Effect of periapical inflammation on calcium binding proteins and ERK in the trigeminal nucleus / Efecto de la inflamación periapical sobre las proteínas fijadoras de calcio y ERK en el núcleo trigeminal

Peripheral inflammation induces plastic changes in neurons and glia which are regulated by free calcium and calcium binding proteins (CaBP). One of the mechanisms associated with the regulation of intracellular calcium is linked to ERK (Extracellular Signal-Regulated Kinase) and its phosphorylated condition (pERK). ERK phosphorylation is important for intracellular signal transduction and participates in regulating neuroplasticity and inflammatory responses. The aim of this study is to analyse the expression of two CaBPs and pERK in astrocytes and neurons in rat trigeminal subnucleus caudalis (Vc) after experimental periapical inflammation on the left mandibular first molar. At seven days post-treatment, the periapical inflammatory stimulus induces an increase in pERK expression both in S100b positive astrocytes and Calbindin D28k positive neurons, in the ipsilateral Vc with respect to the contralateral side and control group. pERK was observed coexpressing with S100b in astrocytes and in fusiform Calbindin D28k neurons in lamina I. These results could indicate that neural plasticity and pain sensitization could be maintained by ERK activation in projection neurons at 7 days after the periapical inflammation.

La inflamación periférica induce cambios plásticos en las neuronas y en la glía, los cuales están regulados por el calcio libre y las proteínas fijadoras calcio (CaBP). Uno de los mecanismos asociados con la regulación del calcio intrace-lular está vinculado con la fosforilación de la pro teína quinasa ERK. Asimismo, ERK fosforilado es importante para la trans-ducción de señales intracelulares y participa en la regulación de la neuroplasticidad y las respuestas inflamatorias. El objetivo de este estudio es analizar la expresión de dos CaBPs y pERK en astrocitos y neuronas del subnúcleo caudal del trigémino (Vc) después de una inflamación periapical experimental en el primer molar inferior izquierdo en ratas. A los siete días posteriores al tratamiento, el estímulo inflamatorio periapical induce un aumento en la expresión de pERK, en el número de astrocitos positivos para la proteína marcadora astroglial S100b y en neuronas positivas para Calbindina D28k, en el Vc ipsilateral respecto del lado contralateral y el grupo de control. Además, se observó coexpresión de pERK tanto en astrocitos S100b positivos, como en neuronas fusiformes Calbindin D28k positivas, de la lámina I. Estas observaciones podrían indicar que la neuroplasticidad y la sensibilización al dolor podrían mantenerse mediante la activación de ERK en las neuronas de proyección a los 7 días de la inflamación periapical.

Orexin-A inhibits capsaicin-induced changes in cyclooxygenase-2 and brain-derived neurotrophic factor expression in trigeminal nucleus caudalis of rats

BACKGROUND: The trigeminal nucleus caudalis (Vc) is a primary central site for trigeminal transmitting. Noxious stimulation of the trigeminal nociceptors alters the central synaptic releases and neural expression of some inflammatory and trophic agents. Orexin-A and the orexin 1 receptor (OX1R) are expressed in pain pathways including trigeminal pain transmission. However, the the mechanism(s) underling orexin-A effects on trigeminal pain modulation have not been fully clarified. METHODS: Trigeminal pain was induced by subcutaneous injection of capsaicin in the upper lip in rats. The effect of trigeminal pain on cyclooxygenase-2 (COX-2) and brain-derived neurotrophic factor (BDNF) expression in the Vc of animals was determined by immunofluorescence. Subsequently, OX1R agonist (orexin-A) and antagonist (SB-334867-A) was administrated in the Vc to investigate the possible roles of the Vc OX1R on changes in COX-2 and BDNF levels following pain induction. RESULTS: The data indicated an increase in COX-2 and decrease in BDNF immuno-reactivity in the Vc of capsaicin, and capsaicin- pretreated with SB-334867-A (80 nM), groups of rat. However, the effect of capsaicin on COX-2 and BDNF expressions was reversed by a Vc microinjection of orexin-A (100 pM). CONCLUSIONS: Overall, the present data reveals that orexin-A can attenuate capsaicin-induced trigeminal pain through the modulation of pain effects on COX-2 and BDNF expressions in the Vc of rats.

