Advances on assessing nanotoxicity in marine fish - the pros and cons of combining an ex vivo approach and histopathological analysis in gills.

The need to overcome logistic and ethical limitations of in vivo nanotoxicity evaluation in marine organisms is essential, mostly when dealing with fish. It is well established that medium/solvent conditions affect dispersion and agglomeration of nanoparticles (NPs), which represents a constraint towards a solid and realistic toxicity appraisal. In this way the pros and cons of an ex vivo approach, using a simplified exposure medium (seawater) and addressing gills histopathology, were explored. The nanotoxic potential of environmentally realistic concentrations of titanium dioxide NPs (TiO2 NPs) was also assessed, disclosing the morpho-functional effects on the gills and the possible uptake/elimination processes. Excised gills of the Senegalese sole (Solea senegalensis) were directly exposed in artificial seawater to 20 and 200 µg L-1 TiO2 NPs, for 2 h and 4 h. Semi-quantitative and quantitative histological analyses were applied. The normal morphology of the gill's epithelia was only slightly altered in the control, reflecting protective mechanisms against the artificiality of the experimental conditions, which, together with the absence of differences in the global histopathological index (Ih), corroborated that the gill's morpho-functional features were not compromised, thereby validating the proposed ex vivo approach. TiO2 NPs induced moderate severity and dissemination of histopathological lesions. After 2 h, a series of compensatory mechanisms occurred in NP treatments, implying an efficient response of the innate defense system (increasing number of goblet cells) and effective osmoregulatory ability (chloride cells proliferation). After 4 h, gills revealed signs of recovery (normalization of the number of chloride and goblet cells; similar Ih), highlighting the tissue viability and effective elimination and/or neutralization of NPs. The uptake of the TiO2 NPs seemed to be favored by the higher particle sizes. Overall, the proposed approach emerged as a high-throughput, reliable, accurate and ethically commendable methodology for nanotoxicity assessment in marine fish.

Renin-angiotensin system function and blood pressure in adult rats after perinatal salt overload.

BACKGROUND AND AIM: To study the influence of high salt intake during pregnancy and lactation on body weight, blood pressure, and the function of the renin-angiotensin system in adult rats. METHODS AND RESULTS: Female Wistar rats received a low (0.15 NaCl), normal (1.30), or high (8% diet) salt diet. Mating occurred on the 12th week of age. From weaning, the offspring received normal salt diet. Weekly tail-cuff blood pressure and body weight measurements were performed during pregnancy and in the offspring (body weight since weaning and tail-cuff blood pressure between the 8th and the 12th week of age). Salt sensitivity of the blood pressure was evaluated and plasma renin activity determinations were performed in the 12-week-old offspring. Immunohistochemistry for renal angiotensin II was performed in the adult offspring. Renal mass and the number of glomeruli were determined. Tail-cuff blood pressure was higher in salt overloaded dams than in normal and low salt ones. In the adult offspring from the high salt dams, lower body weight, higher tail-cuff blood pressure, lower salt sensitivity in females, and increased kidney angiotensin II were observed. Plasma renin activity did not change with changes in salt intake in the adult offspring submitted to high salt environment during the perinatal period. In the offspring, renal mass and the number of glomeruli were not influenced by the dams' salt intake. CONCLUSIONS: Salt overload during pregnancy and/or lactation has long-term effects on offspring's body weight and blood pressure. In addition, high salt diet during the perinatal period induced renin-angiotensin system functional disturbances in the offspring.