Glucagon-Like Peptide-1 Regulates the Proopiomelanocortin Neurons of the Arcuate Nucleus both Directly and Indirectly via Presynaptic Action

Glucagon-like peptide-1 (GLP-1) exerts its anorexigenic effect at least partly via the proopiomelanocortin (POMC) neurons of the arcuate (ARC) nucleus. These neurons are known to express GLP-1 receptor (GLP-1R). The aim of the study was to determine whether in addition to its direct effect, GLP-1 also modulates how neuronal inputs can regulate the POMC neurons by acting on presynaptic terminals, ultrastructural and electrophysiological studies were performed on tissues of adult male mice. GLP-1R-immunoreactivity was associated with the cell membrane of POMC neurons and with axon terminals forming synapses on these cells. The GLP-1 analog exendin 4 (Ex4) markedly increased the firing rate of all examined POMC neurons and depolarized these cells. These effects of Ex4 were prevented by intracellular administration of the G-protein blocker guanosine 5'-[β-thio]diphosphate trilithium salt (GDP-β-S). Ex4 also influenced the miniature postsynaptic currents (mPSCs) and evoked PSCs of POMC neurons. Ex4 increased the frequency of miniature excitatory PSCs (EPSCs) and the amplitude of the evoked EPSCs in half of the POMC neurons. Ex4 increased the frequency of miniature inhibitory PSCs (IPSCs) and the amplitudes of the evoked IPSCs in one-third of neurons. These effects of Ex4 were not influenced by intracellular GDP-β-S, indicating that GLP-1 signaling directly stimulates a population of axon terminals innervating the POMC neurons. The different Ex4 responsiveness of their mPSCs indicates the heterogeneity of the POMC neurons of the ARC. In summary, our data demonstrate that in addition to its direct excitatory effect on the POMC neurons, GLP-1 signaling also facilitates the presynaptic input of these cells by acting on presynaptically localized GLP-1R.

Distribution and ultrastructural localization of the glucagon-like peptide-1 receptor (GLP-1R) in the rat brain

Glucagon-like peptide-1 (GLP-1) inhibits food intake and regulates glucose homeostasis. These actions are at least partly mediated by central GLP-1 receptor (GLP-1R). Little information is available, however, about the subcellular localization and the distribution of the GLP-1R protein in the rat brain. To determine the localization of GLP-1R protein in the rat brain, immunocytochemistry was performed at light and electron microscopic levels. The highest density of GLP-1R-immunoreactivity was observed in the circumventricular organs and regions in the vicinity of these areas like in the arcuate nucleus (ARC) and in the nucleus tractus solitarii (NTS). In addition, GLP-1R-immunreactive (IR) neuronal profiles were also observed in a number of telencephalic, diencephalic and brainstem areas and also in the cerebellum. Ultrastructural examination of GLP-1R-immunoreactivity in energy homeostasis related regions showed that GLP-1R immunoreactivity is associated with the membrane of perikarya and dendrites but GLP-1R can also be observed inside and on the surface of axon varicosities and axon terminals. In conclusion, in this study we provide a detailed map of the GLP-1R-IR structures in the CNS. Furthermore, we demonstrate that in addition to the perikaryonal and dendritic distribution, GLP-1R is also present in axonal profiles suggesting a presynaptic action of GLP-1. The very high concentration of GLP-1R-profiles in the circumventricular organs and in the ARC and NTS suggests that peripheral GLP-1 may influence brain functions via these brain areas.

Semaglutide lowers body weight in rodents via distributed neural pathways

Semaglutide, a glucagon-like peptide 1 (GLP-1) analog, induces weight loss, lowers glucose levels, and reduces cardiovascular risk in patients with diabetes. Mechanistic preclinical studies suggest weight loss is mediated through GLP-1 receptors (GLP-1Rs) in the brain. The findings presented here show that semaglutide modulated food preference, reduced food intake, and caused weight loss without decreasing energy expenditure. Semaglutide directly accessed the brainstem, septal nucleus, and hypothalamus but did not cross the blood-brain barrier; it interacted with the brain through the circumventricular organs and several select sites adjacent to the ventricles. Semaglutide induced central c-Fos activation in 10 brain areas, including hindbrain areas directly targeted by semaglutide, and secondary areas without direct GLP-1R interaction, such as the lateral parabrachial nucleus. Automated analysis of semaglutide access, c-Fos activity, GLP-1R distribution, and brain connectivity revealed that activation may involve meal termination controlled by neurons in the lateral parabrachial nucleus. Transcriptomic analysis of microdissected brain areas from semaglutide-treated rats showed upregulation of prolactin-releasing hormone and tyrosine hydroxylase in the area postrema. We suggest semaglutide lowers body weight by direct interaction with diverse GLP-1R populations and by directly and indirectly affecting the activity of neural pathways involved in food intake, reward, and energy expenditure.

Three new genera of the Teloschistaceae proved by three gene phylogeny

Three new for science genera, i.e.: Erichansenia S. Y. Kondr., Kärnefelt et A. Thell for the ‘Caloplaca’ epithallina group of the subfamily Xanthorioideae, as well as Lendemeriella S. Y. Kondr. for the Caloplaca reptans group, and Pisutiella S. Y. Kondr., L. Lőkös et E. Farkas for the Caloplaca conversa group of the subfamily Caloplacoideae of the Teloschistaceae, are described on the basis of results of the three gene phylogeny of the Teloschistaceae based on nrITS, nrLSU and mtSSU sequences.