Complex Regional Pain Syndrome of the Upper Limbs Caused by Facial Pain / 계명의대학술지

Polyacrylamide hydrogel is a widely used filler material in cosmetic procedures performed on the face and breasts. Recently, however, complications including inflammation, deformity, and pain have been reported. The present article addresses unregulated materials/products injected as dermal fillers. The authors report a case involving a 29-year-old woman who developed severe facial pain after undergoing a cosmetic procedure with injectable triamcinolone and hyaluronidase. Two months later, the pain spread to her upper and lower limbs, and abdomen, which eventually led to the the development and diagnosis of complex regional pain syndrome (CRPS) in the upper limbs. The authors hypothesize that CRPS in the upper limbs was responsible for the facial pain through sensitization of third-order neurons and the trigeminal nucleus caudalis extending to the upper cervical segments.

Quantitative Ultrastructural Analysis of Endings Presynaptic to the Tooth Pulp Afferent Terminals in the Trigeminal Oral Nucleus

The ultrastructural parameters related to synaptic release of endings which are presynaptic to tooth pulp afferent terminals (p-endings) were analyzed to understand the underlying mechanism for presynaptic modulation of tooth pulp afferents. Tooth pulp afferents were labelled by applying wheat-germ agglutinin conjugated horseradish peroxidase to the rat right lower incisor, whereafter electron microscopic morphometric analysis with serial section and reconstruction of p-endings in the trigeminal oral nucleus was performed. The results obtained from 15 p-endings presynaptic to 11 labeled tooth pulp afferent terminals were as follows. P-endings contained pleomorphic vesicles and made symmetrical synaptic contacts with labeled terminals. The p-endings showed small synaptic release-related ultrastructural parameters: volume, 0.82 ± 0.45 µm³ (mean ± SD); surface area, 4.50 ± 1.76 µm²; mitochondrial volume, 0.15 ± 0.07 µm³; total apposed surface area, 0.69 ± 0.24 µm²; active zone area, 0.10 ± 0.04 µm²; total vesicle number, 1045 ± 668.86; and vesicle density, 1677 ± 684/µm². The volume of the p-endings showed strong positive correlation with the following parameters: surface area (r=0.97, P<0.01), mitochondrial volume (r=0.56, P<0.05), and total vesicle number (r=0.73, P<0.05). However, the volume of p-endings did not positively correlate or was very weakly correlated with the apposed surface area (r=-0.12, P=0.675) and active zone area (r=0.46, P=0.084). These results show that some synaptic release-related ultrastructural parameters of p-endings on the tooth pulp afferent terminals follow the "size principle" of Pierce and Mendell (1993) in the trigeminal nucleus oralis, but other parameters do not. Our findings may demonstrate a characteristic feature of synaptic release associated with p-endings.

Immunohistochemical localization of paracetamol sensitive cyclooxygenase [cox-3] in rat trigemino-vascular system: a possible role in the mechanism of migraine/headache pain

Prostaglandins are synthesized by the activity of cyclooxygenase [Cox] isoforms. The newly discovered isoform [Cox-3] has been shown to be potently inhibited by centrally-acting analgesics, such as acetaminophen [paracetamol] which are widely used in treatment of headache. Vascular headaches such as migraine are hypothesized to be due to neural activation in the trigemino-vascular system. This results in vasodilatation of meningeal blood vessels leading to activation of trigeminal sensory afferents and pain. Headache is thus attributable to a neurovascular interaction. In this study the localisation of Cox-3 has been studied in structures known to be involved in pathogenesis of headache including rat dura mater and trigeminal pathway [trigemino-vascular system]. Fifteen adult male Wistar rats weighing 300-400g were killed by decapitation under brief anaesthesia. The dura mater, the trigeminal ganglia and brain were removed and processed for immunohistochemistry using an antibody raised against Cox-3. Dura mater showed Cox-3 immunoreactivity in meningeal blood vessels, perivascular nerve fibres and mast cells. In the trigeminal ganglia, Cox-3 immunoreactivity was localised in neurons of different sizes and in trigeminal nerve fibres. In the brain stem, Cox-3 was localised in neurons in the trigeminal nuclei. These data provide evidence that Cox-3 is expressed in both neuronal and vascular structures known to be involved in pathogenesis of vascular headache. These data support the hypothesis that Cox-3 may be a central target of paracetamol and related analgesics

