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Biomedical subjects

L Jennes

Publications and source records attributed to L Jennes.

At least 73 records · Page 4Linked to original sources
PubMed1988

Development of immunoreactive atrial natriuretic peptide in fetal hearts of spontaneously hypertensive and Wistar-Kyoto rats.

The development of immunoreactive atrial natriuretic peptide (ANP) was studied in fetal hearts of spontaneously hypertensive (SHR) and compared to normotensive Wistar-Kyoto (WKY) rats. While SHR fetal hearts were noticeably less developed than those of WKY at 10 and 11 days gestation, both strains showed ANP immunoreactive cells in some but not all primitive heart tubes. At 12 days additional ANP immunoreactive cells appeared in formative trabeculae of the ventricle and atrium. ANP cells were also observed in the myogenic layer of the truncus and bulbus arteriosus and their derivatives from 11 through 16 days, but not at 18 days. In both strains, there were more ANP cells in the left ventricle than in right beginning at day 13. There were no obvious strain differences in the developmental pattern and timing of ANP producing cells. However, on the day of birth, staining was reduced in hearts from some WKY newborn pups compared with hearts from SHR newborns and ventricular staining was reduced in both strains when compared to fetal hearts. These observations indicate that ANP is one of the earliest peptide hormones produced and that the predisposition to genetic hypertension does not appear to influence the development of ANP.

Animals↗
PubMed1987

Sites of origin of gonadotropin releasing hormone containing projections to the amygdala and the interpeduncular nucleus.

The sites of origin of gonadotropin releasing hormone (GnRH) containing projections to the amygdala and the interpeduncular nucleus were studied with immunofluorescence for GnRH in combination with retrograde transport of True blue. After small injections of True blue into the amygdala, retrogradely labeled GnRH producing neurons were identified in the rostral medial septum, the caudal roots of the nervus terminalis, diagonal band, nucleus triangularis septi, nucleus interstitialis striae terminalis, and in the ventrolateral hypothalamus. After injection of True blue into the interpeduncular nucleus, a small GnRH producing cell group in the ventromedial diagonal band, and certain GnRH-positive neurons in the ventral hypothalamus had retrogradely transported the dye. The results suggest a link between the amygdala and the nervus terminalis which is provided in part by GnRH-containing projections. The heterogeneity of the sites of origin of inputs to the amygdala and the interpeduncular nucleus indicates that the 'behavioral' component of the GnRH system is not restricted to a single brain nucleus, but it may be part of a diffuse network which has close anatomical ties with the 'endocrine' GnRH system.

Amygdala↗
PubMed1987

Inhibition of gastric acid secretion by immunoneutralization of endogenous brain thyrotropin-releasing hormone.

Previous studies have shown that intracisternal (i.c.), but not intravenous administration of thyrotropin-releasing hormone (TRH), an endogenous tripeptide (pGlu-His-Pro-NH2), produces a time-, dose-dependent and vagus-mediated stimulation of acid secretion in rats. This study was designed to test the hypothesis that endogenous brain TRH plays a role in regulation of acid secretion in the pylorus-ligation model. In confirmation of previous reports, i.c. TRH (1 microgram) significantly (P less than 0.01) stimulated gastric acid output, gastric secretory volume and decreased gastric intraluminal pH. Intracerebroventricular (i.c.v.) infusion of TRH antiserum (anti-TRH) 30 min prior to pyloric occlusion significantly reduced acid output, secretory volume and raised gastric pH. This inhibitory gastric acid secretory response to i.c.v. anti-TRH appears to be specific since i.c.v. infusion of normal rabbit serum or antisera raised against neurotensin (NT), Leu-enkephalin (L-enk), gonadotropin-releasing hormone (GnRH), somatostatin (SRIF) and alpha-melanocyte stimulating hormone (alpha-MSH) were without measurable effect. The findings of this study indicate that endogenous brain TRH, but not NT, L-enk, GnRH, SRIF or alpha-MSH plays a physiological role in regulation of acid secretion.