Twenty-seven new combinations, i.e.: Erichansenia epithallina (for Caloplaca epithallina Lynge), Erichansenia cryodesertorum (for Shackletonia cryodesertorum Garrido-Ben., Søchting et Pérez-Ort.), Erichansenia sauronii (for Caloplaca sauronii Søchting et Øvstedal), Fauriea mandshuriaensis (for Caloplaca mandshuriaensis S. Y. Kondr., L. Lőkös et J.-S. Hur), Fauriea trassii (for Caloplaca trassii Galanina et S. Y. Kondr.), Lendemeriella borealis (for Lecanora pyracea f. borealis Vain.), Lendemeriella dakotensis (for Caloplaca dakotensis Wetmore), Lendemeriella exsecuta (for Lecanora exsecuta Nyl.), Lendemeriella lucifuga (for Caloplaca lucifuga G. Thor), Lendemeriella nivalis (for Zeora nivalis Körb.), Lendemeriella reptans (for Caloplaca reptans Lendemer et B. P. Hodk.), Lendemeriella sorocarpa (for Placodium sorocarpum Vain.), Lendemeriella tornoensis (for Caloplaca tornoensis H. Magn.), Pisutiella congrediens (for Lecanora congrediens Nyl.), Pisutiella conversa (for Callopisma conversum Kremp.), Pisutiella furax (for Caloplaca furax Egea et Llimona), Pisutiella grimmiae (for Lecanora grimmiae Nyl.), Pisutiella ivanpisutii (for Caloplaca ivanpisutii S. Y. Kondr., L. Lőkös et Hur), Pisutiella phaeothamnos (for Caloplaca phaeothamnos K. Kalb et J. Poelt), Pyrenodesmia aetnensis (for Caloplaca aetnensis B. de Lesd.), Pyrenodesmia albolutescens (for Lecanora albolutescens Nyl.), Pyrenodesmia aractina (for Parmelia aractina Fr.), Pyrenodesmia atroflava (for Lecidea atroflava Turner), Pyrenodesmia bicolor (for Caloplaca bicolor H. Magn.), Pyrenodesmia molariformis (for Caloplaca molariformis Frolov, Vondrák, Nadyeina et Khodos.), Pyrenodesmia neotaurica (for Caloplaca neotaurica Vondrák, Khodos., Arup et Søchting), Pyrenodesmia peliophylla (for Placodium peliophyllum Tuck.) are proposed based on results from a combined phylogenetic analysis using nrITS, nrLSU and mtSSU gene sequences.

A Glial-Neuronal Circuit in the Median Eminence Regulates Thyrotropin-Releasing Hormone-Release via the Endocannabinoid System

Based on the type-I cannabinoid receptor (CB1) content of hypophysiotropic axons and the involvement of tanycytes in the regulation of the hypothalamic-pituitary-thyroid (HPT) axis, we hypothesized that endocannabinoids are involved in the tanycyte-induced regulation of TRH release in the median eminence (ME). We demonstrated that CB1-immunoreactive TRH axons were associated to DAGLα-immunoreactive tanycyte processes in the external zone of ME and showed that endocannabinoids tonically inhibit the TRH release in this tissue. We showed that glutamate depolarizes the tanycytes, increases their intracellular Ca²⁺ level and the 2-AG level of the ME via AMPA and kainite receptors and glutamate transport. Using optogenetics, we demonstrated that glutamate released from TRH neurons influences the tanycytes in the ME.

In summary, tanycytes regulate TRH secretion in the ME via endocannabinoid release, whereas TRH axons regulate tanycytes by glutamate, suggesting the existence of a reciprocal microcircuit between tanycytes and TRH terminals that controls TRH release.

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Tanycytes tonically inhibit the activity of TRH axons via endocannabinoid release

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Glutamate depolarizes the tanycytes and regulates their 2-AG synthesis

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Glutamate released from the hypophysiotropic TRH axons influences tanycytes

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A microcircuit utilizing glutamate and endocannabinoids regulates TRH release

Thyrotropin-Releasing-Hormone-Synthesizing Neurons of the Hypothalamic Paraventricular Nucleus Are Inhibited by Glycinergic Inputs

Background: Glycine is a classical neurotransmitter that has role in both inhibitory and excitatory synapses. To understand whether glycinergic inputs are involved in the regulation of the hypophysiotropic thyrotropin-releasing hormone (TRH) neurons, the central controllers of the hypothalamic-pituitary-thyroid axis, the glycinergic innervation of the TRH neurons was studied in the hypothalamic paraventricular nucleus (PVN). Methods: Double-labeling immunocytochemistry and patch-clamp electrophysiology were used to determine the role of glycinergic neurons in the regulation of TRH neurons in the PVN. Anterograde and retrograde tracing methods were used to determine the sources of the glycinergic input of TRH neurons. Results: Glycine transporter-2 (GLYT2), a marker of glycinergic neurons, containing axons were found to establish symmetric type of synapses on TRH neurons in the PVN. Furthermore, glycine receptor immunoreactivity was observed in these TRH neurons. The raphe magnus (RMg) and the ventrolateral periaqueductal gray (VLPAG) were found to be the exclusive sources of the glycinergic innervation of the TRH neurons within the PVN. Patch-clamp electrophysiology using sections of TRH-IRES-tdTomato mice showed that glycine hyperpolarized the TRH neurons and completely blocked the firing of these neurons. Glycine also markedly hyperpolarized the TRH neurons in the presence of tetrodotoxin demonstrating the direct effect of glycine. In more than 60% of the TRH neurons, spontaneous inhibitory postsynaptic currents (sIPSCs) were observed, even after the pharmacological inhibition of glutamatergic and GABAergic neuronal transmission. The glycine antagonist, strychnine, almost completely abolished these sIPSCs, demonstrating the inhibitory nature of the glycinergic input of TRH neurons. Conclusions: These data demonstrate that TRH neurons in the PVN receive glycinergic inputs from the RMg and the VLPAG. The symmetric type of synaptic connection and the results of the electrophysiological experiments demonstrate the inhibitory nature of these inputs.

