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Biomedical subjects

A Fasolo

Publications and source records attributed to A Fasolo.

At least 91 records · Page 5Linked to original sources
PubMed1990

Ontogeny of acetylcholinesterase, substance P and calcitonin gene-related peptide-like immunoreactivity in chick dorsal root ganglia.

The distribution of acetylcholinesterase and of two neuropeptide (substance P and calcitonin gene-related peptide) immunoreactivities has been investigated in sensory neurons of lumbosacral dorsal root ganglia during chick embryo development, combining immunolocalization of neuropeptides with simultaneous histochemical detection of acetylcholinesterase, in order to study co-localization of the two peptides and their relations with acetylcholinesterase. Acetylcholinesterase at E7 of development appears in only a few neurons, usually the larger ones located in the lateroventral region of the ganglia. As development proceeds the number of neurons and intensity of staining increase. Until E12-13 acetylcholinesterase positivity is limited to the region of the ganglion containing larger neurons. At later stages (E20) it spreads progressively, leading to staining of cells over the whole ganglion. Substance P-like immunoreactivity appears at E6 and for calcitonin gene-related peptide at E7. These immunoreactivities progressively increase with development, remaining limited to the small neuron compartment of the dorsomedial region of the ganglion. Immunoreactivity for both neuropeptides reaches a maximum around E10-13 and then declines. Using simultaneous double immunostaining, calcitonin gene-related peptide and substance P-like immunoreactivities are largely co-localized, although their distribution is not completely coincident. Neuropeptide-positive cells are usually devoid of any acetylcholinesterase activity until E15. They become positive for the enzyme at later stages. The significance of acetylcholinesterase expression in sensory neurons and the possible relation of its appearance and neuron size is discussed.

Acetylcholinesterase↗
PubMed1990

Neuropeptide Y: localization in the central nervous system and neuroendocrine functions.

Neuropeptide Y (NPY) is a 36-amino acid peptide first isolated and characterized from porcine brain extracts. A number of immunocytochemical investigations have been conducted to determine the localization of NPY-containing neurons in various animal species including both vertebrates and invertebrates. These studies have established the widespread distribution of NPY in the brain and in sympathetic neurons. In the rat brain, a high density of immunoreactive cell bodies and fibers is observed in the cortex, caudate putamen and hippocampus. In the diencephalon, NPY-containing perikarya are mainly located in the arcuate nucleus of the hypothalamus; numerous fibers innervate the paraventricular and suprachiasmatic nuclei of the hypothalamus, as well as the paraventricular nucleus of the thalamus and the periaqueductal gray. At the electron microscope level, using the pre- and post-embedding immunoperoxidase techniques, NPY-like immunoreactivity has been observed in neuronal cell body dendrites and axonal processes. In nerve terminals of the hypothalamus, the product of the immunoreaction is associated with large dense core vesicles. In lower vertebrates, including amphibians and fish, neurons originating from the diencephalic (or telencephalic) region innervate the intermediate lobe of the pituitary where a dense network of immunoreactive fibers has been detected. At the ultrastructural level, positive endings have been observed in direct contact with pituitary melanotrophs of frog and dogfish. These anatomical data suggest that NPY can act both as a neurotransmitter (or neuromodulator) and as a hypophysiotropic neurohormone. In the rat a few NPY-containing fibers are found in the internal zone of the median eminence and high concentrations of NPY-like immunoreactivity are detected in the hypothalamo-hypophyseal portal blood, suggesting that NPY may affect anterior pituitary hormone secretion. Intrajugular injection of NPY causes a marked inhibition of LH release but does not significantly affect other pituitary hormones. Passive immunoneutralization of endogenous NPY by specific NPY antibodies induces stimulation of LH release in female rats, suggesting that NPY could affect LH secretion at the pituitary level. However, NPY has no effect on LH release from cultured pituitary cells or hemipituitaries. In addition, autoradiographic studies show that sites for 125I-labeled Bolton-Hunter NPY or 125I-labeled PYY (2 specific ligands of NPY receptors) are not present in the adenohypophysis, while moderate concentrations of these binding sites are found in the neural lobe of the pituitary. It thus appears that the inhibitory effect of NPY on LH secretion must be mediated at the hypothalamic level.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Endothelin stimulates steroid secretion by frog adrenal gland in vitro: evidence for the involvement of prostaglandins and extracellular calcium in the mechanism of actin of endothelin.

