Phenotypic alterations of neuropeptide Y and calcitonin gene-related peptide-containing neurons innervating the rat temporomandibular joint during carrageenan-induced arthritis

The aim of this study was to identify immunoreactive neuropeptide Y (NPY) and calcitonin gene-related peptide (CGRP) neurons in the autonomic and sensory ganglia, specifically neurons that innervate the rat temporomandibular joint (TMJ). A possible variation between the percentages of these neurons in acute and chronic phases of carrageenan-induced arthritis was examined. Retrograde neuronal tracing was combined with indirect immunofluorescence to identify NPY-immuno-reactive (NPY-IR) and CGRP-immunoreactive (CGRP-IR) neurons that send nerve fibers to the normal and arthritic temporomandibular joint. In normal joints, NPY-IR neurons constitute 78 +/- 3%, 77 +/- 6% and 10 +/- 4% of double-labeled nucleated neuronal profile originated from the superior cervical, stellate and otic ganglia, respectively. These percentages in the sympathetic ganglia were significantly decreased in acute (58 +/- 2% for superior cervical ganglion and 58 +/- 8% for stellate ganglion) and chronic (60 +/- 2% for superior cervical ganglion and 59 +/- 15% for stellate ganglion) phases of arthritis, while in the otic ganglion these percentages were significantly increased to 19 +/- 5% and 13 +/- 3%, respectively. In the trigeminal ganglion, CGRP-IR neurons innervating the joint significantly increased from 31 +/- 3% in normal animals to 54 +/- 2% and 49 +/- 3% in the acute and chronic phases of arthritis, respectively. It can be concluded that NPY neurons that send nerve fibers to the rat temporomandibular joint are located mainly in the superior cervical, stellate and otic ganglia. Acute and chronic phases of carrageenan-induced arthritis lead to an increase in the percentage of NPY-IR parasympathetic and CGRP-IR sensory neurons and to a decrease in the percentage of NPY-IR sympathetic neurons related to TMJ innervation.

Twelve chromatically opponent ganglion cell types in turtle retina

The turtle retina has been extensively used for the study of chromatic processing mechanisms. Color opponency has been previously investigated with trichromatic paradigms, but behavioral studies show that the turtle has ail ultraviolet (UV) channel and a tetrachromatic visual system. Our laboratory has been working ill the characterization of neuronal responses in the retina of vertebrates using stimuli in the UV-visible range of the electromagnetic spectrum. In the present investigation, we recorded color-opponent responses from turtle amacrine and ganglion cells to UV and visible stimuli and extended our previous results that UV color-opponency is present at the level of the inner nuclear layer. We recorded from 181 neurons, 36 of which were spectrally opponent. Among these, there were 10 amacrine (5%), and 26 ganglion cells (15%). Morphological identification of color-opponent neurons was possible for two ganglion cell classes (G17 and G22) and two amacrine cell classes (A22 and A23b). There was a variety of cell response types and a potential for complex processing of chromatic stimuli, with intensity- and wavelength-dependent response components. Ten types of color opponency were found in ganglion cells and by adding previous results from our laboratory, 12 types of opponent responses have been found. The majority of the ganglion cells were R+UVBG- and RG+UVB-color-opponents but there were other less frequent types of chromatic opponency. This study confirms the participation of a UV channel in the processing of color opponency in the turtle inner retina and shows that the turtle visual system has the retinal mechanisms to allow many possible chromatic combinations.

Dynamic Range of Vertebrate Retina Ganglion Cells: Importance of Active Dendrites and Coupling by Electrical Synapses