Animals↗
PubMed1987

Ontogeny of gonadotropin releasing hormone and gonadotropin immunoreactivity in brain and pituitary of normal and estrogen-treated guppies, Poecilia reticulata Peters.

Gonadotropin releasing hormone (GnRH) and gonadotropic hormone (GTH) were identified by immunohistochemistry in the brains and pituitaries of neonate, juvenile and adult guppies. GTH was present in some cells of the pars intermedia (pi) and proximal pars distalis (ppd) of all animals. GnRH was found in the perikarya of the nucleus olfactoretinalis. In the pituitaries of juvenile 30-day-old guppies, GnRH-immunoreactive cells existed in a "juvenile pattern", whereas in adult animals GnRH was recognized in only a few cells. GnRH-immunoreactive fibers were seen in the pituitaries of animals that were 30 days or older. In adult guppies, the ventral and lateral ppd (the gonadotropic region) contained a dense network of GnRH-immunoreactive fibers. Pituitary cells staining for either GnRH or GTH were located in different places. After immunohistochemical double staining of adult pituitaries, none of the GnRH-immunoreactive cells were LH-immunoreactive, although both cell types were often found in close proximity. After 20 days or more of ethinylestradiol treatment, less immunoreactive GnRH was detected in the pituitary cells of juvenile guppies, and fewer animals exhibited the "juvenile pattern" of GnRH-immunoreactive pituitary cells, when compared with untreated controls. The results indicate that GnRH-immunoreactive pituitary cells in the guppy are distinct from gonadotropes and that these cells are involved in regulatory processes along the juvenile brain-pituitary-gonad axis.

Aging↗
PubMed1987

Distribution of atrial natriuretic factor in fetal rat atria and ventricles.

An immunohistochemical study of rat fetal hearts at 20 days of gestation revealed the presence of immunoreactive atrial natriuretic factor (ANF) in cardiocytes of the left and right atria as well as in certain cells is the left and right ventricles. In the atria, cells of the adluminal pectinate muscles appear more densely labeled than the more peripheral mural cells. In the ventricles, immunoreactive cells were found only in adluminal cardiocytes of the presumptive trabeculae and papillary muscles. The results indicate that ANF is synthesized in the perinatal heart, and that the presence of this hormone in the ventricular cardiocytes may be of only temporary nature during certain stages of pre- and postnatal development.

Animals↗
PubMed1987

The nervus terminalis in the mouse: light and electron microscopic immunocytochemical studies.

The distribution of gonadotropin-releasing hormone (GnRH)-containing neurons and fibers in the olfactory bulb was studied with light and electron microscopic immunohistochemistry in combination with retrograde transport of "True Blue" and horseradish peroxidase and lesion experiments. GnRH-positive neurons are found in the septal roots of the nervus terminalis, in the ganglion terminale, intrafascicularly throughout the nervus terminalis, in a dorso-ventral band in the caudal olfactory bulb, in various layers of the main and accessory olfactory bulb, and in the basal aspects of the nasal epithelium. Electron microscopic studies show that the nerve fibers in the nervus terminalis are not myelinated and are not surrounded by Schwann cell sheaths. In the ganglion terminale, "smooth" GnRH neurons are seen in juxtaposition to immunonegative neurons. Occasionally, axosomatic specializations are found in the ganglion terminale, but such synaptic contacts are not seen intrafascicularly in the nervus terminalis. Retrograde transport studies indicate that certain GnRH neurons in the septal roots of the nervus terminalis were linked to the amygdala. In addition, a subpopulation of nervus terminalis-related GnRH neurons has access to fenestrated capillaries whereas other GnRH neurons terminate at the nasal epithelium. Lesions of the nervus terminalis caudal to the ganglion terminale result in sprouting of GnRH fibers at both sites of the knife cut. The results suggest that GnRH in the olfactory system of the mouse can influence a variety of target sites either via the blood stream, via the external cerebrospinal fluid or via synaptic/asynaptic contacts with, for example, the receptor cells in the nasal mucosa.