Preventing Extracellular Diffusion of Trigeminal Nitric Oxide Enhances Formalin-induced Orofacial Pain

Nitric oxide (NO), a diffusible gas, is produced in the central nervous system, including the spinal cord dorsal horn and the trigeminal nucleus, the first central areas processing nociceptive information from periphery. In the spinal cord, it has been demonstrated that NO acts as pronociceptive or antinociceptive mediators, apparently in a concentration-dependent manner. However, the central role of NO in the trigeminal nucleus remains uncertain in support of processing the orofacial nociception. Thus, we here investigated the central role of NO in formalin (3%)-induced orofacial pain in rats by administering membrane-permeable or -impermeable inhibitors, relating to the NO signaling pathways, into intracisternal space. The intracisternal pretreatments with the NO synthase inhibitor L-NAME, the NO-sensitive guanylate cyclase inhibitor ODQ, and the protein kinase C inhibitor GF109203X, all of which are permeable to the cell membrane, significantly reduced the formalin-induced pain, whereas the membrane-impermeable NO scavenger PTIO significantly enhanced it, compared to vehicle controls. These data suggest that an overall effect of NO production in the trigeminal nucleus is pronociceptive, but NO extracellularly diffused out of its producing neurons would have an antinociceptive action.

The Antinociceptive Effect of Sigma-1 Receptor Antagonist, BD1047, in a Capsaicin Induced Headache Model in Rats

Intracranial headaches, including migraines, are mediated by nociceptive activation of the trigeminal nucleus caudalis (TNC), but the precise mechanisms are poorly understood. We previously demonstrated that selective blockage of spinal sigma-1 receptors (Sig-1R) produces a prominent antinociceptive effect in several types of pain models. This study evaluates whether the Sig-1R antagonist (BD1047) has an antinociceptive effect on capsaicin (a potent C-fiber activator) induced headache models in rats. Intracisternal infusion of capsaicin evoked pain behavior (face grooming), which was significantly attenuated by BD1047 pretreatment. BD1047 consistently reduced capsaicin-induced Fos-like immunoreactivity (Fos-LI), a neuronal activator, in the TNC in a dose-dependent manner. Moreover, capsaicin-induced phosphorylation of N-methyl-D-aspartate receptor subunit 1 was reversed by BD1047 pretreatment in the TNC. These results indicate that the Sig-1R antagonist has an inhibitory effect on nociceptive activation of the TNC in the capsaicin-induced headache animal model.

Immunohistochemical Study on the Distribution of Insulin-like Growth Factor Binding Protein 7 (IGFBP7) in the Central Nervous System of Adult Rats / 체질인류학회지

In the present study, we performed immunohistochemical studies to investigate the detailed distribution of insulin-like growth factor binding protein 7 (IGFBP7) in the central nervous system of adult rats. Twelve adult (4~6 month old) Sprague-Dawley rats were examined in this study. Immunohistochemistry using specific antibodies against IGFBP7 was performed in accordance with the free-floating method. In the present study, IGFBP7 immunoreactivity was observed in the cerebral cortex, hippocampus, brainstem, cerebellum and spinal cord. In the cerebral cortex, heavily stained neurons were seen in layers II-VI. In the hippocampus, pyramidal cells in CA1-3 region were strongly immunoreactive for IGFBP7. Strong immunoreactive neurons were also found in the supraoptic nucleus, paraventricular nucleus, periaqueductal gray and oculomotor nucleus. In the cerebellum, IGFBP7 immunoreactivity was prominent in the Purkinje cells and cerebellar output neurons. IGFBP7-immunoreactive neurons were prominent in the superior vestibular nucleus, cochlear nucleus, trigeminal motor nucleus, nucleus of the trapezoid, and facial nucleus. IGFBP7-immunoreactive neurons were also observed mainly in the anterior horn of the spinal cord. The first demonstration of IGFBP7 localization in the whole brain may provide useful data for the future investigations on the structural and functional properties of IGFBP7.