The vertebrate retina has a very high dynamic range. This is due to the concerted action of its diverse cell types. Ganglion cells, which are the output cells of the retina, have to preserve this high dynamic range to convey it to higher brain areas. Experimental evidence shows that the firing response of ganglion cells is strongly correlated with their total dendritic area and only weakly correlated with their dendritic branching complexity. On the other hand, theoretical studies with simple neuron models claim that active and large dendritic trees enhance the dynamic range of single neurons. Theoretical models also claim that electrical coupling between ganglion cells via gap junctions enhances their collective dynamic range. In this work we use morphologically reconstructed multi-compartmental ganglion cell models to perform two studies. In the first study we investigate the relationship between single ganglion cell dynamic range and number of dendritic branches/total dendritic area for both active and passive dendrites. Our results support the claim that large and active dendrites enhance the dynamic range of a single ganglion cell and show that total dendritic area has stronger correlation with dynamic range than with number of dendritic branches. In the second study we investigate the dynamic range of a square array of ganglion cells with passive or active dendritic trees coupled with each other via dendrodendritic gap junctions. Our results suggest that electrical coupling between active dendritic trees enhances the dynamic range of the ganglion cell array in comparison with both the uncoupled case and the coupled case with cells with passive dendrites. The results from our detailed computational modeling studies suggest that the key properties of the ganglion cells that endow them with a large dynamic range are large and active dendritic trees and electrical coupling via gap junctions.

Cone contrast influence on components of the pattern onset/offset VECP

Transient visual evoked cortical potentials (VECP) were recorded from the scalp of healthy normal trichromats (n = 12). VECPs were elicited by onset/offset presentation of patterned stimuli of two kinds: isochromatic luminance-modulated, and equiluminant red-green modulated, sine wave gratings. The amplitude and latency of the major onset components of the onset/offset VECP were measured and plotted as a function of the logarithm of pooled cone contrast. The early onset components, achromatic C1 and chromatic N1, increase linearly with log contrast, but N1 has a higher contrast gain than C1. The late onset components, achromatic C2 and chromatic N2, have similar contrast gain, and similar response as a function of contrast level: both increase in the low-to-medium range of contrasts and saturate at high contrast levels. In the range of pooled cone contrast tested, C1 and N1 show similar latencies, whilst C2 shows shorter latencies than N2. We suggest that C1 and N1 are generated by the same visual mechanism with high red-green contrast gain and low luminance contrast gain, whilst C2 and N2 are generated by different visual mechanisms.

Cone photopigment variations in Cebus apella monkeys evidenced by electroretinogram measurements and genetic analysis

We investigated the color vision pattern in Cebus apella monkeys by means of electroretinogram measurements (ERG) and genetic analysis. Based on ERG we could discriminate among three types of dichromatic males. Among females, this classification is more complex and requires additional genetic analysis. We found five among 10 possible different phenotypes, two trichromats and three dichromats. We also found that Cebus present a new allele with spectral peak near 552 nm, with the amino acid combination SFT at positions 180, 277 and 285 of the opsin gene, in addition to the previously described SYT, AFT and AFA alleles. (C) 2009 Elsevier Ltd. All rights reserved.

Toward a Clinical Protocol for Assessing Rod, Cone, and Melanopsin Contributions to the Human Pupil Response

PURPOSE. To better understand the relative contributions of rod, cone, and melanopsin to the human pupillary light reflex (PLR) and to determine the optimal conditions for assessing the health of the rod, cone, and melanopsin pathways with a relatively brief clinical protocol. METHODS. PLR was measured with an eye tracker, and stimuli were controlled with a Ganzfeld system. In experiment 1, 2.5 log cd/m(2) red (640 +/- 10 nm) and blue (467 +/- 17 nm) stimuli of various durations were presented after dark adaptation. In experiments 2 and 3, 1-second red and blue stimuli were presented at different intensity levels in the dark (experiment 2) or on a 0.78 log cd/m(2) blue background (experiment 3). Based on the results of experiments 1 to 3, a clinical protocol was designed and tested on healthy control subjects and patients with retinitis pigmentosa and Leber`s congenital amaurosis. RESULTS. The duration for producing the optimal melanopsin-driven sustained pupil response after termination of an intense blue stimulus was 1 second. PLR rod-and melanopsin-driven components are best studied with low-and high-intensity flashes, respectively, presented in the dark (experiment 2). A blue background suppressed rod and melanopsin responses, making it easy to assess the cone contribution with a red flash (experiment 3). With the clinical protocol, robust melanopsin responses could be seen in patients with few or no contributions from the rods and cones. CONCLUSIONS. It is possible to assess the rod, cone, and melanopsin contributions to the PLR with blue flashes at two or three intensity levels in the dark and one red flash on a blue background. (Invest Ophthalmol Vis Sci. 2011; 52: 6624-6635) DOI: 10.1167/iovs.11-7586

