Moreover, kidneys from rats exposed to MCYST also presented alterations in renal tubular morphology, adding to the molecular alterations in proximal tubules, as discussed in Sections 3 and 3.2.4. The renal index (kidney mass/body mass) of the MCYST group was increased when compared with the CTRL group (Table 1). This result, accompanied by the increase in GFR in the MCYST group, could indicate an accumulation of fluid in the organ with changes in renal function. The collagen deposition (Fig. 1C and D) could also have contributed to the increased renal index. The changes in physiological parameters indicate an early decrease

in renal function after exposure of one single sublethal dose of find more MCYST-LR, shown by the increase in different processes such as glomerular filtration rate, sodium excretion, proteinuria and renal index, adding to the structural alterations in renal tissue and biochemical modifications, as discussed below. Analyses of H/E staining do not provide any significant differences between the histology of the kidneys from the CTRL group and the rats exposed to MCYST-LR. However, other structural modifications were observed. Using PAS staining, histological analyses from kidney exposed

to MCYST-LR showed a significant increase in interstitial CHIR-99021 supplier space, compared with the CTRL group (Fig. 1A and B). Corresponding quantification of the interstitial space is shown on the right panel of Fig. 1. Tubular limits are better visualized using PAS staining, because the periodic acid oxidizes the glucose residues to produce aldehydes, which react with Schiff

reagent giving rise to a purple-magenta color in the area of the basement membrane. The contrast between the color of the basement membrane and the background image facilitated the quantification of the interstitial space. This result suggests that the presence of MCYST in renal tissue causes an interstitial infiltrate, probably containing plasma electrolytes, glucose and amino acids, characterized as interstitial edema and/or formation for of fibrosis. The edema could contribute to the increased renal index (Table 1). To investigate whether exposure to MCYST could also stimulate renal fibrosis, collagen formation was evaluated by observing the surface density of the intense red coloration achieved with the use of Sirius Red. This stain identifies collagen type IV in basal membrane. Only one single dose of MCYST-LR leads to an increase in collagen deposition in the interstitial space, compared with the CTRL group, in both cortex (Fig. 1C and D) and medulla (Fig. 1E and F) regions of the kidney. Quantification of collagen staining in the interstitial space is shown in the lower right panel of Fig. 1. This increased collagen deposition strongly suggests the initial step of renal fibrosis in MCYST-LR exposed rats.