PubMed Health⌕ Search

Biomedical subjects

L Jennes

Publications and source records attributed to L Jennes.

At least 55 records · Page 3Linked to original sources
PubMed1993

Origin of noradrenergic projections to GnRH perikarya-containing areas in the medial septum-diagonal band and preoptic area.

The purpose of the present study was to identify the sites of origin of the noradrenergic fibers that project to areas containing gonadotropin-releasing hormone (GnRH) perikarya since norepinephrine (NE) is known to influence the activity of GnRH neurons. Fluorescent retrograde tracers were used in combination with immunohistochemistry for dopamine-beta-hydroxylase (DBH) and GnRH. Small volumes of either Fluoro-gold (FG) or Fluoro-Ruby (FR) were pressure injected into areas that contain the largest number of GnRH cell bodies, i.e., the medical septum-diagonal band complex or preoptic area. Retrogradely labeled neurons were observed ipsilaterally in the following noradrenergic cell groups: A2 (in the nucleus tractus solitarii), A1 (in the ventrolateral medulla) and locus coeruleus. Approximately 8% of all DBH-positive neurons within the A2-cell group were retrogradely labeled, while 12% of DBH-ir neurons in the A1-group were double-labeled. Only a few retrogradely labeled DBH-ir neurons were observed in the locus coeruleus (< 1%). Double-labeled neurons were not organized into discrete cell groups, but were dispersed among other NE-neurons within the A2- and A1-cell groups. The highest concentrations of double-labeled neurons were located in the central one-third of both the A2 and A1 cell groups. The results suggest that most noradrenergic terminals in the region of the GnRH perikarya in the medial septum-diagonal band/rostral preoptic area originate from ipsilateral neurons in areas A1 and A2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

c-fos expression in noradrenergic A2 neurons of the rat during the estrous cycle and after steroid hormone treatments.

The expression of the proto-oncogene product fos in noradrenergic neurons of the A2 cell group was studied with immunohistochemistry during the estrous cycle of the rat and after ovariectomy and estrogen treatments. During the estrous cycle the percentage of fos-positive norepinephrine containing neurons was highest at proestrus (39%), followed by estrus (36%) while during diestrus only 4% of the A2 neurons contained immunoreactive fos protein in their nuclei. Ovariectomy caused a further decrease in the number of fos-positive A2 neurons (2%) while long-term estradiol administration partially reversed the effects of ovarian steroid removal (19%). However, 3 h after a single subcutaneous injection of estradiol into ovariectomised rats, 79% of the noradrenergic neurons in the A2 area showed fos immunoreactivity in their nuclei. The results indicate that fos-expression in the noradrenergic neurons in the A2 region varies depending upon the circulating estradiol levels. Since norepinephrine stimulates gonadotropin releasing hormone (GnRH) secretion from the median eminence during proestrus and the GnRH neurons do not contain estrogen receptors, it is suggested that the A2 region is, at least in part, responsible for conveying the estrogen signal to the GnRH neurons.

Animals↗
PubMed1992

Distribution of neurotensin immunoreactivity within the human amygdaloid complex: a comparison with acetylcholinesterase- and Nissl-stained tissue sections.

In a previous study, we reported marked depletion of neurotensin-immunoreactivity (NT-IR) within selected regions of the amygdala of patients with Alzheimer's disease. The significance of these observations was partly obscured largely because we lacked a thorough understanding of the innervation pattern of neurotensin in the normal human amygdala. Accordingly, in the present study, we used a polyclonal antibody against neurotensin to characterize the distribution and morphology of neurotensin-immunoreactive neuronal elements within the human amygdaloid complex. NT-IR occurred in a topographic manner that respected the cytoarchitectural boundaries of the amygdaloid subregions as defined by Nissl staining and acetylcholinesterase histochemistry. Most NT-IR in the amygdala was contained within beaded fibers and dot-like puncta. Within the subnuclei of the amygdala, immunoreactive neuritic elements were most dense within the central nucleus followed by the medial nucleus and intercalated nuclei. The anterior amygdaloid area, basal complex, paralaminar nucleus, cortical nucleus, cortical-amygdaloid transition area, and amygdalohippocampal area contained moderate densities of immunoreactivity. The accessory basal and lateral nuclei exhibited scant NT-IR. Immunoreactive neurons were found only within the anterior amygdaloid area and the central, medial, intercalated, and lateral capsular nuclei. The distribution of NT-immunoreactive processes and cell bodies within selected regions of the amygdala provides an anatomical substrate that may explain, in part, the neuromodulatory actions of neurotensin upon autonomic, endocrine, and memory systems.

