Lúcia Reis

Effect of brain serotoninergic stimulation on sodium appetite of euthyroid and hypothyroid rats

The aim of the present work was to investigate the role of the serotoninergic system in the control of sodium appetite of hypothyroid rats (HTR) by administering drugs that affect the serotoninergic activity, and to compare the same homeostatic behaviour in euthyroid rats (ETR) also given these drugs. Fenfluramine (FEN; 5.0 mg kg−1, I.P.), which releases serotonin in the brain, significantly reduced the intake of 1.8% NaCl in HTR subjected to water and sodium depletion (depleted) or water, sodium and food deprivation (deprived) by 31 and 45%, respectively, 120 min after FEN injection, compared to HTR that received vehicle alone. Similarly, administration of FEN to ETR reduced 1.8% NaCl intake in depleted and deprived rats by 64 and 46%, respectively. The presynaptic serotonin reuptake inhibitor fluoxetine (20.0 mg kg−1, I.P.) led to the inhibition of sodium appetite in HTR during the initial 30 min in depleted rats and for up to 60 min post‐injection in deprived rats, while sodium appetite inhibition persisted for longer periods in ETR. The 5HT2C receptor agonist mCPP (5.0 mg kg−1, I.P.) caused a drastic reduction in sodium appetite in HTR and ETR in depleted and deprived rats, respectively, after 120 min. Prior administration of the 5HT2C receptor antagonist LY53857 (5.0 mg kg−1, I.P.) completely blocked the inhibitory action of mCPP on sodium appetite in both HTR and ETR. In summary, our results suggest that the recruitment of serotoninergic neurons involved in the modulation of sodium appetite seems to be decreased in hypothyroidism due to a probable deficiency in the cerebral signalling pathway.

Effect of losartan on sodium appetite of hypothyroid rats subjected to water and sodium depletion and water, sodium and food deprivation

The involvement of angiotensin AT1 receptors in sodium appetite was studied in hypothyroid rats treated with the angiotensin II antagonist losartan. Losartan was administered chronically by the oral route or acutely by the subcutaneous route after water and sodium depletion or water, sodium and food deprivation. Three days after addition of losartan to the food at the dose of 1.0 mg g−1, the rats significantly reduced (P < 0.02) their spontaneous intake of 1.8% NaCl. Increasing the dose of losartan to 2.0 and 4.0 mg g−1 did not reduce NaCl intake; in contrast, the intensity of the sodium appetite gradually returned to previous levels. The simultaneous administration of captopril, an angiotensin converting enzyme inhibitor, and losartan significantly increased (P < 0.05) NaCl intake and after captopril removal NaCl intake returned to the levels observed with losartan treatment alone. The administration of losartan 4 days after the beginning of captopril treatment significantly reduced (P < 0.0001) NaCl intake. Following acute administration of losartan, water‐ and sodium‐depleted rats significantly reduced their NaCl and water intake (P < 0.001). The administration of losartan also induced a significant reduction in NaCl and water intake in water, NaCl and food‐deprived rats (P < 0.0001 and P < 0.001, respectively). The present results show that chronic treatment with oral losartan inhibited spontaneous sodium appetite in hypothyroid rats. Continuation of treatment rendered rats resistant to the blockade of AT1 receptors. Water and sodium depletion and water, NaCl and food deprivation induced sodium appetite, which in the short term depends on cerebral angiotensinergic activity mediated by the activation of AT1 receptors.

Adenoid bacterial colonization in a paediatric population

Adenoids play a key role in both respiratory and ear infection in children. It has also been shown that adenoidectomy improves these symptoms in this population. The main goal of the present study was to evaluate adenoid bacterial colonization and document a possible relation with infectious respiratory disease. A prospective observational study was designed to evaluate the proposed hypothesis in a paediatric population submitted to adenoidectomy by either infectious or non-infectious indications and compare these two cohorts. A total of 62 patients with ages ranging from 1 to 12 years old were enrolled in the study. Adenoid surface, adenoid core and middle meatus microbiota were compared. A close association between adenoid colonization and nasal infection was found, supporting that adenoids may function as bacterial reservoir for upper airway infection. The obtained results also contribute to explain the success of adenoidectomy in patients with infectious indications.

Pathogens in ornamental waters: a pilot study

In parks, ornamental waters of easy access and populated with animals are quite attractive to children and yet might hide threats to human health. The present work focuses on the microbiota of the ornamental waters of a Lisboa park, characterized during 2015. The results show a dynamic microbiota integrating human pathogens such as Klebsiella pneumoniae, Aeromonas spp. and Enterobacter spp., and also antibiotic resistant bacteria. K. pneumoniae and Aeromonas spp. were present as planktonic and biofilm organized bacteria. In vitro K. pneumoniae and Aeromonas spp. showed an enhanced ability to assemble biofilm at 25 °C than at 37 °C. Bacteria recovered from biofilm samples showed an increased antibiotic resistance compared to the respective planktonic counterparts.

Risk assessment for public health from human interaction with ornamental waters

Absctract publicado em: Microsc Microanal. 2016 Mar;22(Suppl S4):12-13. doi: 10.1017/S1431927616000258. Disponivel em: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=10231261&fulltextType=AB&fileId=S1431927616000258