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[Display omitted] • Mg x Zn 1-x O (x = 0, 0.25, 0.5, 0.75 and 1) NPs were synthesized by Chonemorpha fragrans leaf extract assisted solution combustion method. • The photocatalytic degradation of Fast Blue (FB) and Malachite Green (MG) dyes were tested for all the samples. • MG dyes has higher (90%) degradation compared with FB (87% degradation) dye due to rise in the hydroxyl ions. • The low charge transfer resistance and high capacitance value of Mg x Zn 1-x O electrode were studied for all the samples. • The Nyquist plot is in the order MgO ˃ Zn 0.25 Mg 0.75 O ˃ Zn 0.50 Mg 0.50 O ˃ Zn 0.75 Mg 0.25 O ˃ ZnO. Chonemorpha fragrans leaf extract assisted solution combustion method was carried out for synthesizing Mg x Zn 1−x O (x = 0, 0.25, 0.5, 0.75 and 1) nanoparticles. The obtained samples were characterized using powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, and diffuse reflection spectroscopy techniques. The powder X-ray diffraction patterns of Mg x Zn 1−x O (x = 0 and 1) show pure hexagonal and cubic phases respectively and x = 0.25, 0.5, and 0.75 shows mixed phases. The Rietveld refinement study was done to refine structural parameters of × = 0, 0.5, and 1. A scanning electron microscope shows the high agglomeration with increasing 'x' content. Based on the Williamson-Hall plot, the average size of crystallites was found to be between 25 and 40 nm. Transmission electron microscope results also revealed the formation of nanoparticles. The energy bandgap was calculated from diffuse reflectance spectra using the Kubelka Munk relation and found to vary from 3.2 to 5.28 eV. The photocatalytic degradation of Fast Blue and Malachite Green dyes for all the Mg x Zn 1−x O nanoparticles catalysts was tested under the irradiation of UV light. Mg x Zn 1−x O nanoparticles showed enhanced degradation with increasing 'x' contents for Fast Blue (87%) and Malachite Green (90%) dyes under UV light. This enhanced degradation is due to variation in the bandgap of Mg x Zn 1−x O. Mg x Zn 1−x O electrodes exhibit a reversible electrode reaction based on their low charge transfer resistance and high capacitance value. Based on our results, the synthesized nanoparticles are promising candidates for wastewater treatment and lead sensor applications. [ABSTRACT FROM AUTHOR]

Abstract: The amygdala is activated by fear and plays an important role in the emotional response to life-threatening situations. When rats feel threatened, they respond by biting fiercely. Bite strength is regulated by the trigeminal motor nucleus and the mesencephalic trigeminal nucleus (Me5). The Me5 relays proprioceptive signals from the masticatory muscles and the periodontal ligaments to the trigeminal motor and premotor nuclei. The amygdala projects to the trigeminal motor nucleus and the premotor reticular formation. However, it is unknown whether the amygdala projects directly to the Me5. In the present study, neurons of the central amygdaloid nucleus (ACe) were labeled following injection of a retrograde tracer, Fast Blue, into the caudal Me5, and fibers and terminal buttons from the ACe to the Me5 were examined after injections of an anterograde neuronal tracer, biotinylated dextran amine into the ACe. Furthermore, wheat germ agglutinin-conjugated to horseradish peroxidase was injected into the ACe, and labeled fibers and terminal buttons in the Me5 were examined by electron microscopy. Labeled terminal buttons on Me5 somata were more abundant in the caudal than the rostral Me5. Electron microscopic observation revealed that a part of these terminal buttons formed axo-somatic synapses. These results indicate that the ACe sends direct projections to the Me5, and suggest that the amygdala regulates bite strength by modifying neuronal activity in the Me5. [Copyright &y& Elsevier]

Abstract: Despite the contribution of nodose ganglia neurons to the innervation of the heart being the subject of several studies, specific neuronal subpopulations innervating the four different chambers of the heart have not been distinguished. In our study, the application of Fast Blue-loaded patch to the epicardial surface of different chambers of the rat heart (the right or left atrium or the right or left ventricle) resulted in labeling of discrete populations of immunohistochemically diverse neurons. About one half (55%) of these neurons showed immunoreactivity for the 200-kDa neurofilament protein (marker of myelinated neurons), with a higher proportion of positive staining among neurons projecting to the left than to the right ventricle. Isolectin B4 immunoreactivity (characteristic for a subset of nonmyelinated non-peptidergic neurons) was more abundant among neurons projecting to the right side of the heart (right atria and right ventricles) compared to the left side (23% vs. 16%). Calretinin immunoreactivity (possible marker of mechanosensitive neurons) was significantly higher among neurons projecting to the ventricles than among those projecting to atria (36% vs. 11%). These findings reveal that chambers of the rat heart are innervated with immunohistochemically different subpopulations of neurons from the nodose ganglia. [Copyright &y& Elsevier]

