Expression of Apoptosis, Autophagy and Necroptosis Effectors in Rat Hippocampal Cells after Excessive Fluoride Intake

The expression of apoptosis, autophagy and necroptosis markersin rat hippocampal cells after long-term intake of excessive fluoride(F^–) doses was studied at transcriptionaland translational levels. Male Wistar rats were divided into 4 groupsgiven 0.4 (control), 5, 20, and 50 mg/L F^– (asNaF) with drinking water over 12 months. Changes in the contentof effectors of mitochondrial (Bcl-2, Bax, caspase-9, caspase-3)and receptor (caspase-8, Fas) pathways of apoptosis, mediators (Ulk-1,Beclin-1) and modulators (AMPK, Akt, mTOR) of autophagy, as wellas necroptosis effectors (RIP and MLKL), were assessed by immunoblotting,while the expression of Bcl2, Bax, Casp3, Ulk1, Beclin1, Prkaa1, Akt, and mTor genes—by real-time PCR. In thehippocampus of F^–-exposed animals, theexpression ratio of Bcl2/Bax genesand Bcl-2/Bax proteins decreased, caspase-9 and caspase-3 were activated,but caspase-8 and Fas receptor levels remained stable. Long-termF^– intake had no effect on the contentof the autophagy initiator Ulk-1 and protein kinases AMPK, Akt andmTOR, but led to the inhibition of the key autophagy mediator Beclin-1.Expression levels of the necroptosis effectors RIP and MLKL in hippocampalcells of rats exposed to excessive F^– dosesdid not change as well. Thus, long-term exposure to excessive F^– wasaccompanied by the activation of apoptosis, mainly through the mitochondrial pathway,against the background of autophagy suppression.