RESUMO
OBJECTIVES: The aim of the present work was to study the effect of long-term cyclosporine (CSA) administration on norepinephrine (NE) metabolism and adrenergic-evoked secretion in the rat submandibular gland (SMG). METHODS: Dose-response curves to adrenergic agonists (methoxamine, isoproterenol, NE) were performed in control and CSA (10 and 30 mg/kg every 2 days for 1 month)-treated rats after SMG duct cannulation. In SMG tissue neuronal NE uptake, release, synthesis and endogenous content were determined. In addition phosphoinositide intracellular signaling was also investigated. RESULTS: CSA administration caused an increase in salivary secretion evoked by methoxamine (alpha-adrenergic agonist) and NE but failed to modify salivation evoked by beta-adrenergic stimulation (isoproterenol). Long-term CSA administration decreased NE release and synthesis whereas it enhanced the amine uptake and phosphoinositide hydrolysis in the SMG. CONCLUSIONS: The administration of CSA for 30 days induced salivary gland sensitization likely mediated by diminished adrenergic input. Present results suggest that the decreased sympathetic activity evoked by long-term CSA administration in the rat SMG may lead to sensitization of the gland supported by increased phosphoinositide hydrolysis and enhanced adrenergic-evoked salivation.
Assuntos
Ciclosporina/farmacologia , Imunossupressores/farmacologia , Norepinefrina/metabolismo , Salivação/efeitos dos fármacos , Glândula Submandibular/efeitos dos fármacos , Fibras Simpáticas Pós-Ganglionares/efeitos dos fármacos , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Relação Dose-Resposta a Droga , Esquema de Medicação , Hidrólise/efeitos dos fármacos , Masculino , Metoxamina/farmacologia , Norepinefrina/farmacologia , Fosfatidilinositóis/metabolismo , Ratos , Ratos Wistar , Salivação/imunologia , Glândula Submandibular/inervação , Glândula Submandibular/metabolismo , Fibras Simpáticas Pós-Ganglionares/imunologia , Fibras Simpáticas Pós-Ganglionares/metabolismoRESUMO
Neurons from the superior cervical ganglia (SCG) innervate the submandibular gland and release noradrenaline during the dark phase of the daily photoperiod. Since in the pineal, another structure innervated by sympathetic neurons, nocturnal activation of the SCG is associated with beta-adrenergic sub- and super-sensitivity rhythms, the possible existence of similar phenomena in the rat submandibular gland was assessed. Wistar female rats, kept on a 14:10 light/dark cycle (light from 06:00 to 20:00 h), were sacrificed at 09:00, 14:00, 20:00, 24:00 and 04:00 h. beta-Adrenoceptors were studied by 3H-dihydroalprenolol binding to membrane preparations. The equilibrium dissociation constant (Kd) did not change as a function of time while significant daily variations in maximal binding values (Bmax) were observed with a peak at 20:00 h. Changes in Bmax correlated with a high response of adenylate cyclase to isoproterenol. In addition, when the response in salivary flow to isoproterenol was measured. a shift to the left (about 1 logarithmic unit) in dose-response curves was observed at 19:00-20:00 has compared to 08:00-09:00 h. These daily variations in isoproterenol responsiveness seem not to depend on the pattern of eating since a 24-h starvation or a nocturnal starvation for 16-18 days did not abolish the morning-evening differences in the salivary flow response to isoproterenol. Rather, the results suggest that the daily variations in isoproterenol response correlate with beta-adrenergic super- and sub-sensitivity phenomena associated with the circadian release of noradrenaline from SCG neurons.