electro-physiologic study of trigeminal brainstem circuits in migraine

The study aimed at investigating functional changes in the trigeminal and optic nerves brainstem connections in migraine patients. Trigeminal somatosensory evoked potentials [TSER's], electric blink reflex [EBR] and light stimulus evoked blink reflex [LBR] were carried out interictally on 18 patients suffering from migraine without aura and 12 healthy controls. TSER's latencies [N1, P1, N2, and P2], EBR latencies [R1, ipsilateral and contralateral R2] as well as LBR latencies [direct and indirect responses] and their amplitudes were recorded and compared to healthy controls. The ipsilateral and the contralateral R2 components of the EBR [R2i, R2c] showed a highly significant delay as compared to the control group [p<0.000]. N1, P1 and N2 latencies in patients were significantly longer than the control group bilaterally. P1 latencies showed the most significant prolongation of latency [p<0.0000]. The latencies of the LBR direct and indirect responses were significantly prolonged in the patient group [p<0.000] and had a double fold amplitude compared to those of the control group. Migraine patients show a disruption in the central circuits not only at the level of the brainstem but possibly within the higher cerebral regions as well

Localization of Motor Neuronal Cell Bodies Innervating the Digastric Muscle of the Rat Using Cholera Toxin B Subunit (CTB) / 대한해부학회지

We used cholera toxin B subunit (CTB) as a neural tracer to localize motor neuronal cell bodies innervating the digastric muscle. After CTB injection into the left anterior belly, CTB-labelled motor neuronal cell bodies were found in caudal half of the left and right trigeminal nucleus, the left and right facial nucleus, the accessory facial nucleus and the accessory trigeminal nucleus in pons. The total number of CTB-labelled motor neuronal cell bodies were 1,179+/-119.5 in the left pons and 246+/-61.8 in the right pons after CTB injections into the left anterior belly of digastric muscle. After CTB injection into left posterior belly, CTB-labelled motor neuronal cell bodies were found only in the left ventral part of accessory facial nucleus in caudal pons and the total number of CTB-labelled motor neuronal cell bodies were 270+/-29.3.

Somatic and visceral nociceptive inputs from the orofacial area and the upper alimentary tract converge onto CB-containing neurons in interstitial nucleus of the spinal trigeminal tract in rats / 生理学报

The interstitial nucleus of the spinal trigeminal tract (INV) contains many calbindin-D28k-containing neurons (CB-neurons) receiving convergence information from the somatic and visceral structures. The purpose of the present study was to confirm whether the primary afferent terminals from the inferior alveolar nerve (IAN) make close contact and synaptic connections with the same CB-neurons receiving visceral nociceptive signals in INV. Biotinylated dextran amine (BDA) and horseradish peroxidase (HRP) tracing combined with CB and Fos proteins immunohistochemistry were used. After injections of BDA and formalin into unilateral IAN and upper alimentary tract, respectively, the transganglionic labeled afferent fibers and terminals from IAN were observed in the ipsilateral INV, especially in its enlarged part. A large number of CB- and Fos-like immunoreactive (LI) neurons were found in bilateral INV. These CB- and Fos-LI neurons mostly overlapped with BDA-labeled terminals in the enlarged part of INV. About one half of the CB-LI neurons were double labeled with Fos-LI nuclei (74/153). The terminals from IAN were to made close contacts with many CB/Fos-double labeled or CB-single labeled neurons. After injection of HRP into IAN, HRP-labeled fibers and terminals in INV were similar to that labeled with BDA. Under the electron microscope, a large number of CB-LI dendrites and a few soma in the enlarged part of INV were found to form asymmetrical axo-dendritic and axo-somal synapses with the HRP-labeled axon terminals. These results indicate that the orofacial somatic inputs from IAN and the visceral nociceptive inputs from the upper alimentary tract converge onto the same CB-containing neurons in INV. These CB-containing neurons in INV probably play an important role in information integration as well as visceral and cardiovascular activity.