Acetylcholinesterase↗
PubMed1992

SIIp: a unique secretogranin/chromogranin of the pituitary released in response to gonadotropin-releasing hormone.

A monoclonal antibody prepared by immunization of mice with a rat pituitary granule fraction stained a single band on a Western blot of pituitary homogenate (bovine, ovine, porcine, or rat) with an apparent mol wt of 78,000 (7.5% acrylamide gel in sodium dodecyl sulfate) and pI 5.0-5.1 (isoelectric focusing). Subcellular fractionation studies of rat pituitaries indicated that the determinant of the monoclonal antibody was markedly enriched in the secretory granule fraction, an observation that was independently confirmed by immunohistochemistry of intact cells. Immunohistochemistry also indicated that this determinant was selectively located in gonadotropes and thyrotropes. On Western blots, this band comigrated with adrenal secretogranin-II (SII; chromogranin-C), had the same N-terminal sequence (six amino acids), and was heat stable (95 C; 10 min). The pituitary protein containing the determinant for the monoclonal antibody could be precipitated by a polyclonal antibody prepared by immunization of rabbits with the C-terminal sequence of adrenal SII (triodecapeptide). Conversely, the monoclonal antibody precipitated the protein containing the determinant for the polyclonal antibody. While both the monoclonal and polyclonal antisera recognized the pituitary molecule, only the polyclonal antibody recognized SII from the adrenal. A RIA was established and used to assess the release pattern of this molecule from pituitary cell cultures. Release was stimulated by GnRH and blocked by a GnRH antagonist. Release was Ca2+ dependent and stimulated by either phorbol myristyl acetate (a protein kinase-C activator) or NaF (a G-protein activator). GHRH and TRH were not as effective secretogogues as GnRH. The observations that a unique form of SII is present in the pituitary gonadotrope and secreted in response to a specific endocrine stimulus present the possibility that this substance has an endocrine function. Further, the tissue specificity of the determinant suggest that it may be useful for the specific diagnosis and monitoring of pituitary tumors.

Amino Acid Sequence↗
PubMed1991

Dual projections of gonadotropin releasing hormone containing neurons to the interpeduncular nucleus and to the vasculature in the female rat.

Immunofluorescence for gonadotropin releasing hormone (GnRH) in combination with retrograde labeling from the interpeduncular nucleus, as well as from the vasculature confirms that, in the rat, certain GnRH neurons project from the septum-diagonal band to the interpeduncular nucleus. However, about one half of these GnRH neurons also project to fenestrated capillaries as evidenced by uptake and retrograde transport of both peripherally injected Fluoro-Gold and centrally injected rhodamine labeled microspheres. The results indicate that the endocrine effects of GnRH are exerted in part by neurons which simultaneously project to neurohemal contact zones and to areas in the brain which are involved in the regulation of certain behaviors. It is suggested that certain GnRH neurons can directly couple endocrine events with other intracerebral events, such as regulation of lordosis behavior.

Animals↗
PubMed1991

Localization of 125I-atrial natriuretic peptide (ANP) in the rat fetus.

In this in vitro autoradiographic study of ANP-binding sites in fetal rats, 125I-ANP bound to receptors in certain developing neural crest derivatives, including the boundary caps, dorsal root ganglia, and Schwann cells of peripheral nerves. Within the spinal cord, ANP receptors were localized in the roof plate and floor plate. The developing meningeal layer of the CNS, blood vessels, lung, liver, and wall of the herniated gut were also labeled. The topographical and temporal correlation of the appearance of ANP receptors with the developmental processes of the targets suggests that ANP in the fetus is multifunctional, and may be involved in diverse events such as gliogenesis, formation of axonal pathways or surfactant production.

Animals↗
PubMed1991

Ultrastructural immunolocalization of the atrial natriuretic factor pathways in fetal, neonatal, and adult Syrian hamsters: from the atrial cardiomyocytes to the circulation via the endocardium, atrial capillaries and epicardium.

