RESUMO
We determined if the dorsal raphe nucleus (DRN) exerts tonic control of basal and stimulated sodium and water intake. Male Wistar rats weighing 300-350 g were microinjected with phosphate buffer (PB-DRN, N = 11) or 1 microg/0.2 microl, in a single dose, ibotenic acid (IBO-DRN, N = 9 to 10) through a guide cannula into the DRN and were observed for 21 days in order to measure basal sodium appetite and water intake and in the following situations: furosemide-induced sodium depletion (20 mg/kg, sc, 24 h before the experiment) and a low dose of dietary captopril (1 mg/g chow). From the 6th day after ibotenic acid injection IBO-DRN rats showed an increase in sodium appetite (12.0 +/- 2.3 to 22.3 +/- 4.6 ml 0.3 M NaCl intake) whereas PB-DRN did not exceed 2 ml (P < 0.001). Water intake was comparable in both groups. In addition to a higher dipsogenic response, sodium-depleted IBO-DRN animals displayed an increase of 0.3 M NaCl intake compared to PB-DRN (37.4 +/- 3.8 vs 21.6 +/- 3.9 ml 300 min after fluid offer, P < 0.001). Captopril added to chow caused an increase of 0.3 M NaCl intake during the first 2 days (IBO-DRN, 33.8 +/- 4.3 and 32.5 +/- 3.4 ml on day 1 and day 2, respectively, vs 20.2 +/- 2.8 ml on day 0, P < 0.001). These data support the view that DRN, probably via ascending serotonergic system, tonically modulates sodium appetite under basal and sodium depletion conditions and/or after an increase in peripheral or brain angiotensin II.
Assuntos
Apetite/efeitos dos fármacos , Ingestão de Líquidos/efeitos dos fármacos , Agonistas de Aminoácidos Excitatórios/toxicidade , Ácido Ibotênico/toxicidade , Núcleos da Rafe/efeitos dos fármacos , Sódio na Dieta , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Animais , Apetite/fisiologia , Soluções Tampão , Captopril/farmacologia , Ingestão de Líquidos/fisiologia , Furosemida/farmacologia , Masculino , Fosfatos , Ratos , Ratos Wistar , Inibidores de Simportadores de Cloreto de Sódio e Potássio/farmacologia , Fatores de TempoRESUMO
Respiratory symptoms and past history of chest disease as well as spirometric tests were investigated in 72 of 86 (83.7%) employees of a middle sized quarry in Rio de Janeiro, Brazil. Seventy one were men (98.6%), and the mean age was 36.2 +/- 9.3 years (20-65). Forty two (58.3%) had occupations considered as highly exposed to dust, and 30 (44.7%) were considered as lightly exposed. Forty (55.6%) were smokers, 20 (27.8%) never had been smokers and 12 (16.7%) were former smokers. Symptoms and past history were investigated with a questionnaire based on international models, and adapted for the Brazilian public. A high prevalence of symptoms (except for dyspnea) was noted: 47 (65.3%) had one or more symptoms-there was cough in 31.9%, expectoration in 41.7% dyspnea in 9.7% and wheezing in 33.3%. The symptoms were found to be associated mostly with a past history of chest disease, and also with smoking, factors which explained, in part, the presence of the symptoms. No association with a higher exposure to dust was found. The exposure to dust did not explain the symptoms. The spirometric tests were performed on a 6 liter bell spirometer. The means of the parameters were lower than one would expect in a non selected population sample--89.9 +/- 11.2% of predicted for the Forced Vital Capacity (FVC), 90.1 +/- 12.9% for the Forced Expiratory Volume in 1 second (FEV1) and 92.9 +/- 32.7% for the Forced Expiratory Flow between 25% and 75% of the FVC (FEF25-75). However, the proportions of abnormal results were comparable to the reported ones from unselected samples. There was no statistically significant influence of higher dust exposure, past history or smoking on the means of the results. It is concluded that, in this sample of quarry employees, no association between respiratory symptoms or spirometric results and dust exposure could be demonstrated. There was an association between the symptoms, but not with the spirometric results, and a past history of chest disease, as well as with smoking.