Transcellular stomach absorption of a derivatized glucagon-like peptide-1 receptor agonist

Oral administration of therapeutic peptides is hindered by poor absorption across the gastrointestinal barrier and extensive degradation by proteolytic enzymes. Here, we investigated the absorption of orally delivered semaglutide, a glucagon-like peptide-1 analog, coformulated with the absorption enhancer sodiumN-[8-(2-hydroxybenzoyl) aminocaprylate] (SNAC) in a tablet. In contrast to intestinal absorption usually seen with small molecules, clinical and preclinical dog studies revealed that absorption of semaglutide takes place in the stomach, is confined to an area in close proximity to the tablet surface, and requires coformulation with SNAC. SNAC protects against enzymatic degradation via local buffering actions and only transiently enhances absorption. The mechanism of absorption is shown to be compound specific, transcellular, and without any evidence of effect on tight junctions. These data have implications for understanding how highly efficacious and specific therapeutic peptides could be transformed from injectable to tablet-based oral therapies.

Immunohistochemistry and Reverse Transcriptase Polymerase Chain Reaction on Sentinel Lymph Nodes can Improve the Accuracy of Nodal Staging in Breast Cancer Patients

In this study the nodal staging sensitivity of sentinel lymph node biopsy (SLNB) with detailed pathological and molecular biological examination has been investigated and compared to that of axillary lymph node dissection (ALND) with routine histological evaluation. Sentinel lymph nodes (SLNs) were removed by the dual-agent injection technique in 68 patients with primary, clinically node-negative breast cancer. Forty-seven patients had negative SLNs according to hematoxylin and eosin (H&E) staining. These H&E-negative SLNs were serially sectioned and examined at 250 μm levels by anticytokeratin immunohistochemistry (IHC). In 14 patients the SLNs were also investigated by cytokeratin 20 (CK20) reverse transcriptase polymerase chain reaction (RT-PCR). SLNB with IHC increased the node-positive rate by 26% (by 40% in tumors less than or equal to 2 cm in size (pT1) and by 9% in tumors more than 2 cm but less than or equal to 5 cm in size (pT2)). The sensitivity of SLNB with IHC was superior to that of ALND with routine histology in pT1 tumors and identical in pT2 tumors. The concordance between histology and RT-PCR was only 21%, and in two of three cases with positive histological results RT-PCR was negative. In conclusion, SLNB with detailed pathological and/or molecular biological evaluation can improve the sensitivity of regional staging. ALND can probably be abandoned in patients with pT1 SLN-negative breast cancer. Further prospective studies are required to determine the clinical significance of these detailed SLN evaluation techniques, but at present these methods are still investigational.

Role of TRH/UCN3 neurons of the perifornical area/bed nucleus of stria terminalis region in the regulation of the anorexigenic POMC neurons of the arcuate nucleus in male mice and rats

Two anorexigenic peptides, thyrotropin-releasing hormone (TRH) and urocortin 3 (UCN3), are co-expressed in a continuous neuronal group that extends from the perifornical area to the bed nucleus of stria terminalis, raising the possibility that this cell group may be involved in the regulation of energy homeostasis. In this study, therefore, we tested the hypothesis that the TRH/UCN3 neurons regulate food intake by influencing feeding-related neuropeptide Y (NPY) and/or proopiomelanocortin (POMC) neurons in the arcuate nucleus (ARC). Triple-labeled immunofluorescent preparations demonstrated that only very few NPY neurons (4.3 ± 1.3%) were contacted by double-labeled TRH/UCN3 axons in the ARC. In contrast, more than half of the POMC neurons (52.4 ± 8.5%) were contacted by double-labeled axons. Immuno-electron microscopy demonstrated that the UCN3 axons established asymmetric synapses with POMC neurons, indicating the excitatory nature of these synaptic specializations. Patch clamp electrophysiology revealed that TRH and UCN3 have antagonistic effects on the POMC neurons. While UCN3 depolarizes and increases the firing rate of POMC neurons, TRH prevents these effects of UCN3. These data demonstrate that TRH/UCN3 neurons in the perifornical/BNST region establish abundant synaptic associations with the POMC neurons in the ARC and suggest a potentially important role for these neurons in the regulation of food intake through an antagonistic interaction between TRH and UCN3 on the electrophysiological properties of POMC neurons.

Glucagon-Like Peptide-1 Excites Firing and Increases GABAergic Miniature Postsynaptic Currents (mPSCs) in Gonadotropin-Releasing Hormone (GnRH) Neurons of the Male Mice via Activation of Nitric Oxide (NO) and Suppression of Endocannabinoid Signaling Pathways

Glucagon-like peptide-1 (GLP-1), a metabolic signal molecule, regulates reproduction, although, the involved molecular mechanisms have not been elucidated, yet. Therefore, responsiveness of gonadotropin-releasing hormone (GnRH) neurons to the GLP-1 analog Exendin-4 and elucidation of molecular pathways acting downstream to the GLP-1 receptor (GLP-1R) have been challenged. Loose patch-clamp recordings revealed that Exendin-4 (100 nM-5 μM) elevated firing rate in hypothalamic GnRH-GFP neurons of male mice via activation of GLP-1R. Whole-cell patch-clamp measurements demonstrated increased excitatory GABAergic miniature postsynaptic currents (mPSCs) frequency after Exendin-4 administration, which was eliminated by the GLP-1R antagonist Exendin-3(9-39) (1 μM). Intracellular application of the G-protein inhibitor GDP-β-S (2 mM) impeded action of Exendin-4 on mPSCs, suggesting direct excitatory action of GLP-1 on GnRH neurons. Blockade of nitric-oxide (NO) synthesis by Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME; 100 μM) or N(5)-[Imino(propylamino)methyl]-L-ornithine hydrochloride (NPLA; 1 μM) or intracellular scavenging of NO by 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (CPTIO; 1 mM) partially attenuated the excitatory effect of Exendin-4. Similar partial inhibition was achieved by hindering endocannabinoid pathway using cannabinoid receptor type-1 (CB1) inverse-agonist 1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-(1-piperidyl) pyrazole-3-carboxamide (AM251; 1 μM). Simultaneous blockade of NO and endocannabinoid signaling mechanisms eliminated action of Exendin-4 suggesting involvement of both retrograde machineries. Intracellular application of the transient receptor potential vanilloid 1 (TRPV1)-antagonist 2E-N-(2, 3-Dihydro-1,4-benzodioxin-6-yl)-3-[4-(1, 1-dimethylethyl)phenyl]-2-Propenamide (AMG9810; 10 μM) or the fatty acid amide hydrolase (FAAH)-inhibitor PF3845 (5 μM) impeded the GLP-1-triggered endocannabinoid pathway indicating an anandamide-TRPV1-sensitive control of 2-arachidonoylglycerol (2-AG) production. Furthermore, GLP-1 immunoreactive (IR) axons innervated GnRH neurons in the hypothalamus suggesting that GLP-1 of both peripheral and neuronal sources can modulate GnRH neurons. RT-qPCR study confirmed the expression of GLP-1R and neuronal NO synthase (nNOS) mRNAs in GnRH-GFP neurons. Immuno-electron microscopic analysis revealed the presence of nNOS protein in GnRH neurons. These results indicate that GLP-1 exerts direct facilitatory actions via GLP-1R on GnRH neurons and modulates NO and 2-AG retrograde signaling mechanisms that control the presynaptic excitatory GABAergic inputs to GnRH neurons.

