positive. To further identify immunocytochemically these GABAA receptor expressing cells, double stainings were undertaken with, on one hand, the monoclonal antibodies directed against the receptor complex, and on the other hand polyclonal antisera directed against cat muscle parvalbumin or chicken calbindin D-28K. A high degree of colocalization between either of the two calcium binding proteins and the GABAA receptor was found in the upper layers (I, II and III) of the visual cortex and in the A and C laminae of the dorsal lateral geniculate nucleus; all calbindin D-28K-positive cells were immunoreactive for the GABAA receptor. The parvalbumin-positive cells, scattered throughout all layers of the dorsal lateral geniculate nucleus and the visual cortex, except cortical layer I, were also all positive for the GABAA receptor. However, a large proportion of all GABAA receptor bearing cells were negative for one of the calcium binding proteins.

Animals↗

PubMed1994

Disappearance rate of glycosylated and non-glycosylated chicken growth hormone: influence on biological activity.

The disappearance rates for glycosylated (GcGH) and non-glycosylated chicken growth hormone (NGcGH) were compared following their intravenous injection into anaesthetized adult laying hens. The metabolic clearance rate of GcGH was about 20% lower (P = 0.13) compared to NGcGH. Similarly, there was a tendency towards a longer half-life for GcGH. No major physiological significance could be attributed to the glycosylation state of the preparations as far as their effects on circulating insulin-like growth factor I and iodohormone levels were concerned.

Analysis of Variance↗

PubMed1994

Visualization of gamma-aminobutyric acid A receptors on proopiomelanocortin-producing neurons in the rat hypothalamus.

It has recently been shown that gamma-aminobutyric acid (GABA) and central-type benzodiazepine receptor agonists inhibit the expression of the POMC gene and the release of POMC-derived peptides from hypothalamic neurons. To determine whether the inhibitory effect of GABA could be accounted for by a direct action on POMC neurons, we investigated the localization of the beta 1-subunit of the GABAA-benzodiazepine-receptor complex in the arcuate nucleus. Using a monoclonal antibody raised against a synthetic fragment of the beta 1-subunit, we demonstrate the presence of GABAA receptor on POMC neurons. The proportion of POMC neurons that exhibit immunoreactivity for the beta 1-subunit of the GABAA receptor was not significantly different in the posterior portion (73.0-76.0%) and anterior portion (61.3-62.7%) of the arcuate nucleus. The data also revealed that in the arcuate nucleus, a majority of neurons that were immunostained by the antibody to the beta 1-subunit were not POMC positive. The present results support the concept that GABAA and central-type benzodiazepine receptor agonists exert a direct inhibitory action on POMC neurons. The data also indicate the existence of subsets of POMC neurons within the arcuate nucleus.

Amino Acid Sequence↗

PubMed1993

Comparative distribution of mammalian GnRH (gonadotrophin-releasing hormone) and chicken GnRH-II in the brain of the immature Siberian sturgeon (Acipenser baeri).

The brain of the sturgeon has recently been shown to contain at least two forms of GnRH (gonadotropin-releasing hormone), mammalian GnRH (mGnRH) and chicken GnRH-II (cGnRH-II). In this study, we compared the distribution of immunoreactive (ir) mGnRH and cGnRH-II in the brain of immature Siberian sturgeons (Acipenser baeri). The overall distribution of mGnRH was very similar to the distribution of sGnRH in teleosts such as salmonids or cyprinids. mGnRH-ir perikarya were observed in the olfactory nerves and bulbs the telencephalon, the preoptic region, and the mediobasal hypothalamus. All these cell bodies are located along a continuum of ir-fibers that could be traced from the olfactory nerve to the hypothalamopituitary interface. No ir-fibers were observed in the anterior lobe of the pituitary, but a few were seen to enter the neurointermediate lobe. mGnRH-ir fibers were detected in many parts of the brain, particularly in the forebrain. mGnRH-ir cerebrospinal fluid-contacting cells were observed in the telencephalon, the preoptic region, and the mediobasal hypothalamus. In contrast, cGnRH-II was present mainly in the posterior brain, although a few ir axons were seen in the above-mentioned territories. In particular, cGnRH-II-ir cells bodies, negative for mGnRH, were consistently observed in the nucleus of the medial longitudinal fasciculus of the midbrain tegmentum. The cGnRH-II innervation in the optic tectum, cerebellum, vagal lobe, and medulla oblongata was more abundant than the mGnRH innervation in the same areas. This study provides evidence that the organization of the GnRH systems in a primitive bony fish is highly similar to that reported in teleosts and further documents the differential distribution of two forms of GnRH in the brain of vertebrates.