Atrial natriuretic factor (ANF)-immunoreactivity was identified with peroxidase-antiperoxidase staining and immunoelectron microscopic gold labeling techniques in atrial tissues of fetal, newborn and adult Syrian hamsters. ANF-immunoreactive (ANF-IR) material was present in electron dense granules of the atrial myocytes with a diameter between 150 and 190 nm. In addition, ANF was observed in the extracellular lumen of omega-shaped profiles of the sarcolemma of atrial myocytes where the atrial granules fuse with this sarcolemma, in the endomysial spaces next to the atrial myocytes, and in association with the endocardial endothelial cells. ANF-IR material was detected in the perivascular spaces and the blood vessel endothelia of the oldest atria. In these endothelia, immunolabeling was detected at the basal surfaces of the plasma membrane, in clear vesicles, in the apical surface membrane. ANF-IR product is also observed at the level of the basal lamina, in vacuoles, in apical crypts, and at the surface of the epicardial cells. Our results complement previous data and biochemical findings demonstrating that pro-ANF is released by the atrial myocytes via exocytosis (emiocytosis). After diffusion through the subendocardial and subepicardial space, the atrial peptide is then transported through the endocardial, epicardial, and blood vessel endothelia into the blood by a receptor-mediated endocytosis mechanism. Our observations suggest that the endothelial linings of the heart atria could play an important role in the control of transport, in activating the prohormone, and in the secretion of active ANF into the blood.

Aging↗
PubMed1990

Reduction of neurotensin immunoreactivity in the amygdala in Alzheimer's disease.

The density of neurotensin immunoreactivity (NT-IR) was dramatically decreased in 6 of 12 amygdaloid nuclear subregions in patients with Alzheimer's disease (AD) compared to age-matched normals. Diminution of NT-IR was most pronounced in amygdaloid regions containing the greatest number of senile plaques. This contrasts to our previous findings of little, if any, loss of substance P or somatostatin immunoreactivity within these same regions. The present findings corroborate biochemical reports of a decrease in NT-IR in the AD amygdala and suggest that this peptide may be selectively affected relative to other neuropeptides.

Aged↗
PubMed1990

Evidence for a role of brain thyrotropin-releasing hormone (TRH) on stress gastric lesion formation in rats.

Specific polyclonal antibodies raised against synthetic thyrotropin-releasing hormone (TRH) infused intracerebroventricularly (ICV) significantly decreased gastric lesions induced by cold restraint stress. The antiulcer effect of immunologic blockade of brain TRH was specific. Normal rabbit serum or antibodies raised against somatostatin, alpha-MSH, Leu-enkephalin, gonadotropin-releasing hormone and atrial natriuretic factor were ineffective. These findings suggest that brain TRH may play an important role in experimental stress ulcer formation.

Animals↗
PubMed1990

Brain ACTH prevents stress gastric lesions in rats.

This study evaluated the effect of ACTH and several ACTH fragments on the development of gastric glandular lesions induced by cold-restraint stress in rats. Intracerebroventricular administration of ACTH1-39 dose-dependently (0.1-10 micrograms) inhibited stress gastric lesion formation. Studies with smaller molecular weight forms of ACTH (in a dose equimolar to 10 micrograms of ACTH1-39) revealed that ACTH1-13 and ACTH1-10 were also protective. The ACTH fragments ACTH5-10, ACTH34-39 and ACTH1-17 were without effect. Immunoneutralization of endogenous brain ACTH1-39 significantly increased stress gastric lesion severity. Antisera raised against synthetic somatostatin, gonadotropin-releasing hormone, and L-enkephalin were ineffective. These results with ACTH coupled with our previous demonstration of a protective effect of beta-endorphin suggest that specific brain pro-opiomelanocortin gene products modulate gastric mucosal integrity in response to stress.

Adrenocorticotropic Hormone↗
PubMed1990

Inhibition of neurotensin-induced miosis by blockade of ocular dopamine pathways.

In previous work we have determined that intracameral (IC) administration of neurotensin (NT) produces strong miosis in rabbits. However, the pharmacological mechanism of this response remains undetermined. Blockade of alpha and beta-adrenoceptor subtypes with phenoxybenzamine and propranolol, blockade of M1 muscarinic receptors with atropine or blockade of mu opioid receptors with naloxone did not affect NT-induced miosis. Of interest however was the observation that destruction of ocular dopamine (DA) nerve endings with 6-hydroxydopamine (6-OHDA) + desmethylimipramine (DMI), or blockade of D-2 DA receptors with haloperidol significantly inhibited the miotic response to IC NT. These findings indicate that an intact iridic DA pathway is required for the expression of NT-induced miosis.