Assuntos
Ritmo Circadiano/fisiologia , Receptores Adrenérgicos beta/metabolismo , Glândula Submandibular/inervação , Glândula Submandibular/metabolismo , Adenilil Ciclases/metabolismo , Agonistas Adrenérgicos beta/farmacologia , Antagonistas Adrenérgicos beta/metabolismo , Antagonistas Adrenérgicos beta/farmacologia , Animais , Di-Hidroalprenolol/metabolismo , Di-Hidroalprenolol/farmacologia , Comportamento Alimentar/fisiologia , Feminino , Isoproterenol/farmacologia , Ratos , Ratos Wistar , Saliva/metabolismo , Gânglio Cervical Superior/fisiologia , TrítioRESUMO
IFN gamma is a pleiotropic cytokine that exerts immunologic and non-immunologic functions. We show here that at low doses (10 U/ml), it stimulates amylase secretion in murine submandibular glands (SMG) "via" muscarinic receptor activation, comparable to that produced by the muscarinic agonist carbachol. Both effects are blocked by atropine. NG-monomethyl-L-arginine (L-NMMA) and EGTA inhibited the cytokine effect on amylase secretion, involving the participation of a calcium-dependent isoform of nitric oxide synthase (NOS). We confirm NOS activation because IFN gamma stimulates nitrite production and enzyme activity in SMG. Carbachol (10(-7) M) did not modify basal nitric oxide production. In addition, both IFN gamma and carbachol increase prostaglandin E2 production in SMG, but while indomethacin potentiates IFN gamma effect on amylase secretion, it blunted amylase secretion exerted by carbachol. Thus, IFN gamma and carbachol stimulate IFN gamma secretion on SMG in a dose-dependent manner. Our results are pointing to neuroregulatory functions of IFN gamma in murine SMG, because it regulates its own levels in oral cavity, perhaps to exert a local immuno-surveillance.
Assuntos
Amilases/metabolismo , Interferon gama/farmacologia , Sistema Nervoso Parassimpático/efeitos dos fármacos , Sistema Nervoso Parassimpático/fisiologia , Glândula Submandibular/efeitos dos fármacos , Glândula Submandibular/fisiologia , Animais , Carbacol/farmacologia , Dinoprostona/biossíntese , Ácido Egtázico/farmacologia , Feminino , Interferon gama/biossíntese , Camundongos , Camundongos Endogâmicos BALB C , Óxido Nítrico/biossíntese , Óxido Nítrico Sintase/metabolismo , Receptores Muscarínicos/efeitos dos fármacos , Receptores Muscarínicos/fisiologia , Proteínas Recombinantes , Glândula Submandibular/imunologia , Glândula Submandibular/inervação , ômega-N-Metilarginina/farmacologiaRESUMO
In man, the rate of resting salivary secretion can be influenced by environmental stimuli related to light dark cycles or by noxious stimuli (stressors) of psychological origin. The sympathetic branch of the autonomic nervous system and the adrenal medulla play an important part in homeostatic responses. Previous observations have shown that chronic exposure of rats to constant light promotes degranulation of parotid acini and desensitization of submandibular beta-adrenergic receptors. Now the submandibular secretory response elicited by beta- and alpha2-adrenergic agonists was studied in rats chronically exposed to environmental conditions that modified the activities of sympathetic efferents to the pineal, salivary and adrenal glands. Adult male rats were exposed to constant light (LL) or constant darkness (DD) for 20 days, or to stress (2 h daily immobilization) for 14 days. Control animals were kept under the usual lighting conditions and without immobilization. Dose response curves to isoproterenol (i.v), before and after administration (i.v.) of a dose (20 microg/kg) of clonidine were obtained. Beta-adrenergic desensitization was observed in all the experimental groups, while alpha2-adrenergic desensitization was only observed in the stress and LL groups. The results suggest that circulating catecholamines could mediate light and stress effects on submandibular beta-adrenergic secretory responses. Extrasynaptic alpha2-adrenoceptors might modulate the submandibular secretory response when predictable environmental stimuli (daily light phase) or unpredictable stressors raise the concentrations of circulating catecholamines.
