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Brainstem nitric oxide tissue levels correlate with anoxia-induced gasping activity in the developing rat
1Kosair Children's Hospital Research Institute, Departments of Pediatrics, Pharmacology and Toxicology, University of Louisville School of Medicine, KY 40202, USA. d0goza01@gwise.louisville.edu
Biology of the Neonate
|February 27, 2001
Summary
Nitric oxide (NO) levels in the brainstem correlate with gasping frequency during anoxia in developing rats. This NMDA-receptor and NO-synthase-dependent mechanism influences survival and anoxic tolerance.
Area of Science:
- Neuroscience
- Developmental Biology
- Physiology
Background:
- Gasping is a crucial survival mechanism modulated by the glutamate-nitric oxide (NO) pathway during development.
- The precise temporal relationship between brain tissue NO levels and gasping during anoxia is not well understood.
Purpose of the Study:
- To investigate the temporal dynamics of NO brain tissue concentrations during anoxia-induced gasping in developing and adult rats.
- To determine the correlation between gasping frequency and NO levels in the caudal brainstem.
- To examine the role of NMDA receptors and neuronal NO synthase in modulating these responses.
Main Methods:
- Measurement of brainstem and cortical tissue NO levels using voltammetric electrodes in 5-day-old pups and adult rats during anoxia.
- Administration of NMDA receptor antagonist MK-801 and neuronal NO synthase inhibitor 7-nitro-indazole (7-NI).
- Correlation analysis of gasp frequency and NO tissue concentrations.
Main Results:
- In young rats, NO levels exhibited a triphasic trajectory coinciding with gasp frequency, significantly altered by MK-801 and 7-NI but maintaining the frequency-NO relationship.
- Adult rats displayed 40-fold higher NO levels with a monophasic trajectory during gasping.
- Cortical NO levels showed monophasic increases across all ages.
Conclusions:
- Anoxia-induced gasping neurogenesis in developing rats is modulated by NMDA-NO pathways.
- Elevated brainstem NO concentrations may promote early autoresuscitation but potentially reduce anoxic tolerance.