Endothelin (ET-1) is a pleiotropic regulatory peptide which exerts multiple endocrine actions on the cardiovascular system. In the present study, we have investigated the possible role of ET-1 in the regulation of adrenocortical cells using perifused frog interrenal (adrenal) slices. Graded doses of ET-1 from 10(-11)-10(-9) M stimulated both corticosterone and aldosterone production in a dose-dependent manner. Repeated 20-min pulses of ET-1 (10(-9) M), given at the frequency of one pulse per 90 min, resulted in a marked reduction of the secretory response after the second pulse. Prolonged administration (3 h) of ET-1 induced a rapid increase in corticosterone and aldosterone output, followed by a gradual decline of corticosteroid secretion. Perifusion of frog adrenal tissue with ET-1 (10(-9) M) caused a significant increase in the release of prostaglandin E2 (PGE2) and 6-keto-PGF1 alpha, the stable metabolite of the prostacyclin PGI2. The enhancement of PG biosynthesis preceded by 10 min the peak of corticosteroids. When repeated pulses of ET-1 were administered, a significant diminution of the production of PGE2 and 6-keto-PGF1 alpha was observed after the second pulse. The cyclooxygenase inhibitor indomethacin (5 microM) totally suppressed the stimulatory effect of ET-1 on corticosterone and aldosterone secretion; in contrast, indomethacin did not affect ACTH-evoked corticosteroid secretion. Perifusion of adrenal slices with a calcium-free solution or addition of cobalt (4 mM) induced total inhibition of the stimulatory effect of ET-1. These results demonstrate that ET-1 is a potent stimulator of corticosterone and aldosterone secretion from frog adrenal gland in vitro. Our data show that repeated or prolonged administration of ET-1 induces a rapid desensitization phenomenon. The data also indicate that ET-1-evoked corticosteroid secretion is mediated by an increase in PG biosynthesis and requires the presence of extracellular calcium.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

Tyrosine hydroxylase immunohistochemistry in the normal and 1-methyl-4-phenyl-tetrahydropyridine (MPP+)-treated retina of goldfish.

Dopaminergic interplexiform neurons have been identified in the inner nuclear layer of goldfish retina, with tyrosine hydroxylase (TH) immunocytochemistry in whole-mounted retinae and in cryosections. The neurotoxin 1-methyl-4-phenylpyridinium ion (MPP+), which selectively damages dopaminergic neurons in mammals, caused a marked depletion of TH immunoreactivity in goldfish retina. Three days after intravitreal injection, retinae showed no significant decrease in the number of TH-positive neurons. However most of the TH-immunoreactive cell bodies showed an evident depletion of TH immunoreactivity and their processes, ramified in the inner and outer plexiform layers, disappeared almost completely.

1-Methyl-4-phenylpyridinium↗
PubMed1989

Innervation of the pars intermedia and control of alpha-melanotropin secretion in the newt.

In this study we have investigated the presence of nerve fibers containing dopamine, thyrotropin-releasing hormone (TRH) and neuropeptide Y (NPY) in the pars intermedia of the crested newt and we have examined the possible effect of these neurohormones on the release of alpha-melanotropin (alpha-MSH) by neurointermediate lobes in vitro. By means of immunohistochemistry, we observed the presence of tyrosine hydroxylase (TH)-immunoreactive fibers in the pars intermedia of the crested newt. Using a specific antiserum to dopamine, these fibers appeared to be mainly dopaminergic in nature. Unlike anurans, urodele amphibians do not exhibit TRH or NPY-like immunoreactivity in the pars intermedia. A perifusion system technique for newt pituitaries was developed to investigate the effect of dopamine, TRH and NPY on alpha-MSH secretion. Administration of increasing concentrations of dopamine (from 10(-9) to 10(-5)M) induced a dose-related inhibition of alpha-MSH release. This inhibitory effect was mimicked by the dopamine agonist apomorphine (10(-6)M). In contrast, the secretory activity of the newt pars intermedia was not affected by administration of synthetic TRH or NPY (up to 10(-7) and 10(-6)M, respectively). These results indicate that the neurotransmitter dopamine likely plays a pivotal role in the regulation of melanotropin secretion in urodele amphibians.