Animals↗
PubMed1990

Prenatal development of gonadotropin-releasing hormone receptors in the rat anterior pituitary.

The development of pituitary GnRH receptors was studied in the rat with in vitro and in vivo autoradiography. GnRH receptors were first seen in pituitary primordia of 13-day-old fetuses. The binding was specific and saturable and was abolished in the presence of 10 microM synthetic GnRH. To examine whether GnRH was available to the fetus, amnionic fluid was collected on days E 12-18. RIA analyses showed that GnRH levels in the amnionic fluid were low on days 12 and 13 (0-20 pM/ml) and rose to 225 pM/ml on day E 16 before they declined to 110 pM/ml on fetal day E 18. The highest levels of GnRH in the amnionic fluid on day E 16 coincided with the first appearance of immunoreactive LH cells, as determined by immunohistochemistry. Intravenous injection of 500 microliters amnionic fluid into pentobarbital-anesthetized adult rats caused a transient 40-60% increase in circulating serum LH in the recipient animal. To show that GnRH from the amnionic fluid has access to the developing pituitary, the 125I-labeled GnRH agonist Buserelin was injected into the amnionic fluid of 13-, 14-, and 15-day-old fetuses in the presence or absence of 10 microM unlabeled GnRH. Autoradiographic analysis of the fetal tissue indicated that the labeled GnRH agonist bound to specific receptors in the primordial pituitaries. The results suggest that the pituitary gonadotropes are differentiated before day E 13 because the expression of GnRH receptors is already an indication of cell determination. Since GnRH is present in the amnionic fluid in a biologically active form and can reach the fetal pituitary, it is concluded that GnRH may be an important factor determining the onset LH synthesis, but not the differentiation, of primordial pituitary cells.

Amniotic Fluid↗
PubMed1990

Production of mouse placental lactogen-I by trophoblast giant cells in utero and in vitro.

Mouse placental lactogen-I (mPL-I) is the earliest appearing member of the PRL-GH family of placental hormones. Using immunological techniques, we have localized mPL-I both in utero and in vitro to trophoblast giant cells. Detectable amounts of mPL-I were first seen by immunohistochemistry on day 6 of gestation in the mural trophoblast. On day 7 giant cells of the ectoplacental cone also contained mPL-I, and on day 10 giant cells adjacent to both the decidua basalis and decidua capsularis stained positive. By day 12 however, all intra- and extraembryonic tissues were negative. The pattern of mPL-I staining in the placenta is consistent with its reported gestational serum profile. mPL-I was also present in trophoblast giant cells in vitro shortly after attachment and spreading of day 5 blastocysts. Analysis of conditioned medium from blastocyst outgrowths by immunoprecipitation and two-dimensional electrophoresis, and by immunoblotting, identified mPL-I as the major secretory product from the trophoblast, consisting of a group of acidic proteins of 30,000-45,000 Mr. The synthesis and secretion of mPL-I in vitro occurred in a serum-free medium suggesting that production of this hormone is part of an endogenous program of trophoblast differentiation.

Animals↗
PubMed1989

Prenatal development of the gonadotropin-releasing hormone-containing systems in rat brain.

Pre-embedding immunofluorescence was used to study the development of the gonadotropin-releasing hormone (GnRH)-containing neuronal systems in the brain of fetal and newborn rats. Immunoreactive cell bodies are first seen in association with the ventral olfactory bulb at the fetal embryonic (E) day 15. At day E 17, single GnRH-containing neurons are found in the nasal system, along the olfactory nerve, in the ganglion terminale, olfactory bulb, septum-diagonal band complex, olfactory tubercle and in the ventrolateral hypothalamus. A major spurt in the development of the brain GnRH-containing systems occurs between days E 18 and E 19. At day E 19, immunoreactive cell bodies are present in all areas as in the adult animals, however, in smaller number. GnRH-containing fibers are first detected in the nasal system at day E 17. At day E 18, GnRH positive projections are present in the nervus terminalis, in the developing organum vasculosum of the lamina terminalis and ventral hypothalamus. By day E 19, GnRH containing connections are established with most of the final target areas. These areas include the caudal olfactory bulb, lateral septum, stria terminalis, fimbria hippocampi, habenula, supramammillary commissure and central gray. In the hypothalamus, 3 major pathways are recognized: a ventral projection which runs in and beneath the optic chiasm toward the median eminence; a ventrolateral tract which is located lateral to the optic chiasm and which projects along the optic tract toward the lateral thalamus as well as to the median eminence; a periventricular network which projects to the habenula and, in a caudal direction, to the mediobasal hypothalamus including the median eminence. The results of the present study suggest that the GnRH neuronal systems develop considerably earlier than previously reported and that the intracerebral GnRH-containing fiber connections are established several days before birth.