Abstract: It is morphologically demonstrated that the subfornical organ (SFO) projects to the paraventricular hypothalamic nucleus (PVN) and also projects to the nucleus preopticus medianus (POMe), a relay nucleus of indirect projections from the SFO to PVN. However, it remains unknown, whether or not SFO neurons project collaterally to the POMe and PVN. To confirm this, a double retrograde labeling method was performed on rats using two fluorescent tracers. One tracer (red-colored FluoSpheres: FSR) was injected into the POMe and the other (Fast Blue: FB) was injected into the unilateral PVN at the same time. As a result, many retrogradely labeled neurons were found in the entire SFO. Of these, some neurons showed both FSR and FB fluorescence. Double-labeled neurons were found in about 8.7% of FSR-labeled neurons and 15.5% of FB-labeled neurons. The existence of double-labeled neurons indicates that single neurons in the SFO project simultaneously to the POMe and PVN via collateral axon branches. The data suggest that there are complicated neuronal pathways originating from the SFO in regulating cardiovascular and body fluid homeostasis. [Copyright &y& Elsevier]

Abstract: A common method for identifying collateral projections is to inject different retrograde tracers into two targets and examine labeled cells for the presence of both tracers. Double-labeled cells are considered to have collateral projections to the two injection sites. This method is widely considered to underestimate the extent of collaterals. To test the efficiency of double-labeling, we mixed equal volumes of two tracers, injected them into one site in a guinea-pig brain, and counted the resulting labeled cells. Ideally, the tracers would have precisely overlapping injection sites and all labeled cells would contain both tracers. We tested several combinations of tracers: 1) Fast Blue and fluorescein dextran; 2) fluorescein dextran and FluoroGold; 3) fluorescein dextran and FluoroRuby; 4) FluoroGold and green beads; 5) FluoroGold and red beads; 6) FluoroRuby and green beads; and, 7) green beads and red beads. For each combination, a mixture was injected into the left inferior colliculus. After 1 week to allow for transport, labeled cells were counted in the right inferior colliculus and the left temporal cortex. For each mixture, the results were similar for the two areas. The percentage of cells that were double-labeled varied from 0% to 100%, depending on tracer combination. The highest efficiencies (>96%) were observed with red beads and green beads or with FluoroRuby and fluorescein dextran. The limited efficiency of other mixtures could be accounted for only in part by incomplete overlap of the two tracers at the injection site. The results indicate that the specific combination of tracers used to search for collateral projections can greatly affect the findings. [Copyright &y& Elsevier]

Abstract: This study assesses the effects of ATP and GTP on the kinetic properties of voltage-gated K+ currents in anatomically identified postganglionic sympathetic neurons innervating the submandibular gland and the masseter muscle in rats. Three types of K+ currents were isolated: the I Af steady-state inactivating at more hyperpolarized potentials, I As steady-state inactivating at less hyperpolarized potentials than I Af and the I K current independent of membrane potential. The kinetic properties of these currents were tested in neurons with ATP (4 mM) and GTP (0.5 mM) or without ATP and GTP in the intracellular solution.In glandular and muscular neurons in the absence of ATP and GTP in the intracellular solution, the current density of I Af was significantly larger (142 pA/pF and 166 pA/pF, respectively) comparing to cells with ATP and GTP (96 pA/pF and 100 pA/pF, respectively). The I As was larger only in glandular neurons (52 pA/pF vs. 37 pA/pF).Conversely, I K current density was smaller in glandular and muscular neurons without ATP and GTP (17 pA/pF and 31 pA/pF, respectively) comparing to cells with ATP and GTP (57 pA/pF and 58 pA/pF, respectively). In glandular (15.5 nA/ms vs. 6.9 nA/ms) and muscular (10.9 nA/ms vs. 7.5 nA/ms) neurons, the I Af activated faster in the absence of ATP and GTP. Half inactivation voltage of I Af in glandular (−110.0 mV vs. −119.7 mV) and muscular (−108.4 vs. −117.3 mV) neurons was shifted towards depolarization in the absence of ATP and GTP. We suggest that the kinetic properties of K+ currents in glandular and muscular sympathetic neurons change markedly in the absence of ATP and GTP in the cytoplasm. Effectiveness of steady-state inactivated currents (I Af and IAS) increased, while effectiveness of steady-state noninactivated currents decreased in the absence of ATP and GTP. The effects were more pronounced in glandular than in muscular neurons. [Copyright &y& Elsevier]