Variable proopiomelanocortin expression in tanycytes of the adult rat hypothalamus and pituitary stalk

It is generally believed that proopiomelanocortin (POMC) is expressed exclusively by neurons in the adult rodent brain. Unbeknownst to most researchers, however, Pomc in situ hybridization studies in the rat show specific labeling in the ventral wall of the hypothalamic third ventricle, which is formed by specialized ependymal cells, called tanycytes. Here we characterized this non-neuronal POMC expression in detail using in situ hybridization and immunohistochemical techniques, and report two unique characteristics. First, POMC mRNA and precursor protein expression in non-neuronal cells varies to a great degree as to the extent and abundance of expression. In brains with low-level expression, POMC mRNA and protein was largely confined to a population of tanycytes within the infundibular stalk/caudal median eminence, termed here γ tanycytes, and a subset of closely located β and α2 tanycytes. In brains with high-level expression, POMC mRNA and protein was observed in the vast majority of α2, β, and γ tanycytes. This variability was observed in both adult males and females; of 41 rats between 8 and 15 weeks of age, 17 had low-, 9 intermediate-, and 15 high-level POMC expression in tanycytes. Second, unlike other known POMC-expressing cells, tanycytes rarely contained detectable levels of adrenocorticotropin or α-melanocyte-stimulating hormone. The results indicate either a dynamic spatiotemporal pattern whereby low and high POMC syntheses in tanycytes occur periodically in each brain, or marked interindividual differences that may persist throughout adulthood. Future studies are required to examine these possibilities and elucidate the physiologic importance of POMC in tanycytes. J. Comp. Neurol. 525:411-441, 2017. © 2016 Wiley Periodicals, Inc.

Prevalent polymorphism in thyroid hormone-activating enzyme leaves a genetic fingerprint that underlies associated clinical syndromes

CONTEXT

A common polymorphism in the gene encoding the activating deiodinase (Thr92Ala-D2) is known to be associated with quality of life in millions of patients with hypothyroidism and with several organ-specific conditions. This polymorphism results in a single amino acid change within the D2 molecule where its susceptibility to ubiquitination and proteasomal degradation is regulated.

OBJECTIVE

To define the molecular mechanisms underlying associated conditions in carriers of the Thr92Ala-D2 polymorphism.

DESIGN, SETTING, PATIENTS

Microarray analyses of 19 postmortem human cerebral cortex samples were performed to establish a foundation for molecular studies via a cell model of HEK-293 cells stably expressing Thr92 or Ala92 D2.

RESULTS

The cerebral cortex of Thr92Ala-D2 carriers exhibits a transcriptional fingerprint that includes sets of genes involved in CNS diseases, ubiquitin, mitochondrial dysfunction (chromosomal genes encoding mitochondrial proteins), inflammation, apoptosis, DNA repair, and growth factor signaling. Similar findings were made in Ala92-D2-expressing HEK-293 cells and in both cases there was no evidence that thyroid hormone signaling was affected ie, the expression level of T3-responsive genes was unchanged, but that several other genes were differentially regulated. The combined microarray analyses (brain/cells) led to the development of an 81-gene classifier that correctly predicts the genotype of homozygous brain samples. In contrast to Thr92-D2, Ala92-D2 exhibits longer half-life and was consistently found in the Golgi. A number of Golgi-related genes were down-regulated in Ala92-D2-expressing cells, but were normalized after 24-h-treatment with the antioxidant N-acetylecysteine.

CONCLUSIONS

Ala92-D2 accumulates in the Golgi, where its presence and/or ensuing oxidative stress disrupts basic cellular functions and increases pre-apoptosis. These findings are reminiscent to disease mechanisms observed in other neurodegenerative disorders such as Huntington's disease, and could contribute to the unresolved neurocognitive symptoms of affected carriers.

Ischemia-induced depolarizations and associated hemodynamic responses in incomplete global forebrain ischemia in rats

Spontaneous depolarizations around the core are a consistent feature of focal cerebral ischemia, but the associated regional hemodynamic changes are heterogeneous. We determined how the features of depolarizations relate to subsequent cerebral blood flow (CBF) changes in global forebrain ischemia. Forebrain ischemia was produced in halothane-anesthetized rats (n=13) by common carotid artery occlusion and hypovolemic hypotension. Mean arterial blood pressure (MABP) was monitored via a femoral catheter. Specific illuminations allowed the capture of image sequences through a cranial window to visualize: changes in membrane potential (voltage-sensitive dye method); CBF (laser speckle contrast imaging); cerebral blood volume (intrinsic optical signal, IOS at 540-550nm); and hemoglobin deoxygenation (IOS at 620-640nm). A depolarization occurred (n=9) when CBF fell below 43.4±5% of control (41±4mmHg MABP), and propagated with a distinct wave front at a rate of 2.8mm/min. Depolarizations were either persistent (n=4), intermediate (n=3) or short, transient depolarization (n=2). Persistent and intermediate depolarizations were associated with sustained hypoperfusion (-11.7±5.1%) and transient hypoperfusion (-17.4±5.2, relative to CBF before depolarization). Short, transient depolarizations did not generate clear CBF responses. Depolarizations during incomplete global ischemia occurred at the lower limit of CBF autoregulation, propagated similar to spreading depolarization (SD), and the hemodynamic responses indicated inverse neurovascular coupling. Similar to SDs associated with focal stroke, the propagating event can be persistent or transient.

