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

Autor(es)

Szriber, Shirley Jaqueline ; Novaes, Leonardo Santana ; Dos Santos, Nilton Barreto ; Munhoz, Carolina Demarchi ; Almeida Leite-Dellova, Deise Carla

• Tipo de documento: Artigo Científico
• Fonte: VETERINARY WORLD; v. 15, n. 11, p. 8-pg., 2022-11-01.

Resumo

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. (AU)

• Processo FAPESP: 12/24002-0 - Efeitos do enriquecimento ambiental na manifestação tardia da ansiedade induzida por estresse agudo: implicações na aquisição de memória emocional
• Beneficiário: Leonardo Santana Novaes
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 16/03572-3 - A relação entre a ativação dos receptores de glicocorticoides e a hiperexcitabilidade dos neurônios do complexo basolateral da amígdala na ansiedade tardia induzida por estresse agudo em ratos e sua implicação no déficit de extinção da memória de medo
• Beneficiário: Carolina Demarchi Munhoz
• Modalidade de apoio: Auxílio à Pesquisa - Regular