Animals↗
PubMed1989

Immunohistochemical demonstration of neurotensin and tyrosine hydroxylase in iris nerves of the rabbit eye.

In previous studies we have provided evidence that intracameral administration of neurotensin (NT), an endogenous tridecapeptide, produces strong miosis in the rabbit. The presence of NT immunoreactivity was investigated in rabbit iris whole mounts by light microscopic immunohistochemistry, and its distribution in the iris compared to that, of tyrosine hydroxylase (TH). A few scattered NT-positive cell bodies were localized in the dilator muscle. Both, the NT cell bodies and processes appeared parallel to the muscle cells. Extensive branching of NT-containing cell processes was observed in connection with the sphincter muscle. These NT-positive fibers formed a dense, randomly oriented network throughout the sphincter muscle cells. The distribution of TH immunoreactivity was similar to that of NT-positive cell processes, except that no TH-positive cell bodies were detected in any of the iris structures examined. Moderate branching of TH-positive fibers was observed in the dilator and sphincter iris muscles. These findings provide neuroanatomical support for an important role of NT in pupillary physiology. Its similar topographical distribution with TH suggests that NT and dopamine may be co-localized, as it has already been described in brain.

Animals↗
PubMed1988

Distribution of gonadrotropin releasing hormone agonist binding sites in the rat central nervous system.

Specific binding sites for gonadotropin releasing hormone (GnRH) in the central nervous system of the rat were studied with in vitro autoradiography and with radioligand assays. The results show that GnRH binding sites are present in the lamina glomerulosa and plexiformis externa, the nucleus olfactorius anterior pars externa, and the frontal cortex at the sulcus rhinalis. In the septum, only a few GnRH binding sites are detected in the lateral and dorsal portions of the nucleus septi lateralis. In addition, a small number of GnRH receptors are seen in the mediobasal hypothalamus and amygdala while substantial binding is apparent in the interpeduncular nucleus, central gray and superior collicle. In the hippocampal formation the GnRH agonists bind to the dorsal and ventral subiculum as well as to receptors in the areas CA1 through CA4. The highest concentration of GnRH receptors is found in the parasubiculum. Competitive binding assays with membrane preparations from the hippocampus and interpeduncular nucleus indicate that the binding of the GnRH agonists is reversible and has a binding affinity of 1 X 10(9) M-1. Injections of radioactive GnRH agonist Buserelin into the lateral ventricle results in selective and reversible labeling of the hippocampal areas CA1 through CA4 as well as the interpeduncular nucleus, central gray and the parasubiculum. The results of the present study indicate that GnRH binds to specific receptors in select areas of the central nervous system of the rat where the peptide may regulate sensory, behavioral and endocrine events.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Localization of serotonin- and substance P-like immunofluorescence in the caudal spinal trigeminal nucleus of the rat.

A double immunofluorescence labeling method was used to study the localization of serotonin (5-HT)- and substance P (SP)-like immunoreactivities within neuronal fibers in the caudal spinal trigeminal nucleus of the rat. The 5-HT- and SP-immunoreactive fibers share extensive topographical overlap within the superficial laminae of the caudal trigeminal nucleus; however, the majority of stained fibers are immunoreactive for either 5-HT or SP, but not both simultaneously. A small population of fibers in which 5-HT and SP are co-localized is present and restricted to the marginal zone as well as the inner and outer layers of the substantia gelatinosa. The results of the present study suggest that fibers containing coexistent 5-HT and SP may be involved in the processing of nociceptive somatic sensation in the medullary dorsal horn of rat.

Animals↗