Animals↗
PubMed1989

Brain-gut-skin peptides: an update overview.

The authors present an overview of the main amphibian peptide families mainly derived from the skin and mostly discovered by Erspamer and his associates. The studies of the peptides do not only promote the understanding of their chemical, metabolical and physiological features of those molecules in amphibians, but also contribute to progress in our knowledge of the corresponding mammalian counterparts. Particular reference is made on sauvagine, tachykinin, bombesin and dermorphin families, offering new data mostly from personal contributions to this field.

Amphibians↗
PubMed1989

Hypothalamic target cells of endogenous sexual steroids in female rat. An immunocytochemical approach utilizing antiestradiol antiserum.

The immunostaining proposed in this study identifies cells containing endogenous estrogens in the Central Nervous System, in the presence of both very high and very low serum estrogen levels. Ten adult rats, seven normal and three ovariectomized females, were used for this study. Paraffin sections of hypothalamus and ovary of each female were stained using Avidin-Biotin Complex method and antiestradiol antiserum. Two different antiestradiol antisera were tested in this work: tests for method and antisera specificity are described. The immunostaining used here shows to be specific and sensitive revealing a higher number of labeled hypothalamic areas than those revealed by other techniques.

Animals↗
PubMed1988

Distribution and characterization of neuropeptide Y-like immunoreactivity in the brain of the crested newt.

The newt brain represents a simplified model for the increasingly complex vertebrate neuronal organization. The localization of neuropeptide Y-like (NPY-like) containing neurons in the brain of Triturus cristatus was studied by means of indirect immunofluorescence, peroxidase-antiperoxidase, and avidin-biotin techniques using a highly specific antiserum. NPY-like positive cell bodies were observed in several areas, most notably in the telencephalon (primordium hippocampi and amygdaloid complex), the preoptic and suprachiasmatic areas, the hypothalamus, the dorsal thalamus, the tegmentum, and the rhombencephalon (laterolateral grey column and raphe area). Nerve fibres were particularly abundant in the pallium, striatum, septum, amygdaloid, preoptic neuropils, and pars intercalaris diencephali. Bundles of NPY-immunoreactive fibres also were visualized in the dorsal thalamus and in the posterior hypothalamus. The pars intermedia lacked any NPY-like positive fibres. Neuronal processes also were found in the tectum mesencephali and in the body of the cerebellum. A prominent NPY-like fibre network was observed in the octavolateralis. Concentrations of NPY measured by means of a specific radioimmunoassay were threefold higher in the hypothalamus (15.2 +/- 1.3 ng/mg proteins) than in the rhombencephalon (4.9 +/- 0.3) and the mesencephalon (4.3 +/- 0.2). The concentration found in the telencephalon was 2.1 +/- 0.3 ng/mg proteins. Sephadex G-50 gel chromatography of whole brain extracts indicated the presence of high molecular weight forms of NPY-like material in addition to the authentic peptide. Both amphibian and mammalian NPY peptides had an apparent molecular weight of 4,000 daltons, as evidenced by immunoblotting analysis. High-performance liquid chromatography demonstrated, however, that the newt peptide was slightly less hydrophobic than porcine NPY. The present findings indicate that NPY-immunoreactive neurons are widely distributed in the brain of urodeles. Our data indicate that the NPY molecule has been relatively well preserved during evolution.

Animals↗
PubMed1988

Immunohistochemical localization of gonadotropin-releasing-hormone-associated peptide in the brain of the frog.