Thyrotropin-releasing hormone-containing axons innervate histaminergic neurons in the tuberomammillary nucleus

Recent studies indicate that the effect of thyrotropin-releasing hormone (TRH) on the regulation of food intake may be mediated by histaminergic neurons. To elucidate the anatomical basis for a functional relationship between TRH- and histamine-synthesizing neuronal systems, double-labeling immunocytochemistry was performed on the tuberomammillary nucleus (TMN) of rats, the exclusive location of histaminergic neurons. TRH-immunoreactive (IR) innervation of the histaminergic neurons were detected in all five subnuclei (E1-5) of the TMN, but was most prominent in the E4 and E5 subnuclei where 100% of the histamine-IR neurons were contacted. The number of TRH-IR varicosities in contact with histamine-IR neurons was also greatest in the E4 and E5 subnuclei, averaging 27.0±1.2 in E4 and 7.9±0.5 in E5. Somewhat fewer histamine-IR neurons were juxtaposed by TRH-IR varicosities in E2 and E3 and contacted by 6.3±0.2 and 6.8±0.2 varicosities/innervated cell, respectively. The number of juxtapositions of TRH-IR axon varicosities with histamine-IR neurons was the lowest in the E1 subnucleus (85.7±0.9%; 4.0±0.2 varicosities/innervated cell). Ultrastructural analysis demonstrated that TRH-IR axons established both asymmetric and symmetric type synapses on the perikaryon and dendrites of the histamine-IR neurons, although the majority of synapses were asymmetric type. These data demonstrate that TRH neurons heavily innervate histaminergic neurons in all subdivisions of the TMN, with the densest innervation in the E4 and E5 subdivisions, and are likely to exert activating effects.

Refeeding-activated glutamatergic neurons in the hypothalamic paraventricular nucleus (PVN) mediate effects of melanocortin signaling in the nucleus tractus solitarius (NTS)

We previously demonstrated that refeeding after a prolonged fast activates a subset of neurons in the ventral parvocellular subdivision of the paraventricular nucleus (PVNv) as a result of increased melanocortin signaling. To determine whether these neurons contribute to satiety by projecting to the nucleus tractus solitarius (NTS), the retrogradely transported marker substance, cholera toxin-β (CTB), was injected into the dorsal vagal complex of rats that were subsequently fasted and refed for 2 h. By double-labeling immunohistochemistry, CTB accumulation was found in the cytoplasm of the majority of refeeding-activated c-Fos neurons in the ventral parvocellular subdivision of the hypothalamic paraventricular nucleus (PVNv). In addition, a large number of refeeding-activated c-Fos-expressing neurons were observed in the lateral parvocellular subdivision (PVNl) that also contained CTB and were innervated by axon terminals of proopiomelanocortin neurons. To visualize the location of neuronal activation within the NTS by melanocortin-activated PVN neurons, α-MSH was focally injected into the PVN, resulting in an increased number of c-Fos-containing neurons in the PVN and in the NTS, primarily in the medial and commissural parts. All refeeding-activated neurons in the PVNv and PVNl expressed the mRNA of the glutamatergic marker, type 2 vesicular glutamate transporter (VGLUT2), indicating their glutamatergic phenotype, but only rare neurons contained oxytocin. These data suggest that melanocortin-activated neurons in the PVNv and PVNl may contribute to refeeding-induced satiety through effects on the NTS and may alter the sensitivity of NTS neurons to vagal satiety inputs via glutamate excitation.

A novel pathway regulates thyroid hormone availability in rat and human hypothalamic neurosecretory neurons

Hypothalamic neurosecretory systems are fundamental regulatory circuits influenced by thyroid hormone. Monocarboxylate-transporter-8 (MCT8)-mediated uptake of thyroid hormone followed by type 3 deiodinase (D3)-catalyzed inactivation represent limiting regulatory factors of neuronal T3 availability. In the present study we addressed the localization and subcellular distribution of D3 and MCT8 in neurosecretory neurons and addressed D3 function in their axons. Intense D3-immunoreactivity was observed in axon varicosities in the external zone of the rat median eminence and the neurohaemal zone of the human infundibulum containing axon terminals of hypophysiotropic parvocellular neurons. Immuno-electronmicroscopy localized D3 to dense-core vesicles in hypophysiotropic axon varicosities. N-STORM-superresolution-microscopy detected the active center containing C-terminus of D3 at the outer surface of these organelles. Double-labeling immunofluorescent confocal microscopy revealed that D3 is present in the majority of GnRH, CRH and GHRH axons but only in a minority of TRH axons, while absent from somatostatin-containing neurons. Bimolecular-Fluorescence-Complementation identified D3 homodimers, a prerequisite for D3 activity, in processes of GT1-7 cells. Furthermore, T3-inducible D3 catalytic activity was detected in the rat median eminence. Triple-labeling immunofluorescence and immuno-electronmicroscopy revealed the presence of MCT8 on the surface of the vast majority of all types of hypophysiotropic terminals. The presence of MCT8 was also demonstrated on the axon terminals in the neurohaemal zone of the human infundibulum. The unexpected role of hypophysiotropic axons in fine-tuned regulation of T3 availability in these cells via MCT8-mediated transport and D3-catalyzed inactivation may represent a novel regulatory core mechanism for metabolism, growth, stress and reproduction in rodents and humans.

