RESUMO
Chemokines and their receptors have the key role in inflammatory responses. The phenomenon of low grade inflammation is associated with the development of type 2 diabetes. Postprandial hyperglycemia increases the systemic inflammatory responses, which promotes the development of type 2 diabetic associating autonomic nervous injuries or cardiovascular disease. Neferine is a bisbenzylisoquinline alkaloid isolated from a Chinese medicinal herb. The objectives of this study will examine the CCL5 and CCR5 expression in the superior cervical ganglion (SCG) of type 2 diabetic rats. The effects of neferine on the expression of CCL5 and CCR5 mRNA and protein in the superior cervical ganglion (SCG) of type 2 diabetic rats will also be observed. The studies showed that in type 2 diabetic rats, body weight, blood pressure, heart rates, fasting blood glucose, insulin, total cholesterol and triglyceride were enhanced and high density lipoprotein was decreased, and CCL5 and CCR5 expression levels in the SCG of type 2 diabetic rats were up-regulated. In type 2 diabetic rats treated with neferine, body weight, blood pressure, fasting blood glucose, insulin, total cholesterol and triglyceride were decreased and high density lipoprotein was increased. The elevated expressions of CCL5 and CCR5 in SCG were decreased after type 2 diabetic rats treated with neferine. The motor nerve conduction velocity (MNCV) in diabetic rats treated with neferine group showed a significantly increment in comparison with that in type 2 diabetic group. Neferine can decrease the expression of CCL5 and CCR5 in the SCG and reduce the SCG neuronal signaling mediated by CCL5 and CCR5 in regulating diabetic cardiovascular autonomic complications.
Assuntos
Benzilisoquinolinas/uso terapêutico , Quimiocina CCL5/metabolismo , Diabetes Mellitus Experimental/patologia , Regulação da Expressão Gênica/efeitos dos fármacos , Receptores CCR5/metabolismo , Gânglio Cervical Superior/efeitos dos fármacos , Análise de Variância , Animais , Glicemia/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Quimiocina CCL5/genética , Diabetes Mellitus Experimental/tratamento farmacológico , Modelos Animais de Doenças , Jejum/metabolismo , Feminino , Frequência Cardíaca/efeitos dos fármacos , Hipoglicemiantes/metabolismo , Insulina/sangue , Metabolismo dos Lipídeos/efeitos dos fármacos , Lipoproteínas HDL/metabolismo , Masculino , Condução Nervosa/efeitos dos fármacos , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores CCR5/genética , Rosiglitazona , Tiazolidinedionas/farmacologiaRESUMO
Presynaptic imidazoline receptors (R(i-pre)) are found in the sympathetic axon terminals of animal and human cardiovascular systems, and they regulate blood pressure by modulating the release of peripheral noradrenaline (NA). The cellular mechanism of R(i-pre)-induced inhibition of NA release is unknown. We, therefore, investigated the effect of R(i-pre) activation on voltage-dependent Ca(2+) channels in rat superior cervical ganglion (SCG) neurons, using the conventional whole-cell patch-clamp method. Cirazoline (30 µM), an R(i-pre) agonist as well as an α-adrenoceptor (R(α)) agonist, decreased Ca(2+) currents (I(Ca)) by about 50% in a voltage-dependent manner with prepulse facilitation. In the presence of low-dose rauwolscine (3 µM), which blocks the α(2)-adrenoceptor (R(α2)), cirazoline still inhibited I(Ca) by about 30%, but prepulse facilitation was significantly attenuated. This inhibitory action of cirazoline was almost completely prevented by high-dose rauwolscine (30 µM), which blocks R(i-pre) as well as R(α2). In addition, pretreatment with LY320135 (10 µM), another R(i-pre) antagonist, in combination with low-dose rauwolscine (3 µM), also blocked the R(α2)-resistant effect of cirazoline. Addition of guanosine-5-O-(2-thiodiphosphate) (2 mm) to the internal solutions significantly attenuated the action of cirazoline. However, pertussis toxin (500 ng ml(1)) did not significantly influence the inhibitory effect of cirazoline. Moreover, cirazoline (30 µM) suppressed M current in SCG neurons cultured overnight. Finally, omega-conotoxin (omega-CgTx) GVIA (1 µM) obstructed cirazoline-induced current inhibition, and cirazoline (30 µM) significantly decreased the frequency of action potential firing in a partly reversible manner. This cirazoline-induced inhibition of action potential firing was almost completely occluded in the presence of omega-CgTx. Taken together, our results suggest that activation of R(i-pre) in SCG neurons reduced N-type I(Ca) in a pertussis toxin- and voltage-insensitive pathway, and this inhibition attenuated repetitive action potential firing in SCG neurons.