Voltage-gated Na+ currents were recorded from anatomically identified postganglionic muscular sympathetic neurons without and with ATP and GTP in the intracellular solution. The main findings of the study were that cells without ATP and GTP in the intracellular solution express a higher amplitude and greater density of voltage-gated Na+ current, and their Na+ current activates faster and also inactivates faster time dependently. The current is also steady-state inactivated to a lesser degree and recovers from inactivation more slowly in cells without added ATP and GTP. These findings suggest that the presence of ATP and GTP, substrates for channel phosphorylation, changes the kinetic properties of Na+ currents. [Copyright &y& Elsevier]

The expression and functional responses of P2X receptors in bladder and cutaneous sensory neurons of adult rats and mice have been studied using immunohistochemistry and patch clamp techniques. Cell bodies of bladder pelvic afferents were identified in L6 and S1 dorsal root ganglia (DRG), following Fast Blue injection into the muscle wall of the urinary bladder. Similarly, cutaneous sensory neurons were identified in L3 and L4 DRG, following Fast Blue injection into the saphenous nerve innervating the skin. Bladder sensory neurons contained only weak to moderate P2X3-immunoreactivity (IR), in contrast to strong P2X3-IR observed in a sub-population of cutaneous afferents. Whole-cell patch-clamp recordings revealed that approximately 90% of bladder afferent neurons responded to αβ-methylene ATP (αβmeATP) and ATP (30 μM) with persistent currents, which were inhibited by 2′,3′-O-trinitrophenyl-ATP (TNP-ATP) (0.3 μM) to 6.4±1.9% and 8.0±2.6% of control, respectively (n=8). The remaining bladder sensory neurons demonstrated biphasic, transient or no response to P2X agonists. In contrast, only 24% of cutaneous afferent neurons gave persistent currents to αβmeATP (30 μM), with 66% of cells giving transient or biphasic currents and the remaining 10% being non-responsive. Our results suggest that, in contrast to DRG neurons in general, bladder sensory neurons projecting via pelvic nerves express predominantly P2X2/3 heteromeric receptors, which are likely to mediate the important roles of ATP as a signaling molecule of urinary bladder filling and nociception. [Copyright &y& Elsevier]

We have assessed the expression and kinetics of voltage-gated K+ currents in cardiac dorsal root ganglion (DRG) neurons in rats. The neurons were labelled by prior injection of a fluorescent tracer into the pericardial sack. Ninety-nine neurons were labelled: 24% small (diameter<30 μm), 66% medium-sized (diameter 30 μm>.48 μm) and 10% large (>48 μm) neurons. Current recordings were performed in small and medium-sized neurons. The kinetic and pharmacological properties of K+ currents recorded in these two groups of neurons were identical and the results obtained from these neurons were pooled. Three types of K+ currents were identified:a) IAs, slowly activating and slowly time-dependently inactivating current, with V1/2 of activation −18 mV and current density at +30 mV equal to 164 pA/pF, V1/2 of inactivation at −84 mV. b) IAf current, fast activating and fast time-dependently inactivating current, with V1/2 of activation at two mV and current density at +30 mV equal to 180 pA/pF, V1/2 of inactivation at −26 mV. At resting membrane potential IAs was inactivated, whilst IAf, available for activation. The IAs currents recovered faster from inactivation than IAf current. 4-Aminopiridyne (4-AP) (10 mM) and tetraethylammonium (TEA) (100 mM) produced 98% and 92% reductions of IAf current, respectively and 27% and 66% of IAs current, respectively. c) The IK current that did not inactivate over time. Its V1/2 of activation was −11 mV and its current density equaled 67 pA/pF. This current was inhibited by 95% (100 mM) TEA, whilst 4-AP (10 mM) produced its 23% reduction. All three K+ current components (IAs, IAf and IK) were present in every small and medium-sized cardiac DRG neuron.We suggest that at hyperpolarized membrane potentials the fast reactivating IAs current limits the action potential firing rate of cardiac DRG neurons. At depolarised membrane potentials the IAf K+ current, the reactivation of which is very slow, does not oppose the firing rate of cardiac DRG neurons. [Copyright &y& Elsevier]