Animals↗
PubMed1986

The olfactory gonadotropin-releasing hormone immunoreactive system in mouse.

The olfactory gonadotropin-releasing hormone (GnRH) system in mice was studied with immunofluorescence in combination with lesions of the olfactory bulb and retrograde transport of horseradish peroxidase (HRP) which was administered intravascularly, intranasally or into the subarachnoid space. GnRH-positive neurons were located in the two major branches forming the septal roots of the nervus terminalis, in the ganglion terminale, within the fascicles of the nervus terminalis throughout its extent, in a conspicuous band which connects the ventral neck of the caudal olfactory bulb with the accessory olfactory bulb and in the nasal mucosa. GnRH-positive fibers were seen in all areas in which neurons were found, i.e. in the rostral septum, the ganglion and nervus terminalis and in the nasal subepithelium. In addition, a broad bundle of fibers was observed to surround the entire caudal olfactory bulb, connecting the rostral sulcus rhinalis with the ventrocaudal olfactory bulb. Fibers were seen in close association with the main and accessory olfactory bulb, with the fila olfactoria and with the nasal mucosa. Throughout the olfactory bulb and the nasal epithelium, an association of GnRH fibers with blood vessels was apparent. Intravascular and intranasal injection of HRP resulted in labeling of certain GnRH neurons in the septal roots of the nervus terminalis, the ganglion terminale, the nervus terminalis, the caudal ventrodorsal connection and in the accessory olfactory bulb. After placement of HRP into the subarachnoid space dorsal to the accessory olfactory bulb, about 50% of the GnRH neurons in the accessory olfactory bulb and in the ventrodorsal connection were labeled with HRP. Also, a few GnRH neurons in the rostral septum, the ganglion terminale and in the fascicles of the nervus terminalis had taken up the enzyme. Lesions of the nervus terminalis caudal to the ganglion terminale resulted in sprouting of GnRH fibers at both sites of the knife cut. Lesions rostral to the ganglion terminale induced sprouting mostly at the distal site of the knife cut while most but not all GnRH fibers proximal to the lesion had disappeared. The results of the present study indicate that the olfactory GnRH system is mostly associated with the nervus terminalis. This cranial nerve apparently projects to the central nervous system as well as the periphery. The results of the HRP uptake studies suggest that the GnRH neurons in the nervus terminalis have access to fenestrated capillaries in the subepithelial connective tissue of the nasal mucosa, to the nasal epithelium proper, and to the subarachnoid space.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Gonadotropin-releasing hormone immunoreactive neurons with access to fenestrated capillaries in mouse brain.

Gonadotropin-releasing hormone (GnRH) producing neurons which have access to fenestrated capillaries were identified through a combination of indirect immunofluorescence for GnRH with a fluorescein-taged second antibody and histochemical demonstration of the localization of blood borne and retrogradely transported horseradish peroxidase. In the mouse, GnRH positive neurons were present in the septum, which includes neurons originating from the nervus terminalis, the nucleus medialis and triangularis septi, and the nucleus of the diagonal band. Also, GnRH immunoreactive neurons could be seen in the lateral anterior hypothalamus, the nucleus preopticus medianus, the rostral nucleus periventricularis hypothalami and, to a lesser extent, the nucleus preopticus medialis. Single GnRH positive neurons were found in the nucleus supraopticus, the bed nucleus of the stria terminalis and the cingulate cortex. GnRH neurons which showed uptake of horseradish peroxidase were located in all of these regions and intermingled with unlabeled GnRH neurons. No preferential topographical concentration of GnRH neurons with access to the fenestrated vasculature was apparent. In animals in which GnRH secretion was stimulated by castration for 2 weeks, 65% of all GnRH neuronal perikarya contained horseradish peroxidase. This was reduced to 35% after a 2-week treatment of ovariectomized animals with 10 micrograms/day estradiol while the total number of immunoreactive GnRH cells remained unchanged. No differences in the number of GnRH-horseradish peroxidase positive cells was seen when the dose of horseradish peroxidase of the survival time were increased. While the presence of certain GnRH neurons with dual actions via collaterals cannot be excluded, the results suggest that there are two populations of GnRH neurons, one with access to fenestrated capillaries which is probably related to neurosecretory endocrine regulation of anterior pituitary gonadotropin secretion, and one without access to fenestrated capillaries which is probably related to intracerebral neurotransmission only.

