RESUMO
The melanin-concentrating hormone and neuropeptide glutamic acid-isoleucine are expressed in neurons located mainly in the hypothalamus that project widely throughout the CNS. One of the melanin-concentrating hormone main targets is the medial mammillary nucleus, but the exact origin of these fibers is unknown. We observed melanin-concentrating hormone and neuropeptide glutamic acid-isoleucine immunoreactive fibers coursing throughout the mammillary complex, showing higher density in the pars lateralis of the medial mammillary nucleus, while the lateral mammillary nucleus showed sparse melanin-concentrating hormone innervation. The origins of these afferents were determined by using implant of the retrograde tracer True Blue in the medial mammillary nucleus. Double-labeled neurons were observed in the lateral hypothalamic area, rostromedial zona incerta and dorsal tuberomammillary nucleus. A considerable population of retrogradely labeled melanin-concentrating hormone perikaryal profiles was also immunoreactive to neuropeptide glutamic acid-isoleucine (74+/-15% to 85+/-15%). The afferents from the lateral hypothalamic area, rostromedial zona incerta and dorsal tuberomammillary nucleus to the medial mammillary nucleus were confirmed using implant of the anterograde tracer Phaseolus vulgaris leucoagglutinin. In addition, using double-labeled immunohistochemistry, we found no co-localization between neurons expressing melanin-concentrating hormone and adenosine deaminase (histaminergic marker) in the dorsal tuberomammillary nucleus. We hypothesize that these melanin-concentrating hormone projections participate in spatial memory process mediated by the medial mammillary nucleus. These pathways would enable the animal to look for food during the initial moments of appetite stimulation.
Assuntos
Axônios/metabolismo , Região Hipotalâmica Lateral/metabolismo , Hormônios Hipotalâmicos/metabolismo , Corpos Mamilares/metabolismo , Melaninas/metabolismo , Vias Neurais/metabolismo , Hormônios Hipofisários/metabolismo , Subtálamo/metabolismo , Animais , Axônios/ultraestrutura , Comportamento Alimentar/fisiologia , Corantes Fluorescentes , Região Hipotalâmica Lateral/citologia , Imuno-Histoquímica , Masculino , Corpos Mamilares/citologia , Memória/fisiologia , Vias Neurais/citologia , Fito-Hemaglutininas , Ratos , Ratos Wistar , Percepção Espacial/fisiologia , Subtálamo/citologiaRESUMO
Previous studies that have used retrograde axonal tracers (horseradish peroxidase alone or conjugated with wheat germ agglutinin) have shown that the temporomandibular joint (TMJ) is supplied with nerve fibers originating mainly from the trigeminal ganglion, in addition to other sensory and sympathetic ganglia. The existence of nerve fibers in the TMJ originating from the trigeminal mesencephalic nucleus is unclear, and the possible innervation by parasympathetic nerve fibers has not been determined. In the present work, the retrograde axonal tracer, fast blue, was used to elucidate these questions and re-evaluated the literature data. The tracer was deposited in the supradiscal articular space of the rat TMJ, and an extensive morphometric analysis was performed of the labeled perikaryal profiles located in sensory and autonomic ganglia. This methodology permitted us to observe labeled small perikaryal profiles in the trigeminal ganglion, clustered mainly in the posterior-lateral region of the dorsal, medial, and ventral thirds of horizontal sections, with some located in the anterior-lateral region of the ventral third. Sensory perikarya were also labeled in the dorsal root ganglia from C2 to C5. No labeled perikaryal profiles were found in the trigeminal mesencephalic nucleus. On the other hand, autonomic labeled perikaryal profiles were distributed in the sympathetic superior cervical and stellate ganglia, and parasympathetic otic ganglion. Our results confirmed those of previous studies and also demonstrated that: (i) there is a distribution pattern of labeled perikaryal profiles in the trigeminal ganglion; (ii) some perikaryal profiles located in the otic ganglion were labeled; and (iii) the trigeminal mesencephalic nucleus did not show any retrogradely labeled perikaryal profiles.