Assuntos
Meio Ambiente , Receptores Adrenérgicos alfa 2/fisiologia , Receptores Adrenérgicos beta/fisiologia , Estresse Fisiológico/fisiopatologia , Glândula Submandibular/fisiologia , Glândulas Suprarrenais/efeitos dos fármacos , Glândulas Suprarrenais/inervação , Glândulas Suprarrenais/fisiologia , Agonistas alfa-Adrenérgicos/administração & dosagem , Agonistas alfa-Adrenérgicos/sangue , Agonistas alfa-Adrenérgicos/farmacologia , Agonistas Adrenérgicos beta/administração & dosagem , Agonistas Adrenérgicos beta/farmacologia , Animais , Ritmo Circadiano , Clonidina/administração & dosagem , Clonidina/farmacologia , Escuridão , Relação Dose-Resposta a Droga , Vias Eferentes/efeitos dos fármacos , Vias Eferentes/fisiologia , Imobilização , Injeções Intravenosas , Isoproterenol/administração & dosagem , Isoproterenol/farmacologia , Iluminação , Masculino , Norepinefrina/sangue , Glândula Pineal/efeitos dos fármacos , Glândula Pineal/inervação , Glândula Pineal/fisiologia , Ratos , Ratos Wistar , Receptores Adrenérgicos alfa 2/efeitos dos fármacos , Receptores Adrenérgicos beta/efeitos dos fármacos , Saliva/metabolismo , Glândula Submandibular/efeitos dos fármacos , Glândula Submandibular/inervação , Glândula Submandibular/metabolismo , Sistema Nervoso Simpático/efeitos dos fármacos , Sistema Nervoso Simpático/fisiologiaRESUMO
Rats exposed for 2, 5, 10, 20, 35 and 50 days to constant light (CL) showed beta-adrenergic desensitization of the submandibular gland as indicated by dose-response curves to 1.5, 2.0, 3.0, 10.0, 30.0 and 50.0 micrograms/kg isoproterenol. The phenomenon, evident with 1.5, 2.0 and 50.0 micrograms/kg after 2 days at CL, was more intense as time of exposure increased to reach values of about 50% those for controls after 20 days. After 35 and 50 days, desensitization showed some reversion, but the secretory responses were still lower than for controls maintained under a typical photoperiod. In the groups of rats exposed to CL for 20 days, gland wet and dry weights were higher (10%) than those of controls. These changes probably indicate an adaptation of the sympathetic control of salivary secretion induced by environmental illumination.
Assuntos
Fotoperíodo , Receptores Adrenérgicos beta/efeitos da radiação , Saliva/metabolismo , Glândula Submandibular/inervação , Glândula Submandibular/metabolismo , Animais , Relação Dose-Resposta a Droga , Isoproterenol/farmacologia , Luz , Masculino , Tamanho do Órgão , Ratos , Ratos Wistar , Receptores Adrenérgicos beta/efeitos dos fármacos , Taxa Secretória , Estimulação Química , Glândula Submandibular/efeitos dos fármacos , Glândula Submandibular/efeitos da radiaçãoRESUMO
The properties (kD and Bmax) of alpha-1 and alpha-2 adrenoceptors in rat submaxillary gland have been determined by the binding process of radioactive ligands. Data of dissociation constants compiled from several tissues by this technique closely agree with physiological measurements. The radioactive ligand binding method has afforded evidence for changes in receptor number elicited by procedures that induce either hyper or hyposensitivity of the response. Chemical sympathectomy with reserpine increases 10 fold the number of alpha-2 receptors in rat submaxillary gland, as determined by the binding of [3H] clonidine. Sympathetic surgical denervation also increases the number of alpha-2 adrenoceptors by about 50%. Alpha-1 adrenoceptors were studied using [3H] prazosin or [3H] WB 4101. In gangliectomized submaxillary glands, we did not find an increase in the number of binding sites. Alpha-1 and alpha-2 adrenoceptors are also modulated by the parasympathetic system. Sectioning of the chordalingual nerve 21 days before the experiment produces an increase of about 50% in both types of alpha adrenoceptors in the submaxillary gland. These results indicate a major modulatory role of the cholinergic system on postsynaptic adrenoceptors. This type of regulation has also been found in other tissues such as brown adipose tissue and in complex systems like the brain. The results show that the major salivary glands of the rat are a useful model for the study of adrenoceptor regulation and that the data obtained can be extrapolated to more complex systems.