Animals↗
PubMed1985

Ultrastructural characterization of gonadotropin-releasing hormone (GnRH)-producing neurons.

By means of preembedding immunohistochemistry, two types of gonadotropin-releasing hormone (GnRH) positive neurons in the rat could be identified and characterized in the preoptic region and in the diagonal band: (1) a "smooth" GnRH neuron with relatively even cytoplasmic contours, and (2) a "spiny" GnRH neuron with thorn-like protrusions of the perikaryon and cell processes. Both cell types contain the same organelles in similar number and distribution, but they differ in the number of synaptic contacts. In general, GnRH cell bodies have a large round or ovoid nucleus, well-developed rough endoplasmic reticulum arranged in multilayered stacks or as individual cisternae, and several Golgi complexes. Lysosomes are not numerous under the conditions studied. Specializations include kinocilia, nematosomes, and lamellar whorls. Throughout the cytoplasm, scattered dense core vesicles with a diameter of 100 nm and clear vesicles with a diameter of 30-40 nm can be seen with a preferential localization close to the cell membrane. The cell processes of smooth GnRH cells close to the perikaryal appear as extensions of the perikaryal cytoplasm with all organelles except the nucleus. The two neurites originate from the perikaryon as tapering cones over a distance of 200-300 micron, until they reach a diameter of 0.5-3 micron. Cell processes of spiny GnRH cells show bifurcations, protrusions, or invaginations and contain clear and dense core vesicles in their spines. In areas distant from the perikaryon, immunoreactive fibers with a large number of dense core and clear vesicles can occasionally be seen to terminate synaptically or asynaptically on other neurons. The GnRH neurons show postsynaptic specializations at the level of the perikaryon and at cell processes, when apposed by a presynaptic terminal. Such synaptic contacts are seen less frequently on smooth cells than on spiny cells. Large areas of the GnRH cell may be covered by a thin glial lamella, which separates the cell body from the surrounding neuropil. The results indicate the existence of two populations of GnRH cell bodies with different patterns of innervation, which suggest different integrative capacities.

Animals↗
PubMed1985

A catecholaminergic projection from the ventral tegmental area to the diagonal band of Broca: modulation by neurotensin.

The ventral tegmental area contains a high density of dopaminergic perikarya having ascending projections to a number of limbic forebrain regions. In this study, we use combined retrograde labeling with horseradish peroxidase (HRP) and immunohistochemical staining for tyrosine hydroxylase to examine the catecholaminergic projection from the ventral tegmental area to the diagonal band of Broca. When injection of HRP was restricted to the diagonal band, only neurons in the nucleus linearis, nucleus interfascicularis and ventromedial portion of the nucleus paranigralis were labeled. In contrast, HRP injection into the adjacent nucleus accumbens labeled neurons throughout these nuclei, plus the nucleus parabrachialis pigmentosus, nucleus retroruber and substantia nigra, pars compacta. Approximately 60% of neurons in the ventral tegmental area labeled from the diagonal band contained tyrosine hydroxylase, compared with 79% of the neurons labeled from the nucleus accumbens. Neurotensin is a tridecapeptide found in the ventral tegmental area which has been shown to activate dopamine neurons projecting to the nucleus accumbens. In this study, microinjection of neurotensin into ventral tegmental nuclei which contained neurons retrogradely labeled from the diagonal band significantly elevated the levels of dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, in the diagonal band. The results of this study demonstrate that a catecholaminergic projection exists from the ventral tegmental area to the diagonal band of Broca, and that this pathway can be stimulated by intra-ventral tegmental injection with neurotensin.