Gonadotropin-releasing-hormone (GnRH)-associated peptide (GnRH-AP) is a 56 amino acid neuropeptide derived from the GnRH prohormone. GnRH-AP corresponds to the C-terminal fragment flanking the GnRH peptide. Using an antiserum raised against human GnRH-AP [1-56], or against human GnRH, we have investigated the neuronal systems containing either peptide in the central nervous system of the frog Rana ridibunda by immunohistological techniques. A main group of GnRH-AP-containing perikarya was found in a dorsoventral orientation of the supra anterior preoptic area (SAPA) just in front of the preoptic recess. Fibers originating from these perikarya projected rostrally toward the medial septal nucleus and the diagonal band of Broca. A network of GnRH-AP-immunoreactive (ir) fibers runs caudally from the SAPA toward the ventral hypothalamus. A high density of GnRH-AP-ir terminals was found in the median eminence. A few positive fibers were detected in the neural lobe of the pituitary, particularly in the region bordering the pars intermedia. Labelling of consecutive sections by either GnRH-AP or GnRH antibodies showed that GnRH and GnRH-AP-like irs were contained in the same cells of the SAPA. The double-staining technique with electrophoretic elution confirmed the colocalization of GnRH and GnRH-AP within the same neurons. Such a coexistence indicates that frog GnRH originates from a high molecular weight precursor which is closely related to rat pro-GnRH. The relative preservation of the C-terminal sequence of the pro-GnRH during evolution suggests that GnRH-AP may possess intrinsic biological activity. The high density of GnRH-AP-containing neurons projecting through the external zone of the median eminence would support the concept that GnRH-AP is involved in the modulation of pituitary hormone secretion.

Animals↗
PubMed1988

Distribution and characterization of neuropeptide Y in the brain of an elasmobranch fish.

Using a specific antiserum raised against synthetic neuropeptide Y (NPY), the distribution of immunoreactivity in the brain and pituitary of the elasmobranch fish Scyliorhinus canicula has been examined with the indirect fluorescence and the peroxidase-antiperoxidase methods. The highest density of NPY-immunoreactive neurons was found in the basal telencephalon and in the hypothalamus. Numerous NPY-containing perikarya were located in the entopeduncular and the preoptic nuclei, in the nucleus lobi lateralis and in the nucleus lateralis tuberis. NPY-immunopositive fibers were observed throughout the fish brain. In particular, dense networks of fibers were present in the entopeduncular and the habenular nuclei, in the nucleus tuberculi posterioris and in the lateral lobes. Scattered fibers were observed in all other parts of the brain except in the cerebellum where no NPY-immunoreactive material could be detected. A plexus of NPY-immunoreactive fibers arising from the preoptic neurosecretory complex appeared to run through the basal hypothalamus and the pituitary stalk. These fibers terminated in the intermediate lobe of the pituitary, suggesting that NPY may be involved in the control of melanotropin secretion. The NPY-immunoreactive material localized in the brain and pituitary was characterized by combining high-performance liquid chromatography (HPLC) analysis and radioimmunological detection. Brain and pituitary extracts showed a good cross-reactivity to the NPY antiserum, but serial dilutions of tissue samples did not completely parallel the standard curve. HPLC analysis resolved two major forms of immunoreactive NPY in the hypothalamus while the pars intermedia contained only authentic NPY. The widespread distribution of NPY neurons in the fish brain and pituitary suggests the involvement of NPY in a variety of physiological functions, including the neuroendocrine control of the pituitary.

Animals↗
PubMed1988

Hypothalamus-hypophysis and testicular GnRH control of gonadal activity in the frog, Rana esculenta: seasonal GnRH profiles and annual variations of in vitro androgen output by pituitary-stimulated testes.