Assuntos
Receptores Adrenérgicos alfa/fisiologia , Glândula Submandibular/inervação , Animais , Sistema Nervoso Autônomo/fisiologia , Denervação , Dioxanos/farmacologia , Modelos Animais de Doenças , Prazosina/farmacologia , Ratos , Reserpina/farmacologiaRESUMO
The submaxillary gland (SM) of rat is innervated by both branches of the autonomic nervous system. Secretion is mediated by the activation of both muscarinic-cholinergic and alpha/beta adrenergic receptors. Studies of the relative affinity of pharmacological agonists and antagonists have warranted a subclassification of alpha adrenoceptors into types alpha 1 and alpha 2. Our studies involve an analysis of the physiologic role of both types of alpha adrenoceptors in salivary secretion. Dose response curves (DRC) to noradrenaline (NA) following administration of alpha adrenoceptor antagonists, i.e. prazosin (alpha 1 antagonist), yohimbine (alpha 2 antagonist) and phentolamine (alpha 1-alpha 2 antagonist) were constructed. Our results demonstrate that prazosin is 100 times more effective than yohimbine in blocking NA-induced salivary secretion. The alpha 2 agonist clonidine (10 micrograms/Kg) blocked the DRCs to methacholine, noradrenaline and substance P-but failed to modify the DRC to isoproterenol. Our results reveal that the subtypes of alpha adrenergic receptors play antagonistic roles in salivary secretion. Alpha 1 stimulation elicits profuse salivary secretion whereas alpha 2 stimulation inhibits salivary secretion induced by 3 different types of agonists, i.e. alpha 1, muscarinic-cholinergic and neurokininergic without affecting beta receptor mediated responses.
Assuntos
Receptores Adrenérgicos alfa/fisiologia , Glândula Submandibular/inervação , Glândula Submandibular/metabolismo , Animais , Sistema Nervoso Autônomo/fisiologia , Clonidina/farmacologia , Relação Dose-Resposta a Droga , Feminino , Norepinefrina , Fentolamina/farmacologia , Prazosina/farmacologia , Ratos , Ratos Endogâmicos , Receptores Adrenérgicos alfa/efeitos dos fármacos , Ioimbina/farmacologiaRESUMO
The SMG of mice and rats contain a heterologous group of biologically active factors. Some are well known, can be obtained at high purity and are well-characterized. There is strong evidence for the presence of others although they have not been purified. Finally, some of them are questionable and/or have not yet been characterized. EPO would be one of the factors whose presence in the SMG is strongly suspected, although its biological activity has not been demonstrated yet. Its presence in the gland, therefore, is only supported by radioimmunoassay data and immunocytochemical methods. Immunoreactive EPO is undetectable in the mouse SMG until the 30th day of postnatal life, increasing thereafter at a uniform rate and reaching adult levels by 50-60 days of age. The parallelism between its concentration in extracts of the gland, the size and relative proportion of GCT cells, could be accepted as indirect evidence for its localization in these cells. The rise in iEPO concentration in SMGs after androgen treatment, its fall following orchiectomy, and its reduction after duct ligation in proportion to the degree of degranulation of GCT cells lend support to the above hypothesis. Salivary secretions induced by either NE or ISO contain high levels of iEPO. A significant depletion of gland content is also observed. These two sets of data indicate that SMG exocrine iEPO secretion occurs and that this secretion is mediated by adrenergic receptors. The question whether the SMG also functions as an endocrine organ in relation to EPO can not be answered at present.
