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Subtipos de receptores colinérgicos centrais envolvidos na salivação, ingestão de água e resposta pressora induzidas pela pilocarpina injetada perifericamente
(Universidade Federal de São Carlos, 2008-04-08) Borella, Thais Leoni; Menani, José Vanderlei; https://lattes.cnpq.br/1023597870118105; https://lattes.cnpq.br/9799044075192147
The study of sialagog drugs has a relevant clinical interest for its use in patients with reduced salivatory secretion. Cholinergic agonists are a type of sialagog drug and pilocarpine is the most important cholinergic agonist drug. It is known that pilocarpine-direct action in salivatory glands muscarinic cholinergic receptors stimulate salivatory secretion. However, recent studies from our laboratory have shown that salivation induced by periferic pilocarpine seems to be dependent from central muscarinic activation. The pilocarpine-intense salivation is the well known main effect of this drug but side effects as cardiovasculars alterations and dipsogenesis are observed. Periferic injection of muscarinic agonists usually decreases periferic resistence and arterial pressure but pilocarpine-intraperitoneal (ip) injection induces an inesperate long-term pressor response associated with enhancement in mesenteric vascular resistence and salivatory glands vasodilatation, without changes in esqueletic musculature vascular resistence or heart rate. The ip pilocarpine-pressor response is atributed to an central action of this sialagog drug. The aim of the present study was to investigate central muscarinic cholinergic receptors subtype involved in salivation, water intake and pressor response induced by ip or intravenous (iv) pilocarpine injection. In addiction, the central activation induced by ip injection of pilocarpine and muscarinic receptors subtype antagonist were investigated by Fos-immunoreactivity (Fos-ir). Adult male Holtzman rats (250-300 g) with stainless steel cannulas implanted in the lateral ventricle (LV) were used. Intracerebroventricular (icv) injection of pirenzepine (M1 subtype muscarinic receptor), methoctramine (M2/M4 subtype muscarinic receptor), 4-DAMP (M1/M3 subtype muscarinic receptor) or tropicamide (M4 subtype muscarinic receptor) was performed to investigate its effect on salivation, water intake and pressor response-induced pilocarpine ip injection (4 µmol/kg of body weight (bw)). The salivation was determined in ketamine- (100 mg/kg bw) anesthetized rats using previous weighted cotton balls into oral cavity for 7 minutes. Arterial pressure and heart rate were recorded in non-anesthetized rats submitted to previous femoral artery cannulation. Fos-ir was investigated after ip injection of only pilocarpine or pilocarpine combined with pre-treatment of 4-DAMP, M1/M3 subtype muscarinic antagonist which was more efficient to block salivatory, dipsogenic and cardiovascular responses induced by ip pilocarpine. Salivatory response due to ip pilocarpine varied between 476 ± 54 to 718 ± 61 mg/7 min and was reduced by icv injection of 25, 50, 100 and 250 nmol 4-DAMP, respectively: 425.13 ± 89.73, 376.76 ± 28.01, 261.00 ± 38.28, 230.85 ± 68.61 mg/7 min. Icv injection of 0.1 and 1.0 nmol pirenzepine (0.77 ± 0.30 and 1.05 ± 0.54 ml/60 min, respectively), 50 nmol methoctramine (0.89 ± 0.30 ml/60 min) or 5 and 10 nmol 4- DAMP (1.43 ± 0.57 and 2.19 ± 0.66 ml/60 min, respectively) reduced dipsogenic effect-induced ip pilocarpine, which ranged between 3.20 ± 0.70 to 5.90 ± 1.30 ml/60 min. The pressor response-induced by ip pilocarpine varied between 40 ± 5 to 53 ± 4 mmHg and was decreased by icv injection of 100 nmol pirenzepine (9.00 ± 7.00 mmHg) or 25 and 50 nmol 4-DAMP (14.00 ± 7.00 and 3.00 ± 6.00 mmHg, respectively). Pilocarpine increased Fos-ir only in the supra-optic nuclei (SON), but not in other encephalic areas such as septal or medial lateral areas, paraventricular nuclei, subfornical nuclei, organnum vasculosum of lamina terminalis, median pre-optic nuclei had not alter its activation. The enhancement on Fos-ir in the SON induced by pilocarpine (12.8 ± 2.4 positive cell nuclei/10-2 mm2) was reduced by pre-treatment with 25 nmol 4-DAMP (3.26 ± 1.62 positive cell nuclei/10-2 mm2). Taken all together, M3 subtype central muscarinic receptor plays a role in salivation, M1 and M2 subtype central are involved in dipsogenic and M1 subtype central is involved in pressor response induced by pilocarpine. The role of central muscarinic receptor M3 subtype on dipsogenic and pressor response is not clear due to the fact 4-DAMP is not a specific antagonist, that binds M1 and M3 subtype muscarinic receptors. In addiction, these results suggest that responses evoked by periferic injection of 4 µmol/kg bw of pilocarpine could occur due to its activation through SON.
Catalisadores à base de Cu, Co ou Fe trocados ou suportados em zeólita USY avaliação na redução de NO com CO
(Universidade Federal de São Carlos, 2008-04-08) Silva, Edilene Deise da; Urquieta-González, Ernesto Antonio; https://lattes.cnpq.br/3672771633840838; http://lattes.cnpq.br/2389975677904655
The emissions of the nitrogen oxides (NOx) must be hardly reduced in the next years. The catalytic reduction of NO with CO is one of the possible processes with potential to be able to transform those oxides in N2. In that process, supported noble metals have been the most used, however, their low stability in the presence of water steam or SO2, have led to develop studies to overcome those limitations. Perovkites type catalysts or transition metal oxides supported in a variety of support show activity in this reaction. Nevertheless, no adequate information about the activity of metal oxides supported on zeolites is found in the literature. In this context, the present work was focused to prepare and evaluate between 150°C and 500°C, Cu, Co or Fe containing catalysts dispersed on USY (Si/Al=3,4) or ZSM-5 (Si/Al=12,8) zeolites in the reduction of NO with CO and in the oxidation of CO to CO2. The oxide activity was also compared with that of the respective metal cations located in charge compensation sites. The catalysts were prepared by ion exchange or impregnation and characterized by AAS, XRD, DRS-UV and H2-TPR. Conversion data of NO to N2 on USY and ZSM-5 zeolites containing predominantly Cu2+ or Co2+ cations in exchangeable sites were more active when located on ZSM-5 zeolite (MFI structure), with the Cu2+ cations being more active. On the other hand, Cu, Co or Fe oxides supported on USY or ZSM-5 were more active than cations of considered metals in exchangeable sites, with conversion being dependent on the type and metal content and the type of zeolite. Among the studied metal oxides, the Fe one was the most active and selective. However the presence of O2 or water steam in the feed inhibited the NO reduction with CO on Fe oxide, which was attributed to the deactivation of the active sites by the water steam and the CO direct oxidation by O2 occurring preferentially than CO oxidation via NO reduction. This result gives evidence of the water steam leads to the deactivation of the metallic active sites and O2 favors the direct oxidation of CO to CO2 in detriment of its oxidation by NO reduction. The NO conversion was not significantly affected by the presence of SO2 in the feed (40 ppm).