Molecular and Chemical Neuropathology

, Volume 35, Issue 1, pp 77–95

Aging modulates nitric oxide synthesis and cGMP levels in hippocampus and cerebellum

Effects of amyloid β peptide
Original Articles

DOI: 10.1007/BF02815117

Cite this article as:
Chalimoniuk, M. & Strosznajder, J.B. Molecular and Chemical Neuropathology (1998) 35: 77. doi:10.1007/BF02815117

Abstract

The biological roles of nitric oxide (NO) and cGMP as inter- and intracellular messengers have been intensively investigated during the last decade. NO and cGMP both mediate physiological effects in the cardiovascular, endocrinological, and immunological systems as well as in central nervous system (CNS). In the CNS, activation of theN-methyl-d-aspartic acid (NMDA) type of glutamatergic receptor induces Ca2+-dependent NOS and NO release, which then activates soluble guanylate cyclase for the synthesis of cGMP.

Both compounds appear to be important mediators in long-term potentiation and long-term depression, and thus may play important roles in the mechanisms of learning and memory. Aging and the accumulation of amyloid β (Aβ) peptides are important risk factors for the impairment of memory and development of dementia. In these studies, the mechanism of basal- and NMDA receptor-mediated cGMP formation in different parts of adult and aged brains was evaluated. The relative activity of the NO cascade was determined by assay of NOS and guanylate cyclase activities. In addition, the effect of the neurotoxic fragment 25–35 of Aβ (Aβ) peptide on basal and NMDA receptor-mediated NOS activity was investigated. The studies were carried out using slices of hippocampus, brain cortex, and cerebellum from 3- and 28-mo-old rats.

Aging coincided with a decrease in the basal level of cGMP as a consequence of a more active degradation of cGMP by a phosphodiesterase in the aged brain as compared to the adult brain. Moreover, a loss of the NMDA receptor-stimulated enhancement of the cGMP level determined in the presence of cGMP-phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) was observed in hippocampus and cerebellum of aged rats. However, this NMDA receptor response was preserved in aged brain cerebral cortex. A significant enhancement of the basal activity of NOS by about 175 and 160% in hippocampus and cerebellum, respectively, of aged brain may be involved in the alteration of the NMDA receptor response. The neurotoxic fragment of Aβ, peptide 25–35, decreased significantly the NMDA receptor-mediated calcium, and calmodulin-dependent NO synthesis that may then be responsible for disturbances of the NO and cGMP signaling pathway.

We concluded that cGMP-dependent signal transduction in hippocampus and cerebellum may become insufficient in senescent brain and may have functional consequences in disturbances of learning and memory processes. Aβ peptide accumulated during brain aging and in Alzheimer disease may be an important factor in decreasing the NO-dependent signal transduction mediated by NMDA receptors.

Index Entries

Nitric oxide guanylate cyclase cGMP NMDA receptors glutamate receptors hippocampus cerebellum β-amyloid peptide aging calcium calmodulin phosphodiesterase signal transduction cerebral cortex 

Abbreviations

β-amyloid peptide

CNS

central nervous system

NMDA

N-methyl-d-aspartic acid

APP

β-amyloid precursor proteins

NOS

nitric oxide synthese

NO

nitric oxide

Copyright information

© Humana Press Inc. 1999

Authors and Affiliations

  • Malgorzata Chalimoniuk
    • 1
  • Joanna B. Strosznajder
    • 1
  1. 1.Department of Cellular Signalling, Medical Research CentrePolish Academy of ScienceWarsawPoland

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