The dental pulp is a favorable model for studies of interactions between nociceptive sensory neurons and their peripheral target tissues. In the present study, we retrogradely labeled pulpal afferent neurons with an improved method that permits monitoring of changes in neuronal phenotype in response to controlled tooth injuries. The capacity of retrograde neuronal tracers to diffuse through dentinal tubules was exploited, thereby avoiding the severe injury to the pulp associated with previous tracer application methods. The strategy was to apply the durable fluorescent tracer, Fluoro-gold (FG), to exposed dentin in the floor of shallow cavities in molars, in order to pre-label pulpal neurons in trigeminal ganglia of young adult Sprague–Dawley rats. A high percentage of pupal afferent neurons were retrogradely labeled by application of FG to exposed dentin and the FG fluorescent signal persisted in most labeled neurons for at least 8 weeks. Following tracer application to dentin, the pulp tissue appeared normal histologically, with the exception that a layer of reactive dentin was deposited at the pulp-dentin border beneath the shallow cavities. Assessment of expression of calcitonin gene-related peptide (CGRP) and brain derived neurotrophic factor (BDNF) indicated that pulpal neurons remained in a quiescent, baseline condition cytochemically following application of tracer to cavities in dentin and upregulation of these markers could be detected in neurons that projected to teeth that received a test injury subsequent to tracer application. Thus, labeling of trigeminal neurons via dentinal tubules provides the basis for a useful model for precisely assessing properties of pulpal afferents in both quiescent and activated states. [Copyright &y& Elsevier]

This study presents the kinetic and pharmacological properties of voltage-gated Ca2+ currents in anatomically defined cardiac dorsal root ganglion (DRG) neurons in rats. The neurons were labelled by prior injection of fluorescent tracer Fast Blue into the pericardial sack. There were three distinct groups of neurons with respect to cell size: small (27% of total; cell capacitance <30 pF), medium (65% of total; capacitance 30–80 pF) and large neurons (8% of total; capacitance >80 pF). The properties of Ca2+ currents were tested in small and medium-sized neurons. In large neurons currents could not be adequately controlled and were not analysed. Ca2+ currents did not completely inactivate during 100 ms depolarising voltage steps. The activation thresholds in small (−36.9±1.3 mV) and medium (−39.0±1.3 mV) size neurons were similar. Current densities were 105.8 pA/pF in small and 97.4 pA/pF in large neurons and also did not differ. The kinetic properties of activation and inactivation did not differ between small and medium-sized cardiac DRG neurons. At membrane potentials between −50 and −60 mV (the expected resting membrane potential in these neurons) 55 to 70% of Ca2+ currents in small and medium-sized neurons were available for activation. Both, small and medium-sized neurons expressed similar proportions of L (7.5%), N (25%) and P/Q (36%) type Ca2+ currents. We conclude that small and medium-sized cardiac DRG neurons are homogeneous with respect to the expression and properties of voltage-gated Ca2+ currents. Voltage-gated Ca2+ currents probably play an important role in action potential generation in cardiac DRG neurons due to their availability for activation at resting membrane potential, their high density and voltage threshold close to the threshold for voltage-gated Na+ currents. [Copyright &y& Elsevier]

The expression and properties of voltage-gated Na+ currents in cardiac dorsal root ganglion (DRG) neurons were assessed in this study. Cardiac DRG neurons were labelled by injecting the Fast Blue fluorescent tracer into the pericardium. Recordings were performed from 138 cells. Voltage-dependent Na+ currents were found in 115 neurons. There were 109 neurons in which both tetrodotoxin-sensitive (TTX-S, blocked by 1 μM of TTX) and tetrodotoxin-resistant (TTX-R, insensitive to 1 μM of TTX) Na+ currents were present. Five cells expressed TTX-R current only and one cell only the TTX-S current. The kinetic properties of Na+ currents and action potential waveform parameters were measured in neurons with cell membrane capacitance ranging from 15 to 75 pF. The densities of TTX-R (110.0 pA/pF) and TTX-S (126.1 pA/pF) currents were not significantly different. Current threshold was significantly higher for TTX-R (−34 mV) than for TTX-S (−40.4 mV) currents. V1/2 of activation for TTX-S current (−19.6 mV) was significantly more negative than for TTX-R current (−9.2 mV), but k factors did not differ significantly. V1/2 and the k constant for inactivation for TTX-S currents were −35.6 and −5.7 mV, respectively. These values were significantly lower than those recorded for TTX-R current for which V1/2 and k were −62.3 and −7.7 mV, respectively. The action potential threshold was lower, the 10–90% rise time and potential width were shorter before than after the application of TTX. Based on this we drew the conclusion that action potential recorded before adding tetrodotoxin was mainly TTX-S current dependent, while the action potential recorded after the application of toxin was TTX-R current dependent. We also found 23 cells with mean membrane capacitance ranging from 12 to 35 pF (the smallest labelled DRG cells found in this study) that did not express the Na+ current. The function of these cells is unclear. We conclude that the overwhelming majority of cardiac dorsal root ganglion neurons in which voltage-dependent Na+ currents were present, exhibited both TTX-S and TTX-R Na+ currents with remarkably similar expression and kinetic properties. [Copyright &y& Elsevier]