Contrast Sensitivity Mediated by Inferred Magno- and Parvocellular Pathways in Type 2 Diabetics with and without Nonproliferative Retinopathy

PURPOSE. To evaluate achromatic contrast sensitivity (CS) with magnocellular-(M) and parvocellular-(P) probing stimuli in type 2 diabetics, with (DR) or without (NDR) nonproliferative retinopathy. METHODS. Inferred M-and P-dominated responses were assessed with a modified version of the steady-/pulsed-pedestal paradigm (SP/PP) applied in 26 NDR (11 male; mean age, 55 +/- 9 years; disease duration, 5 +/- 4 years); 19 DR (6 male; mean age, 58 +/- 7 years; disease duration = 9 +/- 6 years); and 18 controls (CTRL; 12 male; mean age, 55 +/- 10 years). Thresholds were measured with pedestals at 7, 12, and 19 cd/m(2), and increment durations of 17 and 133 ms. The thresholds from the two stimulus durations were used to estimate critical durations (Tc) for each data set. RESULTS. Both DR and NDR patients had significant reduction in CS in both SP and PP paradigms in relation to CTRL (Kruskal-Wallis, P < 0.01). Patients` critical duration estimates for either paradigm were not significantly different from CTRL. CONCLUSIONS. The significant reduction of CS in both paradigms is consistent with losses of CS in both M and P pathways. The CS losses were not accompanied by losses in temporal processing speed in either diabetic group. Significant CS loss in the group without retinopathy reinforces the notion that neural changes associated with the cellular and functional visual loss may play an important role in the etiology of diabetic visual impairment. In addition, the results show that the SP/PP paradigm provides an additional tool for detection and characterization of the early functional damage due to diabetes. (Invest Ophthalmol Vis Sci. 2011; 52:1151-1155) DOI:10.1167/iovs.09-3705

Influence of biliary anastomosis on recovery from secondary biliary cirrhosis

Objective The influence of choledochoduodenostomy and choledochojejunostomy on the repair of hepatic lesions secondary to biliary obstruction is not well known. The aim of the present study was to compare the effects of choledochoduodenostomy and choledochojejunostomy on the recovery of these lesions in rats with biliary obstruction. Methods Rats subjected to 4 weeks of biliary obstruction underwent choledochoduodenostomy (n=10) or choledochojejunostomy (n=10). The following variables were measured: total bilirubin, alkaline phosphatase, aminotransferases, and albumin. Hepatic mitochondrial energy metabolism was evaluated by calculating the respiratory control ratio and the oxidative phosphorylation index. Hepatic morphometry was used to estimate the mass of the hepatocytes, bile ducts, and fibrosis, as well as the hepatic stellate cell count. Results After choledochoduodenostomy and choledochojejunostomy, there was a regression in cholestasis and a reduction in the oxidative phosphorylation index. However, the total bilirubin, alkaline phosphatase, albumin, and respiratory control ratio values improved only after choledochojejunostomy. The mass of the liver, spleen, and fibrosis was reduced after both choledochoduodenostomy and choledochojejunostomy, but the number of hepatic stellate cells increased. After choledochojejunostomy, the hepatic mass recovered completely, and the spleen mass was significantly reduced compared with that after choledochoduodenostomy. After both choledochoduodenostomy and choledochojejunostomy, enterobiliary reflux, biliary contamination, and an exacerbation in hepatic inflammation developed. Conclusion Choledochojejunostomy was more effective than choledochoduodenostomy, but both techniques induced enterobiliary reflux and biliary contamination, which may explain the maintenance of hepatic alterations, especially after choledochoduodenostomy. Eur J Gastroenterol Hepatol 24: 1039-1050 (C) 2012 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Cardiovascular effects of the microinjection of L-proline into the third ventricle or the paraventricular nucleus of the hypothalamus in unanesthetized rats