Amino Acid Sequence↗

PubMed1993

Laminar distribution of NMDA receptors in cat and monkey visual cortex visualized by [3H]-MK-801 binding.

Glutamate is the major excitatory neurotransmitter of the mammalian central nervous system. Two major classes of glutamate receptors have been reported. The actions of glutamate on its N-methyl-D-aspartate (NMDA)-type receptor may underlie developmental and adult plasticity as well as neurotoxicity. The NMDA-type of glutamate receptor in cat and monkey visual cortex was visualized by means of in vitro receptor autoradiography with the noncompetitive NMDA-receptor antagonist [3H]-MK-801. The kinetics, performed on tissue sections, revealed an apparently single, saturable site with an approximate dissociation constant (KD) of 18.5 nM in cat and 15.9 nM in monkey visual cortex. Autoradiography, performed on frontal sections of cat and monkey visual cortex, revealed a heterogeneous laminar distribution of NMDA receptors. Cat areas 17, 18, 19, and the lateral suprasylvian areas exhibited a similar NMDA-receptor distribution. In these areas, NMDA receptors were most prominent in layer II and the upper part of layer III. In monkey striate cortex, NMDA receptors were primarily concentrated in layers II, upper III, IVc, V, and VI. In monkey secondary visual cortex, [3H]-MK-801 labeling was most prominent in layers II, V, and VI; whereas in the temporal visual areas included in this study layer II displayed the heaviest receptor labeling. In neither cat nor monkey could we observe significant differences in NMDA-receptor distribution between different retinotopic subdivisions within a single visual area. Neither did we detect any periodic changes in NMDA-receptor distribution that would correspond to the compartments defined by cytochrome-oxidase in monkey V1 and V2.

Animals↗

PubMed1993

Distribution of luteinizing hormone-releasing hormones I and II (LHRH-I and -II) in the quail and chicken brain as demonstrated with antibodies directed against synthetic peptides.

Polyclonal antibodies were raised in rabbits against polypeptides corresponding to the N-terminal part (heptapeptides) of the two avian gonadotropin-releasing hormones, chicken (c) LHRH-I and -II. These peptides, which were synthesized by the continuous-flow technique, were selected because they contained the smallest number of common amino acid residues. The pGlu-His-Trp-Ser sequence at the C-terminal was suppressed to avoid possible cross-reactions between the antisera. The antisera generated in this way were tested for specificity by solid and liquid phase absorption as well as by antigen spot tests. The antiserum raised against cLHRH-I recognized this peptide preferentially though not exclusively. Some cross-reaction with cLHRH-II was observed in the absorption test, although spotting tests suggested a total specificity. The anti cLHRH-II appeared to be completely specific in all tests. These two antibodies were then used to study the distribution of cLHRH-I and -II immunoreactive structures in the quail and chicken brain. cLHRH-I immunoreactive perikarya were observed in a fairly wide area covering the preoptic-anterior hypothalamic and septal region. By contrast, cLHRH-II cells were confined to a single group located in the dorsal aspects of the occulomotor nuclei, at the junction of the di- and mesencephalon. A sex difference in the number of cLHRH-I cells was detected in the anterior lateral preoptic region of the quail. Fibers immunoreactive for either cLHRH-I or cLHRH-II were widely distributed in the telencephalon, diencephalon, and mesencephalon but showed a specific pattern of anatomical localization. In particular, a high density of cLHRH-I fibers were seen in the external layer of the median eminence, while cLHRH-II fibers were less prominent at this level. Contrary to previous reports, a significant amount of cLHRH-II fibers were however seen throughout the median eminence (mostly external layer). The extensive distribution of both cLHRH-I and -II fibers in the quail and chicken brain is consistent with the potential role played by these peptides in the gonadotropin secretion and in the control of reproductive behavior. The specific role of cLHRH-II remains however elusive at present.