Assuntos
Eritropoetina/análise , Glândula Submandibular/inervação , Glândula Submandibular/metabolismo , Fatores Etários , Animais , Sistema Nervoso Autônomo/fisiologia , Masculino , Camundongos , Orquiectomia , Ratos , Ratos Endogâmicos , Saliva/químicaRESUMO
Tissue parasitism, inflammatory process (histologic methods) and sympathetic denervation (glyoxylic acid-induced histofluorescence for demonstration of catecholamines) were studied in the heart (atrium and verntricle) and the submandibular gland of rats infected with the Y strain of Trypanosoma cruzi. In the heart paralleling intense parasitism and inflammatory process, the sympathetic denervation started at day 6 of infection and at the end of the acute phase (day 20) practically no varicose nerve terminals were found in both myocardium and vessels. In the submandibular gland, in spite of the rarity of anastigote pseudocysts and the scarcity of inflammatory foci, slight to moderate (days 13-15 of infection) or moderate to severe denervation (day 20) was found. At day 120 of infection both organs exhibited normal pattern of sympathetic innervation and only the heart showed some inflammatory foci and rare psudocysts (ventricle). Our data suggest the involvement of circulating factors in the sympathetic denervation phenomena but indicate that local inflammatory process is, at least, an aggravating factor
Assuntos
Ratos , Animais , Masculino , Feminino , Cardiomiopatia Chagásica/patologia , Glândula Submandibular/patologia , Miocárdio/patologia , Simpatectomia Química , Cardiomiopatia Chagásica/terapia , Coração/parasitologia , Ratos Endogâmicos , Glândula Submandibular/inervaçãoRESUMO
Tissue parasitism, inflammatory process (histologic methods) and sympathetic denervation (glyoxylic acid-induced histofluorescence for demonstration of catecholamines) were studied in the heart (atrium and ventricle) and the submandibular gland of rats infected with the Y strain of Trypanosoma cruzi. In the heart paralleling intense parasitism and inflammatory process, the sympathetic denervation started at day-6 of infection and at the end of the acute phase (day 20) practically no varicose nerve terminals were found in both myocardium and vessels. In the submandibular gland, in spite of the rarity of amastigote pseudocysts and the scarcity of inflammatory foci, slight to moderate (days 13-15 of infection) or moderate to severe denervation (day 20) was found. At day 120 of infection both organs exhibited normal pattern of sympathetic innervation and only the heart showed some inflammatory foci and rare pseudocysts (ventricle). Our data suggest the involvement of circulating factors in the sympathetic denervation phenomena but indicate that local inflammatory process is, at least, an aggravating factor.
Assuntos
Cardiomiopatia Chagásica/parasitologia , Coração/parasitologia , Miocardite/parasitologia , Glândula Submandibular/parasitologia , Animais , Cardiomiopatia Chagásica/terapia , Feminino , Coração/inervação , Masculino , Ratos , Ratos Endogâmicos , Glândula Submandibular/inervaçãoRESUMO
Histological methods were used for studying the left superior cervical ganglia of control and T. cruzi infected female rats killed 13, 20, and 34 days after inoculation. Concomitantly, the sympathetic innervation of the heart auricular appendages and of the submandibular gland was studied by a glyoxylic acid-induced fluorescence method for catecholamines. At day 34 of infection, the superior cervical ganglia of an additional group of control and infected animals were studied morphometrically through the determination of ganglion volume, total number, and nuclear diameter of the principal neurons. No amastigote pseudocyst could be detected inside the ganglia at any time during infection. Inflammatory reactions were very discrete or absent at day 13 of infection, but were clearly present at day 20 as periganglionitis (in all infected animals) or ganglionitis (in 62.5% of the infected animals). These reactions again became very discrete at day 34 of infection. None of the morphometric parameters analyzed were altered by Chagas' disease. Histochemical studies on the sympathetic innervation of the heart and submandibular gland showed disappearance or rarefaction of fluorescent nerve fibers, starting around the 13th day of infection. The involvement of sympathetic nerve terminals in Chagas' disease is a local phenomenon rather than a consequence of parasitism or destruction.