Assuntos
Articulação Temporomandibular/inervação , Amidinas , Animais , Axônios , Corantes Fluorescentes , Gânglios Parassimpáticos , Gânglios Espinais , Masculino , Neurônios Aferentes/citologia , Ratos , Ratos Wistar , Gânglio Estrelado , Gânglio Cervical Superior , Gânglio TrigeminalRESUMO
Immunohistochemistry was used to analyze the rat brain distribution of thimet oligopeptidase and neurolysin. Both enzymes appear ubiquitously distributed within the entire rat brain. However, neuronal perikarya and processes stained for neurolysin, while intense nuclear labeling was only observed for thimet oligopeptidase. These data suggest that neurolysin and thimet oligopeptidase, endopeptidases sharing several functional and structural similarities, are present in distinctive intracellular compartments in neuronal cells.
Assuntos
Química Encefálica , Metaloendopeptidases/análise , Neurônios/química , Animais , Masculino , Ratos , Ratos WistarRESUMO
Melanin-concentrating hormone was identified in the brain of Cebus monkey using immunohistochemical and in situ hybridization. MCH-immunoreactive neurons were found in the lateral hypothalamus and dorsolateral zona incerta. MCH-ir fibers were seen in the medial mammillary nucleus, and in the median eminence, and very few fibers in the globus pallidus. This is the first report describing the MCH-ir cell and fiber distribution in the monkey brain.
Assuntos
Encéfalo/metabolismo , Cebus/metabolismo , Hormônios Estimuladores de Melanócitos/metabolismo , Animais , Globo Pálido/metabolismo , Região Hipotalâmica Lateral/metabolismo , Imuno-Histoquímica , Hibridização In Situ , Masculino , Corpos Mamilares/metabolismo , Eminência Mediana/metabolismo , Fibras Nervosas/metabolismo , Distribuição TecidualRESUMO
A quantitative evaluation of the types of afferent synaptic contacts in the pars oralis, using transganglionic degeneration and a comparison of previous data obtained from the pars interpolaris (Lapa & Bauer, 1992), of the rat was performed. Following left inferior alveolar nerve transection or partial pulpectomy of the first and second left lower molar teeth well-defined degenerating terminals appeared bilaterally. In both experiments, the majority of these afferent synapses formed single asymmetric contacts with intermediate and distal dendritic segments in the pars oralis. Fewer contacts were observed with dendritic spines, proximal dendritic segments, perikarya, and other terminals. Double and multiple synaptic contacts, preferentially with small dendritic profiles, were also found. Pars oralis showed higher density of degenerating terminals and higher proportion of the contralateral contacts than pars interpolaris suggesting that it is a prime input area and that it may play a role in the bilateral management of sensory information. Pars oralis showed a higher density of contacts with intermediate and distal dendritic segment and a lower density of double contacts in comparison to the pars interpolaris. Partial pulpectomy revealed a distribution in synaptic types similar to that following IAN transection suggesting that sensory fibers conveying pain-related stimuli are not distinguished from fibers of other sensory modalities as to preference of synaptic contacts. The overall pattern demonstrates a structural organization of the sensory inputs to the spinal trigeminal nucleus regarding the bilateral handling of sensory information.
Assuntos
Degeneração Neural/fisiologia , Fibras Nervosas/ultraestrutura , Sinapses/ultraestrutura , Núcleo Espinal do Trigêmeo/ultraestrutura , Vias Aferentes/ultraestrutura , Animais , Ratos , Ratos Wistar , Núcleo Espinal do Trigêmeo/fisiologiaRESUMO
Endo-oligopeptidase (EC 3.4.22.19), an enzyme capable of generating enkephalin by single cleavage from enkephalin-containing peptides, was examined in several areas of the central nervous system (CNS) as well as in the immune and endocrine tissues of rats chronically treated with morphine and submitted to naloxone-induced withdrawal. A specific fluorogenic substrate was used to determine the endopeptidase 22.19 activity. A non-uniform increase in endopeptidase 22.19 activity was detected in the CNS. The highest increase in endopeptidase 22.19 specific activity was found in the dorsal hippocampus (about 3.5-fold higher than control), followed by occipital and frontal cortex, substantia nigra, thalamus and hypothalamus. In peripheral tissues, a significant decrease of endopeptidase 22.19 was observed in the pineal gland, whereas the morphine withdrawal syndrome caused a slight but significant increase in lymphoid tissues such as lymph nodes and thymus. These findings are indicative of a possible participation of endopeptidase 22.19 in naloxone-induced withdrawal.
