Drakulić D, Veličković N, Stanojlović M, Grković I, Mitrović N, Lavrnja I, Horvat A. Low-dose dexamethasone treatment promotes the pro-survival signalling pathway in the adult rat prefrontal cortex.
J Neuroendocrinol 2013;
25:605-16. [PMID:
23551329 DOI:
10.1111/jne.12037]
[Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 02/15/2013] [Accepted: 03/24/2013] [Indexed: 11/29/2022]
Abstract
Synthetic glucocorticoid dexamethasone (DEX), a highly potent anti-inflammatory and immunosuppressive agent, is widely used in the treatment of brain cancer, as well as for inflammatory and autoimmune diseases. The present study aimed to determine whether low-dose subchronic DEX treatment (100 μg/kg for eight consecutive days) exerts long-term effects on apoptosis in the adult rat prefrontal cortex (PFC) by examining the expression of cell death-promoting molecules [poly(ADP-ribose) polymerase (PARP), p53, procaspase 3, cleaved caspase 3, Bax] and cell-survival molecules (AKT, Bcl-2). The results obtained revealed that body, thymus and adrenal gland weights, as well corticosterone levels, in the serum and PFC were reduced 1 day after the last DEX injection. In the PFC, DEX caused activation of AKT, augmentation of pro-survival Bcl-2 protein and an enhanced Bcl-2/Bax protein ratio, as well Bcl-2 translocation to the mitochondria. An unaltered profile with respect to the protein expression of apoptotic molecules PARP, procaspase 3 and Bax was detected, whereas p53 protein was decreased. Reverse transcriptase -polymerase chain reaction analysis showed a decrease of p53 mRNA levels and no significant difference in Bcl-2 and Bax mRNA expression in DEX-treated rats. Finally, a DNA fragmentation assay and Fluoro-Jade staining demonstrated no considerable changes in apoptosis in the rat PFC. Our findings support the concept that low-dose DEX creates a hypocorticoid state in the brain and also indicate that subchronic DEX treatment activates the pro-survival signalling pathway but does not change apoptotic markers in the rat PFC. This mechanism might be relevant for the DEX-induced apoptosis resistance observed during and after chemotherapy of patients with brain tumours.
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