We investigated the cardiovascular effects of the microinjection of L-proline (L-Pro) into the third ventricle (3V) and its peripheral mechanisms. Different doses of L-Pro into the 3V caused dose-related pressor and bradycardiac responses. The pressor response to L-Pro injected into the 3V was potentiated by intravenous pretreatment with the ganglion blocker pentolinium (5 mg/kg), thus excluding any significant involvement of the sympathetic nervous system. Because the response to the microinjection of L-Pro into the 3V was blocked by intravenous pretreatment with the V1-vasopressin receptor antagonist dTyr(CH2)5(Me)AVP (50 mu g/kg), it is suggested that these cardiovascular responses are mediated by a vasopressin release. The pressor response to the microinjection of L-Pro into the 3V was found to be mediated by circulating vasopressin, so, given that the paraventricular nucleus of the hypothalamus (PVN) is readily accessible from the 3V, we investigated whether the PVN could be a site of action for the L-Pro microinjected in the 3V. The microinjection of L-Pro (0.033 mu moles/0.1 mu l) into the PVN caused cardiovascular responses similar to those of injection of the 3V and were also shown to be mediated by vasopressin release. In conclusion, these results show that the microinjection of L-Pro into the 3V causes pressor and bradycardiac responses that could involve stimulation of the magnocellular cells of the PVN and release of vasopressin into the systemic circulation. Also, because the microinjection of L-Pro into the PVN caused a pressor response, this is the first evidence of cardiovascular effects caused by its injection in a supramedullary structure. (c) 2012 Wiley Periodicals, Inc.

Cardiovascular responses to glutamate microinjection in the dorsomedial periaqueductal gray of unanesthetized rats

The periaqueductal gray area (PAG) is a mesencephalic area involved in cardiovascular modulation. Glutamate (L-Glu) is an abundant excitatory amino acid in the central nervous system (CNS) and is present in the rat PAG. Moreover, data in the literature indicate its involvement in central blood pressure control. Here we report on the cardiovascular effects caused by microinjection of L-Glu into the dorsomedial PAG (dmPAG) of rats and the glutamatergic receptors as well as the peripheral mechanism involved in their mediation. The microinjection of L-Glu into the dmPAG of unanesthetized rats evoked dose-related pressor and bradycardiac responses. The cardiovascular response was significantly reduced by pretreatment of the dmPAG with a glutamatergic M-methyl-D-aspartate (NMDA) receptor antagonist (LY235959) and was not affected by pretreatment with a non-NMDA receptor antagonist (NBQX), suggesting a mediation of that response by the activation of NMDA receptors. Furthermore, the pressor response was blocked by pretreatment with the ganglion blocker pentolinium (5 mg/kg, intravenously), suggesting an involvement of the sympathetic nervous system in this response. Our results indicate that the microinjection of L-Glu into the dmPAG causes sympathetic-mediated pressor responses in unanesthetized rats, which are mediated by glutamatergic NMDA receptors in the dmPAG. (c) 2012 Wiley Periodicals, Inc.

Spermatophoric reaction reappraised: Novel insights into the functioning of the loliginid spermatophore based on Doryteuthis plei (Mollusca: Cephalopoda)

During copulation, spermatophores produced by male coleoid cephalopods undergo the spermatophoric reaction, a complex process of evagination that culminates in the attachment of the spermatangium (everted spermatophore containing the sperm mass) on the female's body. To better understand this complicated phenomenon, the present study investigated the functional morphology of the spermatophore of the squid Doryteuthis plei applying in vitro analysis of the reaction, as well as light and electron microscopy investigation of spermatangia obtained either in vitro, or naturally attached on females. Hitherto unnoticed functional features of the loliginid spermatophore require a reappraisal of some important processes involved in the spermatophoric reaction. The most striking findings concern the attachment mechanism, which is not carried out solely by cement adhesive material, as previously believed, but rather by an autonomous, complex process performed by multiple structures during the spermatophoric reaction. During evagination, the ejaculatory apparatus provides anchorage on the targeted tissue, presumably due to the minute stellate particles present in the exposed spiral filament. Consequently, the ejaculatory apparatus maintains the attachment of the tip of the evaginating spermatophore until the cement body is extruded. Subsequently, the cement body passes through a complex structural rearrangement, which leads to the injection of both its viscid contents and pointed oral region onto the targeted tissue. The inner membrane at the oral region of the cement body contains numerous stellate particles attached at its inner side; eversion of this membrane exposes these sharp structures, which presumably adhere to the tissue and augment attachment. Several naturally attached spermatangia were found with their bases implanted at the deposition sites, and the possible mechanisms of perforation are discussed based on present evidence. The function of the complex squid spermatophore and its spermatophoric reaction is revisited in light of these findings. J. Morphol. 2012. (C) 2011 Wiley Periodicals, Inc.