Amino Acid Sequence↗

PubMed1993

Immunocytochemical demonstration of chicken hypophyseal thyrotropes and development of a radioimmunological indicator for chicken TSH using monoclonal and polyclonal homologous antibodies in a subtractive strategy.

The production and characterization of monoclonal antibodies (mAbs) toward the chicken pituitary glycoproteins are described. MAbs were first subdivided on an immunocytochemical (ICC) basis: one category of mAbs reacts with both thyrotropic and gonadotropic cells whereas another stains exclusively gonadotropic cells. The hypothesis that the former are anti-glycoprotein alpha and that the latter are anti-beta LH and/or anti-beta FSH mAbs was further elaborated in a homologous tracer binding assay. The putative anti-beta gonadotropin mAbs exclusively recognize iodinated USDA-cLH-I-1, whereas the supposed anti-alpha mAbs react with both USDA-cLH-I-1 and USDA-cFSH-I-1. The ICC localization of pituitary thyrotropes has been achieved in a double-staining protocol using an anti-LH mAb to subtract specifically the gonadotropic cells from the complete alpha-subunit-containing cell population. The result is a strictly cephalic cell population that is densely granulated in hyperthyroid and hardly detectable in hypothyroid birds. A similar subtractive approach was used to develop a thyroid-stimulating hormone (TSH)-indicator in RIA. The total titer of alpha-containing molecules is first quantified with an anti-alpha mAb. The contribution of both LH and FSH to this titer is then measured by homologous USDA-RIA and subtracted from the total alpha-immunoreactivity to give an indication of the TSH level of the sample. The direct effect of thyroid-releasing hormone on pituitary TSH release in vitro in juvenile chicks and the effect of hypo- and hyperthyroidism on circulating TSH levels in vivo in juvenile broilers have been demonstrated.

Animals↗

PubMed1993

Immunolocalization of catecholamine enzymes, serotonin, dopamine and L-dopa in the brain of Dicentrarchus labrax (Teleostei).

Antisera to serotonin (5-HT), dopamine, and L-dopa, and to the catecholamine synthesizing enzymes, tyrosine hydroxylase (TH), dopamine beta-hydroxylase (DBH), and phenylethanolamine N-methyl transferase (PNMT), were used to localize monoamine containing neurones in the brain of Dicentrarchus labrax (sea bass). In the brain stem, 5-HT-immunoreactive (ir) neurones were recognized in the ventrolateral medulla, vagal motor area, medullary, and mesencephalic raphe nuclei and in the dorsolateral isthmal tegmentum. In the hypothalamus, liquor-contacting 5-HT neurones were seen in various regions of the paraventricular organ. Virtually all regions of the brain contained a dense innervation by 5-HT fibres and terminals. DBH-ir neurones were restricted to three brain stem areas: the locus coeruleus, the area postrema, and the reticular formation of the lower medulla. Neurones in these three groups also displayed TH-ir, and in the latter area, PNMT-ir in addition. In the locus coeruleus and area postrema, TH-ir neurones outnumbered DBH-ir neurones, an observation substantiated by the presence of dopamine-ir neurones. In the forebrain, dopamine- and TH-ir neurones were found in the olfactory bulb, ventral/central telencephalon, periventricular preoptic, and suprachiasmatic areas, dorsolateral and ventromedial thalamus, and posterior tuberal nucleus. In the paraventricular organ, the distribution and morphology of dopamine-ir neurones was similar to that observed with anti-5-HT, but the vast majority of cells were not TH-ir, suggesting accumulation of dopamine by uptake from the ventricle, rather than by synthesis. L-dopa-ir neurones were found only in the central telencephalon, preoptic recess, and dorsolateral thalamus. Fibres and terminals immunoreactive for dopamine, TH, and DBH showed a broadly similar distribution. The results are discussed in relation to the monoaminergic systems previously reported in other teleostean species and the mammalian brain.