Processing Mechanism of Sensory Information Originated from the Oral Cavity in the Trigeminal Nucleus Oralis / 대한해부학회지

To analyze the synaptic characteristics of axon terminals originated from the tooth pulp in the trigeminal nucleus oralis, labeling of tooth pulp afferents with wheat-germ agglutinin conjugated horseradish peroxidase and morphometric analysis with electron microscopic photographs were performed. The results obtained from 23 labeled endings were as follows. All of the labeled boutons contained clear and round synaptic vesicles (dia. 45~55 nm). 3 (13.64%) out of 23 labeled endings have 20~105 dense cored vesicles and do not make synaptic contacts with p-endings. But remaining 20 labeled endings (86.36%) almost do not have dense cored vesicles and 12 of them make synaptic contacts with p-endings. The mean number of synaptic contacts was 2.61+/-2.06 and the postsynaptic profiles were usually middle or distal dendrite and dendritic spine (1.74+/-1.36) rather than soma or proximal dendrite. The mean number of synaptic contacts with pendings was 0.87+/-1.01. And the frequency of the synaptic triads were 0.39+/-0.58. The vesicle density was 993.23+/-267.41/mum(2). The volume of labeled bouton was 3.54+/-2.20 mum(3) and highly correlated (P < 0.01) with surface area (11.78+/-4.92 mum(2), r = 0.95), total apposed surface area (2.90+/-1.56 mum(2), r=0.72), total active zone area (0.61+/-0.37 mum(2), r = 0.82), mitochondrial volume (0.75+/-0.53 mum(3), r = 0.94), the number of synaptic vesicles (2621.30+/-1473.61, r= 0.91) and the number of synaptic contacts (r = 0.76). These results suggest that there are two groups of tooth pulp afferent terminals according to the presence of dense cored vesicles in the trigeminal nucleus oralis. And the sensory processing mechanism of each groups may be different. And the "size principle" of Pierce & Mendell (1993) is also applicable to these terminals.

Nociceptive and Trigeminal Cardiovascular Reflex Mechanisms after Noxious Intrapulpal Stimulation of the Rat Incisors / 대한해부학회지

Expression of c-Fos, an immediate early gene, has accepted to be a marker of functional activity in neurons. This study was aimed to investigate the dental pain pathway and the affection of dental pain on other brain regions such as the cardiovascular regulation center using c-Fos immunohistochemistry. Expression of c-Fos in Sprague Dawley rats weighting 300 ~350 gm was examined 1.5 hr after dental pain elicited by intrapulpal injecton of 2 M KCl into upper and lower incisor pulps exposed by bone cutter. c-Fos positive neurons were demonstrated in the trigeminal nucleus caudalis and the ventroposterior medial nucleus of thalamus known to be a sharp pathway. Dental pain enhanced mean arterial pressure and heart rate. In addition, c-Fos expression was induced in the rostral ventrolateral nucleus of medulla oblongata, nucleus tractus solitarius, paraventricular nucleus and supraoptic nucleus of hypothalamus, central presser areas of systemic blood pressure. These results suggest that trigeminal nucleus caudalis and ventroposterior medial nucleus of thalamus plays vital roles in the transmission of dental pain besides, dental pain affected the central cardiovescular regulation centers, resulting to the elevation of systemic blood pressure.

Dual effect of dynorphin A on single-unit spike potentials in rat trigeminal nucleus

The amygdala is known as a site for inducing analgesia, but its action on the trigeminal nucleus has not been known well. Little information is available on the effect of dynorphin on NMDA receptor-mediated electrophysiological events in the trigeminal nucleus. The purpose of this study was to investigate the changes in the single neuron spikes at the trigeminal nucleus caused by the amygdala and the action of dynorphin on the trigeminal nucleus. In the present study, extracellular single unit recordings were made in the dorsal horn of the medulla (trigeminal nucleus caudalis) and the effects of microiontophoretically applied compounds were examined. When (D-Ala2, N-Me-Phe4, Glys5-ol)enkephalin (DAMGO, 10-25 mM), a mu-opioid receptor agonist, was infused into the amygdala, the number of NMDA-evoked spikes at the trigeminal nucleus decreased. However, the application of naloxone into the trigeminal nucleus while DAMGO being infused into the amygdala increased the number of spikes. Low dose (1 mM) of dynorphin in the trigeminal nucleus produced a significant decrease in NMDA-evoked spikes of the trigeminal nucleus but the NMDA-evoked responses were facilitated by a high dose (5 mM) of dynorphin. After the kappa receptors were blocked with naloxone, dynorphin induced hyperalgesia. After the NMDA receptors were blocked with AP5, dynorphin induced analgesia. In conclusion, dynorphin A exerted dose-dependent dual effects (increased & decreased spike activity) on NMDA-evoked spikes in the trigeminal nucleus. The inhibitory effect of the dynorphin at a low concentration was due to the activation of kappa receptors and the excitatory effect at a high concentration was due to activation of NMDA receptors in the trigeminal neurons.