Phosphene Thresholds Elicited by Transcorneal Electrical Stimulation in Healthy Subjects and Patients with Retinal Diseases

PURPOSE. To evaluate electrically evoked phosphene thresholds (EPTs) in healthy subjects and in patients with retinal disease and to assess repeatability and possible correlations with common ophthalmologic tests. METHODS. In all, 117 individuals participated: healthy subjects (n = 20) and patients with retinitis pigmentosa (RP, n = 30), Stargardt's disease (STG, n = 14), retinal artery occlusion (RAO, n = 20), nonarteritic anterior ischemic optic neuropathy (NAION, n = 16), and primary open-angle glaucoma (POAG, n = 17). EPTs were determined at 3, 6, 9, 20, 40, 60, and 80 Hz with 5+5-ms biphasic current pulses using DTL electrodes. Subjects were examined twice (test-retest range: 1-6 weeks). An empirical model was developed to describe the current-frequency relationship of EPTs. Visual acuity, visual field (kinetic + static), electrophysiology (RP, RAO, STG: Ganzfeld-electroretinography [ERG]/multifocal-ERG; POAG: pattern-ERG; NAION: VEP), slit-lamp biomicroscopy, fundus examination, and tonometry were assessed. RESULTS. EPTs varied between disease groups (20 Hz: healthy subjects: 0.062 +/- 0.038 mA; STG: 0.102 +/- 0.097 mA; POAG: 0.127 +/- 0.09 mA; NAION: 0.244 +/- 0.126 mA; RP: 0.371 +/- 0.223 mA; RAO: 0.988 +/- 1.142 mA). In all groups EPTs were lowest at 20 Hz. In patients with retinal diseases and across all frequencies EPTs were significantly higher than those in healthy subjects, except in STG at 20 Hz (P = 0.09) and 40 Hz (P = 0.17). Test-retest difference at 20 Hz was 0.006 mA in the healthy group and 0.003-0.04 mA in disease groups. CONCLUSIONS. Considering the fast, safe, and reliable practicability of EPT testing, this test might be used more often under clinical circumstances. Determination of EPTs could be potentially useful in elucidation of the progress of ophthalmologic diseases, either in addition to standard clinical assessment or under conditions in which these standard tests cannot be used meaningfully. (ClinicalTrials.gov number, NCT00804102.) (Invest Ophthalmol Vis Sci. 2012; 53: 7440-7448) DOI:10.1167/iovs.12-9612

Unraveling the structure of squids' spermatophores: a combined approach based on Doryteuthis plei (Blainville, 1823) (Cephalopoda: Loliginidae)

Marian, J.E.A.R. and Domaneschi, O. 2012. Unraveling the structure of squids spermatophores: a combined approach based on Doryteuthis plei (Blainville, 1823) (Cephalopoda: Loliginidae). Acta Zoologica (Stockholm) 93: 281307. Male coleoid cephalopods produce elaborate spermatophores, which function autonomously outside the male body during copulation, undergoing a complicated process of evagination. In order to contribute to the understanding of this unique structure, this study investigated the morphology of the spermatophore of Doryteuthis plei applying several microscopy techniques. A hitherto unreported, much more complex structural arrangement was revealed for the loliginid spermatophore, the most striking findings being: (1) the complex, layered structure of the middle membrane, which bears an additional, chemically distinct segment surrounding part of the cement body; (2) the presence of a space between the inner tunic and middle membrane filled with a fine reticulated material; (3) the presence of stellate particles not only embedded in the spiral filament, but also closely applied to the inner membrane at the level of the cement body; (4) the presence of a pre-oral chamber in the cap region; and (5) the complex organization of the cement body, formed by two distinct layers encompassing contents of different chemical and textural properties. Careful literature reassessment suggests several of these features are common to loliginids, and to some extent to other squids. Their possible functional implications are discussed in light of our knowledge of the spermatophoric reaction mechanics.