Effect of beta-sitosterol concentration and high pressure homogenization on the chlorhexidine release from vesicular gels

Previous studies have confirmed that the phase transition of vesicular gels of hydrogenated phospholipids to the less ordered fluid vesicular state was induced by the increase of the beta-sitosterol ratio in the whole gel system and consequently in the lipid bilayer. The purpose of the present study was to evaluate the influence of the beta-sitosterol portion in the lipid bilayer and the effect of high pressure homogenization on the structural characteristics of the prepared gel systems. In addition the influence of beta-sitosterol on the consequent chlorhexidine release from the obtained vesicles and liposomes was also examined. Lipid mixtures were prepared from different molar ratios of lecithin:sterol components (90:10-65:35 mol%). The obtained mixtures were hydrated with the aqueous solution of chlorhexidine digluconate in order to achieve a 30% (w/w) final concentration of the lipid mixtures and a 4% (w/w) concentration of the drug. One portion of the resultant multilamellar vesicles was homogenized by using high pressure. To characterize the homogenized and non-homogenized systems, transmission electron microscopy of the freeze-fractured samples and differential scanning calorimetry (DSC) were carried out. A vertical type diffusion cell was applied to determine the amount of released chlorhexidine digluconate. Along with the increase in beta-sitosterol concentration, the fluidity of the membrane as well as its permeability also increased. The increased permeability--caused by the higher beta-sitosterol concentration--and the high pressure homogenization, which increased the dispersity and therefore the surface area, enabled a higher amount of chlorhexidine to be released. The increase of drug release was more pronounced in the case of samples prepared with high pressure homogenization.

Structural and functional MRI following 4-aminopyridine-induced seizures: a comparative imaging and anatomical study

Structural and functional MRI was used in conjunction with computerized electron microscopy morphometry to study changes 2 h, 24 h and 3 days after 4-aminopyridine-induced seizures lasting 2 h in rats. T2 (relaxation time) values showed changes throughout the cerebral cortex, hippocampus, amygdala and medial thalamus, with a different temporal progression, showing a complete recovery only after 3 days. Two hours after seizures, the apparent diffusion coefficient was decreased throughout the brain compared to control animals, and a further decrease was evident 24 h after seizures. This was followed by a complete recovery at 3 days post-seizures. Functional MRI was performed using regional cerebral blood volume (rCBV) maps. The rCBV was increased shortly after convulsions (2 h) in all structures investigated, with a significant return to baseline values in the parietal cortex and hippocampus, but not in the medial thalamic nuclei, 24 h after seizure onset. No rCBV alterations were detected 3 days after seizures. Electron microscopy of tissue samples of parietal neocortex and hippocampus revealed prominent astrocytic swelling 2 h post-convulsions which decreased thereafter gradually. In conclusion, this experiment reports for the first time structural and functional brain alterations, lasting several hours, in 4-aminopyridine-treated rats after seizure onset. MRI approach combined with histological and ultrastructural analysis provided a clarification of the mechanisms involved in the brain acute response to ictal activity.

Study on the transfer of components of Aetheroleum carvi and Aetheroleum foeniculi oils

The transfer through a membrane of the main organic components and mineral elements of Carum carvi and Foeniculum vulgare volatile oils was studied. The transfer was studied from buffer solution pH 1.1 (stomach) and pH 6.5 (intestine) to pH 7.5 (plasma) in a Sartorius model. The transferred components were measured by GC-MS for volatile components and ICP-OES for inorganic elements. The main components (trans-anethole and fenchone from F. vulgare, carvone and D-limonene from C. carvi), as well as some mineral elements (Ca, Mg, S, Zn), transferred through the membrane.

Enzyme-catalysed synthesis of galactosylated 1d- and 1l-chiro-inositol, 1d-pinitol, myo-inositol and selected derivatives using the β-galactosidase from the thermophile Thermoanaerobacter sp. strain TP6-B1

The products from the enzymatic beta-D-galactopyranosylation of 1D-chiro-inositol, 1D-pinitol, 1D-3-O-allyl-4-O-methyl-chiro-inositol, 1D-3,4-di-O-methyl-chiro-inositol, 1L-chiro-inositol and myo-inositol in combined yields ranging from 46% to 64% have been obtained using the beta-galactosidase isolated from an anaerobic extreme thermophile, Thermoanaerobacter sp. strain TP6-B1 and p-nitrophenyl beta-D-galactopyranoside as the donor. Analysis of the products from these reactions reveals information about the acceptor preferences of the enzyme.

Effect of β-sitosterol on the characteristics of vesicular gels containing chlorhexidine

Previous studies confirm that beta-sitosterol is very effective in altering the molecular packing of soybean lecithin bilayers even more than the cholesterol. The primary aim of the present study was to evaluate the influence of the beta-sitosterol portion in the lipid bilayer on the physical-chemical characteristics of the prepared gel systems, and its influence on the consequent drug release from the liposomes obtained from vesicular phospholipid gels (VPG-s) by redispersion. VPG-s were prepared of different molar ratios of lecithin:sterol components (10:90-35:65 mol%). The mixture was hydrated with the aqueous solution of chlorhexidin digluconate in order to achieve 30% (w/w) final concentration of the lipid mixtures and 4% (w/w) concentration of the drug in each homogenized VPG sample. To characterize the obtained VPG systems optical microscopic examinations using polarized light, differential scanning calorimetry (DSC), photon correlation spectroscopy (PCS), and dynamic surface tension measurements were carried out. Vertical type diffusion cell was applied to determine the amount of released chlorhexidine digluconate. As a result of the surface tension-decreasing effect of beta-sitosterol, the membrane deformability and the dispersity of the system increased. The increased dispersity and fluidity significantly increased the extent of released chlorhexidine from the vesicles.