The binding of a gonadotrophin-releasing hormone (GnRH) long acting analog (GnRHA), D-Ser (But)6,Pro9-NEt GnRH (HOE 766), to pituitary and testicular extracts and the presence of GnRH-like material in testes and hypothalamuses were measured in the frog, Rana esculenta. Also, the cellular localization of immunoreactive GnRH was investigated in testes by immunohistochemical staining. Furthermore, lyophilized preparations of pituitary crude homogenates from animals caught monthly were tested in vitro for their ability to stimulate androgen production by December testes. Satisfactory results on specific 125I-GnRH binding were difficult to obtain in view of its low binding capacity. Moreover, binding in testicular homogenates was of the same order of magnitude (about 2%) as that found in pituitaries. In a cospecific radioimmunoassay for GnRH nonapeptide, both hypothalamic and testicular extracts gave displacement parallel to the standard curve. Immunoreactive GnRH did not significantly fluctuate in hypothalamuses, while it peaked in testes during December and July. Immunoreactive GnRH was evidenced in June and September testes employing immunohistochemical staining. In particular, the interstitial cells and the Sertoli cells were faintly stained. Testes of December animals stimulated by February pituitaries produced larger quantities of androgens as compared with testes stimulated with hypophyseal preparations from the remaining periods of the year. In conclusion, the present results are consistent with the idea that seasonal changes of the hypothalamus-hypophyseal activity play an important role in regulating the hormonal response in vertebrate testes. Moreover, we report that, in addition to rats, GnRH-like material is present in frog testes and for the first time it has been shown that such putative intratesticular material undergoes seasonal fluctuations in a vertebrate.

Androgens↗
PubMed1988

Comparative chemical anatomy of the brain: concepts and methods.

The study of neuropeptides represents an appropriate playground for comparative and evolutionary research. Comparative analysis can give insight into the conservative pattern of intercellular transmission molecules, possibly bound both to some evolutionary antiquity and to cellular constraints. In the same time it can teach us how modulation has occurred at molecular, cellular, multicellular levels in order to give the species-specific functional organization. Using some examples from vertebrate central neurons system (CNS) immunocytochemical analyses, the results so far obtained suggest the rise of a new comparative chemical neuroanatomy. The rationale of "what" and "why" we are comparing is, however, needed in order to understand constancy, heterogeneity or else trends toward complexity in the distribution of neuropeptides.

Anatomy, Comparative↗
PubMed1987

Coexistence of substance P and calcitonin gene-related peptide in the frog spinal cord.

The localization of substance P (SP) and calcitonin gene-related peptide (CGRP) was studied in the untreated spinal cord of the frog using single or double immunohistochemical stainings. SP and CGRP appear to coexist in the primary afferent fibers and in the marginal and submarginal dorsal horn zones, as well as in the dorsolateral zone. In other parts of the spinal cord CGRP immunoreactivity was scanty while diffuse SP systems were seen, suggesting that the coexistence of the two peptides is restricted to primary afferent fibers.

Animals↗
PubMed1987

Topography of cholinergic and substance P pathways in the habenulo-interpeduncular system of the rat. An immunocytochemical and microchemical approach.

The topography of cholinergic and substance P containing habenulo-interpeduncular projections has been studied in the rat. The research has been carried out by combining choline acetyltransferase and substance P immunohistochemistry to experimental lesions and biochemical assays in microdissected brain areas. In addition, computer-assisted image analysis has been performed in order to obtain quantification of immunohistochemical data. The results show that cholinergic and substance P containing neurons have a different localization in the medial habenula and project to essentially different areas of the interpeduncular nucleus. Cholinergic neurons are crowded in the ventral two-thirds of the medial habenula while substance P containing cells are exclusively localized in the dorsal part of the nucleus. In most parts of the interpeduncular nucleus, choline acetyltransferase and substance P containing fibres and terminals are similarly segregated and no overlapping is apparent except for the rostralmost and the caudalmost ends of the nucleus. Cholinergic activity is largely concentrated in the central core of the nucleus, while substance P is preferentially localized in the peripheral subnuclei of the interpeduncular nucleus. In addition, both substance P and choline acetyltransferase levels show peculiar regional variations along the rostrocaudal axis of the interpeduncular nucleus. The results of experimental lesions demonstrate that the substance P projection carried by each fasciculus retroflexus is prevailingly ipsilateral in the rostral part of the interpeduncular nucleus and becomes progressively bilateral as far as more caudal regions of the nucleus are reached. By contrast, the cholinergic projections carried by each fasciculus retroflexus intermingle more rapidly and only show a slight ipsilateral dominance in the interpeduncular nucleus. The results of the study are discussed with reference to previous anatomical and neurochemical data which, in several instances, had given rise to discrepant interpretations.