Assuntos
Encéfalo/enzimologia , Metaloendopeptidases/metabolismo , Morfina/toxicidade , Síndrome de Abstinência a Substâncias/enzimologia , Animais , Comportamento Animal/efeitos dos fármacos , Glândulas Endócrinas/enzimologia , Lobo Frontal/enzimologia , Gânglios Espinais/enzimologia , Hipotálamo/enzimologia , Tecido Linfoide/enzimologia , Masculino , Naloxona/administração & dosagem , Naloxona/farmacologia , Lobo Occipital/enzimologia , Ratos , Ratos Wistar , Substância Negra/enzimologia , Tálamo/enzimologiaRESUMO
The purpose of the present study was to carry out a histologic study of the periapical changes of the maxillary first molar of rats submitted to endodontic treatment under different occlusal conditions. The experiment was carried out under conditions analogous to those used in clinical practice. Pulpotomy, pulpectomy and chemomechanical preparation of the mesial root canal were carried out according to previously established techniques and the mesial root canal was filled with cement and gutta-percha. A glass ionomer cement was used as restorative material under conditions of subocclusion, normal occlusion and excessive occlusal forces. No inflammatory reaction of periapical tissue was observed under the three conditions used, and active closing of the root canal was observed 15 days after the procedure, with the formation of cementum replacing the pulpar remnant.
Assuntos
Oclusão Dentária , Tecido Periapical/patologia , Tratamento do Canal Radicular , Ápice Dentário/patologia , Animais , Oclusão Dentária Traumática/fisiopatologia , Masculino , Maxila , Dente Molar , Pulpectomia , Pulpotomia , Ratos , Ratos Wistar , Obturação do Canal Radicular , Preparo de Canal Radicular , Tratamento do Canal Radicular/efeitos adversos , Tratamento do Canal Radicular/métodosRESUMO
Transganglionic degeneration was used in an electron microscopic study of afferent synaptic contacts in the dorsomedial region of the pars interpolaris of rats. In one experiment, the left inferior alveolar nerve was transected and in the other, partial pulpectomy of the first and second left lower molars was performed. Well defined degenerating terminals, almost completely occupied by round synaptic vesicle profiles were found in both ipsi and contralateral sides. In both experiments, approximately 70% of these terminals formed single asymmetric contacts with intermediate or distal dendritic segments. Fewer contacts were observed with proximal dendritic segments, dendritic spines, perikarya and other terminals. In addition, double and multiple synaptic contacts (synaptic glomeruli), accounting for 10% of the total, were also observed. Quantitative data regarding ultrastructural synaptic elements suggest that there is no preference for post-synaptic sites of fibers related to different sensory modalities such as pain, conveyed by dental fibers or other modalities, conveyed by the inferior alveolar nerve fibers.
Assuntos
Degeneração Neural/fisiologia , Fibras Nervosas/ultraestrutura , Células Receptoras Sensoriais/ultraestrutura , Sinapses/ultraestrutura , Dente/inervação , Núcleo Espinal do Trigêmeo/ultraestrutura , Vias Aferentes/fisiologia , Animais , Polpa Dentária/fisiologia , Masculino , Ratos , Ratos WistarRESUMO
Quantifications in parasympathetic ganglia are not available in literature. The otic ganglia of 9 Wistar rats were studied (thick and semi-thin sections) in order to determine the following quantitative data: ganglionic volume (GV), neuronal volume density (Vv), neuronal cellular surface per cell volume (Sv), and neuronal numerical density (Nv). The results showed (mean +/- SD): GV = 0.31 +/- 0.05 mm3, Vv = 39.62 +/- 12.25%, Sv = 0.169 +/- 0.056 microns-1 and Nv = 3.84 x 10(-5) +/- 1.69 x 10(-5) microns-3. These determinations provide a basis for comparisons of parasympathetic with sympathetic ganglia.
Assuntos
Gânglios Parassimpáticos/anatomia & histologia , Neurônios/citologia , Ratos Endogâmicos/anatomia & histologia , Animais , Gânglios Parassimpáticos/citologia , Masculino , RatosRESUMO
Observations were concentrated on the ultrastructure of perikarya and satellite cells of the otic ganglion of the adult rat. Characteristics of both cell types were morphologically analysed as well as their relationship. Quantitative data concerning the volumetric density were calculated for the following elements of the ganglion: glial cells together (28.5%), unmyelinated fibres (13.4%), myelinated fibres (2.7%), connective tissue (13.6%). This electron microscopic study is a sequence of our previous light microscopic study which determined neuronal densities (COSTA, MANDARIM-DE-LACERDA and BAUER, in press).