Assuntos
Bloqueadores dos Canais de Cálcio/farmacologia , Canais de Cálcio Tipo N/efeitos dos fármacos , Sinalização do Cálcio/efeitos dos fármacos , Imidazóis/farmacologia , Receptores de Imidazolinas/agonistas , Neurônios/efeitos dos fármacos , Terminações Pré-Sinápticas/efeitos dos fármacos , Receptores Pré-Sinápticos/agonistas , Gânglio Cervical Superior/efeitos dos fármacos , Potenciais de Ação , Antagonistas de Receptores Adrenérgicos alfa 2/farmacologia , Animais , Benzofuranos/farmacologia , Canais de Cálcio Tipo N/metabolismo , Células Cultivadas , Relação Dose-Resposta a Droga , Guanosina Difosfato/análogos & derivados , Guanosina Difosfato/farmacologia , Receptores de Imidazolinas/metabolismo , Cinética , Masculino , Neurônios/metabolismo , Norepinefrina/metabolismo , Técnicas de Patch-Clamp , Toxina Pertussis/farmacologia , Canais de Potássio/efeitos dos fármacos , Canais de Potássio/metabolismo , Terminações Pré-Sinápticas/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores Pré-Sinápticos/metabolismo , Gânglio Cervical Superior/citologia , Gânglio Cervical Superior/metabolismo , Tionucleotídeos/farmacologia , Ioimbina/farmacologia , ômega-Conotoxina GVIA/farmacologiaRESUMO
1. 1,8-Cineole is a non-toxic small terpenoid oxide believed to have medicinal properties in folk medicine. It has been shown to have various pharmacological effects, including blockade of the compound action potential (AP). In the present study, using intracellular recording techniques, we investigated the effects of 1,8-cineole on the electrophysiological parameters of neurons of the superior cervical ganglion (SCG) in rats. 2. 1,8-Cineole (0.1-6 mmol/L) showed reversible and concentration-dependent effects on various electrophysiological parameters. At 3 and 6 mmol/L, but not at 0.1 and 1 mmol/L, 1,8-cineole significantly diminished the input resistance (R(i)) and altered the resting potential (E(m)) to more positive values. At 6 mmol/L, 1,8-cineole completely blocked all APs within 2.7 +/- 0.6 min (n = 12). In neurons exposed to 3 and 1 mmol/L 1,8-cineole, the effects regarding excitability varied from complete AP blockade to minor inhibition of AP parameters. The depolarization of E(m) and the decrease in R(i) induced by 6 mmol/L 1,8-cineole were unaltered by 200 micromol/L niflumic acid, a well known blocker of Ca(2+)-activated Cl(-) currents. 3. Significant correlations (Pearson correlation test) were found between changes in E(m) and decreases in AP amplitude (r = -0.893; P < 0.00282) and maximum ascendant inclination (r = -0.799; P < 0.0173), but not for maximum descendant inclination (r = 0.598; P < 0.117). Application of current to restore the transmembrane potential equal to control E(m) values in the presence of 6 mmol/L 1,8-cineole resulted in the partial recovery of AP. 4. The present study shows that 1,8-cineole effectively blocks the excitability of SCG neurons, probably through various mechanisms, one of which acts indirectly via depolarization of the neuronal cytoplasmatic membrane.
