Effect of U18666a on Beta-Glucosidase, Sphingomyelinase, and Beta-Galactosidase Activities in Astrocytes of Young Rats

Abstract

Niemann-Pick type C disease (NPC) is a neurodegenerative genetic disorder caused by accumulation of lipids, especially cholesterol, in the perinuclear space. U18666A is a cholesterol transport-inhibiting agent, being used to mimic NPC, mainly in fibroblasts. The objective of this study was to observe the effect of the drug U18666A, which causes the accumulation of cholesterol in the cytoplasm of astrocytes from newborn rats, on some lysosomal hydrolase activities. Filipin staining and fluorescence microscopy, through CellM software, were used for visualization and quantification of cholesterol. The dose of U18666A that provided the greatest accumulation of cholesterol was that of 0.25 µg/mL in incubation for 48 h. Primary rat astrocytes incubated with the drug (NPC) showed a significantly higher amount of cholesterol than those without U18666A (controls). The measurement of activity of enzymes sphingomyelinase and beta-glucosidase in astrocytes of rats with NPC was significantly lower than that of control astrocytes, which is consistent with the disease in humans. The activity of the enzyme beta-galactosidase showed no significant difference between both groups. We concluded that U18666A appears to be an excellent intracellular cholesterol transport-inhibiting agent affecting some metabolic pathways in astrocytes of young rats, which mimics NPC in these animals. Just like the change in the activity of lysosomal enzymes has been demonstrated, other biochemical parameters of the cell can be tested with this animal model, thus contributing to a better understanding of the disease.

Antiviral activity of cationic amphiphilic drugs

“…It has been shown that the antidepressant desipramine and related drugs induce the detachment of aSMase from the inner membrane leaflet of Lys with its consecutive inactivation, resulting in the accumulation of sphingomyelin [13]. The reduction of the aSMase activity has been also reported for other two CADs: the antiarrhythmic amiodarone and the inhibitor of cholesterol transport U18666A [21,22]. Furthermore, it has been reported that structurally different CADs have an additive effect on the inhibition of aSMase activity, arguing for action of these compounds on the same molecular target [13].…”

“…The interaction of CADs with membranes can modify their permeability as well as the membrane-proximal pH, thus affecting several biological processes in particular at the level of LE/Lys, such as the inhibition of several enzymatic activities and the change in the distribution of lysosomal enzymes [13,14,[18][19][20]. The acid sphingomyelinase (aSMase), a lysosomal enzyme which catalyzes the hydrolysis of sphingomyelin into ceramide and phosphorylcoline, is one of the targets of several CADs [13,21]. It has been shown that the antidepressant desipramine and related drugs induce the detachment of aSMase from the inner membrane leaflet of Lys with its consecutive inactivation, resulting in the accumulation of sphingomyelin [13].…”

Activation of PKC triggers rescue of NPC1 patient specific iPSC derived glial cells from gliosis

“…The treatment with U18666A resulted in an accumulation of cholesterol as expected, but moreover we observed gliosis in the control cells, demonstrated by a significantly increased number of GFAP + /vimentin + cells, accompanied by a reduced amount of phosphorylated GFAP and vimentin. Recent studies described U1866A induced cholesterol accumulations in rat astrocytes influencing the metabolic pathway of these cells [ 56 , 57 ], but effects in regards of gliosis were not topic of these studies.…”