Role of transient receptor potential vanilloid 4 in rat joint inflammation

Objective To determine whether activation of transient receptor potential vanilloid 4 (TRPV-4) induces inflammation in the rat temporomandibular joint (TMJ), and to assess the effects of TRPV-4 agonists and proinflammatory mediators, such as a protease-activated receptor 2 (PAR-2) agonist, on TRPV-4 responses. Methods Four hours after intraarticular injection of carrageenan into the rat joints, expression of TRPV-4 and PAR-2 in trigeminal ganglion (TG) neurons and in the TMJs were evaluated by real-time reverse transcriptionpolymerase chain reaction and immunofluorescence, followed by confocal microscopy. The functionality of TRPV-4 and its sensitization by a PAR-2activating peptide (PAR-2AP) were analyzed by measuring the intracellular Ca2+ concentration in TMJ fibroblast-like synovial cells or TG neurons. Plasma extravasation, myeloperoxidase activity, and the head-withdrawal threshold (index of mechanical allodynia) were evaluated after intraarticular injection of selective TRPV-4 agonists, either injected alone or coinjected with PAR-2AP. Results In the rat TMJs, TRPV-4 and PAR-2 expression levels were up-regulated after the induction of inflammation. Two TRPV-4 agonists specifically activated calcium influx in TMJ fibroblast-like synovial cells or TG neurons. In vivo, the agonists triggered dose-dependent increases in plasma extravasation, myeloperoxidase activity, and mechanical allodynia. In synovial cells or TG neurons, pretreatment with PAR-2AP potentiated a TRPV-4 agonistinduced increase in [Ca2+]i. In addition, TRPV-4 agonistinduced inflammation was potentiated by PAR-2AP in vivo. Conclusion In this rat model, TRPV-4 is expressed and functional in TG neurons and synovial cells, and activation of TRPV-4 in vivo causes inflammation in the TMJ. Proinflammatory mediators, such as PAR-2 agonists, sensitize the activity of TRPV-4. These results identify TRPV-4 as an important signal of inflammation in the joint.

Neural mobilization reverses behavioral and cellular changes that characterize neuropathic pain in rats

Background: The neural mobilization technique is a noninvasive method that has proved clinically effective in reducing pain sensitivity and consequently in improving quality of life after neuropathic pain. The present study examined the effects of neural mobilization (NM) on pain sensitivity induced by chronic constriction injury (CCI) in rats. The CCI was performed on adult male rats, submitted thereafter to 10 sessions of NM, each other day, starting 14 days after the CCI injury. Over the treatment period, animals were evaluated for nociception using behavioral tests, such as tests for allodynia and thermal and mechanical hyperalgesia. At the end of the sessions, the dorsal root ganglion (DRG) and spinal cord were analyzed using immunohistochemistry and Western blot assays for neural growth factor (NGF) and glial fibrillary acidic protein (GFAP). Results: The NM treatment induced an early reduction (from the second session) of the hyperalgesia and allodynia in CCI-injured rats, which persisted until the end of the treatment. On the other hand, only after the 4th session we observed a blockade of thermal sensitivity. Regarding cellular changes, we observed a decrease of GFAP and NGF expression after NM in the ipsilateral DRG (68% and 111%, respectively) and the decrease of only GFAP expression after NM in the lumbar spinal cord (L3-L6) (108%). Conclusions: These data provide evidence that NM treatment reverses pain symptoms in CCI-injured rats and suggest the involvement of glial cells and NGF in such an effect.