Inguinal sentinel lymph node biopsy for staging anal cancer

BACKGROUND AND AIMS

The optimal treatment of clinically negative inguinal lymph nodes in patients with primary anal cancer has not yet been clearly defined. The presence of metastases in the inguinal lymph nodes is an adverse prognostic factor for anal cancer. In the present study the feasibility of sentinel lymph node biopsy (SLNB) for staging anal cancer was investigated.

PATIENTS AND METHODS

From September 1999 to March 2002, 8 patients with biopsy proven primary anal cancer underwent lymphoscintigraphy and dual-agent guided inguinal SLNB for nodal staging before starting multimodality treatment.

RESULTS

Inguinal SLNB was successful in all 8 patients (13 groins). A total of 20 hot and blue SLNs (mean 1,5 (1-2) per groins) were removed. In 2 patients (25%) the SLN was positive for metastasis.

CONCLUSIONS

Lymphoscintigraphy followed by dual-agent guided inguinal SLNB is technically feasible for staging patients with primary anal cancer. The detection of metastases in the removed sentinel lymph node(s) may alter the treatment and thus may improve the locoregional control and overall survival of these patients.

Elevated levels of synovial fluid antibodies reactive with the small proteoglycans biglycan and decorin in patients with rheumatoid arthritis or other joint diseases

OBJECTIVES

To determine whether patients with rheumatoid arthritis (RA) express humoral immunity to the small proteoglycans biglycan and decorin and to compare the response to that of patients suffering from other joint diseases.

METHODS

Serum and synovial fluid IgG and IgM antibody levels were determined by enzyme-linked immunosorbent assay. Antibodies to biglycan and decorin as well as to other known and extensively investigated cartilage matrix components such as type II collagen, aggrecan and fibronectin were investigated. Patients suffering from RA, osteoarthritis (OA), psoriatic arthritis and other seronegative spondylarthropathies were included in the study. Correlation between antibody levels and clinical/laboratory parameters was determined.

RESULTS

Patients with RA expressed an increased humoral immunity to biglycan, while patients with seronegative spondylarthropathies displayed elevated decorin-specific synovial antibody levels compared with OA patients.

CONCLUSION

These results indicate a significantly higher immunity to small proteoglycans in RA and seronegative spondylarthropathies than in OA suggesting a possible involvement in the pathogenesis of inflammatory rheumatic diseases.

[Laparoscopic resection of the rectum]

Improving the laparoscopic equipments and the techniques have spreaded the repertoire of the laparoscopic procedures. In the beginning, it was performed the laparoscopic-assisted resection of the rectum, and later was performed the entire laparoscopic procedures on the colon. It had presented a patient, 71 years old man with diagnosis of the adenocarcinoma recti. After preoperately prepare carried out the laparoscopic procedure with T-T anastomosis by EEA stapler. We presented the first case of the laparoscopical performed resection of the rectum with desire to show possibilities and advantages of the laparoscopic surgery in the relation with conventional surgery and with hope that this techniques would be found the application in our land.

Penicillin productivity and glutathione-dependent detoxification of phenylacetic and phenoxyacetic acids in Penicillium chrysogenum

Both toxicity and penicillin productivity of the hydroxylated derivatives of phenylacetic acid (PA) and phenoxyacetic acid (POA) were highly dependent on the position of hydroxylation on the aromatic ring in Penicillium chrysogenum. Hydroxylation at position 2 diminished penicillin production but the compounds retained most of their toxicity. On the other hand, hydroxylation at position 4 resulted in barely toxic derivatives with still significant penicillin productivity. 3-Hydroxy-PA was a weak side-chain precursor with considerably reduced toxicity. The activity of the glutathione-dependent detoxification pathway correlated well with the toxicity of the compounds but there was no correlation between acidity, toxicity and penicillin productivity.

[Examination of liquid crystalline gel systems containing chlorhexidine on the structure and the drug release]

The aim of the thesis was to examine liquid crystalline gel systems as novel, locally applied drug delivery systems. For developing liquid crystalline vehicle, different ratio of Synperonic A7--water mixtures was prepared. Chlorhexidine, chlorhexidine acetate and chlorhexidine gluconate were used as model drugs. Liquid crystalline structure, drug release and drug release kinetic of the samples were studied at increasing surfactant concentration and the effect of the different drugs on the physicochemical properties of the samples and on the membrane transport was examined. For the analysis of the prepared liquid crystalline systems polarising microscopy, rheology test, differential scanning calorimetry, small-angle neutron scattering and transmission electron microscopy were carried out. The drug release and membrane transport experiments were performed by Franz type vertical diffusion cell and Sartorius Resorptionsmodell apparatus. According to our results liquid crystalline vehicles of lamellar and hexagonal structure formed by increasing the surfactant concentration. The drug release studies indicated, that the kinetic of the release strongly depend on the liquid crystalline structure, zero order release occurs from hexagonal structures and anomalous transport occurs from lamellar structures. The addition of chlorhexidine species to the systems modified the structure of the liquid crystalline system. As a results of liquid crystal-drug interaction the solubility of chlorhexidine base and its diffusion through lipophilic membranes increased in comparison with those of the chlorhexidine salts.