Animals↗
PubMed1985

Evidence for an association between calmodulin and membrane patches containing gonadotropin-releasing hormone--receptor complexes in cultured gonadotropes.

participation of calmodulin, clathrin, and actin in receptor mediated endocytosis of gonadotropin-releasing hormone (GnRH) was studied in an in vitro system of dispersed pituitary cells with a triple staining procedure. Cells were incubated in D-Lys6-Pro9-Des10-GnRH-biotin and stained with avidin-peroxidase-diaminobenzidine. Calmodulin, clathrin, and actin as well as luteinizing hormone were identified by indirect immunofluorescence with FITC- and rhodamine-labeled second antibody. The results indicate a close spatial association of calmodulin, but not of clathrin and actin, with GnRH-containing plasma membrane patches.

Actins↗
PubMed1984

Monosodium glutamate lesions in rat hypothalamus studied by immunohistochemistry for gonadotropin releasing hormone, neurotensin, tyrosine hydroxylase, and glutamic acid decarboxylase and by autoradiography for [3H] estradiol.

Adult male and female rats treated neonatally with monosodium glutamate (MSG) exhibit lesions in the arcuate nucleus of the hypothalamus. Immunohistochemical analysis of the distribution of tyrosine hydroxylase (TH), glutamic acid decarboxylase (GAD), neurotensin (NT) and gonadotropin-releasing hormone (GnRH) reveals substantial destructions of tuberoinfundibular dopamine and NT systems accompanied by a marked reduction of immunoreactivity in the median eminence. GAD immunoreactivity in the arcuate nucleus and median eminence is greatly reduced, while GnRH containing structures in the mediobasal hypothalamus are not noticeably affected. Evaluation of autoradiograms after intravenously administered [3H] estradiol in the ventral hypothalamus indicate an almost complete loss of target neurons in the arcuate nucleus but not in the nearby ventromedial nucleus. The results suggest that: (a) NT- and dopamine-containing neurons of the arcuate nucleus project to the median eminence via tuberoinfundibular NT and dopaminergic pathways; (b) GABA in the median eminence originates to a major extent from neurons of the arcuate nucleus through a tuberoinfundibular GABAergic system; (c) GnRH is produced in the rat outside the arcuate nucleus; (d) the MSG-induced lesion in the basal tuberal region abolishes or strongly diminishes estradiol target neurons in the arcuate nucleus.

Animals↗
PubMed1984

Receptor-mediated binding and uptake of GnRH agonist and antagonist by pituitary cells.

The intracellular pathway of an enzyme resistant GnRH agonist (D-Lys6-GnRH) conjugated to ferritin or to colloidal gold was followed in cultured pituitary cells. After an initial uniform distribution over the cell surface of gonadotropes, the electrondense marker was internalized, either individually or in small groups. Some, but not all marker was associated with invaginated membrane specializations showing a proteineous coat at their cytoplasmic site. After longer incubation times, the marker appeared in the lysosomal compartment and the Golgi apparatus, where it could be found in the vesicular as well as cisternal portion. In addition, the receptor-mediated endocytosis of the GnRH antagonist D-p-Glu1-D-Phe2-D-Trp3-D-Lys6-GnRH was studied by light and electron microscopic autoradiography after 30 and 60 min of incubation to ensure uptake. At both time points, in in vitro as well as in vivo studies, silver grains were localized over cytoplasmic organelles of castration cells, including dilated endoplasmic reticulum, lysosomes, and clear vesicles. No consistent association with cell nuclei, mitochondria, or secretory vesicles could be observed. The results suggest that both agonist and antagonist are binding selectively to the plasma membrane of gonadotropes and subsequently are taken up via receptor-mediated endocytosis for degradation or possible action on synthetic processes.

Animals↗
PubMed1984

The A-B-C (Allocortex-Brainstem-Core) circuitry of endocrine-autonomic integration and regulation: a proposed hypothesis on the anatomical-functional relationships between estradiol sites of action and peptidergic-aminergic neuronal systems.