Animals↗
PubMed1986

Organization of tyrosine-hydroxylase immunopositive neurons in the brain of the crested newt, Triturus cristatus carnifex.

The localization of neurons, fibers, and terminals containing tyrosine hydroxylase (TH)-like immunoreactivity was studied in the brain of the crested newt by using an antiserum to rat phaeochromocytoma tyrosine hydroxylase. Immunoreactive cells and fibers were found in the spinal cord, the medulla oblongata (lateral periventricular areas), and the acousticolateral area. In the tegmentum mesencephali, two bilateral clusters of labelled cells were localized in the ventrolateral periventricular gray extending toward the caudal hypothalamus. In the hypothalamic tuberal lobes, the TH-like reactive neurons, frequently of CSF-contacting type, lined the dorsal wall of the lateral infundibular recesses. A thick network of TH-like reactive nerve fibers and terminals was observed in the perivascular zone of the median eminence and in the adenohypophysial pars intermedia. A number of labelled cell bodies were also found in the dorsal thalamus (pars intercalaris diencephali), the paraventricular organ, and the ventral wall of the preoptic recess. In the telencephalon, immunoreactive innervation was identified in the striatum, together with immunopositive cell bodies in the olfactory bulbs. The pattern of organization of TH-immunoreactive systems in the newt showed, except for some peculiarities (e.g., the labelled cell bodies in dorsal thalamus), close similarities to the arrangement typical of mammals.

Animals↗
PubMed1986

The organization of serotonin-immunoreactive neuronal systems in the brain of the crested newt, Triturus cristatus carnifex Laur.

The distribution of serotonin (5-HT) immunoreactive structures has been investigated in the brain of the crested newt by means of indirect immunofluorescence, and unlabeled antibody peroxidase-antiperoxidase-complex (PAP) or biotin-avidin-system (BAS) techniques. In the newt, the bulk of the serotoninergic system extends from the raphe region of the medulla oblongata, through the isthmus, toward the mesencephalic tegmentum, and is characterized by pyriform neurons mainly located in a subependymal position, close to the midline. Also in the caudal hypothalamus, in addition to some 5-HT-positive adenohypophysial cells, many immunoreactive CSF-contacting neurons are found lining the paraventricular organ and the nucleus infundibularis dorsalis. A rich serotoninergic innervation was observed in the preoptic area and in the habenular complex. Concerning the telencephalon, immunopositive nerve fibers are encountered in the dorsal pallium, primordium hippocampi, striatum and olfactory bulbs. The general organization of serotoninergic systems in the newt brain exhibit close similarities to that described in higher vertebrates.

Animals↗
PubMed1986

CRF-like immunoreactive system in the quail brain.

Nerve cells and fibres immunoreactive for synthetic ovine corticotropin releasing factor were shown to be present in several brain areas of the quail by use of immunocytochemical techniques. CRF-like immunoreactive cell bodies are mainly clustered in the hypothalamic paraventricular nucleus, in the telencephalic nucleus accumbens and in the mesencephalic periventricular grey. The external zone of the anterior median eminence contains a rich network of immunoreactive fibers. CRF-like immunopositive fibers are not restricted to circumventricular organs, but have been observed in several prosencephalic regions and in close proximity of large vasotocin-containing neurons in the supraoptic and paraventricular regions. These observations suggest that, in birds, CRF-like material might be not only involved in the hypothalamic control of anterior pituitary hormone secretion, but also in different functions likely related to neurotransmission or neuromodulation.

Animals↗