Double-Blind Placebo-Controlled Randomized Clinical Trial of Zolmitriptan in Acute Treatment of Migraine

BACKGROUND: Zolmitriptan (Zomig) is a selective serotonin agonist at the 5-hydroxytryptamine (5-HT1B/1D) receptor that acts both centrally and peripherally in the trigeminal nucleus and axon terminals and at adjacent meningeal vessels. The clinical efficacy of zolmitriptan in adult migraine has been documented in several placebo-controlled studies, but not studied yet in Korea. METHODS: This multicenter, double-blind, placebo-controlled study was directed to evaluate the efficacy and tolerability of a single 2.5-mg dose of zolmitriptan for the acute treatment of a single moderate or severe migraine attack in Korean patients. A sample consisting of 129 outpatients was randomized to receive either zolmitriptan (n=67) or placebo (n=62). RESULTS: The headache response at 2 hours after treatment was significantly greater in patients receiving zolmitriptan than in patients receiving placebo (52.2% versus 30.7%, p<0.05). At 4 hours, the response rate in the zolmitriptan group (91.5%) was significantly higher than in the placebo group (65.6%; p<0.05). Among the nonheadache symptoms, phonophobia was more relieved in the zolmitriptan group than in the placebo group (p=0.038). There were no clinically serious adverse events that were judged by the physicians to be related to zolmitriptan. CONCLUSIONS: The results of this study demonstrate that zolmitriptan tablets 2.5-mg taken for acute migraine attacks are effective and well-tolerated in Korean patients. (J Korean Neurol Assoc 19(1):29~35, 2001

Inter-relaçäo eletrofisiológica e neuroanatômica do núcleo paratrigeminal com estruturas bulbares envolvidas no controle da pressäo arterial / Eletrophysiological and neuroanatomical interactions between the paratrigeminal nucleus and medullary structures involved in the arterial blood pressure control

Recentemente foi demonstrado que o Pa5 possui um papel na mediação do efeito pressor a BK injetada na região dorso-lateral do bulbo de ratos não anestesiados, agindo através de receptores do tipo B2. Esta resposta pressora tem origem central e é acompanhada por um moderado aumento da freqüência cardíaca, proveniente de uma estimulação simpática central. Efeito semelhante pode ser obtido por microinjeções de substância P, L-glutamato ou ibotenato no Pa5, sugerindo uma ação excitatória da BK sobre os neurônios do Pa5. O Pa5 possui um grande número de projeções para a área peribraquial, descrita em ratos. Em adição a estes dados, foram sugeridas projeções para os núcleos do trato solitário, reticular lateral e formação reticular de ratos. As projeções do Pa5 para o NTS e área peribraquial sugerem que este núcleo esteja envolvido em processos regulatórios vegetativos e termosensoriais. Resultados deste laboratório demonstraram a presença de eferências bilaterais do Pa5 para o NTS comissural e intermediário, e para a área pressora bulbar rostral ventral lateral. Apesar destes dados obtidos com o uso de traçadores retrógrados indicarem as possíveis áreas de projeção, eles possuem um valor limitado para uma identificação precisa das projeções para pequenas estruturas. O presente estudo determinou as áreas de projeções do Pa5 para o NTS e RVLM, com o uso de traçador de transporte anterógrado, e o envolvimento eletrofisiológico do Pa5 com estas estruturas através de um sistema de registro simultâneo de múltiplos neurônios. O traçador anterógrado biocetina microinjetado no Pa5 proveu uma detalhada imagem das projeções bilaterais do núcleo para o trato solitário, na mesma porção do NTS que recebe as aferências dos baroreceptores, receptores cardiopulmonares e quimioreceptores. As projeções do Pa5 para a medula ventral lateral mostraram uma distinta organização topográfica. No sentido rostral, terminais sinápticos marcados foram observados, em ordem sequencial, no LRt, Amb, na parte rostral do Amb e no RVL, e somente no RVL. A análise eletrofisiológica foi realizada em 112 neurônios do NTS e em 81 neurônios da RVLM após o estímulo do Pa5 por BK e injeção de PHE, S-HT, SNP e KCN iv, e em 74 neurônios do Pa5 após a aplicação de BK sobre o mesmo. Após a aplicação de bradicinina sobre o Pa5 de ratos anestesiados foram registrados 57 neurônios (74 por cento) que aumentaram a freqüência de disparos após a aplicaçäo do peptídio, indicando uma açäo..(au)

