Effects of co-application of corticosterone and growth hormone on hippocampal neurons involve nmda receptor upregulation of nr2b protein expression and increasing nr2b/nr2a ratio

Document Type : Original Article

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1 Department of Medical Physiology, Faculty of Medicine, Assiut University, Assiut, Egypt.

2 Department of Human Anatomy and Embryology, Faculty of Medicine, Assiut University, Assiut, Egypt.

Abstract

Objectives to investigate the possible mechanism underlying the protective effect of growth hormone (GH) on hippocampal function during periods of acute stress. Methods the effects of co-application of GH and corticosterone (CORT) at different concentration on field excitatory postsynaptic potential (fFEPSPs) of hippocampal slices of rats at two different age groups were examined. Also, the protein expression of N-methyl-D-aspartate receptor (NMDARs) subunits; NR1, NR2B, and NR2A in hippocampal brain slices treated with artificial cerebrospinal fluid (ACSF) or low concentration of CORT alone or both CORT and GH for three hours were measured. Results We found an additive effect of co-application of CORT and GH on hippocampal synaptic transmission compared to CORT alone. Furthermore, we found that the combined use of low concentration of GH and CORT have significantly higher effects on enhancement of fFEPSPs in old rats compared to young ones. We showed that both GH and CORT enhanced protein expression of NR2A subunit of NMDARs. Meanwhile, we demonstrated that the coexposure to low concentration of GH and CORT significantly enhanced NR2B expression and increased the NR2B/NR2A. In contrast, perfusion with CORT alone caused significant suppression in NR1 and NR2B protein expression and decrease in NR2B/NR2A. Conclusion we suggest that NMDARs provide potential target for mediating GH potential protective effect against stress and age related memory and cognitive impairment

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