Assuntos
Cicloexanóis/farmacologia , Potenciais da Membrana/efeitos dos fármacos , Monoterpenos/farmacologia , Neurônios/fisiologia , Gânglio Cervical Superior/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Eucaliptol , Feminino , Masculino , Medicina Tradicional , Ácido Niflúmico/farmacologia , Ratos , Ratos WistarRESUMO
The open state of M(Kv7.2/7.3) potassium channels is maintained by membrane phosphatidylinositol-4,5-bisphosphate (PI(4,5)P(2)). They can be closed on stimulating receptors that induce PI(4,5)P(2) hydrolysis. In sympathetic neurons, closure induced by stimulating M1-muscarinic acetylcholine receptors (mAChRs) has been attributed to depletion of PI(4,5)P(2), whereas closure by bradykinin B(2)-receptors (B2-BKRs) appears to result from formation of IP(3) and release of Ca(2+), implying that BKR stimulation does not deplete PI(4,5)P(2). We have used a fluorescently tagged PI(4,5)P(2)-binding construct, the C-domain of the protein tubby, mutated to increase sensitivity to PI(4,5)P(2) changes (tubby-R332H-cYFP), to provide an on-line read-out of PI(4,5)P(2) changes in single living sympathetic neurons after receptor stimulation. We find that the mAChR agonist, oxotremorine-M (oxo-M), produces a near-complete translocation of tubby-R332H-cYFP into the cytoplasm, whereas bradykinin (BK) produced about one third as much translocation. However, translocation by BK was increased to equal that produced by oxo-M when synthesis of PI(4,5)P(2) was inhibited by wortmannin. Further, wortmannin 'rescued' M-current inhibition by BK after Ca(2+)-dependent inhibition was reduced by thapsigargin. These results provide the first direct support for the view that BK accelerates PI(4,5)P(2) synthesis in these neurons, and show that the mechanism of BKR-induced inhibition can be switched from Ca(2+) dependent to PI(4,5)P(2) dependent when PI(4,5)P(2) synthesis is inhibited.
Assuntos
Canal de Potássio KCNQ2/efeitos dos fármacos , Canal de Potássio KCNQ2/metabolismo , Neurônios/metabolismo , Fosfatidilinositol 4,5-Difosfato/fisiologia , Bloqueadores dos Canais de Potássio , Receptores Acoplados a Proteínas G/efeitos dos fármacos , Animais , Bradicinina/farmacologia , Células CHO , Membrana Celular/metabolismo , Cricetinae , Cricetulus , DNA Complementar/biossíntese , DNA Complementar/genética , Agonistas Muscarínicos/farmacologia , Neurônios/efeitos dos fármacos , Técnicas de Patch-Clamp , Fosfatidilinositol 4,5-Difosfato/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores Muscarínicos/efeitos dos fármacos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Gânglio Cervical Superior/citologia , Gânglio Cervical Superior/efeitos dos fármacos , Translocação GenéticaRESUMO
Beta(2)-adrenergic receptors (beta(2)-AR) and CB1 cannabinoid receptors share the property of being constitutively active. The CB1 cannabinoid receptor can also sequester G(i/o) proteins; however, it is not known whether the beta(2)-AR can also sequester G proteins. Beta(2)-ARs were heterologously expressed in rat superior cervical ganglion neurons by microinjection of cDNA and studied using the patch-clamp technique. The beta-AR agonist isoproterenol increased the Ca(2+) current 25.9+/-1.6% in neurons microinjected with 100 ng/microl beta(2)-AR cDNA but was without effect on control neurons. Pretreatment with cholera toxin (CTX) abolished the effect of isoproterenol, indicating coupling via G(s) proteins. In neurons microinjected with 200 ng/microl beta(2)-AR cDNA, isoproterenol had the opposite effect of inhibiting the Ca(2+) current 36.5+/-2.0%. Inhibition of the Ca(2+) current was sensitive to pertussis toxin, indicating beta(2)-AR coupling to G(i/o) proteins. Pretreatment with CTX resulted in a greater 54+/-3.8% inhibition of the Ca(2+) current, indicating that G(s) coupling masks the full effect of G(i/o) coupling. Expression of beta(2)-ARs abolished signaling by G(s)-coupled receptors for vasoactive intestinal polypeptide (VIP). VIP inhibited the Ca(2+) current 49.5+/-0.5% in control neurons but had no effect in neurons expressing beta(2)-ARs. In contrast, expression of beta(2)-ARs had no effect on signaling by the G(i/o)-coupled alpha(2)-adrenergic receptor. This study demonstrates that the beta(2)-AR couples to both G(s) and G(i/o) proteins but specifically sequesters G(s) proteins, preventing their interaction with another G(s)-coupled receptor. beta(2)-adrenergic receptors thus have the potential to prevent other G(s)-coupled receptors from transducing their biological signals.