Assuntos
Doença de Chagas/patologia , Gânglios Simpáticos/patologia , Animais , Feminino , Coração/inervação , Histocitoquímica , Neurônios/patologia , Ratos , Glândula Submandibular/inervaçãoRESUMO
No presente trabalho foram estudadas as alteraçöes morfológicas submandibulares de rato, após secçäo do nervo corda lingual. Com base nos resultados foi possível concluir: o peso médio das glândulas experimentais foi maior nos grupos de 1 dia após a secçäo do corda lingual. Para todas as outras glândulas desnervadas, o peso foi menor que o do controle. O aumento de peso inicial foi atribuído à uma retençäo de secreçäo no interior das células acinares. A partir de 2 dias, foram observadas regiöes de atrofia mais acentuadas na regiäo acinar do que nas outras estruturas, as glândulas diminuíram, sofreram fibrose e invasäo de polimorfonucleares. A partir de 60 dias de observaçäo, após secçäo dos nervos, a glândula parece caminhar para uma regeneraçäo do parênquima. As glândulas após secçäo do corda lingual, apresentaram valores dos diâmetros acinares maiores para o grupo com 1 dia pós-neurotomia e menores para os demais grupos, em relaçäo aos controles
Assuntos
Ratos , Animais , Peso Corporal , Glândula Submandibular/inervação , Glândula Submandibular/patologia , Nervo LingualRESUMO
No presente trabalho foram estudadas as alteraçöes morfológicas das glândulas submandibulares de rato, após secçäo do nervo corda do tímpano. Com base nos resultados foi possível concluir: o peso médio das glândulas experimentais foi maior nos grupos de 1 e 2 dias para as que tiveram o corda do tímpano seccionado. Para todas as outras glândulas desnervadas, o peso da glândula experimental foi menor do que a controle. O aumento de peso inicial foi atribuído à uma retençäo ou acúmulo de secreçäo no interior das células acinares. A partir de 3 dias foram observadas regiöes de atrofia mais acentuada na regiäo acinar do que nas outras estruturas, as glândulas ficaram menores, fibrosadas, com reduçäo da parte glandular acinosa e com grande invasäo de polimorfonucleares. Nas glândulas com secçäo do nervo corda do tímpano foram observadas fibras nervosas e neurônios com características normais. A partir de 60 dias de observaçäo após secçäo do nervo, a glândula parece caminhar para uma regeneraçäo do parênquima
Assuntos
Ratos , Animais , Glândula Submandibular/inervação , Nervo da Corda do Tímpano/cirurgiaRESUMO
The effect of chronic sympathetic denervation (SCG) or parasympathetic decentralization (PSD) on the vascularization of the submaxillary gland (SM) of rat was studied in connection with morphological and functional changes. The resection of the superior cervical ganglion or the section of the chorda tympani was performed in adult male Wistar rats prior to the injection of Microfil MV Orange 3.25 cm3/kg. Once dissected, the glands were made transparent in increasing concentrations of methyl salicylate--alcohol. Three longitudinal sections were performed and the central one was projected in an automatic image analyzer (Kontron Zeiss), where vascular length and vascular volume were measured. Another group of animals was injected with Microfil after having received an injection of noradrenaline (10 g/kg) in SCG glands and methacholine in PSD glands. In SCG glands, vascular length underwent a 60% increase and the vascular volume increased from 0.26 +/- 0.15 cu mm/cu mm in controls to 0.54 +/- 0.15 cu mm/cu mm in SCG. The intravenous administration of noradrenaline prior to Microfil injection reverted the phenomenon. PSD caused a reduction of the vascular bed which resulted mainly in increased vascular volume. The administration of methacholine (10 g/kg) reverted the-response. It was concluded that SCG induced a loss of the existing vasoconstrictor tone, thus causing increase of vascular length and volume (passive vascular dilatation). Increased vascular volume after chronic PSD is compatible with vascular stasis and the absence of variations in vascular volume after the injection of methacholine would indicate that in the SM glands of rats there is no vascular dilatation tone.