Differential Effects of Aging on NADPH-diaphroase and Tyrosine Hydroxylase-Positive Neurons in Rat Brain Stem / 대한해부학회지

Nitric oxide is synthesized by neurons containing the nitric oxide synthase (NOS), and the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) is a selective histochemical marker for the brain. Although, many reports have been published describing in detail the distribution of NADPH-d and tyrosine hydroxylase (TH), little information is available on possible morphological changes of NADPH-d and TH containing neurons during aging of the brain stem. Therefore, in this study, we assessed the effects of aging on the somal area and staining intensity of NADPH-d-positive and TH-immunoreactive (TH-IR) neurons in rat brain stem. In previous studies, enzyme activities of nitric oxide synthase (NOS) and NADPH-d were shown to be in an almost perfect correlation in the brain. Therefore, we evaluated the change of NADPH-d-positive neurons using a microdensitometrical method as a way of measuring changes in NOS activity. By using a double-labelling technique, we have shown that these two enzymes are located in separate neurons in most brain stem nuclei. In the aged group, the size of NADPH-d-positive neurons was not significantly changed in most nuclei of the brain stem compared to the control group. Staining intensity of NADPH-d-positive neurons was significantly changed in periaqueductal gray, superior colliculus and inferior colliculus in the aged group. In the aged rats, the size of TH-IR neurons was significantly changed in locus ceruleus and lateral paragigantocellular nucleus. Staining intensity of TH-IR neurons was significantly decreased in principal trigeminal nucleus, locus ceruleus and lateral paragigantocellular nucleus of the aged group. These results demonstrate that the NADPH-d-positive and TH-IR neurons are differently influenced by aging than the control group in the brain stem of rats. Difference in the changes of NADPH-d-positive neurons in brain stem nuclei suggest that neuronal NOS is regulated by different mechanims in the regions of the brain stem during aging.

Immunohistochemical Study on the Nitric Oxide Synthase in the Developing Rat Brain / 대한해부학회지

Nitric oxide(NO) is thought to play an important role in development and plasticity of brain. In this study, we aimed to examine the expression of neuronal NOS and NADPH-diaphorase (NADPH-d) activity in the developing rat brain. The results show that there is a great variation in the time of appearance of the earliest NOS containing cells depending on their location: At the 15th embryonic day weakly stained cells were present in caudate-putamen, and neurons in the sensory trigeminal nucleus and the solitary nucleus displayed an intense staining. The NOS neurons in orbital neocortex, bed nucleus of stria terminalis, paraventricular hypothalamic nucleus, lateral hypothalamic area and mammillary body appeared first at the 18th embryonic day. The supraoptic nucleus and superior and inferior colliculi also weakly labeled at the 18th embryonic day, At the loth embryonic day, positive cells appeared in horizontal limb of diagonal band, anterior olfactory nucleus and parafascicular thalamic nucleus. In the cerebellum, weak NOS staining was present in fibers and cells situated below Purkinje cert layer. The Purkinje cell layer displayed a weak, rather diffuse activity throughout the cerebellum at postnatal day 0. At the 4th postnatal day. the reaction product in the Purkinje cell layer became more distinct. At the 10th postnatal day, the inner part of molecular layer became populated by NOS positive basket cells, and the reaction products on the Purkinje cells began to disappear. The present results showed that NOS in the rat brain is expressed in different populations of neurons at different stages of development. This expression pattern of NOS suggests that NO may play a role in the developmental remodelling of the mammalian brain.