Assuntos
Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/metabolismo , Subunidades alfa Gs de Proteínas de Ligação ao GTP/metabolismo , Proteínas Heterotriméricas de Ligação ao GTP/metabolismo , Neurônios/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Gânglio Cervical Superior/metabolismo , Agonistas Adrenérgicos beta/farmacologia , Animais , Sinalização do Cálcio/efeitos dos fármacos , Sinalização do Cálcio/fisiologia , Células Cultivadas , Toxina da Cólera/farmacologia , DNA Complementar , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/efeitos dos fármacos , Subunidades alfa Gs de Proteínas de Ligação ao GTP/efeitos dos fármacos , Proteínas Heterotriméricas de Ligação ao GTP/efeitos dos fármacos , Masculino , Neurônios/efeitos dos fármacos , Ratos , Ratos Wistar , Receptores Adrenérgicos beta 2/efeitos dos fármacos , Receptores Adrenérgicos beta 2/genética , Receptores de Canabinoides , Receptores de Droga/efeitos dos fármacos , Receptores de Droga/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Gânglio Cervical Superior/citologia , Gânglio Cervical Superior/efeitos dos fármacos , Peptídeo Intestinal Vasoativo/farmacologiaRESUMO
Trigeminal neuralgia (TN) is defined as a chronic, severe, electrifying and burning pain in one side of the face. The attacks are initiated by tactile irritations in a so-called trigger area of the trigeminal nerve and are perceived within the borders of this nerve's innervation. TN is a chronic condition which initially goes into spontaneous remission but these become fewer as the condition progresses. TN is classified as symptomatic when the etiology is known and as idiopathic when the etiology is unknown. There are various forms of treatment: drugs such as anticonvulsants, local ganglionic opioid analgesia (GLOA) at the superior cervical ganglion or sphenopalatine ganglion, percutaneous intervention at the trigeminal ganglion as well as neurosurgery. None of these various procedures has been found to be the most suited and best method. A retrospective analysis of the data of 39 patients who had sought treatment for TN at our pain and acupuncture outpatients' department from 1993 to 1994 was undertaken. Group A (n = 17) had received carbamazepine and acupuncture therapy, group B (n = 11) carbamazepine and GLOA + acupuncture, whereas group C (n = 11) had received carbamazepine and GLOA without acupuncture. All subjects had taken carbamazepine for at least 4 weeks and their plasma levels were within the therapeutic range. Acupuncture therapy was carried out once a week and the number recorded. GLOA was carried out with 0.045 mg buprenorphine at the superior cervical ganglion or the sphenopalatine ganglion as a series of at least 5 injections. The number of attacks of pain and the degree of pain (visual analogue scale [VAS]) were documented. The reduction in pain was categorized in 4 groups: I = pain free, II = reduction of at least 50% on the VAS, III = reduction of less than 50% on the VAS, and IV = no improvement. The statistical analysis was carried out using the chi 2-text, p < 0.05 was considered as significant. Of the groups who received acupuncture as an additive, 8 of the 17 subjects of group A, and 5 of the 11 subjects of group B were pain free, but only 2 of the 11 subjects of group C (no acupuncture). The results of the patients with marked pain reduction (category II) were similar. The most patients with no improvement were from the group which did not receive acupuncture (C). The statistical analysis showed significant differences in the categories I, II, and IV between groups A and C. These results show that the combined use of acupuncture and carbamazepine with/without GLOA achieves an additional therapeutic effect in the treatment of trigeminal neuralgia. The addition of acupuncture seems to have a superior effect to the addition of GLOA. These results support the use of acupuncture as an additional form of therapy for the treatment of trigeminal neuralgia.