A sex steroid hormone sensitive brainstem-allocortex axis of neuronal cell groups and projections is recognized with convergent pathways of aminergic-peptidergic messenger systems, which subserves the adjustment for varying reproductive and environmental conditions and the coordination of endocrine-autonomic functions. Main stations in the A-B-C (Allocortex-Brainstem-Core) periventricular axis include the substantia gelatinosa, nucleus (n.) tractus solitarii-dorsal vagal nucleus-area postrema complex, locus ceruleus, n. parabrachialis, central gray and associated raphe nuclei, ventral tegmental area, lateral and periventricular hypothalamus, n. paraventricularis, bed nucleus of the stria terminalis, preoptic-septal nuclei and n. centralis amygdalae with associated amygdaloid nuclei, as well as the ventral and dorsal allocortex. All of these stations and their periventricular and medial forebrain bundle projections contain estradiol sites of action and represent elements of earlier defined periventricular estradiol-target neuron systems. Results from colocalization of 3H estradiol by thaw-mount autoradiography and aminergic and peptidergic messengers by immunohistochemistry or other histochemical techniques indicate direct nuclear effects of estradiol on certain noradrenalin, dopamine, gamma aminobutyric acid, somatostatin, and neurophysin neurons. Additional data about correspondence of estradiol-target neuron accumulations with neuronal sites of peptide messenger production suggest direct effects of estradiol on certain enkephalin, endorphin, corticotropin releasing hormone, adrenalin, serotonin, cholecystokinin, pancreatic polypeptide and gonadotropin releasing hormone neurons--and probably others. As documented for the pituitary, and as an approach to understand varying and dual effects, it is postulated that estradiol activation of brain messenger systems parallels the heterogeneous estradiol binding in the A-B-C- system. This is expressed in the concept of differential Multiple Activation of Heterogeneous Systems (MAHS).(ABSTRACT TRUNCATED AT 250 WORDS)

Amines↗
PubMed1983

Anatomical relationships of dopaminergic and GABAergic systems with the GnRH-systems in the septo-hypothalamic area. Immunohistochemical studies.

Immunohistochemical double staining for gonadotropin releasing hormone (GnRH) and tyrosine hydroxylase (TH) or glutamic acid decarboxylase (GAD) reveals in the septo-preoptic-diagonal band complex of the rat brain close spatial associations between GnRH-immunoreactive perikarya and TH and GAD immunoreactive fibers. In the organum vasculosum laminae terminalis, no close spatial relationships could be observed between TH- or GAD-positive fibers and the GnRH-containing system. In contrast, in the median eminence substantial overlap exists in the distribution of GnRH with TH and GAD containing nerve fibers. This overlap is most intense for TH throughout the lateral palisade zone, while for GAD it is more restricted to the outermost portion of the external palisade zone. The results suggest that dopamine and GABA influence GnRH secretion via axosomatic contacts in the septo-preoptic-diagonal band complex, as well as via axo-axonic interactions in the median eminence, while no such interactions seem to exist in the organum vasculosum laminae terminalis. Since dopaminergic cell bodies in the ventral hypothalamus are closely apposed by GnRH and GAD containing fibers, the existence of feedback circuits among GnRH, dopamine and GABA systems is proposed.

Animals↗
PubMed1983

Intracellular pathways of electron-opaque gonadotropin-releasing hormone derivatives bound by cultured gonadotropes.

A metabolically stable GnRH agonist (D-Lys6-GnRH) has been coupled to electron-opaque markers (colloidal gold and ferritin) to characterize the intracellular pathway of the releasing hormone bound by pituitary gonadotropes. This approach has the advantage of increasing the resolution of localization to a "circle of uncertainty" about 10- to 20-fold smaller than that which can be obtained by autoradiography. After an initial uniform distribution on the cell surface, the derivatives were taken up individually as well as in small clusters in coated and uncoated membrane invaginations and moved to the lysosomal compartment either directly or after passage through the Golgi apparatus. The results suggest that labeled GnRH or GnRH-receptor complex may be routed to two distinct intracellular compartments: the lysosome and the Golgi cisternae. It is unclear whether each releasing hormone-marker conjugate must be transported through both compartments before degradation.

Animals↗