Imbalance in the ratio between mineralocorticoid and glucocorticoid receptors and neurodegeneration in the dentate gyrus of aged dogs.

Autor: Szriber SJ; Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, University of Sao Paulo, Duque de Caxias Norte Avenue, 225, 13635-900, Pirassununga, Brazil., Novaes LS; Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo, Professor Lineu Prestes Avenue, 1524, Room 323, 05508-000, Sao Paulo, Brazil., Santos NBD; Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo, Professor Lineu Prestes Avenue, 1524, Room 323, 05508-000, Sao Paulo, Brazil., Munhoz CD; Department of Pharmacology, Institute of Biomedical Science, University of Sao Paulo, Professor Lineu Prestes Avenue, 1524, Room 323, 05508-000, Sao Paulo, Brazil., Leite-Dellova DCA; Department of Veterinary Medicine, Faculty of Animal Science and Food Engineering, University of Sao Paulo, Duque de Caxias Norte Avenue, 225, 13635-900, Pirassununga, Brazil.
Jazyk: angličtina
Zdroj: Veterinary world [Vet World] 2022 Nov; Vol. 15 (11), pp. 2543-2550. Date of Electronic Publication: 2022 Nov 10.
DOI: 10.14202/vetworld.2022.2543-2550
Abstrakt: Background and Aim: Cortisol binds to mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) found in the hippocampus. The balanced expression of these receptors is essential to neuronal survival as MR and GR activations have antiapoptotic and proapoptotic effects, respectively. Given the aging changes in dogs' dentate gyrus (DG) and the possible involvement of cortisol receptors in this process, this study aimed to evaluate the expression of MR and GR and neuronal degeneration in this hippocampal region of aged dogs.
Materials and Methods: This study included cadaveric histologic hippocampus sections from six dogs aged 10 years and older (AG group) and 12 young/adult dogs aged up to 8 years (YAd group). Nissl staining and immunohistochemistry were performed to identify cells and investigate MR and GR expression, respectively. Furthermore, fluorescent labeling (fluoro-Jade B) was used to detect degenerating neurons.
Results: The AG group's polymorphic layer of the DG had a lower cell count (16%) and more degenerating neurons than the YAd group. In addition to these cellular changes, the AG group had lower MR immunoreactivity and MR-to-GR ratio. Furthermore, the lowest MR expression was associated with neuronal degeneration in the polymorphic layer of the DG of dogs.
Conclusion: An imbalance in the MR-to-GR ratio was observed in the polymorphic layer of the DG of aged dogs, along with lower MR expression and a greater number of degenerating neurons. These findings have clinical implications for understanding the decline in hippocampal memory formation associated with cognitive changes in aged dogs.
Competing Interests: The authors declare that they have no competing interests.
(Copyright: © Szriber, et al.)
Databáze: MEDLINE
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