Animals↗

PubMed1993

Immunocytochemical detection of astrocyte GABAA receptors in cat visual cortex.

A nine amino-acid peptide derived from the beta 1-subunit of the bovine GABAA receptor was used for immunization of mice and subsequent production of monoclonal antibodies (MAb). In view of the later immunocytochemical application of the MAb to sections of cat visual cortex, the MAb were characterized on similar tissue. The GABAA receptor was isolated by affinity chromatography of protein material obtained from cat cortical gray matter. The antibodies were characterized by SDS-PAGE, followed by immunoblotting and immunoadsorption. Immunocytochemical staining with the MAb revealed labeled cells throughout all layers of the cat visual cortex as well as within the white matter. The morphology of most stained cells in the white matter and of some cells in the cortical gray matter closely resembled that of astrocytes. Double immunocytochemical staining with an antiserum against glial fibrillary acidic protein (GFAP), followed by light microscopic examination, indeed confirmed that astrocytes in both white and gray matter in the cat cortex possess GABAA receptors.

Amino Acid Sequence↗

PubMed1993

Immunocytochemical demonstration of progesterone and estrogen receptors in feathers and skin of adult hens.

Clinical evidence indicates that ovarian steroids are involved in the control of moulting in the chicken. This immunocytochemical study investigates if feather papillae and growing feathers are target tissues for ovarian steroids. Progesterone (PR) and estrogen (ER) receptors were demonstrated using monoclonal antibodies in feathers and surrounding skin of laying hens. Both receptor types were present in the nuclei of dermal papillae and in the nuclei of the epidermal germinative layer cells of growing and full-grown feathers. In growing feathers most nuclei of the intermediate layer (ramogenic column, rachis, axial plate) were immunostained, but during the final stages of differentiation into barbules, only estrogen receptors remained prominent. Skin adjacent to feathers showed ER and PR receptors in nuclei of cells from epidermis, muscles and arteries. During egg-laying pause, plasma progesterone levels decrease ten-fold and it is supposed that this results in a much greater endocrine efficiency of the remaining estrogen levels which are only reduced by 50% when egg-laying stops. The moult-inhibiting effect of progesterone in laying hens could be due to its well-established downregulation on estrogen receptors and therefore, on the endocrine effect of ER at cellular level in feather papillae. Such may account for the presence of both receptor types on the same feather cells, as observed in the present study.

Animals↗

PubMed1992

Immunocytochemistry and immunoblotting of avian prolactins using polyclonal and monoclonal antibodies toward a synthetic fragment of chicken prolactin.

A major obstacle in the production of specific antibodies toward chicken prolactin (PRL) has been overcome by mimicking a putative epitope of the molecule using the synthetic decapeptide Lys-chPRL 59-67. This peptide represents the highest hydrophilicity peak of the amino acid sequence of chPRL that was recently derived from the nucleotide sequence. Polyclonal mouse antisera against the fragment specifically recognized the lactotropes in the cephalic lobe of the chicken pars distalis as illustrated by immunocytochemical double staining experiments. Monoclonal antibody production yielded antibodies that specifically labeled purified turkey PRL upon SDS-PAGE separation and immunoblotting. Turkey and chicken PRL showed a very similar polymorphism with respect to their apparent molecular weights, including the occurrence of a glycosylated variant of chicken PRL. The monoclonal antibodies were finally used to demonstrate the presence of PRL-like immunoreactivity both in the pituitary gland and in the brain of the quail. In the brain, immunoreactive neurons were in the nucleus accumbens and in the lateral parts of the ventro-medial hypothalamus, partly similar to those described in the rat.

Amino Acid Sequence↗

PubMed1992

Effect of dietary protein content on episodic growth hormone secretion and on heat production of male broiler chickens.