Cerebral microvascular pathology in aging and Alzheimer's disease

The aging of the central nervous system and the development of incapacitating neurological diseases like Alzheimer's disease (AD) are generally associated with a wide range of histological and pathophysiological changes eventually leading to a compromised cognitive status. Although the diverse triggers of the neurodegenerative processes and their interactions are still the topic of extensive debate, the possible contribution of cerebrovascular deficiencies has been vigorously promoted in recent years. Various forms of cerebrovascular insufficiency such as reduced blood supply to the brain or disrupted microvascular integrity in cortical regions may occupy an initiating or intermediate position in the chain of events ending with cognitive failure. When, for example, vasoconstriction takes over a dominating role in the cerebral vessels, the perfusion rate of the brain can considerably decrease causing directly or through structural vascular damage a drop in cerebral glucose utilization. Consequently, cerebral metabolism can suffer a setback leading to neuronal damage and a concomitant suboptimal cognitive capacity. The present review focuses on the microvascular aspects of neurodegenerative processes in aging and AD with special attention to cerebral blood flow, neural metabolic changes and the abnormalities in microvascular ultrastructure. In this context, a few of the specific triggers leading to the prominent cerebrovascular pathology, as well as the potential neurological outcome of the compromised cerebral microvascular system are also going to be touched upon to a certain extent, without aiming at total comprehensiveness. Finally, a set of animal models are going to be presented that are frequently used to uncover the functional relationship between cerebrovascular factors and the damage to neural networks.

Calcium antagonists decrease capillary wall damage in aging hypertensive rat brain

Chronic hypertension during aging is a serious threat to the cerebral vasculature. The larger brain arteries can react to hypertension with an abnormal wall thickening, a loss of elasticity and a narrowed lumen. However, little is known about the hypertension-induced alterations of cerebral capillaries. The present study describes ultrastructural alterations of the cerebrocortical capillary wall, such as thickening and collagen accumulation in the basement membrane of aging spontaneously hypertensive stroke-prone rats. The ratio of cortical capillaries with such vascular pathology occurred significantly more frequently in hypertensive animals. Nimodipine and nifedipine are potential drugs to decrease blood pressure in hypertension but their beneficial effects in experimental studies reach beyond the control of blood pressure. Nimodipine and nifedipine can alleviate ischemia-related symptoms and improve cognition. These drugs differ in that nifedipine, but not nimodipine reduces blood pressure at the here-used concentration while both drugs can penetrate the blood-brain barrier. Here we show that chronic treatment of aging hypertensive stroke-prone rats with nimodipine or nifedipine could preserve microvascular integrity in the cerebral cortex.

[Oncocytic carcinoid tumor of the lung]

An elderly female patient was admitted and operated on for a lesion in the upper lobe of the right lung. After lobectomy the patient has recovered without complications. Histology proved oncocyter carcinoid tumour. This neuro-endocrine tumour is a rarity in the lungs with less than forty cases reported in the reviewed literature. This is the first case reported in Hungary.

Influence of chlorhexidine species on the liquid crystalline structure of vehicle

The aim of this study was to investigate the influence of three chlorhexidine species, chlorhexidine base and its salts (diacetate and digluconate), on the physico-chemical features of liquid crystalline systems and on drug transport through lipophilic membranes. Nonionic surfactant, Synperonic A7 (PEG(7)-C(13--15)) was selected for the preparation of the liquid crystalline systems. Mixtures of different ratios of Synperonic A7 and water were prepared. The liquid crystalline systems were characterized using polarizing microscopy, small-angle neutron scattering and transmission electron microscopy. Membrane transport was also examined. The addition of chlorhexidine species to the liquid crystalline system modified the structure of the liquid crystalline system. As a result of liquid crystal--drug interaction, the solubility of chlorhexidine base and its diffusion through lipophilic membranes increased in comparison with those of the chlorhexidine salts.

Interaction between iron(II) and hydroxamic acids: oxidation of iron(II) to iron(III) by desferrioxamine B under anaerobic conditions

Interaction between iron(II) and acetohydroxamic acid (Aha), alpha-alaninehydroxamic acid (alpha-Alaha), beta-alaninehydroxamic acid (beta-Alaha), hexanedioic acid bis(3-hydroxycarbamoyl-methyl)amide (Dha) or desferrioxamine B (DFB) under anaerobic conditions was studied by pH-metric and UV-Visible spectrophotometric methods. The stability constants of complexes formed with Aha, alpha-Alaha, beta-Alaha and Dha were calculated and turned out to be much lower than those of the corresponding iron(II) complexes. Stability constants of the iron(II)-hydroxamate complexes are compared with those of other divalent 3d-block metal ions and the Irving-Williams series of stabilities was found to be observed. Above pH 4, in the reactions between iron(II) and desferrioxamine B, the oxidation of the metal ion to iron(III) by the ligand was found. The overall reaction that resulted in the formation of the tris-hydroxamato complex [Fe(HDFB)]+ and monoamide derivative of DFB at pH 6 is: 2Fe2+ + 3H4DFB+ = 2[Fe(HDFB)]+ + H3DFB-monoamide+ + H2O + 4H+. Based on these results, the conclusion is that desferrioxamine B can uptake iron in iron(III) form under anaerobic conditions.

[Feasibility and accuracy of the combined radioisotope and blue-dye guided sentinel lymph node biopsy in breast cancer]

Sentinel lymph node biopsy is a minimally invasive operation for staging regional lymph nodes in breast cancer. This method was introduced in the last decade. However there are some remaining questions regarding labelling, surgical technique, indications, and the pathological examination of the removed sentinel lymph nodes which have to be answered before can be introduced as the routine clinical practice. 98 patients with primary breast cancer underwent double guided (radioisotope and blue-dye) sentinel lymph node biopsy in our department during a surgical feasibility study between December 1997 and February 2000. The operation was successful in 92 patients (94%). False negative rate, sensitivity and accuracy were 15%, 85% and 95% retrospectively. During the learning curve the success rate improved from 83% to 99%, the sensitivity from 79% to 89% and the accuracy from 88% to 97% and the false negative rate decreased from 21% to 11%. In T1 tumors the false negative rate and accuracy were 6% and 98%, while in T2 tumors these were 24% and 86%. Application of a larger particle sized colloid (200-600 nm), subareolar injection and next day operation technique had no effects on the results. Double guided sentinel lymph node biopsy is a sensitive surgical staging procedure which accurately predicts the lymph node status in T1 breast tumors. The technique used by us is easy to reproduce, and learn and is beneficial in technical and radiation protection aspects.