1. The effect of the crude protein content (200 and 150 g/kg) of isoenergetic diets on episodic growth hormone (GH) release and on heat production was investigated in male broiler chickens. 2. Decreasing the crude protein content of isoenergetic diets from 200 g/kg (HP diet) to 150 g/kg (LP diet) resulted in depressed body weight gain, impaired food conversion efficiency and increased abdominal fat deposition. 3. The pattern of growth hormone secretion was markedly affected by dietary treatment. Broiler chickens fed on the LP diet had higher overall mean, amplitude, baseline and peak frequency than the HP chickens. 4. The LP chickens produced more heat per unit of metabolic body weight than the HP chickens. 5. The hypothesis relating the pattern of GH secretion to protein conversion efficiency was corroborated.

Animal Feed↗

PubMed1991

Distribution of somatostatin receptors in the cat and monkey visual cortex demonstrated by in vitro receptor autoradiography.

Somatostatin (SRIF, S14) receptors in the cat and monkey visual cortex were visualized by means of in vitro autoradiography with an iodinated agonist of SRIF, [125I-Tyr0,DTrp8]S14. The kinetics, performed on tissue sections, revealed an apparently single, saturable site (KD = 3.92 +/- 0.31 10(-10) M for the cat, and 3.82 +/- 0.28 10(-10) M for the monkey visual cortex) with pharmacological specificity for S14 and [DTrp]-substituted S14. Autoradiography, performed on frontal sections of the cat and monkey visual cortex, revealed a heterogeneous regional and laminar distribution of SRIF receptors. In cat areas 17, 18, and 19, SRIF receptors occur mainly in the supragranular layers, although small interareal and intra-areal differences are observed. The infragranular layers (V-VI) in area 19 contain a significantly higher proportion of SRIF receptors compared to both areas 17 and 18. In the antero- (AMLS) and posteromedial lateral suprasylvian area (PMLS), layers V and VI contain the highest proportion of SRIF receptors. This latter pattern is also observed in the area prostriata medially adjoining area 17 in the splenial sulcus. In the monkey visual cortex, areas 17 and 18 exhibit similar distribution patterns, SRIF receptors being primarily concentrated in layers V and VI. Neither in the cat nor the monkey visual cortex could we observe significant differences in SRIF receptor distribution between different retinotopic subdivisions within one area.

Animals↗

PubMed1991

Laminar and regional distribution of galanin binding sites in cat and monkey visual cortex determined by in vitro receptor autoradiography.

The distribution of galanin (GAL) binding sites in the visual cortex of cat and monkey was determined by autoradiographic visualization of [125I]-GAL binding to tissue sections. Binding conditions were optimized and, as a result, the binding was saturable and specific. In cat visual cortex, GAL binding sites were concentrated in layers I, IVc, V, and VI. Areas 17, 18, and 19 exhibited a similar distribution pattern. In monkey primary visual cortex, the highest density of GAL binding sites was observed in layers II/III, lower IVc, and upper V. Layers IVA and VI contained moderate numbers of GAL binding sites, while layer I and the remaining parts of layer IV displayed the lowest density. In monkey secondary visual cortex, GAL binding sites were mainly concentrated in layers V-VI. Layer IV exhibited a moderate density, while the supragranular layers contained the lowest proportion of GAL binding sites. In both cat and monkey, we found little difference between regions subserving central and those subserving peripheral vision. Similarities in the distribution of GAL and acetylcholine binding sites are discussed.

Animals↗

PubMed1991

Autoradiographic distribution of galanin binding sites in the brain and pituitary of the sea bass (Dicentrarchus labrax).

Specific binding sites for galanin (GAL) were detected in brain and pituitary of a marine teleost fish, the sea bass, after in vitro incubation of tissue sections with [125I]GAL and light microscopic autoradiography. Binding conditions were optimized and as a result the binding was saturable and specific. In the brain, [125I]GAL binding was found to occur in all parts of the dorsal and ventral telencephalon, in the anterior, tuberal and posterior hypothalamus, in the thalamus and in the tectum opticum, in the inferior lobe and in the ventral medulla oblongata. In the pituitary dense [125I]GAL binding was confined to the area occupied by the prolactin cells in the rostral part of the adenohypophysis. These findings provide the first anatomical evidence for the presence of GAL specific binding sites in the teleost brain and pituitary.

Animals↗